tag:blogger.com,1999:blog-32898255021617183782024-03-14T00:49:41.099-07:00Looking inside the standard modelA tourist guide to our research on the standard model of particle physics and beyondAxel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.comBlogger122125tag:blogger.com,1999:blog-3289825502161718378.post-53094090340128249422020-08-11T02:22:00.003-07:002020-08-11T02:22:34.393-07:00Making big plans<p> Occasionally, you have an idea, and you can do the required research within a couple of weeks. But this is the rare exception. Most research requires months, and often years, to complete. In particle physics, with its huge experiments running for decades, this is probably even more aware to people than in many other cases. This requires plans. A very recent example of such a plan is the <a href="http://cds.cern.ch/record/2721370/files/CERN-ESU-015-2020%20Update%20European%20Strategy.pdf">European Strategy on Particle Physics (Update)</a>, in which all of Europe came together to make a plan. I have contributed to this as coordinating the theory input for the <a href="https://indico.cern.ch/event/765096/contributions/3295753/">national Austrian roadmap</a>. It is a huge effort to get everyone agreeing on what to do next - and what to do in the next half-a-century. Because this is how long you have to plan in advance for the big experiments.</p><p><br /></p><p>Aside from these big plans, there are also smaller ones. Even for me as a theoretician. Occasionally, I have to sit down, and formulate a research plan for a couple of years into the future. The reason is often that I write a so-called grant proposal to get a considerable amount of money to hire postdocs and PhD students. Such a large proposal requires you to formulate what you want to do with all these people, usually for about five years. Last year, we <a href="https://www.oeaw.ac.at/hephy/forschung/forschungsnetzwerke/">got one already</a>, for <a href="http://axelmaas.blogspot.de/2015/09/something-dark-on-move.html">dark matter</a>.</p><p><br /></p><p>This year, I write another one. Why again, if we just got one? Well, on the one hand each would roughly take up half my time. So, I can manage both, and thereby do more. But putting this up front is cheating. The main reason is that it is unlikely I will get it in the first attempt. As there are currently many more people wanting to do particle physics than resources are allocated for this purpose at the national and international level, these resources need to be distributed. Thus, you write a proposal to get some of these. Then some panel judges the submitted proposals, and decides, who will get resources. And thus where efforts in particle physics will be concentrated. Usually, the are many more proposals the panel would like to fund than there are resources available, and so small points tip the scale to one or the other proposals, and the others are rejected. One can then try again. On average, less than one in five proposals is successful. Thus, you often need to try again, with an optimized proposal. And thus, I already submit another one.</p><p><br /></p><p>Coming back to the original topic: For such a proposal I need to make a five-years plan. Of course, its research. Nobody can guarantee me that I (or, more likely, someone else) will not discover something which requires a fundamental change of plans. This is always allowed. But you are still required to make a plan what you want to do, if nothing unexpected happens. Usually, in my personal experience, about half what is planned will be done, and the rest of the resources is spent on unexpected stuff. Which is as well.</p><p><br /></p><p>Still, you need to make a plan, if everything happens as you would expect it now. And that is what I did.</p><p><br /></p><p>The first thing you need to decide is to what part of your research you would like to base it on. If you read my blog since a while, you may have seen that I actually do quite a lot of different topics, ranging from <a href="http://axelmaas.blogspot.de/2013/03/un-dead-stars-and-particles.html">neutron stars</a> to <a href="https://axelmaas.blogspot.com/2019/08/making-connections.html">quantum gravity</a>. But not all of this research is something I would like to extend at this level. The neutron star physics is something I currently do not work too much on. It is very interesting. But I would need to focus much more efforts on it, and needed to mainly concentrate on technical details. That is not what I currently want. The quantum gravity part is very exciting, and we develop quickly new ideas. There is much more to come. But currently it is too much at an exploratory stage as I would be able to formulate a large-scale five-years program. This will have to cook for a little time longer before it warrants this kind of attention.</p><p><br /></p><p>So, I am down to my <a href="http://axelmaas.blogspot.com/2018/03/asking-questions-leads-to-change-of-mind.html">Higgs physics</a> and <a href="http://axelmaas.blogspot.de/2015/02/take-your-theory-seriously.html">beyond-the</a>-<a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">standard-model</a> research. For the latter, we are currently having enough people to work on. Also, it is a bit more speculative, as we did not yet see anything new in experiments. It is thus somewhat less easy to identify where to concentrates ones efforts on. The combination of our current research and what the next few years of experiments, especially <a href="https://home.cern/">LHC Run 3</a>, will bring, will make this clearer.</p><p><br /></p><p>So I concentrate this time on our attempts to find some new, <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">subtle effects</a> from <a href="https://axelmaas.blogspot.com/2020/02/what-is-proton-made-of.html">theory in experiments</a>: That there is an additional Higgs contribution <a href="https://axelmaas.blogspot.com/2020/02/what-is-proton-made-of.html">inside the proton</a>.</p><p><br /></p><p>Right now, what we did was making a good guess, and looked, whether experiment told us we are right. Iterating this would be a time-honed approach to identifying a new effect. But for this plan, I wanted to be more ambitious. I wanted to have some prediction that rather just guess and iterate. This is very demanding. As a suitable tool, I choose <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">simulations</a>. While I will not be able to really simulate an actual proton and its Higgs content, the effort made possible by such a big grant should be enough to get a decent proxy for it. Something, which is close enough to the real thing that from a guess I can move to something which only requires a few more numbers, which I can get from experiments. That would be a huge success. We then use slightly <a href="https://axelmaas.blogspot.com/2020/02/what-is-proton-made-of.html">different methods</a> to fix the numbers.</p><p><br /></p><p>But this is not easy. Based on what we learned so far, this is a big endeavour. At least for a theoretician. I estimated that I will need about four people with PhD, plus myself, and five more doing a PhD to get there. Not to mention that many master students and bachelor students will be able to work on this as well. This also means that especially several of the PhD students will work on this project, but will complete their PhD only on a part of it, and be done before the whole project is done. This required me to break the project down into smaller workpackages, 17 in total. Each of them is a milestone in itself, and provides intermediate (and eventually final) results. Each requires several of the people, and each at least half a year of time, and some even a year. I needed to make a plan, how each of them intersect with the other, and how they depend on each other. If you are interested in how such a thing looks in the end (it has a lot of tech babble in it), contact me. But it is actually not that different from any other large scale project, even in industry, like building a house. Thus, you also need some project management skills to do research. Even as a theoretician.</p><p><br /></p><p>I am quite pleased with how it turned out in the end. It really has a good flow, and a succession of reasonable and manageable steps. In the end, it holds the promise of a guaranteed discovery - i.e. we will see a new physics effect, as long as we just keep on with the experiments, it will happen. Likely by the end of the runtime of the LHC in about 15 years. Or with the next generation of machines latest, which are part of the Strategy mentioned in the beginning. By this, I come full circle: My small research project ties in into the big ones. And together, we push the boundaries of human knowledge just a bit further.</p>Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-33146751264046889842020-07-27T02:24:00.001-07:002020-07-27T02:27:34.781-07:00What happens if gluons meet?We have published a <a href="https://arxiv.org/abs/2006.08248">new paper</a> on how <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">gluons</a> interact, which is described by the strong force. In fact, how exactly one gluon interacts by being absorbed or emitted by another one. There can be interactions with more of them. These are much more complicated to determine, and so we concentrate on this simplest one.<br />
<br />
You may ask yourself, how we cannot yet know this, and still do stuff like calculate the mass of a <a href="http://axelmaas.blogspot.de/2010/01/forces-of-nature-iii-strong-force-part.html">hadron</a>? And not even bother to do more than this simplest process? Because for the proton we need to now what gluons do, right? Well, not exactly. When we want to calculate the properties of a proton we need to know only how they do so in a particular way of averaging. We do not need to resolve the full details. But if we really want to understand how they interact in detail, this is not enough. And this is crucial, if we want to be able to build up not only the proton, but any particle or thing we want to measure. Being able to do a particular averaging good enough is not sufficient to do all of them as well.<br />
<br />
In fact, this way of gluons interacting is the simplest way they can interact. Because of this, we know already quite a bit of it, if the gluons are very energetic. But we know less about how they interact, if they have little energy or travel over very long distances. And there a surprise arose some years back. It was raised in a <a href="http://arxiv.org/abs/hep-lat/0605011">much older work</a> by myself and other people. It indicated that the gluons undergo a drastic change when they start to traverse distances of the order of the size of a proton or even further (inside <a href="http://axelmaas.blogspot.de/2010/01/the-forces-of-nature-iii-strong-force.html">bigger hadrons</a>, because of <a href="http://axelmaas.blogspot.de/2012/04/why-colors-cannot-be-seen.html">confinement</a>). It appears that at distances of the order of a proton diameter they stop interacting. But they become much stronger interacting again at even longer distances. This is, of course, a very interesting insight what happens, in a sense, at the boundary of a proton.<br />
<br />
We used <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">simulations</a> for this back then. But we very limited at this time, because of the available computing power. This was aggravated, because at this time, I was working as a postdoc in Brazil. Which, as a disadvantaged country, does have bright minds, but much less resources than I have nowadays in Austria. At any rate, the result nonetheless got people excited, and there were a lot of follow-up works since then. Still, while most results supported the indications, it is not yet possible to give a fully satisfactory answer.<br />
<br />
In our latest work, we picked up the idea of looking at the behavior in a world with one direction less. This saves a lot of computing time. And we did not yet had a final answer there either. This we provided now. There is a clear answer, confirming the behavior described above: First getting weaker, until the interaction vanishes at roughly a (flat) proton across, and then becoming quickly much stronger.<br />
<br />
Still, doing the same in our world was too expensive. But we did a trick. Having the results from the fewer dimensions, we knew what to anticipate. So we used this information to test our world for consistency. And this checked out surprisingly well. In fact, we could even predict how much more computing time would be needed for a final confirmation also for our world. Could be done in the next few years. So hang around just a little longer for the final answer.<br />
<br />
And, perhaps, we can then also do more complicated interactions. But this is a really tedious business. So you need patience and a long-term perspective.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-88569771136093588622020-04-21T06:28:00.006-07:002020-04-21T06:28:55.984-07:00A more complicated photonThe <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">photon</a> - the particle which makes up light - is probably one of the best known elementary particles. Nonetheless, everything can be made more involved. Thus, we studied a more complicated version of it in our most <a href="http://arxiv.org/abs/arXiv:2002.08221">recent paper</a>.<br /><br />"Why in the world should we do this?" is a valid question at this point. That proceeded in multiple stages. I have <a href="http://axelmaas.blogspot.de/2014/05/why-does-chemistry-work.html">written</a> quite some time ago that for a particle physicist it is baffling that chemistry works. Chemistry works, among other things, because the electric charge of nuclei and electrons are perfectly balanced. Well, as perfect as we can measure, anyhow. In the standard model of particle physics there is no reason why this should be the case. However, the standard model is mathematical consistent only if this is the case. In fact, only if the balance is really perfect. Mathematical consistency is not a sufficient argument why a theory needs to be correct. Experiment is. So people have investigated this baffling fact since decades. In this process, the idea came up that there is a reason for this. And that reason would be that the standard model is only a facet of an underlying theory. This underlying theory enforces the equality of the electric charges by combining the <a href="http://axelmaas.blogspot.de/2010/02/forces-of-nature-iv-weak-force.html">weak</a>, <a href="http://axelmaas.blogspot.de/2010/01/lthe-forces-of-nature-iii-strong-force.html">strong</a>, and <a href="http://axelmaas.blogspot.de/2009/12/forces-of-nature-ii-electromagnetism.html">electromagnetic</a> forces into one force. Such theories are called grand-unified theories, or short GUTs.<br /><br />Such GUTs use a single <a href="http://axelmaas.blogspot.de/2010/10/electromagnetism-photons-and-symmetry.html">gauge</a> <a href="http://axelmaas.blogspot.de/2011/02/in-previous-discussion-it-was-described.html">theory</a> to combine all these forces. This is only possible with a certain kind, which is fundamentally different from the one we use for electromagnetism alone. It is more similar to the ones of the strong and weak force. We have investigated this type of theories for a long time. And one <a href="http://axelmaas.blogspot.co.at/2015/08/looking-for-one-thing-in-another.html">central insight</a> is that in such theories none of the elementary particles can be observed individually. Only so-called <a href="http://axelmaas.blogspot.co.at/2015/06/the-nature-of-particles.html">bound states</a>, which are made from two or more elementary particles, can be. That is very different from the ordinary photon of electromagnetism, which is, essentially, elementary.<br /><br />The central question was therefore whether any such bound state could have the properties of the photon which we know from experiment. Otherwise a GUT would (very likely) not be a possible candidate to explain the balance of electric charges in chemistry. The photon has three important features. It does not carry itself electric charge. It is massless. And it has one unit of so-called <a href="http://axelmaas.blogspot.co.at/2012/01/spin.html">spin</a>.<br /><br />Thus we needed to build a bound state in a GUT with these properties. The spin and absence of charge is actually quite simple, and you get this almost for free in any GUT. It is really the fact that it should not have mass which makes it so complicated. It is even more complicated to verify that it has no mass.<br /><br />We had some ideas from our <a href="https://arxiv.org/abs/1709.07477">previous work</a>, using pen-and-paper calculations, how this could work. There had also been some numerical simulations looking into similar questions in the early 1980ies, though they were, given resources back then, very exploratory. So we set up our own, modern-day <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">numerical simulations</a>. However, it is not yet possible to simulate a full, realistic GUT. For this all computing power on earth would not suffice, if we want to be done in a lifetime. So we used the simplest possible theory which had all the correct features relevant to a true GUT. This is an often employed trick in physics. One reduces a problem to the absolutely essential features, throwing away the rest, which has no or little impact on the particular question at hand. And by this getting a manageable problem.<br /><br />So we did. And due to some ingenious ideas of my collaborators, especially my PhD student Vincenzo Afferrante, we were able to perform the simulations. There was a lot of frustrating work for the first few months, actually. But we persevered. And we were rewarded. In the end, we got our massless photon in exactly the way we hoped! We thus demonstrated that such a mechanism is possible. We got a massless photon made up out of elementary particles! A huge success for the whole setup. In addition, the things which make up the photon are (partly) very massive. That a bound state can be lighter than its constituents is an amazing consequence of special relativity. For us, this is an added bonus. Because you cannot see the fact that a particle is made up of other particles if you have not enough energy available to create the constituents. Again, this comes from the theory of relativity. In this scenario one of the constituents is indeed so heavy that we would not be able to produce it in experiments yet. Hence, with our current experiments, we would not yet detect that the photon is made up from other particles. And this is indeed what we observe. So everything is consistent. Very reassuring. Unfortunately, it is so heavy that also none of the currently planned experiments would be able to do so. Hence, we will not be able to test this idea directly experimentally. This will need to resort to indirect evidence.<br /><br />Of course, I gloss over a lot of details and technicalities here, which took most of our time. Describing them would fill multiple entries.<br /><br />Now, the only thing we need to do is to figure out whether anything we neglected could interfere. None of it will at a qualitative level. But, of course, we have very good experiments. And thus to make the whole idea a suitable GUT to describe nature, we also need to get it quantitatively correct. But this will be a huge step. Therefore we broke it down in small steps. We will do them one by one. Our next step is now to get the electron right. Let's see if this also works out.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-81612587639484107352020-02-18T06:08:00.004-08:002020-02-18T06:08:55.304-08:00What is a proton made of?We have published a <a href="http://arxiv.org/abs/arXiv:2002.01688">new paper</a>, which has quite a bold topic: That a proton has a bit more structure than what you usually hear about.<br />
<br />
Usually, you hear a proton is <a href="http://axelmaas.blogspot.de/2010/01/forces-of-nature-iii-strong-force-part.html">made up out of three quarks</a>, the so-called valence quarks. These quarks, <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">two up-quarks and one down quark</a>, are termed valence quarks. Valence particles provide the proton with its characteristic properties, like its electric charge and <a href="http://axelmaas.blogspot.co.at/2012/01/spin.html">spin</a>. In addition, every other particle can also appear inside the proton, as a so-called sea particle. But these are quantum fluctuations, which are only very short lived. There existence has been tested in experiments for <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">gluons, strange quarks, charm quarks, and bottom quarks, as well as photons</a>. We understand this relatively well. Their contribution gets smaller the larger their mass is. So what do we want to add?<br />
<br />
Those people reading this blog longer have already seen that one of the central topics we are looking at in our research are the <a href="http://axelmaas.blogspot.de/2010/02/forces-of-nature-iv-weak-force.html">weak interactions</a> and the <a href="http://axelmaas.blogspot.de/2010/03/higgs-effect.html">Higgs</a>. Especially, we figured out that this part of the standard model of particle physics is <a href="http://axelmaas.blogspot.co.at/2015/08/looking-for-one-thing-in-another.html">more</a> <a href="http://axelmaas.blogspot.de/2015/01/what-is-so-important-to-me-about-higgs.html">involved</a> than is usually assumed. Most importantly, it requires for mathematical consistency that most particles, which we usually call elementary, are more involved <a href="http://axelmaas.blogspot.co.at/2015/06/the-nature-of-particles.html">bound states</a>, i.e. made up out of multiple particles. Such bound states are very different from elementary particles. E.g., they should have a <a href="http://axelmaas.blogspot.com/2018/02/how-large-is-elementary-particle.html">size</a>. And, in principle, this should <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">show up in experiments</a>.<br />
<br />
Of course, mathematical consistency is not sufficient for nature to behave is a certain way. Though it is nice if it does. Therefore 'should' is not sufficient. If we are right, it *must* show up in experiments. Unfortunately, as all of this is associated with the <a href="http://axelmaas.blogspot.de/2010/03/higgs-effect.html">Higgs</a>, which is very heavy, this requires a lot of energy. Since there is currently only one powerful enough experiment available, the LHC at CERN, we need to figure out how to test our ideas with this one. Which, unfortunately, is not ideally suited. But you have to make do with what you have.<br />
<br />
Already <a href="http://arxiv.org/abs/1701.02881">two years back</a> we figured out that all of the mathematical consistency arguments had a surprising impact for our proton. You see, the proton is one of two very similar particles, the proton and the neutron, the so-called nucleons. They make up all atomic nuclei. The difference between proton and neutron are threefold. Two are their mass and electric charge. They are explained by the valence quarks. The third is the protoness and neutroness - a feature which is called flavor (or sometimes isospin). The aforementioned valence quarks can actually not be really responsible for this quantum number. The argument is very technical, and has a lot to do with <a href="http://axelmaas.blogspot.de/2011/02/in-previous-discussion-it-was-described.html">gauge symmetry</a>, and especially its more <a href="http://axelmaas.blogspot.de/2013/09/blessing-and-bane-redundancy.html">involved</a> <a href="http://axelmaas.blogspot.co.at/2015/10/being-formal.html">aspects</a>. Those who are interested in all the technical details can find it in my <a href="https://arxiv.org/abs/1712.04721">review article</a>. Ultimately, it boils down that this flavor cannot come from the valence quarks. Something else needs to provide it.<br />
<br />
This something else should not upset those things which are explained by the valence quarks, the mass and spin. Thus, it needs to be spinless and chargeless. The Higgs is the only particle in the standard model, which fits the bill. And it indeed carries something, which can provide the difference between protons and neutrons. In technical terms, it is called the custodial quantum number. What only matters is that this quantity can have two different values, and one can be associated with being proton and the other with being neutron, mathematically completely consistent, if the Higgs is another valence particle.<br />
<br />
As the Higgs is much heavier than the proton, the immediate question is, how can that be? But here the combination of quantum mechanics and relativity comes to the rescue. It allows a bound state to be lighter (or heavier) than the sum of the masses of their constituents. Actually, an hydrogen atom is, e.g., lighter than the mass of the constituent proton and electron. But only by an extremely small amount. In the proton, this now works in the same way, but hugely amplified. But we have examples that this is <a href="http://axelmaas.blogspot.de/2012/11/a-higgs-and-higgs-make-what.html">actually possible</a>. So this is fine.<br />
<br />
When we now smash two protons together, like at the LHC, we actually get its constituents to interact with each other. And we have now additional Higgs content, so these Higgs can interact as well. However, this will be suppressed by the large mass of the Higgs, as in this case the interaction is as 'if it was alone'. And then it is heavy. Thus, even at the LHC this will be rare.<br />
<br />
What we did in the <a href="http://arxiv.org/abs/arXiv:2002.01688">paper</a> was to estimate how rare, and which processes could best be sensitive to this. We find that the LHC so far is not too sensitive to the valence Higgs beyond uncertainties, if the effect is really there. But we figure out that with the production of <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">top quarks</a> at the LHC we should have a sensitive handle for looking for the valence Higgs.<br />
<br />
This is really just the first step in hunting the valence Higgs. And it may well be that we need a more powerful experiment in the future to really see the effect. Not to mention that our estimates a very crude, and a lot of calculations need still to be done much better. But it is the first time that the effect of the valence Higgs, as required from mathematical consistency of the standard model, is tested experimentally. And this is a big step into a completely unknown domain. Who knows what we will find along the way.<br />
<div>
<br /></div>
Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-291472128014911672020-01-09T07:20:00.003-08:002020-01-09T07:20:22.019-08:00A personal perspective on how capitalism hurts scienceIn a number of my recent blog entries, and also occasionally on <a href="http://www.twitter.com/axelmaas">twitter</a>, I have made statements about how bad our current late stage capitalism is for science. It is time that I follow up with a more detailed blog entry on this.<br />
<br />
Before delving into it, I should discuss reasons why I hesitate to write on this subject. Those who have read my scientific blog entries may have noticed that I work on many ideas, which are unconventional. While I do my best to back them up with many different types of calculations, I have not been (yet) able to get these issues across as important. Thus, despite there have been quite a number of people in the past who did work on these subjects, and my own results are in line with theirs, there are very few contemporary people doing so. It is quite easy to be frustrated about this, especially since I think that are important things which need to be taken into considerations. Because they may change a lot of particle physics on a very fundamental level.<br />
<br />
If you are in such a situation, it is very tempting to search guilt for your continued failure to make your stuff popular in some external reason. Hence, I am very much double guessing myself, if part of what I write here is affected by this. Probably part of it is. If I would be the only one having these thoughts it surely would be the case. However, over recent years I saw more and more studies being published or popping up on the <a href="http://arxiv.org/">arXiv</a> which agree with my own perception. Hence, I am more and more convinced that a larger issue is at work here. And whether I am affected by this or not is not easy to say. Hence, I will try to avoid making any personal connections here, and just tell how in my perspective I see the results of these studies realized. Most of the studies I linked on <a href="http://www.twitter.com/axelmaas">twitter</a> over time.<br />
<br />
The gist of many of these studies is twofold. The way how research results are published and perceived is not necessarily correlated with its relevance. In fact, there appears to be anti-correlation between long-term relevance (measured by number of citations) and the impact factor of the journal in which the research has been published. Meaning more prestigious journals tend to not accept research where the short-term relevance is not obvious. On the other hand, also in funding there is a strong tendency that those who have get more, and bold claims are more important than well-funded statements or even checks.<br />
<br />
While these issues are on their own troublesome, it is the way how they resemble other elements of public life, which is alarming. To say the least. And which is typical for late-stage capitalism. This is the fact that those who have get more. That those who have, or have the favor of someone who has, can do anything essentially anything, and get rewarded. While those who do not have a hard time to get anything. This is amplified by gate-keeping and a lack of diversity in academia, which is far from resolved. Of course, this is also a problem appearing in society in general.<br />
<br />
In my personal experience, this manifests itself in a very strong tendency to create hype. If the results is only promising enough, any assumption, even if it is just wishful thinking, becomes acceptable. Theoreticians seem to be much more prone to this than experimentalists. The reason is simple. As long as no one disproves your statement, you will get attention. And if somebody, who has, picks it up and promotes it (or is actually the origin), it will gain traction. If it fails eventually, you just cook up another thing, and so on. This is in particle physics supported by our current lack of hard experimental evidence beyond the standard model. Thus it is easy to escape experimental falsification. Theoretical falsification is much more complicated. Because in sufficiently complicated theories, doing an exact falsification is technically hard. Even if you there is a lot of evidence, it is always possible to find a loop hole to not accept a falsification. And given the promises made, it is for most much better to just ignore any claim of invalidity. Especially, most of the assumptions often simplify, or even trivialize, calculations. Hence, it is possible to get results with little effort. And since they promise so much, it is easy to publish them or get funding for them.<br />
<br />
This even happens in a less dramatic fashion quite often. Even without anything wrong any new field has first a lot of simple problems. They can be done with little or moderate effort. Thus, the return-on-investment is large. Therefore many people flock to these new fields, to have a large output compared to work invested. Thereby, they gain resources. As soon as the inevitable complications set in, most of these leave the field, and move to the next field of the same type. However, they take with them the resources, leaving those trying to solve the hard problems with little. While in any case resources are limited it is necessary to focus effort, this should be decided upon the relevance of the question, rather than on how easy it is to get results.<br />
<br />
All of this mirrors trends in society. As long as one can get much without solving actual problem, everyone goes for it. And if you can gain an advantage by making too strong claims, the better. We see how this damages our society from the climate crises to the rise of authoritarianism. All of that follows this pattern. You claim that there is an easy solution how you can get profit and avoid investing solving the reason for the climate crises. See greenwashing. Or you claim social problems have an easy solution, because others are at fault, so you just need to get rid of them. Yielding the rise of rightwing extremism and authoritarian systems. All of this is fueled by capitalism, which puts profits before solutions.<br />
<br />
And these effects find their mirror in science, as science is not set apart from society. Thus, capitalistic thinking - gathering resources, in science renown and funding, become more important than the actual solution of problems.<br />
<br />
How can this by avoided? Well, probably the same way as in society at large. That what damages the scientific process needs to be got rid off. A scientific system which focuses on what people did instead of who did it, and a distribution of resources based on the relevance of problem rather than renown or promises, would probably go a long way. This was recognized by quite some people. And there are tentative steps ongoing. Like banishing renown as a measure of success. Putting the actual works at center, rather than how and where they are published. But it is a slow process, and one which can again be misused. Probably, only if we as a society change fundamentally science will get closer to its ideals.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-36581431472192840652019-11-19T06:49:00.001-08:002019-11-19T06:49:44.861-08:00Going abroad: Yes or no?One topic which reemerges in many discussions online and offline is that many scientists, especially in (particle) physics, have to move around several times as postdocs. For me, this was after the PhD in Germany first going to Brazil, then back to Germany, then to Slovakia, Austria, Germany, and finally back to Austria.<br />
<br />
The discussion evolves usually around whether this is good or bad, and whether the price tag in terms of private life associated with so many moves is worth what one gains from it. There are three aspects, I would like to address, especially from personal experience. One is the cost to one's social net. The other is the personal and professional gain. And the last is suffering because of a lack of predictability. Because you usually do not know, where it will go to in one or two years.<br />
<br />
Let me start with the most obvious price tag: Social contacts. And especially partnership. The last one is the most individual point. Here, it is really up to you and your family members, how all of you think about it. But this needs to be addressed well before you start with such moves. How many are acceptable? How long may it take? Which countries are acceptable? And so on. That has to be agreed upon by everyone involved, and that is really different for every one.<br />
<br />
More general is the question of the general social net. Despite modern communication methods, a social net will tear if someone moves away. Without direct contact, it is for most people hard to hold contact. Even with video communication, its is not easy to transfer everything. And not everyone is able to keep a connection in written form. Especially if it is not clear when, or even if, one will meet again in person. In addition, even when moving somewhere and building a new social net, this will tear again with the next move. And so can easily leave behind several fragmented nets. It depends, of course, on how much you rely on our own social net, and what kind of people are in there. But too me, this was always the highest cost. Because building a new net takes time, and the old one is missed.<br />
<br />
If the cost is so high, how could I even consider moving to be a good thing? Before I did it, I would actually would have no good thing to think about other than our current scientific society is requiring it. And I will come back to this later. Already during the first place, my opinion changed. I expected that just by working with other on a day-by-day basis, not so much would change in my own work. But the constant exposure to very different approaches to science, emphasizing very different aspects and questions, has fundamentally changed the way I think about my own research, and about how I should perform research. At the same time, the need to live in a very different society than the one I came from also taught me a lot about people, and about how to deal with life. In hindsight, I am very sure that I would have been both a lesser person and a lesser scientist if not for these other places I lived and worked at. Again, this is my very own experience, though I heard similar stories by most people. Especially those people who went to a place, which was welcoming to them, if not always simple to deal with.<br />
<br />
So, I have now both a strong argument against moving and in favor of moving. And really, I could not decide for me, which is now the stronger point. I am pretty sure that everyone has an opinion about this, but this is probably very individual. Still, in my personal experience most people who have moved to different places are better scientist, and also often show better abilities in dealing with the not hardcore-technical part of science.<br />
<br />
While their maybe no optimal choice for everyone on the previous issue, there is certainly one part, in which we can make the whole story better for everyone: Predictability. Right now, you usually move to a place, and while there, you somehow need to get a new position somewhere else for the time afterwards. Usually on a two-year or three-year basis. Until you hit jackpot, and get a permanent position. Which, depending on the country, can take a decade or so. Especially not knowing where things go next, and how long, is in my experience something which makes everything, especially with social nets, much, much harder. On top of this, especially older scientists, insist that some places are as a place important, and you have to go there to be a good scientist. This latter point is very annoying, because it usually boils down to where money is, and where the best people in marketing are, and this creates a self-sustaining cycle. But this is an aspect of late-stage capitalistic science I will write about sometimes else.<br />
<br />
Thus, in my opinion, the best compromise between the drawbacks of moving and the advantages of moving could be achieved by making this predictable. Say, you have six years to move around, including say three moves, and there is an assessment every two years, and if all of them are sufficiently positive, then you have a permanent position at the place where you came from. This should make it possible to plan your life. Also, knowing that the stress on the social net is only temporary, this may more often than not preventing it from tearing.<br />
<br />
Sure, this will still not be a workable solution for everyone. There are too many individual issues, which cannot be taken into account with a one-fits-all solution. Thus, it is still necessary to help individual researchers to work around their individual situations.<br />
<br />
Still, in the end, this means arguably that I think moving around, at least for a while, is important. It is just right now not supported in a good way. However, it will likely be impossible to quantify my personal experience generally. There are far too many soft factors involved. And, of course, I also encountered the occasional exception.<br />
<br />
The take-home message for me from these considerations is that I will put effort into making going abroad more sustainable, but will not argue against it. Also, I will counsel everyone about all the aspects one has to think about, and the deliberate obstructions one currently faces, as well as the impact it has beyond work. Thus, everyone can at least make an informed decision, though unfortunately not yet a free one. I hope that I can contribute in changing this.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-28077893891003484172019-10-30T03:11:00.003-07:002019-10-30T03:11:49.128-07:00About toxic working culture in scienceRecently, I have read this excellent <a href="https://www.neuro-central.com/2019/10/08/world-mental-health-day-facts-figures-flaws-academia/">article on mental health in academia</a>. It emphasizes the consequences of a toxic working culture in academia on mental health, with a focus on PhD students. I would like to provide here a few reflections on my own experience with this topic, both as a scientist, but also as a professor.<br />
<br />
The first experience is that I very often encounter the phrase that 'we should be grateful that we have the opportunity to do what we like/love' to justify bad working conditions. While I am certainly happy that I do something I like to do, this should never be used in any circumstances to justify circumstances. Because it puts us as people being only granted something, and which equally well can be taken away. Because its meaning can be easily shifted to 'we should be thankful that it is not worse', and thus to justify the status quo for being afraid of consequences when trying to improve the situation. And ultimately to paint the picture of willful suffering just to be able to do something which is important to one.<br />
<br />
This is then used to justify almost anything. Even more so, it is seen as an act of individual heroism to still do science, in face of such conditions. I have often witness scenes where people have tried to outdo others by the sheer amount of hours/week they worked. Or how many days of holiday they did not use. Of course, this is fired up by a perpetual overcommitment of people, necessitated often by all the various things we have to do. As scientists, we are expected not only to do science, but also teaching, outreach, presentation in form of talks and paper writing, fact checker as reviewers, marketing in form of research grants, and administrative duties both for research grants as well as within University and for national and international infrastructure in many commissions, i.e. management. While at the same time it is expected to explored with creativity and solve the deepest problems of research. To this comes often the impression of our own grandeur that we know everything better and we cannot delegate anything because we are the only ones who can get it done right. Which is outright wrong.<br />
<br />
Of course, this is driven by precarious working conditions until one reaches a permanent position, often for decades, at payment levels which are very low compared to research and development positions in industry. By making the resource of permanent employment scarce and competitive, essentially by turning science into another branch of capitalism, the same happens as everywhere else in capitalism: To ensure ones survival, one puts up with being slowly destroyed by the working conditions. This gets its toxic turn by accusing people of not having enough dedication if they do not overwork themselves. This goes on at a reduced level once permanency is reached, by making resources to do our work scarce and getting them again competitive.<br />
<br />
Given that research into work has established that peak effectivity is attained around thirty hours of work a week, this is actually damaging science. When we work much longer, we usually do not get so much more work done. And at some point, we get even less work done, because we start to err too often. Of course, this is a distribution, and there are tails. But an average scientist is also an average human being. Scientist may still overpopulate the tail of this distribution, but this is then selected by the working conditions, and who can suffer them, and not by the brilliance and creativity of the researcher.<br />
<br />
Of course, it is easy to buy into the picture of the never-tiring scientist, working all time to discover the greatest secrets. This is how we are often depicted in literature or film. Can you name any scientist, who actually saves the day, who is regularly working only forty hours? I cannot. And especially as a young person, it is even easier to find oneself in pursuit of such a heroic idealization. At the time we get a permanent position, most just carry on like this, because it has become very internalized.<br />
<br />
My own experience is in the beginning quite like this. I wanted to solve the scientific problem. I cannot remember actually to reflect upon my working times, or even track it. It was certainly much more than I got paid for. And when many years later I started to change this, I had a very bad consciousness when moving my actual work time towards the amount of time I was paid for. Even though I realized quite quickly that I still get essentially the same amount of work done. Thus proving to myself that what I written about peak effectivity is true for me. However, I have been quite privileged in this development, because failing in getting a permanent position was quite acceptable for me. And even now I do not feel the urge to 'discover something really big' or 'getting acknowledge by grants or prizes', the later being recognized to be just another tool to exploit scientists by letting them actively fight against each other for scraps of resources.<br />
<br />
Now, as a professor, I feel the obligation to bring through these points to students. Which turns out to be very complicated. I hear my younger self echoed too often. Like I want to finish fast, or I think this is too important. It is very hard arguing, because the counter argument is self care. And we have so often seen the trope of the scientists sacrificing themselves for the greater good. How can I be a good scientist (or even a good human being), when I do not put the greater good of science above petty personal necessities?<br />
<br />
Well, the true answer is that a sane, well-cared for scientist will be doing just as much as an overworked one. And will do so for a much longer time. Not only bodily, because I can better avoid problems like cardiac arrest by stress, by also mentally. Just as the <a href="https://www.neuro-central.com/2019/10/08/world-mental-health-day-facts-figures-flaws-academia/">article</a> points out.<br />
<br />
What do I do concretely? Besides trying to implement the points mentioned in the <a href="https://www.neuro-central.com/2019/10/08/world-mental-health-day-facts-figures-flaws-academia/">article</a>, I do my best to reduce the capitalistic structures in science. By using my influence wherever possible to create easier career paths, and by generally attempting to espouse a cooperative rather than a competitive culture. I certainly fail far too often in this endeavour. Because it means unlearning something I have engulfed in for far too long. But I listen to those doing research about work, about mental and bodily well-being, and to those I work with. Perhaps I can improve it at least a little bit.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-34799606006931914602019-09-05T07:51:00.002-07:002019-09-05T07:51:52.335-07:00Reflection, self-criticism, and audacity as a scientistToday, I want to write a bit about me as a scientist, rather than about my research. It is about how I deal with our attitude towards being right.<br />
<br />
As I still do particle physics, we are not done with it. Meaning, we have no full understanding. As we try to understand things better, we make progress, and we make both wrong assumptions and actual errors. The latter because we are human, after all. The former because we do not yet know better. Thus, we necessarily know that whatever we do will not be perfect. In fact, especially when we enter unexplored territory, what we do is more likely not the final answer than not. This led to a quite defensive way of how results are presented. In fact, many conclusions of papers read more like an enumeration what all could be wrong with what was written than what has been learned. And because we are not in perfect control of what we are doing, anyone who is trying to twist things in a way they like, they will find a way due to all the cautious presentation. On the other hand, if we would not be so defensive, and act like we think we are right, but we are not - well, this would also be held against us, right?<br />
<br />
Thus, as a scientist one is caught in an eternal limbo about actually believing one's own results and thinking that they can only be wrong. If you browse through scientist on, e.g, Twitter, you will see that this is a state which is not easy to endure. This becomes aggravated by a science system which was geared by neoliberalism towards competition and populist movements who need to discredit science to further their own ends, no matter the cost. To deal with both, we need to be audacious, and make our claims bold. At the same time, we know very well that any claims to be right are potentially wrong. Thus enhancing the perpetual cycle of self-doubt on an individual level. On a collective level this means that science gravitates to things which are simple and incremental, as there the chance to being wrong is smaller then when trying to do something more radical or new. Thus, this kind of pressure reduces science from revolutionary to evolutionary, with all the consequences. It also damns us to avoid taking all consequences of our results, because they could be wrong, couldn't they?<br />
<br />
In the case of particle physics, this slows us down. One of the reasons, at least in my opinion, why there is no really big vision of how to push forward, is exactly being too afraid of being wrong. We are at a time, where we have too little evidence to do evolutionary steps. But rather than to make the bold step of just go exploring, we try to cover every possible evolutionary direction. Of course, one reason is that because of being in a competitive system, we have no chance of being bold more than once. If we are wrong with this, this will probably create a dead stop for decades. Of course, it other fields of science the consequence can be much more severe. E.g. in climate sciences, this may very well be the difference between extinction of the human species and its survival.<br />
<br />
How do I deal with this? Well, I have been far too privileged and in addition was lucky a couple of time. As a consequence, I could weather the consequences to be a bit more revolutionary and bit more audacious than most. However, I also see that if I would not have been, I would probably had an easier career still. But this does not remove my own doubt about my results. After all, what I do has far-reaching consequences. In fact, I am questioning very much conventional wisdom in textbooks, and want to reinterpret the way how the standard model (and beyond) describes the particles of the world we are living in. Once in a while, when I realize what I claim, I can get scared. Other times, I feel empowered by how things seem to fall into place, and I do not see how edges not fit. Thus, I live in my own cycle of doubt.<br />
<br />
Is there anything we can do about the nagging self-doubt, the timidity and the feeling of being an imposter? Probably not so much as individuals, except for taking good care of oneself, and working with people with a positive attitude about our common work. Much of the problems are systemic. Some of them could be dealt with by taking the heat of completion out of science, and have a cooperative model. This will only work out, if there is more access to science positions, and more resources to do science. After all, there are right now far too many people wanting a position as a scientist than there are available. No matter what we do, this always creates additional pressure. But even that could be reduced by having controllable career paths, more mentoring, easier transitions out of science, and much more feedback. But this not only requires long-term commitments on behalf of research institutes, but also that scientists themselves acknowledge these problems. I am very happy to see that this consciousness grows, especially with younger people getting into science. Too many scientist I encounter blatantly deny that these problems exist.<br />
<br />
However, in the end, also these problems are connected to societal issues at large. The current culture is extremely competitive, and more often than not rewards selfish behavior. Also, there is, both in science and in society, a strong tendency to give those who have already. And such a society shapes also science. It will be necessary that society reshapes itself to a more cooperative model to get a science, which is much more powerful and forward-moving than we have today. On the other hand, existential crises of the world, like the climate crises or the rise of fascism, are also facilitated by a competitive society. And could therefore likely be overcome by having a more cooperative and equal society. Thus, dealing with the big problems will also help solving the problems of scientists today. I think this is worthwhile, and invite any fellow scientist, and anyone, to do so.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-49867995310815574182019-08-07T01:37:00.000-07:002019-08-07T01:37:07.290-07:00Making connectionsOver time, it has happened that some solution in one area of physics could also be used in a quite different area. Or, at least, inspired the solution. Unfortunately, this does not always work. Even quite often it happened that when reaching the finer points it turns out that something promising did in the end not work. Thus, it pays off to be always careful with such a transfer, and never believe a hype. Still, in some cases it worked, and even lead to brilliant triumphs. And so it is always worthwhile to try.<br />
<br />
Such an attempt is precisely the content of my <a href="https://arxiv.org/abs/1908.02140">latest paper</a>. In it, I try to transfer ideas from <a href="http://axelmaas.blogspot.co.at/2015/08/looking-for-one-thing-in-another.html">my research</a> on <a href="http://axelmaas.blogspot.de/2010/02/forces-of-nature-iv-weak-force.html">electroweak physics</a> and the <a href="http://axelmaas.blogspot.de/2010/03/higgs-effect.html">Brout-Englert-Higgs effect</a> to quantum <a href="http://axelmaas.blogspot.de/2009/11/forces-of-nature-i-gravity.html">gravity</a>. <a href="https://axelmaas.blogspot.com/2019/05/acquiring-new-field.html">Quantum gravity</a> is first and foremost still an unsolved issue. We know that mathematical consistency demands that there is some unification of quantum physics and gravity. We expect that this will be by having a quantum theory of gravity. Though we are yet lacking any experimental evidence for this assumption. Still, I also make the assumption for now that quantum gravity exists.<br />
<br />
Based on this assumption, I take a candidate for such a quantum gravity theory and pose the question what are its observable consequences. This is a question <a href="http://axelmaas.blogspot.co.at/2017/11/reaching-closure-completing-review.html">which has driven me</a> since a long time in particle physics. I think that by now I have an understanding of how it works. But last year, I was <a href="https://axelmaas.blogspot.com/2019/05/acquiring-new-field.html">challenged</a> whether these ideas can still be right if there is gravity in the game. And this new paper is essentially my first step towards an answerhttps://arxiv.org/abs/1908.02140. Much of this answer is still rough, and especially mathematically will require much work. But at least it provides a first consistent picture. And, as advertised above, it draws from a different field.<br />
<br />
The starting point is that the simplest version of quantum gravity currently considered is actually not that different from other theories in particle physics. It is a so-called <a href="http://axelmaas.blogspot.de/2010/10/electromagnetism-photons-and-symmetry.html">gauge theory</a>. As such, many of its fundamental objects, like the structure of space and time, are not really observable. Just like most of the elementary particles of the standard model, which is also a gauge theory, are not. Thus, we cannot see them directly in an experiment. In the standard model case, it was possible to construct observable particles by <a href="http://axelmaas.blogspot.co.at/2015/08/looking-for-one-thing-in-another.html">combining the elementary ones</a>. In a sense, the particles we observe are <a href="http://axelmaas.blogspot.co.at/2015/06/the-nature-of-particles.html">bound states</a> of the elementary particles. However, in electroweak physics one of the bound elementary particles totally dominates the rest, and so the whole object looks very similar to the elementary one, <a href="http://axelmaas.blogspot.com/2018/02/how-large-is-elementary-particle.html">but not quite</a>.<br />
<br />
This works, because the Brout-Englert-Higgs effect makes it possible. The reason is that there is a dominating kind of not observable structure, the so-called Higgs condensate, which creates this effect. This is something coincidental. If the parameters of the standard model would be different, it would not work. But, luckily, our standard model has just the right parameter values.<br />
<br />
Now, when looking at gravity around us, there is a very similar feature. While we have the powerful theory of general relativity, which describes how matter warps space, we rarely see this. Most of our universe behaves much simpler, because there is so little matter in it. And because the parameters of gravity are such that this warping is very, very small. Thus, we have again a dominating structure: A vacuum which is almost not warped.<br />
<br />
Using this analogy and the properties of gauge theories, I figured out the following: We can use something like the Brout-Englert-Higgs effect in quantum gravity. And all observable particles must still be some kind of bound states. But they may now also include gravitons, the elementary particles of quantum gravity. But just like in the standard model, these bound states are dominated by just one of its components. And if there is a standard model component it is this one. Hence, the particles we see at LHC will essentially look like there is no gravity. And this is very consistent with experiment. Detecting the <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">deviations</a> will be so hard in comparison to those which come from the standard model, we can pretty much forget about it for earthbound experiments. At least for the next couple of decades.<br />
<br />
However, there are now also some combinations of gravitons without standard model particles involved. Such objects have been long speculated about, and are called geons, or gravity balls. But in contrast to the standard model case, they are not stable classically. But they may be stabilized due to quantum effects. The bound state structure strongly suggests that there is at least one stable one. Still, this is pure speculation at the moment. But if they are, these objects could have dramatic consequences. E.g., they could be part of the <a href="http://axelmaas.blogspot.de/2015/09/something-dark-on-move.html">dark matter</a> we are searching for. Or, they could make up black holes very much like neutrons make a neutron star. I have no idea, whether any of these speculations could be true. But if there is only a tiny amount of truth in it, this could be spectacular.<br />
<br />
Thus, some master students and I will set out to have a look at these ideas. To this end, we will need to some hard calculations. And, eventually, the results should be tested against observation. These will be coming form the universe, and from astronomy. Especially from the astronomy of black holes, where recently there have been many interesting and exciting developments, like observing two black holes merge, or the first direct image of a black hole (obviously just black inside a kind of halo). These are exciting times, and I am looking forward to see whether any of these ideas work out. Stay tuned!Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-22416617912381172292019-07-25T01:27:00.000-07:002019-07-25T01:27:36.157-07:00Talking about the same thingIn this blog entry I will try to explain my <a href="https://arxiv.org/abs/1907.10435">most recent paper</a>. The theme of the paper is rather simply put: You should not compare apple with oranges. The subtlety comes from knowing whether you have an apple or an orange in your hand. This is far less simple than it sounds.<br />
<br />
The origin of the problem are once more <a href="http://axelmaas.blogspot.de/2010/10/electromagnetism-photons-and-symmetry.html">gauge theories</a>. In gauge theories, we have introduced additional degrees of freedom. And, in fact, we have a choice of how we do this. Of course, our final results will not depend on the choice. However, getting to the final result is not always easy. Thus, ensuring that the intermediate steps are right would be good. But they depend on the choice. But then they are only comparable between two different calculations, if in both calculations the same choice is made.<br />
<br />
Now it seems simple at first to make the same choice. Ultimately, it is our choice, right? But this is actually not that easy in such theories, due to their <a href="http://axelmaas.blogspot.de/2013/09/blessing-and-bane-redundancy.html">mathematical complexity</a>. Thus, rather than making the choice explicit, the choice is made implicitly. The way how this is done is, again for technical reasons, different for methods. And because of all of these technicalities and the fact that we need to do approximations, figuring out whether the implicit conditions yield the same explicit choice is difficult. This is especially important as the choice modifies the <a href="http://axelmaas.blogspot.de/2012/03/equations-that-describe-world.html">equations</a> describing our auxiliary quantities.<br />
<br />
In the paper I test this. If everything is consistent between two particular methods, then the solutions obtained in one method should be a solution to the equations obtained in the other method. Seems a simple enough idea. There had been various arguments in the past which suggested that this should be he case. But there had been more and more pieces of evidence over the last couple of years that led me to think that there was something amiss. So I made this test, and did not rely on the arguments.<br />
<br />
And indeed, what I find in the article is that the solution of one method does not solve the equation from the other method. The way how this happens strongly suggests that the implicit choices made are not equivalent. Hence, the intermediate results are different. This does not mean that they are wrong. They are just not comparable. Either method can still yield in itself consistent results. But since neither of the methods are exact, the comparison between both would help reassure that the approximations made make sense. And this is now hindered.<br />
<br />
So, what to do now? We would very much like to have the possibility to compare between different methods at the level of the auxiliary quantities. So this needs to be fixed. This can only be achieved if the same choice is made in all the methods. The though question is, in which method we should work on the choice. Should we try to make the same choice as in some fixed of the methods? Should we try to find a new choice in all methods? This is though, because everything is so implicit, and affected by approximations.<br />
<br />
At the moment, I think the best way is to get one of the existing choices to work in all methods. Creating an entirely different one for all methods appears to me far too much additional work. And I, admittedly, have no idea what a better starting point would be than the existing ones. But in which method should we start trying to alter the choice? In neither method this seems to be simple. In both cases, fundamental obstructions are there, which need to be resolved. I therefore would currently like to start poking around in both methods. Hoping that there maybe a point in between where the choices of the methods could meet, which is easier than to push all all the way. I have a few ideas, but they will take time. Probably also a lot more than just me.<br />
<br />
This investigation also amazes me as the theory where this happens is nothing new. Far from it, it is more than half a century old, older than I am. And it is not something obscure, but rather part of the standard model of particle physics. So a very essential element in our description of nature. It never ceases to baffle me, how little we still know about it. And how unbelievable complex it is at a technical level.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-78334790644554049672019-06-19T07:53:00.003-07:002019-06-19T07:53:23.400-07:00Creativity in physicsOne of the most widespread misconceptions about physics, and other natural sciences, is that they are quite the opposite to art: Precise, fact-driven, logical, and systematic. While art is perceived as emotional, open, creative, and inspired.<br />
<br />
Of course, physics has experiments, has data, has math. All of that has to be fitted perfectly together, and there is no room for slights. Logical deduction is central in what we do. But this is not all. In fact, these parts are more like the handiwork. Just like a painter needs to be able to draw a line, a writer needs to be able to write coherent sentences, so we need to be able to calculate, build, check, and infer. But just like the act of drawing a line or writing a sentence is not what we recognize already as art, so is not the solving of an equation physics.<br />
<br />
We are able to solve an equation, because we learned this during our studies. We learned, what was known before. Thus, this is our tool set. Like people read books before start writing one. But when we actually do research, we face the fact that nobody knows what is going on. In fact, quite often we do not even know what is an adequate question to pose. We just stand there, baffled, before a couple of observations. That is, where the same act of creativity has to set in as when writing a book or painting a picture. We need an idea, need inspiration, on how to start. And then afterwards, just like the writer writes page after page, we add to this idea various pieces, until we have a hypotheses of what is going on. This is like having the first draft of a book. Then, the real grinding starts, where all our education comes to bear. Then we have to calculate and so on. Just like the writer has to go and fix the draft to become a book.<br />
<br />
You may now wonder whether this part of creativity is only limited to the great minds, and at the inception of a whole new step in physics? No, far from it. On the one hand, physics is not the work of lone geniuses. Sure, somebody has occasionally the right idea. But this is usually just the one idea, which is in the end correct, and all the other good ideas, which other people had, did just turn out to be incorrect, and you never hear of them because of this. And also, on the other hand, every new idea, as said above, requires eventually all that what was done before. And more than that. Creativity is rarely borne out of being a hermit. It is often by inspiration due to others. Talking to each other, throwing fragments of ideas at each other, and mulling about consequences together is what creates the soil where creativity sprouts. All those, with whom you have interacted, have contributed to the idea you have being born.<br />
<br />
This is, why the genuinely big breakthroughs have often resulted from so-called blue-sky research or curiosity-driven research. It is not a coincidence that the freedom of doing whatever kind of research you think is important is an, almost sacred, privilege of hired scientists. Or should be. Fortunately I am privileged enough, especially in the European Union, to have this privilege. In other places, you are often shackled by all kinds of external influences, down to political pressure to only do politically acceptable research. And this can never spark the creativity you need to make something genuine new. If you are afraid about what you say, you start to restrain yourself, and ultimately anything which is not already established to be acceptable becomes unthinkable. This may not always be as obvious as real political pressure. But if whether you being hired, if your job is safe, starts to depend on it, you start going for acceptable research. Because failure with something new would cost you dearly. And with the currently quite common competitive funding prevalent particularly for non-permanently hired people, this starts to become a serious obstruction.<br />
<br />
As a consequence, real breakthrough research can be neither planned nor can you do it on purpose. You can only plan the grinding part. And failure will be part of any creative process. Though you actually never really fail. Because you always learn how something does not work. That is one of the reasons why I strongly want that failures become also publicly available. They are as important to progress as success, by reducing the possibilities. Not to mention the amount of life time of researchers wasted because they fail with them same attempt, not knowing that others failed before them.<br />
<br />
And then, perhaps, a new scientific insight arises. And, more often than not, some great technology arises along the way. Not intentionally, but because it was necessary to follow one's creativity. And that is actually where most technological leaps came from. So,real progress in physics, in the end, is made from about a third craftsmanship, a third communication, and a third creativity.<br />
<br />
So, after all this general stuff, how do I stay creative?<br />
<br />
Well, first of all, I was and am sufficiently privileged. I could afford to start out with just following my ideas, and either it will keep me in business, or I will have to find a non-science job. But this only worked out because of my personal background, because I could have afforded to have a couple of months with no income to find a job, and had an education which almost guarantees me a decent job eventually. And the education I could only afford in this quality because of my personal background. Not to mention that as a white male I had no systemic barriers against me. So, yes, privilege plays a major role.<br />
<br />
The other part was that I learned more and more that it is not effort what counts, but effect. Took me years. But eventually, I understood that a creative idea cannot be forced by burying myself in work. Time off is for me as important. It took me until close to the end of my PhD to realize that. But not working overtime, enjoying free days and holidays, is for me as important for the creative process as any other condition. Not to mention that I also do all non-creative chores much more efficiently if well rested, which eventually leaves me with more time to ponder creatively and do research.<br />
<br />
And the last ingredient is really exchange. I have had now the opportunity, in a sabbatical, to go to different places and exchange ideas with a lot of people. This gave me what I needed to <a href="https://axelmaas.blogspot.com/2019/05/acquiring-new-field.html">acquire a new field</a> and have already new ideas for it. It is the possibility to sit down with people for some hours, especially in a nicer and more relaxing surrounding than an office, and just discuss ideas. That is also what I like most about conferences. And one of the reasons I think conferences will always be necessary, even though we need to make going there and back ecologically much more viable, and restrict ourselves to sufficiently close ones until this is possible.<br />
<br />
Sitting down over a good cup of coffee or a nice meal, and just discuss, is really jump starting my creativity. Even sitting with a cup of good coffee in a nice cafe somewhere and just thinking does wonders for me in solving problems. And with that, it seems not to be so different for me than for artists, after all.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-43465583862854082892019-05-14T08:03:00.002-07:002019-05-14T08:03:43.049-07:00Acquiring a new fieldI have recently started to look into a new field: Quantum gravity. In this entry, I would like to write a bit about how this happens, acquiring a new field. Such that you can get an idea what can lead a scientist to do such a thing. Of course, in future entries I will also write more about what I am doing, but it would be a bit early to do so right now.<br />
<br />
Acquiring a new field in science is not something done lightly. One has always not enough time for the things one does already. And when you enter a new field, stuff is slow. You have to learn a lot of basics, need to get an overview of what has been done, and what is still open. Not to mention that you have to get used to a different jargon. Thus, one rarely does so lightly.<br />
<br />
I have in the past written already <a href="https://axelmaas.blogspot.com/2018/03/asking-questions-leads-to-change-of-mind.html">one entry</a> about how I came to do Higgs physics. This entry was written after the fact. I was looking back, and discussed my motivation how I saw it at that time. It will be an interesting thing to look back at this entry in a few years, and judge what is left of my original motivation. And how I feel about this knowing what happened since then. But for now, I only know the present. So, lets get to it.<br />
<br />
Quantum gravity is the hypothetical quantum version of the ordinary theory of gravity, so-called <a href="https://axelmaas.blogspot.com/2009/11/forces-of-nature-i-gravity.html">general relativity</a>. However, it has withstood quantization for a quite a while, though there has been huge progress in the last 25 years or so. If we could quantize it, its combination with the standard model and the simplest version of <a href="http://axelmaas.blogspot.de/2015/09/something-dark-on-move.html">dark matter</a> would likely be able to explain almost everything we can observe. Though even then a few <a href="http://axelmaas.blogspot.de/2012/05/above-and-beyond.html">open questions</a> appear to remain.<br />
<br />
But my interest in quantum gravity comes not from the promise of such a possibility. It has rather a quite different motivation. My interest started with the Higgs.<br />
<br />
I have <a href="http://axelmaas.blogspot.de/2015/01/what-is-so-important-to-me-about-higgs.html">written many times</a> that we work on an improvement in the way we look at the Higgs. And, by now, in fact of the standard model. In what we get, we see a clear distinction between two concepts: So-called <a href="http://axelmaas.blogspot.de/2010/10/electromagnetism-photons-and-symmetry.html">gauge symmetries</a> and <a href="http://axelmaas.blogspot.de/2010/08/global-and-local-symmetries.html">global symmetries</a>. As far as we understand the standard model, it appears that global symmetries determine how many particles of a certain type exists, and into which particles they can decay or be combined. Gauge symmetries, however, seem to be just auxiliary symmetries, which we use to make calculations feasible, and they do not have a direct impact on observations. They have, of course, an indirect impact. After all, in which theory which gauge symmetry can be used to facilitate things is different, and thus the kind of gauge symmetry is more a statement about which theory we work on.<br />
<br />
Now, if you add gravity, the distinction between both appears to blur. The reason is that in gravity space itself is different. Especially, you can deform space. Now, the original distinction of global symmetries and gauge symmetries is their relation to space. A global symmetry is something which is the same from point to point. A gauge symmetry allows changes from point to point. Loosely speaking, of course.<br />
<br />
In gravity, space is no longer fixed. It can itself be deformed from point to point. But if space itself can be deformed, then nothing can stay the same from point to point. Does then the concept of global symmetry still make sense? Or does all symmetries become just 'like' local symmetries? Or is there still a distinction? And what about general relativity itself? In a particular sense, it can be seen as a theory with a gauge symmetry of space. Makes this everything which lives on space automatically a gauge symmetry? If we want to understand the results of what we did in the standard model, where there is no gravity, in the real world, where there is gravity, then this needs to be resolved. How? Well, my research will hopefully answer this question. But I cannot do it yet.<br />
<br />
These questions were already for some time in the back of my mind. A few years, I actually do not know how many exactly. As quantum gravity pops up in particle physics occasionally, and I have contact with several people working on it, I was exposed to this again and again. I knew, eventually, I will need to address it, if nobody else does. So far, nobody did.<br />
<br />
But why now? What prompted me to start now with it? As so often in science, it were other scientists.<br />
<br />
Last year at the end of November/beginning of December, I took part in a <a href="https://indico.cern.ch/event/712873/">conference in Vienna</a>. I had been invited to talk about our research. The meeting has a quite wide scope, and also present were several people, who work on black holes and quantum physics. In this area, one goes, in a sense, halfway towards quantum gravity: One has quantum particles, but they life in a classical gravity theory, but with strong gravitational effects. Which is usually a black hole. In such a setup, the deformations of space are fixed. And also non-quantum black holes can swallow stuff. This combination appears to make the following thing: Global symmetries appear to become meaningless, because everything associated with them can vanish in the black hole. However, keeping space deformations fixed means that local symmetries are also fixed. So they appear to become real, instead of auxiliary. Thus, this seems to be quite opposite to our result. And this, and the people doing this kind of research, challenged my view of symmetries. In fact, in such a half-way case, this effect seems to be there.<br />
<br />
However, in a full quantum gravity theory, the game changes. Then also space deformations become dynamical. At the same time, black holes need no longer to have the characteristic to swallow stuff forever, because they become dynamical, too. They develop. Thus, to answer what happens really requires full quantum gravity. And because of this situation, I decided to start to work actively on quantum gravity. Because I needed to answer whether our picture of symmetries survive, at least approximately, when there is quantum gravity. And to be able to answer such challenges. And so it began.<br />
<br />
Within the last six months, I have now worked through a lot of the basic stuff. I have now a rough idea of what is going on, and what needs to be done. And I think, I see a way how everything can be reconciled, and make sense. It will still need a long time to complete this, but I am very optimistic right now. So optimistic, in fact, that a few days back I gave my <a href="http://physik.uni-graz.at/~axm/jena-2019-maas.pdf">first talk</a>, in which I discussed this issues including quantum gravity. It will still need time, before I have a first real result. But I am quite happy how thing progress.<br />
<br />
And that is the story how I started to look at quantum gravity in earnest. If you want to join me in this endeavor: I am always looking for collaboration partners and, of course, students who want to do their thesis work on this subject 😁Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-16990249565864564382019-02-07T01:17:00.004-08:002019-02-07T01:17:59.455-08:00Why there won't be warp travel in times of global crisesOne of the questions I get most often at outreach events is: "What is about warp travel?", or some other wording for faster-than-light travel. Something, which makes interstellar travel possible, or at least viable.<br />
<br />
Well, the first thing I can say is that there is nothing which excludes it. Of course, within our well established theories of the world it is not possible. Neither the standard model of particle physics, nor general relativity, when constrained to the matter we know of, allows it. Thus, whatever describes warp travel, it needs to be a theory, which encompasses and enlarges what we know. Can a quantized combination of general relativity and particle physics do this? Perhaps, perhaps not. Many people think about it really hard. Mostly, we run afoul of causality when trying.<br />
<br />
But these are theoretical ideas. And even if some clever team comes up with a theory which allows warp travel, this does not say that this theory is actually realized in nature. Just because we can make it mathematical consistent does not guarantee that it is realized. In fact, we have many, many more mathematical consistent theories than are realized in nature. Thus, it is not enough to just construct a theory of warp travel. Which, as noted, we failed so far to do.<br />
<br />
No, what we need is to figure out that it really happens in nature. So far, this did not happen. Neither did we observe it in any human-made experiment, nor did we have any observation in nature which unambiguously point to it. And this is what makes it real hard.<br />
<br />
You see, the universe is a tremendous place, which is unbelievable large, and essentially three times as old as the whole planet earth. Not to mention humanity. There happen extremely powerful events out there. This starts from quasars, effectively like a whole galactic core on fire, to black hole collisions and supernovas. These events put out an enormous amount of energy. Much, much more than even our sun generates. Hence, anything short of a big bang is happening all the time in the universe. And we see the results. The earth is hit constantly by particles with much, much higher energies than we can produce in any experiment. And this since earth came into being. Incidentally, this also tells us that nothing we can do at a particle accelerator can really be dangerous. Whatever we do there has happened so often in our Earth's atmosphere, it would have killed this planet long before humanity entered the scene. Only bad thing about it, we do never know when and where such an event happens. And the rate is also not that high, it is only that earth existed already so very long. And is big. Hence, we cannot use this to make controlled observations.<br />
<br />
Thus, whatever could happen, happens out there. In the universe. We see some things out there, which we cannot explain yet, e.g. <a href="http://axelmaas.blogspot.de/2015/09/something-dark-on-move.html">dark matter</a>. But by and large a lot works as expected. Especially, we do not see anything which begs warp travel to explain. Or anything else remotely suggesting something happening faster than the speed of light. Hence, if something like faster-than-light travel is possible, it is neither common nor easily happening.<br />
<br />
As noted, this does not mean it is impossible. Only that if it is possible, it is very, very hard. Especially, this means it will be very, very hard to make an experiment to demonstrate the phenomenon. Much less to actually make it a technology, rather than a curiosity. This means, a lot of effort will be necessary to get to see it, if it is really possible.<br />
<br />
What is a lot? Well, the CERN is a bit. But human, or even robotic, space exploration is an entire different category, some one to two orders of magnitudes more. Probably, we would need to combine such space exploration with particle physics to really get to it. Possible the best example for such an endeavor is the future <a href="https://www.elisascience.org/">LISA project</a> to measure gravitational waves in space. It is perhaps even our current best bet to observe any hints of faster-than-light phenomena, aside from bigger particle physics experiments on earth.<br />
<br />
Do we have the technology for such a project? Yes, we do. We have it since roughly a decade. But it will likely take at least one more decade to have LISA flying. Why not now? Resources. Or, often put equivalently, costs.<br />
<br />
And here comes the catch. I said, it is our best chance. But this does not mean it is a good chance. In fact, even if faster-than-light is possible, I would be very surprised if we would see it with this mission. There is probably a few more generations of technology, and another order of magnitude of resources, needed, before we could see something, given of what I know how well everything currently fits. Of course, there can always be surprises with every little step further. I am sure, we will discover something interesting, possibly spectacular with LISA. But I would not bet anything valuable that it will be having to do with warp travel.<br />
<br />
So, you see, we have to scale up, if we want to go to the stars. This means investing resources. A lot of them. But resources are needed to fix things on earth as well. And the more we damage, the more we need to fix, and the less we have to get to the stars. Right now, humanity moves into a state of perpetual crises. The damage wrought by the climate crises will require enormous efforts to mitigate, much more to stop the downhill trajectory. As a consequence of the climate crises, as well as social inequality, more and more conflicts will create further damage. Finally, isolationism, both nationally as well as socially, driven by fear of the oncoming crises, will also soak up tremendous amounts of resources. And, finally, a hostile environment towards diversity and putting individual gains above common gains create a climate which is hostile to anything new and different in general, and to science in particular. Hence, we will not be able to use our resources, or the ingenuity of the human species as a whole, to get to the stars.<br />
<br />
Thus, I am not hopeful to see faster-than-light in my lifetime, or those of the next generation. Such a challenge, if it is possible at all, will require a common effort of our species. That would be truly one worthy endeavour to put our minds at. But right now, as a scientist, I am much more occupied with protecting a world in which science is possible, both metaphorically as well as literally.<br />
<br />
But, there is always hope. If we rise up, and decide to change fundamentally. When we put the well-being of us as a whole in front. Then, I would be optimistic that we can get out there. Well, at least as fast as nature permits. How fast this ever will be.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-28058178085004972122019-01-08T02:15:00.002-08:002019-01-08T02:15:43.000-08:00Taking your theory seriouslyThis blog entry is somewhat different than usual. Rather than writing about some particular research project, I will write about a general vibe, directing my research.<br />
<br />
As usual, research starts with a 'why?'. Why does something happen, and why does it happen in this way? Being the theoretician that I am, this question often equates with wanting to have mathematical description of both the question and the answer.<br />
<br />
Already very early in my studies I ran into peculiar problems with this desire. It usually left me staring at the words '...and then nature made a choice', asking myself, how could it? A simple example of the problem is a magnet. You all know that a magnet has a north pole and a south pole, and that these two are different. So, how does it happen which end of the magnet becomes the north pole and which the south pole? At the beginning you always get to hear that this is a random choice, and it just happens that one particular is made. But this is not really the answer. If you dig deeper than you find that originally the metal of any magnet has been very hot, likely liquid. In this situation, a magnet is not really magnetic. It becomes magnetic when it is cooled down, and becomes solid. At some temperature (the so-called Curie temperature), it becomes magnetic, and the poles emerge. And here this apparent miracle of a 'choice by nature' happens. Only that it does not. The magnet cools down not all by itself, but it has a surrounding. And the surrounding can have magnetic fields as well, e.g. the earth's magnetic field. And the decision what is south and what is north is made by how the magnet forms relative to this field. And thus, there is a reason. We do not see it directly, because magnets have usually moved since then, and thus this correlation is no longer obvious. But if we would heat the magnet again, and let it cool down again, we could observe this.<br />
<br />
But this immediately leaves you with the question of where did the Earth's magnetic field comes from, and got its direction? Well, it comes from the liquid metallic core of the Earth, and aligns along or oppositely, more or less, the rotation axis of the Earth. Thus, the question is, how did the rotation axis of the Earth comes about, and why has it a liquid core? Both questions are well understood, and arise from how the Earth has formed billions of years ago. This is due to the mechanics of the rotating disk of dust and gas which formed around our fledgling sun. Which in turns comes from the dynamics on even larger scales. And so on.<br />
<br />
As you see, whenever one had the feeling of a random choice, it was actually the outside of what we looked at so far, which made the decision. So, such questions always lead us to include more into what we try to understand.<br />
<br />
'Hey', I now can literally hear people say who are a bit more acquainted with physics, 'does not quantum mechanics makes really random choices?'. The answer to this is yes and no in equal measures. This is probably one of the more fundamental problems of modern physics. Yes, our description of quantum mechanics, as we teach it also in courses, has intrinsic randomness. But when does it occur? Yes, exactly, whenever we jump outside of the box we describe in our theory. Real, random choice is encountered in quantum physics only whenever we transcend the system we are considering. E.g. by an external measurement. This is one of the reasons why this is known as the 'measurement problem'. If we stay inside the system, this does not happen. But at the expense that we are loosing the contact to things, like an ordinary magnet, which we are used to. The objects we are describing become obscure, and we talk about wave functions and stuff like this. Whenever we try to extend our description to also include the measurement apparatus, on the other hand, we again get something which is strange, but not as random as it originally looked. Although talking about it becomes almost impossible beyond any mathematical description. And it is not really clear what random means anymore in this context. This problem is one of the big ones in the concept of physics. While there is a relation to what I am talking about here, this question can still be separated.<br />
<br />
And in fact, it is not this divide what I want to talk about, at least not today. I just wanted to get away with this type of 'quantum choice'. Rather, I want to get to something else.<br />
<br />
If we stay inside the system we describe, then everything becomes calculable. Our mathematical description is closed in the sense that after fixing a theory, we can calculate everything. Well, at least in principle, in practice our technical capabilities may limit this. But this is of no importance for the conceptual point. Once we have fixed the theory, there is no choice anymore. There is no outside. And thus, everything needs to come from inside the theory. Thus, a magnet in isolation will never magnetize, because there is nothing which can make a decision about how. The different possibilities are caught in an eternal balanced struggle, and none can win.<br />
<br />
Which makes a lot of sense, if you take physical theories really seriously. After all, one of the basic tenants is that there is no privileged frame of reference: 'Everything is relative'. If there is nothing else, nothing can happen which creates an absolute frame of reference, without violating the very same principles on which we found physics. If we take our own theories seriously, and push them to the bitter end, this is what needs to come about.<br />
<br />
And here I come back to my own research. One of the driving principles has been to really push this seriousness. And ask what it implies if one really, really takes it seriously. Of course, this is based on the assumption that the theory is (sufficiently) adequate, but that is everyday uncertainty for a physicist anyhow. This requires me to very, very carefully separate what is really inside, and outside. And this leads to quite surprising results. Essentially most of my research on Brout-Englert-Higgs physics, as described in previous entries, is coming about because of this approach. And leads partly to results quite at odds with common lore, often meaning a lot of work to convince people. Even if the mathematics is valid and correct, interpretation issues are much more open to debate when it comes to implications.<br />
<br />
Is this point of view adequate? After all, we know for sure that we are not yet finished, and our theories do not contain all there is, and there is an 'outside'. However it may look. And I agree. But, I think it is very important that we very clearly distinguish what is an outside influence, and what is not. And as a first step to ensure what is outside, and thus, in a sense, is 'new physics', we need to understand what our theories say if they are taken in isolation.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-33675664148751870332018-12-13T08:15:00.001-08:002018-12-13T08:15:21.958-08:00The size of the WAs discussed in an <a href="https://axelmaas.blogspot.com/2018/02/how-large-is-elementary-particle.html">earlier entry</a> we set out to measure the size of a particle: The <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">W boson</a>. We have now finished this, and published a <a href="https://arxiv.org/abs/1811.03395">paper about our results</a>. I would like to discuss these results a bit in detail.<br />
<br />
This project was motivated because we think that the W (and its sibling, the <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">Z boson</a>) are actually more complicated than usually assured. We think that they may have a <a href="http://axelmaas.blogspot.co.at/2015/08/looking-for-one-thing-in-another.html">self-similar structure</a>. The bits and pieces of this is quite technical. But the outline is the following: What we see and measure as a W at, say, the LHC or earlier, is actually not a point-like particle. Although this is the currently most common view. But science has always been about changing the common ideas and replacing them with something new and better. So, our idea is that the W has a substructure. This substructure is a bit weird, because it is not made from additional elementary particles. It rather looks like a bubbling mess of quantum effects. Thus, we do not expect that we can isolate anything which resembles a physical particle within the W. And if we try to isolate something, we should not expect it to behave as a particle.<br />
<br />
Thus, this scenario gives two predictions. One: Substructure needs to have space somewhere. Thus, the W should have a size. Two: Anything isolated from it should not behave like a particle. To test both ideas in the same way, we decided to look at the same quantity: The radius. Hence, we <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">simulated</a> a part of the standard model. Then we measured the size of the W in this simulation. Also, we tried to isolate the most particle-like object from the substructure, and also measured its size. Both of these measurements are very expensive in terms of computing time. Thus, our results are rather exploratory. Hence, we cannot yet regard what we found as final. But at least it gives us some idea of what is going on.<br />
<br />
The first thing is the size of the W. Indeed, we find that it has a size, and one which is not too small either. The number itself, however, is far less accurate. The reason for this is twofold. On the one hand, we have only a part of the standard model in our simulations. On the other hand, we see artifacts. They come from the fact that our simulations can only describe some finite part of the world. The larger this part is, the more expensive the calculation. With what we had available, the part seems to be still so small that the W is big enough to 'bounce of the walls' fairly often. Thus, our results still show a dependence on the size of this part of the world. Though we try to accommodate for this, this still leaves a sizable uncertainty for the final result. Nonetheless, the qualitative feature that it has a significant size remains.<br />
<br />
The other thing are the would-be constituents. We indeed can identify some kind of lumps of quantum fluctuations inside. But indeed, they do not behave like a particle, not even remotely. Especially, when trying to measure their size, we find that the square of their radius is negative! Even though the final value is still uncertain, this is nothing a real particle should have. Because when trying to take the square root of such a negative quantity to get the actual number yields an imaginary number. That is an abstract quantity, which, while not identifiable with anything in every day, has a well-defined mathematical meaning. In the present case, this means this lump is nonphysical, as if you would try to upend a hole. Thus, this mess is really not a particle at all, in any conventional sense of the word. Still, what we could get from this is that such lumps - even though they are not really lumps, 'live' only in areas of our W much smaller than the W size. So, at least they are contained. And let the W be the well-behaved particle it is.<br />
<br />
So, the bottom line is, our simulations agreed with our ideas. That is good. But it is not enough. After all, who can tell if what we simulate is actually the thing happening in nature? So, we will need an experimental test of this result. This is <a href="https://axelmaas.blogspot.com/2018/06/how-to-test-idea.html">surprisingly complicated</a>. After all, you cannot really get a measure stick to get the size of a particle. Rather, what you do is, you throw other particles at them, and then see how much they are deflected. At least in principle.<br />
<br />
Can this be done for the W? Yes, it can be done, but is very indirect. Essentially, it could work as follows: Take the LHC, at which two protons are smashed in each other. In this smashing, it is possible that a <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">Z boson</a> is produced, which smashes of a W. So, you 'just' need to look at the W before and after. In practice, this is more complicated. Since we cannot send the W in there to hit the Z, we use that mathematically this process is related to another one. If we get one, we get the other for free. This process is that the produced Z, together with a lot of kinetic energy, decays into two W particles. These are then detected, and their directions measured.<br />
<br />
As nice as this sounds, this is still horrendously complicated. The problem is that the Ws themselves decay into some <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">leptons and neutrinos</a> before they reach the actual detector. And because neutrinos escape essentially always undetected, one can only indirectly infer what has been going on. Especially the directions of the Ws cannot easily be reconstructed. Still, in principle it should be possible, and we discuss this in <a href="https://arxiv.org/abs/1811.03395">our paper</a>. So we can actually measure this size in principle. It will be now up to the experimental experts if it can - and will - be done in practice.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-32268923830540556632018-10-24T00:25:00.001-07:002018-10-24T00:26:57.956-07:00Looking for something when no one knows how much is thereThis time, I want to continue the discussion from <a href="https://axelmaas.blogspot.com/2018/06/how-to-test-idea.html">some months ago</a>. Back then, I was rather general on how we could test our <a href="http://axelmaas.blogspot.com/2018/03/asking-questions-leads-to-change-of-mind.html">most dramatic idea</a>. This idea is connected to what we regard as elementary particles. So far, our idea is that those you have heard about, <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">the electrons, the Higgs, and so on</a> are truly the basic building blocks of nature. However, we have found a lot of evidence that indicate that we see in experiment, and call these names, are actually not the same as the elementary particles themselves. Rather, they are a kind of <a href="http://axelmaas.blogspot.de/2015/06/the-nature-of-particles.html">bound state</a> of the elementary ones, which only look at first sight like they themselves <a href="http://axelmaas.blogspot.de/2012/11/a-higgs-and-higgs-make-what.html">would be the elementary ones</a>. Sounds pretty weird, huh? And if it sounds weird, it means it needs to be tested. We did so with <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">numerical simulations</a>. They all <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">agreed perfectly</a> with the ideas. But, of course, its physics, and thus we need also an experiment. The only question is which one.<br />
<br />
We had some ideas already a <a href="http://axelmaas.blogspot.com/2018/02/how-large-is-elementary-particle.html">while</a> <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">back</a>. <a href="http://axelmaas.blogspot.com/2018/02/how-large-is-elementary-particle.html">One of them</a> will be ready soon, and I will talk again about it in due time. But this will be rather indirect, and somewhat qualitative. The other, however, <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">required a new experiment</a>, which may need two more decades to build. Thus, both cannot be the answer alone, and we need something more.<br />
<br />
And this more is what we are currently closing in. Because one has this kind of weird bound state structure to make the standard model consistent, not only exotic particles are more complicated than usually assumed. Ordinary ones are too. And most ordinary are <a href="http://axelmaas.blogspot.de/2010/01/forces-of-nature-iii-strong-force-part.html">protons</a>, the nucleus of the hydrogen atom. More importantly, protons is what is smashed together at the <a href="https://home.cern/about/accelerators">LHC</a> at <a href="https://home.cern/">CERN</a>. So, we have a machine already, which may be able to test it. But this is involved, as protons are very messy. They are already in the conventional picture bound states of <a href="http://axelmaas.blogspot.de/2010/01/lthe-forces-of-nature-iii-strong-force.html">quarks and gluons</a>. Our results just say there are more components. Thus, we have somehow to disentangle old and new components. So, we have to be very careful in what we do.<br />
<br />
Fortunately, there is a trick. All of this revolves around the <a href="http://axelmaas.blogspot.de/2010/03/higgs-effect.html">Higgs</a>. The Higgs has the property that interacts stronger with particles the heavier they are. The heaviest particles we know are the <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">top quark</a>, followed by the <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">W and Z bosons</a>. And the <a href="http://cms.cern/">CMS</a> experiment (and other experiments) at CERN has a measurement campaign to look at the production of these particles together! That is exactly where we expect something interesting can happen. However, our ideas are not the only ones leading to top quarks and Z bosons. There are many known processes which produce them as well. So we cannot just check whether they are there. Rather, we need to understand if there are there as expected. E.g., if they fly away from the interaction in the expected direction and with the expected speeds.<br />
<br />
So what a master student and myself do is the following. We use a program, called <a href="https://herwig.hepforge.org/">HERWIG</a>, which simulates such events. One of the people who created this program helped us to modify this program, so that we can test our ideas with it. What we now do is rather simple. An input to such simulations is how the structure of the proton looks like. Based on this, it simulates how the top quarks and Z bosons produced in a collision are distributed. We now just add our conjectured additional contributions to the proton, essentially a little bit of Higgs. We then check, how the distributions change. By comparing the changes to what we get in experiment, we can then deduced how large the Higgs contribution in the proton is. Moreover, we can even indirectly deduce its shape, i.e. how in the proton the Higgs is located.<br />
<br />
And this we now study. We iterate modifications of the proton structure with comparison to experimental results and predictions without this Higgs contribution. Thereby, we constraint the Higgs contribution in the proton bit by bit. At the current time, we know that the data is only sufficient to provide an upper bound to this amount inside the proton. Our first estimates show already that this bound is actually not that strong, and quite a lot of Higgs could be inside the proton. But on the other hand, this is good, because that means that the expected data in the next couple of years from the experiments will be able to actually either constraint the contribution further, or could even detect it, if it is large enough. At any rate, we now know that we have a sensitive leverage to understand this new contribution.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-61968981145680629612018-09-27T04:40:00.000-07:002018-09-27T04:53:07.226-07:00Unexpected connectionsThe history of physics is full of stuff developed for one purpose ending up being useful for an entirely different purpose. Quite often they also failed their original purpose miserably, but are paramount for the new one. Newer examples are the first attempts to describe the <a href="http://axelmaas.blogspot.de/2010/02/forces-of-nature-iv-weak-force.html">weak interactions</a>, which ended up describing the <a href="http://axelmaas.blogspot.de/2010/01/lthe-forces-of-nature-iii-strong-force.html">strong one</a>. Also, string theory was originally invented for the strong interactions, and failed for this purpose. Now, well, it is the popular science star, and a serious candidate for quantum gravity.<br />
<br />
But failing is optional for having a second use. And we just start to discover a second use for<a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html"> our investigations</a> of <a href="http://axelmaas.blogspot.de/2014/05/why-does-chemistry-work.html">grand-unified theories</a>. There our research used a toy model. We did this, because we wanted to understand a mechanism. And because doing the full story would have been much too complicated before we did not know, whether the mechanism works. But it turns out this toy theory may be an interesting theory on its own.<br />
<br />
And it may be interesting for a very different topic: <a href="http://axelmaas.blogspot.de/2015/09/something-dark-on-move.html">Dark matter</a>. This is a hypothetical type of matter of which we see a lot of indirect evidence in the universe. But we are still mystified of what it is (and whether it is matter at all). Of course, such mysteries draw our interests like a flame the moth. Hence, our group in Graz starts to push also in this direction, being curious on what is going on. For now, we follow the most probable explanation that there are additional particles making up dark matter. Then there are two questions: What are they? And do they, and if yes how, interact with the rest of the world? Aside from gravity, of course.<br />
<br />
Next week I will go to a <a href="http://www.ectstar.eu/node/4226">workshop</a> in which new ideas on dark matter will be explored, to get a better understanding of what is known. And in the course of preparing for this workshop I noted that there is this connection. I will actually present this idea at the workshop, as it forms a new class of possible explanations of dark matter. Perhaps not the right one, but at the current time an equally plausible one as many others.<br />
<br />
And here is how it works. Theories of the type of grand-unified theories were for a long time expected to have a lot of massless particles. This was not bad for their original purpose, as we know quite some of them, like the <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">photon and the gluons</a>. However, our results showed that with an <a href="https://axelmaas.blogspot.com/2018/06/how-to-test-idea.html">improved treatment and shift in paradigm</a> that this is <a href="http://axelmaas.blogspot.com/2018/01/finding-and-curing-disagreements.html">not always true</a>. At least some of them do not have massless particles.<br />
<br />
But dark matter needs to be massive to influence stars and galaxies gravitationally. And, except for very special circumstances, there should not be additional massless dark particles. Because otherwise the massive ones could <a href="http://axelmaas.blogspot.de/2013/02/almost-nothing-is-forever-decays.html">decay</a> into the massless ones. And then the mass is gone, and this does not work. Thus the reason why such theories had been excluded. But with our new results, they become feasible. Even more so, we have a lot of indirect evidence that dark matter is not just a single, massive particle. Rather, it needs to interact with itself, and there could be indeed many different dark matter particles. After all, if there is dark matter, it makes up four times more stuff in the universe than everything we can see. And what we see consists out of many particles, so why should not dark matter do so as well. And this is also realized in our model.<br />
<br />
And this is how it works. The scenario I will describe (you can download my <a href="http://physik.uni-graz.at/~axm/trento-2018-maas.pdf">talk</a> already now, if you want to look for yourself - though it is somewhat technical) finds two different types of stable dark matter. Furthermore, they interact. And the great thing about our approach is that we can calculate this quite precisely, giving us a chance to make predictions. Still, we need to do this, to make sure that everything works with what astrophysics tells us. Moreover, this setup gives us two more additional particles, which we can couple to the <a href="http://axelmaas.blogspot.de/2010/03/higgs-effect.html">Higgs</a> through a so-called <a href="https://axelmaas.blogspot.com/2015/12/touching-dark-matter-with-higgs.html">portal</a>. Again, we can calculate this, and how everything comes together. This allows to test this model not only by astronomical observations, but at CERN. This gives the basic idea. Now, we need to do all the detailed calculations. I am quite excited to try this out :) - so stay tuned, whether it actually makes sense. Or whether the model will have to wait for another opportunity.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-44049291132633524392018-08-13T07:46:00.002-07:002018-08-13T07:46:29.109-07:00Fostering an idea with experienceIn the <a href="https://axelmaas.blogspot.com/2018/06/how-to-test-idea.html">previous entry</a> I wrote how hard it is to establish a new idea, if the only existing option to get experimental confirmation is to become very, very precise. Fortunately, this is not the only option we have. Besides experimental confirmation, we can also attempt to test an idea theoretically. How is this done?<br />
<br />
The best possibility is to set up a situation, in which the new idea creates a most spectacular outcome. In addition, it should be a situation in which older ideas yield a drastically different outcome. This sounds actually easier than it is. There are three issues to be taken care of.<br />
<br />
The first two have something to do with a very important distinction. That of a theory and that of an observation. An observation is something we measure in an experiment or calculate if we play around with models. An observation is always the outcome if we set up something initially, and then look at it some time later. The theory should give a description of how the initial and the final stuff are related. This means that we look for every observation for a corresponding theory to give it an explanation. To this comes the additional modern idea of physics that there should not be an own theory for every observation. Rather, we would like to have a unified theory, i.e. one theory which explains all observations. This is not yet the case. But at least we have reduced it to a handful of theories. In fact, for anything going on inside our solar system we need so far just two: The standard-model of particle physics and general relativity.<br />
<br />
Coming back to our idea, we have now the following problem. Since we do a gedankenexperiment, we are allowed to chose any theory we like. But since we are just a bunch of people with a bunch of computers we are not able to calculate all the possible observations a theory can describe. Not to mention all possible observations of all theories. And it is here, where the problem starts. The older ideas still exist, because they are not bad, but rather explain a huge amount of stuff. Hence, for many observations in any theory they will be still more than good enough. Thus, to find spectacular disagreement, we do not only need to find a suitable theory. We also need to find a suitable observation to show disagreement.<br />
<br />
And now enters the third problem: We actually have to do the calculation to check whether our suspicion is correct. This is usually not a simple exercise. In fact, the effort needed can make such a calculation a complete master thesis. And sometimes even much more. Only after the calculation is complete we know whether the observation and theory we have chosen was a good choice. Because only then we know whether the anticipated disagreement is really there. And it may be that our choice was not good, and we have to restart the process.<br />
<br />
Sounds pretty hopeless? Well, this is actually one of the reasons why physicists are famed for their tolerance to frustration. Because such experiences are indeed inevitable. But fortunately it is not as bad as it sounds. And that has something to do with how we chose the observation (and the theory). This I did not specify yet. And just guessing would indeed lead to a lot of frustration.<br />
<br />
The thing which helps us to hit more often than not the right theory and observation is insight and, especially, experience. The ideas we have tell us about how theories function. I.e., our insights give us the ability to estimate what will come out of a calculation even without actually doing it. Of course, this will be a qualitative statement, i.e. one without exact numbers. And it will not always be right. But if our ideas are correct, it will work out usually. In fact, if we would regularly not estimate correctly, this should require us to reevaluate our ideas. And it is our experience which helps us to get from insights to estimates.<br />
<br />
This defines our process to test our ideas. And this process can actually be well traced out in our research. E.g. in a <a href="https://arxiv.org/abs/1709.07477">paper</a> from last year we collected many of such qualitative estimates. They were based on some much older, much more crude estimates <a href="http://arxiv.org/abs/1502.02421">published</a> several years back. In fact, the newer paper already included some quite involved semi-quantitative statements. We then used massive <a href="shttp://axelmaas.blogspot.de/2012/02/simulating-universe.html">computer simulations</a> to test our predictions. They were indeed as good confirmed as possible with the amount of computers we had. This we reported in another <a href="https://arxiv.org/abs/1804.04453">paper</a>. This gives us hope to be on the right track.<br />
<br />
So, the next step is to enlarge our testbed. For this, we already came up with some <a href="https://arxiv.org/abs/1806.11373">new first ideas</a>. However, these will be even more challenging to test. But it is possible. And so we continue the cycle.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-35572251707488049122018-06-12T03:49:00.000-07:002018-06-12T03:49:02.131-07:00How to test an ideaAs you may have guessed from reading <a href="http://axelmaas.blogspot.de/2015/01/what-is-so-important-to-me-about-higgs.html">through the blog</a>, our work is centered around a <a href="http://axelmaas.blogspot.com/2018/03/asking-questions-leads-to-change-of-mind.html">change of paradigm</a>: That there is a very intriguing structure of the Higgs and the W/Z bosons. And that what we <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">observe in the experiments</a> are actually more complicated than what we usually assume. That they are <a href="http://axelmaas.blogspot.com/2018/02/how-large-is-elementary-particle.html">not just essentially point-like</a> objects.<br />
<br />
This is a very bold claim, as it touches upon very basic things in the standard model of particle physics. And the interpretation of experiments. However, it is at the same time a necessary consequence if one takes the underlying more formal theoretical foundation seriously. The reason that there is not a huge clash is that the standard model is very special. Because of this both pictures give almost the same prediction for experiments. This can also be understood quantitatively. That is where I have written a <a href="http://axelmaas.blogspot.com/2017/11/reaching-closure-completing-review.html">review</a> about. It can be imagined in this way:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5mY3v4Eff0DZncoHaRHMq7qnqL95dRnHgbM5_x3w1mmsAfImsNaKuhUxxjB8r5DecYMY7PxK3-YkCOFgvHChTjWGLuA8atNyAT9_vEA0ZsbW-R0lH9939EWscFgXPR7u4jyNaAC5-7LHA/s1600/higgs2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="794" data-original-width="1058" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5mY3v4Eff0DZncoHaRHMq7qnqL95dRnHgbM5_x3w1mmsAfImsNaKuhUxxjB8r5DecYMY7PxK3-YkCOFgvHChTjWGLuA8atNyAT9_vEA0ZsbW-R0lH9939EWscFgXPR7u4jyNaAC5-7LHA/s320/higgs2.gif" width="320" /></a></div>
<br />
Thus, the actual particle, which we observe, and call the Higgs is actually a complicated object made from two <a href="http://axelmaas.blogspot.de/2012/11/a-higgs-and-higgs-make-what.html">Higgs particles</a>. However, one of those is so much eclipsed by the other that it looks like just a single one. And a very tiny correction to it.<br />
<br />
So far, this does not seem to be something where it is necessary to worry about.<br />
<br />
However, there are many and good reasons to believe that the standard model is <a href="http://axelmaas.blogspot.de/2012/05/above-and-beyond.html">not the end of particle physics</a>. There are many, many blogs out there, which explain the reasons for this much better than I do. However, our research provides hints that what works so nicely in the standard model, may work much less so in some extensions of the <a href="http://axelmaas.blogspot.com/2018/01/finding-and-curing-disagreements.html">standard model</a>. That there the composite nature makes huge differences for experiments. This was what <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">came out</a> of our <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">numerical simulations</a>. Of course, these are not perfect. And, after all, unfortunately we did not yet discover anything beyond the standard model in experiments. So we cannot test our ideas against actual experiments, which would be the best thing to do. And without experimental support such an enormous shift in paradigm seems to be a bit far fetched. Even if our numerical simulations, which are far from perfect, support the idea. Formal ideas supported by numerical simulations is just not as convincing as experimental confirmation.<br />
<br />
So, is this hopeless? Do we have to wait for new physics to make its appearance?<br />
<br />
Well, not yet. In the figure above, there was 'something'. So, the ideas make also a statement that even within the standard model there should be a difference. The only question is, what is really the value of a 'little bit'? So far, experiments did not show any deviations from the usual picture. So 'little bit' needs indeed to be really rather small. But we have a <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">calculation prescription</a> for this 'little bit' for the standard model. So, at the very least what we can do is to make a calculation for this 'little bit' in the standard model. We should then see if the value of 'little bit' may already be so large that the basic idea is ruled out, because we are in conflict with experiment. If this is the case, this would raise a lot of question on the basic theory, but well, experiment rules. And thus, we would need to go back to the drawing board, and get a better understanding of the theory.<br />
<br />
Or, we get something which is in agreement with current experiment, because it is smaller then the current experimental precision. But then we can make a statement how much better experimental precision needs to become to see the difference. Hopefully the answer will not be so much that it will not be possible within the next couple of decades. But this we will see at the end of the calculation. And then we can decide, whether we will get an experimental test.<br />
<br />
Doing the calculations is actually not so simple. On the one hand, they are technically challenging, even though our method for it is rather well under control. But it will also not yield perfect results, but hopefully good enough. Also, it depends strongly on the type of experiment how simple the calculations are. We did a <a href="http://axelmaas.blogspot.com/2017/04/a-shift-in-perspective-or-what-makes.html">first few steps</a>, though for a type of experiment not (yet) available, but hopefully in about twenty years. There we saw that not only the type of experiment, but also the type of measurement matters. For some measurements the effect will be much smaller than for others. But we are not yet able to predict this before doing the calculation. There, we need still much better understanding of the underlying mathematics. That we will hopefully gain by doing more of these calculations. This is a project I am currently pursuing with a number of master students for various measurements and at various levels. Hopefully, in the end we get a clear set of predictions. And then we can ask our colleagues at experiments to please check these predictions. So, stay tuned.<br />
<br />
By the way: This is the standard cycle for testing new ideas and theories. Have an idea. Check that it fits with all existing experiments. And yes, this may be very, very many. If your idea passes this test: Great! There is actually a chance that it can be right. If not, you have to understand why it does not fit. If it can be fixed, fix it, and start again. Or have a new idea. And, at any rate, if it cannot be fixed, have a new idea. When you got an idea which works with everything we know, use it to make a prediction where you get a difference to our current theories. By this you provide an experimental test, which can decide whether your idea is the better one. If yes: Great! You just rewritten our understanding of nature. If not: Well, go back to fix it or have a new idea. Of course, it is best if we have already an experiment which does not fit with our current theories. But there we are at this stage a little short off. May change again. If your theory has no predictions which can be testable in any foreseeable future experimentally. Well, that is a good question how to deal with this, and there is not yet a consensus how to proceed.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-57025700899786246062018-03-29T06:09:00.008-07:002018-03-29T06:09:54.824-07:00Asking questions leads to a change of mindIn this entry, I would like to digress a bit from my usual discussion of our physics research subject. Rather, I would like to talk a bit about how I do this kind of research. There is a twofold motivation for me to do this.<br />
<br />
One is that I am currently teaching, together with somebody from the philosophy department, a <a href="https://online.uni-graz.at/kfu_online/wbLv.wbShowLVDetail?pStpSpNr=503025">course on science philosophy of physics</a>. It cam to me as a surprise that one thing the students of philosophy are interested in is, how I think. What are the objects, or subjects, and how I connect them when doing research. Or even when I just think about a physics theory. The other is the <a href="https://arxiv.org/abs/1712.04721">review</a> I have have <a href="http://axelmaas.blogspot.co.at/2017/01/writing-review.html">recently</a> <a href="http://axelmaas.blogspot.co.at/2017/11/reaching-closure-completing-review.html">written</a>. Both topics may seem unrelated at first. But there is deep connection. It is less about what I have written in the review, but rather what led me up to this point. This requires some historical digression in my own research.<br />
<br />
In the very beginning, I started out with doing research on the <a href="http://axelmaas.blogspot.de/2010/01/lthe-forces-of-nature-iii-strong-force.html">strong interactions</a>. One of the features of the strong interactions is that the supposed elementary particles, <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">quarks and gluons</a>, are never seen separately, but only in combinations as <a href="http://axelmaas.blogspot.de/2010/01/forces-of-nature-iii-strong-force-part.html">hadrons</a>. This is a phenomenon which is called <a href="http://axelmaas.blogspot.de/2012/04/why-colors-cannot-be-seen.html">confinement</a>. It always somehow presented as a mystery. And as such, it is interesting. Thus, one question in my early research was how to understand this phenomenon.<br />
<br />
Doing that I came across an interesting result from the 1970ies. It appears that a, at first sight completely unrelated, effect is very intimately related to confinement. At least in some theories. This is the <a href="http://axelmaas.blogspot.de/2010/03/higgs-effect.html">Brout-Englert-Higgs effect</a>. However, we seem to observe the particles responsible for and affected by the Higgs effect. And indeed, at that time, I was still thinking that the particles affected by the Brout-Englert-Higgs effect, especially the <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">Higgs and the W and Z bosons</a>, are just ordinary, observable particles. When one reads my <a href="http://arxiv.org/abs/1007.0729">first paper</a> of this time on the Higgs, this is quite obvious. But then there was the results of the 1970ies. It stated that, on a very formal level, there should be no difference between confinement and the Brout-Englert-Higgs effect, in a very definite way.<br />
<br />
Now the implications of that serious sparked my interest. But I thought this would help me to understand confinement, as it was still very ingrained into me that confinement is a particular feature of the strong interactions. The mathematical connection I just took as a curiosity. And so I started to do extensive <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">numerical simulations</a> of the situation.<br />
<br />
But while trying to do so, things which did not add up started to accumulate. This is probably most evident in a <a href="https://arxiv.org/abs/1110.0908">conference proceeding</a> where I tried to put sense into something which, with hindsight, could never be interpreted in the way I did there. I still tried to press the result into the scheme of thinking that the Higgs and the W/Z are physical particles, which we observe in experiment, as this is the standard lore. But the data would not fit this picture, and the more and better data I gathered, the more conflicted the results became. At some point, it was clear that something was amiss.<br />
<br />
At that point, I had two options. Either keep with the concepts of confinement and the Brout-Englert-Higgs effect as they have been since the 1960ies. Or to take the data seriously, assuming that these conceptions were wrong. It is probably signifying my difficulties that it took me more than a year to come to terms with the results. In the end, the decisive point was that, as a theoretician, I needed to take my theory seriously, no matter the results. There is no way around it. And it gave a prediction which did not fit my view of the experiments than necessarily either my view was incorrect or the theory. The latter seemed more improbable than the first, as it fits experiment very well. So, finally, I found an explanation, which was consistent. And this explanation accepted the curious mathematical statement from the 1970ies that confinement and the Brout-Englert-Higgs effect are qualitatively the same, but not quantitatively. And thus the conclusion was what we observe are not really the Higgs and the W/Z bosons, but rather some interesting composite objects, just like hadrons, which due to a quirk of the theory just behave almost as if they are the elementary particles.<br />
<br />
This was still a very challenging thought to me. After all, this was quite contradictory to usual notions. Thus, it came as a very great relief to me that during a trip a couple months later someone pointed me to a few, almost forgotten by most, papers from the early 1980ies, which gave, for a completely different reason, the <a href="http://axelmaas.blogspot.co.at/2015/08/looking-for-one-thing-in-another.html">same answer</a>. Together with my own observation, this made click, and everything started to fit together - the 1970ies curiosity, the standard notions, my data. That I<a href="http://arxiv.org/abs/1205.6625"> published</a> in the mid of 2012, even though this still lacked some more systematic stuff. But it required still to shift my thinking from agreement to really understanding. That came then in the years to follow.<br />
<br />
The important click was to recognize that confinement and the Brout-Englert-Higgs effect are, just as pointed out in the 1970ies mathematically, really just two faces to the same underlying phenomena. On a very abstract level, essentially all particles which make up the standard model, are really just a means to an end. What we observe are objects which are described by them, but which they are not themselves. They emerge, just like hadrons emerge in the strong interaction, but with very different technical details. This is actually very deeply connected with the concept of <a href="http://axelmaas.blogspot.de/2010/10/electromagnetism-photons-and-symmetry.html">gauge</a> <a href="http://axelmaas.blogspot.co.at/2013/09/blessing-and-bane-redundancy.html">symmetry</a>, but this becomes quickly technical. Of course, since this is fundamentally different from the usual way, this required confirmation. So we went, made <a href="http://axelmaas.blogspot.de/2015/03/can-we-tell-when-unification-works.html">predictions</a> which could distinguish between the standard way of thinking and this way of thinking, and tested them. And it <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">came out</a> as we predicted. So, seems we are on the right track. And all details, all the if, how, and why, and all the technicalities and math you can find in the review.<br />
<br />
To make now full circle to the starting point: That what happened during this decade in my mind was that the way I thought about how the physical theory I tried to describe, the standard model, changed. In the beginning I was thinking in terms of particles and their interactions. Now, very much motivated by gauge symmetry, and, not incidental, by its more deeper <a href="http://axelmaas.blogspot.co.at/2016/10/redundant-ghosts.html">conceptual challenges</a>, I think differently. I think no longer in terms of the elementary particles as entities themselves, but rather as auxiliary building blocks of actually experimentally accessible quantities. The standard 'small-ball' analogy went fully away, and there formed, well, hard to say, a new class of entities, which does not necessarily has any analogy. Perhaps the best analogy is that of, no, I really do not know how to phrase it. Perhaps at a later time I will come across something. Right now, it is more math than words.<br />
<br />
This also transformed the way how I think about the original problem, confinement. I am curious, where this, and all the rest, will lead to. For now, the next step will be to go ahead from simulations, and see whether we can find some way how to test this actually in experiment. We have some ideas, but in the end, it may be that present experiments will not be sensitive enough. Stay tuned.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-83449605025571609222018-02-07T03:18:00.000-08:002018-02-07T03:18:18.860-08:00How large is an elementary particle?Recently, in the context of a master thesis, our group has begun to determine the size of the <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">W boson</a>. The natural questions on this project is: Why do you do that? Do we not know it already? And does elementary particles have a size at all?<br /><br />It is best to answer these questions in reverse order.<br /><br />So, do elementary particles have a size at all? Well, elementary particles are called elementary as they are the most basic constituents. In our theories today, they start out as pointlike. Only particles made from other particles, so-called bound states like a nucleus or a <a href="http://axelmaas.blogspot.de/2010/01/forces-of-nature-iii-strong-force-part.html">hadron</a>, have a size. And now comes the but.<br /><br />First of all, we do not yet know whether our elementary particles are really elementary. They may also be bound states of even more elementary particles. But in experiments we can only determine upper bounds to the size. Making better experiments will reduce this upper bound. Eventually, we may see that a particle previously thought of as point-like has a size. This has happened quite frequently over time. It always opened up a new level of elementary particle theories. Therefore measuring the size is important. But for us, as theoreticians, this type of question is only important if we have an idea about what could be the more elementary particles. And while some of our <a href="http://axelmaas.blogspot.de/2012/05/above-and-beyond.html">research</a> is going into this <a href="http://axelmaas.blogspot.de/2015/02/take-your-theory-seriously.html">direction</a>, this project is not.<br /><br />The other issue is that <a href="http://axelmaas.blogspot.co.at/2011/09/why-mass-depends-on-energy.html">quantum effects</a> give all elementary particles an 'apparent' size. This comes about by how we measure the size of a particle. We do this by shooting some other particle at it, and measure how strongly it becomes deflected. A truly pointlike particle has a very characteristic reflection profile. But quantum effects allow for additional particles to be created and destroyed in the vicinity of any particle. Especially, they allow for the existence of another particle of the same type, at least briefly. We cannot distinguish whether we hit the original particle or one of these. Since they are not at the same place as the original particle, their average distance looks like a size. This gives even a pointlike particle an apparent size, which we can measure. In this sense even an elementary particle has a size.<br /><br />So, how can we then distinguish this size from an actual size of a bound state? We can do this by calculations. We determine the apparent size due to the quantum fluctuations and compare it to the measurement. Deviations indicate an actual size. This is because for a real bound state we can scatter somewhere in its structure, and not only in its core. This difference looks pictorially like this:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZkAI5L1_3p75CwZoxBMRFZJOna5i765EsNoG6tY4SdZ6uA6-mtPSzJfFFSFM-iv0uGx2S8WcuhxCehwzzR4Dqrj36jaC4wKqJ22fzHRDAUz7OMRW_BotlI0yCml7C6UuEr9OTfPKFYmjg/s1600/bspl-illi.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="794" data-original-width="1058" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZkAI5L1_3p75CwZoxBMRFZJOna5i765EsNoG6tY4SdZ6uA6-mtPSzJfFFSFM-iv0uGx2S8WcuhxCehwzzR4Dqrj36jaC4wKqJ22fzHRDAUz7OMRW_BotlI0yCml7C6UuEr9OTfPKFYmjg/s400/bspl-illi.gif" width="400" /></a></div>
<br /><br />So, do we know the size already? Well, as said, we can only determine upper limits. Searching for them is difficult, and often goes via detours. One of such detours are so-called <a href="http://axelmaas.blogspot.co.at/2013/10/looking-for-something-out-of-ordinary.html">anomalous couplings</a>. Measuring how they depend on energy provides indirect information on the size. There is an active program at <a href="http://www.cern.ch/">CERN</a> underway to do this experimentally. The results are so far say that the size of the W is below 0.0000000000000001 meter. This seems tiny, but in the world of particle physics this is not that strong a limit.<br /><br />And now the interesting question: Why do we do this? As written, we do not want to make the W a bound state of something new. But one of our main <a href="http://axelmaas.blogspot.de/2012/11/a-higgs-and-higgs-make-what.html">research</a> <a href="http://axelmaas.blogspot.de/2015/01/what-is-so-important-to-me-about-higgs.html">topics</a> is driven by an interesting theoretical structure. If the standard model is taken seriously, the particle which we observe in an experiment and call the W is actually not the W of the underlying theory. <a href="http://axelmaas.blogspot.co.at/2015/08/looking-for-one-thing-in-another.html">Rather</a>, it is a bound state, which is very, very similar to the elementary particle, but actually build from the elementary particles. The difference has been so small that identifying one with the other was a very good approximation up to today. But with better and better experiments may change. Thus, we need to test this.<br /><br />Because then the thing we measure is a bound state it should have a, probably tiny, size. This would be a hallmark of this theoretical structure. And that we understood it. If the size is such that it could be actually measured at CERN, then this would be an important test of our theoretical understanding of the standard model.<br /><br />However, this is not a simple quantity to calculate. Bound states are intrinsically complicated. Thus, we use <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">simulations</a> for this purpose. In fact, we actually go over the same detour as the experiments, and will determine an anomalous coupling. From this we then infer the size indirectly. In addition, the need to perform efficient simulations forces us to simplify the problem substantially. Hence, we will not get the perfect number. But we may get the order of magnitude, or be perhaps within a factor of two, or so. And this is all we need to currently say whether a measurement is possible, or whether this will have to wait for the next generation of experiments. And thus whether we will know whether we understood the theory within a few years or within a few decades.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com2tag:blogger.com,1999:blog-3289825502161718378.post-50044847597572326542018-01-22T08:52:00.000-08:002018-01-22T08:54:34.887-08:00Finding - and curing - disagreementsThe topic of grand-unified theories came up in the blog <a href="http://axelmaas.blogspot.de/2015/03/can-we-tell-when-unification-works.html">several</a> <a href="http://axelmaas.blogspot.de/2014/05/why-does-chemistry-work.html">times</a>, most recently <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">last year in January</a>. To briefly recap, such theories, called GUTs for short, predict that all <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">three forces</a> between elementary particles emerge from a single master force. That would explain a lot of unconnected observations we have in particle physics. For example, <a href="http://axelmaas.blogspot.de/2014/05/why-does-chemistry-work.html">why atoms are electrically neutral</a>. The latter we can describe, but not yet explain.<br />
<br />
However, if such a GUT exists, then it must not only explain the forces, but also somehow why we see the numbers and kinds of elementary particles we observe in nature. And now things become complicated. As discussed in the <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">last entry on GUTs</a> there maybe a serious issue in how we determine which particles are actually described by such a theory.<br />
<br />
To understand how this issue comes about, I need to put together many different things my research partners and I have worked on during the last couple of years. All of these issues are actually put into an expert language in the review of which I talked in the <a href="http://axelmaas.blogspot.co.at/2017/11/reaching-closure-completing-review.html">previous entry</a>. It is now finished, and if your interested, you can get it free from <a href="https://arxiv.org/abs/1712.04721">here</a>. But it is very technical.<br />
<br />
So, let me explain it less technically.<br />
<br />
Particle physics is actually superinvolved. If we would like to write down a theory which describes what we see, and only what we see, it would be terribly complicated. It is much more simple to introduce <a href="http://axelmaas.blogspot.co.at/2013/09/blessing-and-bane-redundancy.html">redundancies</a> in the description, so-called <a href="http://axelmaas.blogspot.de/2010/10/electromagnetism-photons-and-symmetry.html">gauge</a> <a href="http://axelmaas.blogspot.de/2011/02/in-previous-discussion-it-was-described.html">symmetries</a>. This makes life much easier, though still not easy. However, the most prominent feature is that we add auxiliary particles to the game. Of course, they cannot be really seen, as they are just auxiliary. Some of them are very obviously unphysical, called therefore <a href="http://axelmaas.blogspot.co.at/2016/10/redundant-ghosts.html">ghosts</a>. They can be taken care of comparatively simply. For others, this is less simple.<br />
<br />
Now, it turns out that the <a href="http://axelmaas.blogspot.de/2010/02/forces-of-nature-iv-weak-force.html">weak interaction</a> is a very special beast. In this case, there is a <a href="http://axelmaas.blogspot.de/2015/01/what-is-so-important-to-me-about-higgs.html">unique one-to-one identification</a> between a really observable particle and an auxiliary particle. Thus, it is almost correct to identify both. But this is due to the very special structure of this part of particle physics.<br />
<br />
Thus, a natural question is whether, even if it is special, it is justified to do the same for other theories. Well, in some cases, <a href="http://axelmaas.blogspot.co.at/2016/02/more-than-one-higgs-means-more-structure.html">this seems to be the case</a>. But we <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">suspected</a> that this may not be the case in general. And especially not in GUTs.<br />
<br />
Now, recently we were going about this much more systematically. You can again access the (very, very technical) result for free <a href="https://arxiv.org/abs/1709.07477">here</a>. There, we looked at a very generic class of such GUTs. Well, we actually looked at the most relevant part of them, and still by far not all of them. We also ignored a lot of stuff, e.g. what would become <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">quarks and leptons</a>, and concentrated only on the generalization of the weak interaction and the <a href="http://axelmaas.blogspot.de/2010/03/higgs-effect.html">Higgs</a>.<br />
<br />
We then checked, based on our earlier <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">experiences and methods</a>, whether a one-to-one identification of experimentally accessible and auxiliary particles works. And it does essentially never. Visually, this result looks like<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjL1gBe1RotUSPjE32ejIpa7n2pvq8ql3AsrT-mCEwrd2dqa4_Rva_bFfFrM8ndyyEnoXG3zYDG6jTt79rDSj3XECT8iMuHq6HbX6yBrDGEi3Z4JIaTUYK42IYj-aVauI-3ZbeATcMzonvZ/s1600/gut-illi.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="794" data-original-width="1058" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjL1gBe1RotUSPjE32ejIpa7n2pvq8ql3AsrT-mCEwrd2dqa4_Rva_bFfFrM8ndyyEnoXG3zYDG6jTt79rDSj3XECT8iMuHq6HbX6yBrDGEi3Z4JIaTUYK42IYj-aVauI-3ZbeATcMzonvZ/s400/gut-illi.gif" width="400" /></a></div>
<br />
<br />
On the left, it is seen that everything works nicely with a one-to-one identification in the standard model. On the right, if one-to-one identification would work in a GUT, everything would still be nice. But a our more precise calculation shows that the actually situation, which would be seen in an experiment, is different. There is non one-to-one identification possible. And thus the prediction of the GUT differs from what we already see inn experiments. Thus, a previously good GUT candidate is no longer good.<br />
<br />
Though more checks are needed, as always, this is a baffling, and at the same time very discomforting, result.<br />
<br />
Baffling as we did originally expect to have problems under very special circumstances. It now appears that actually the standard model of particles is the very special case, and having problems is the standard.<br />
<br />
It is discomforting because in the powerful method of <a href="http://axelmaas.blogspot.de/2012/01/perturbation-theory.html">perturbation theory</a> the one-to-one identification is essentially always made. As this tool is widely used, this seems to question the validity of many predictions on GUTs. That could have far-reaching consequences. Is this the case? Do we need to forget everything about GUTs we learned so far?<br />
<br />
Well, not really, for two reasons. One is that we also showed that methods almost as easily handleable as perturbation theory can be used to fix the problems. This is good, because more powerful methods, like the <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">simulations</a> we <a href="http://axelmaas.blogspot.co.at/2017/01/can-we-tell-when-unification-works-some.html">used before</a>, are much more cumbersome. However, this leaves us with the problem of having made so far wrong predictions. Well, this we cannot change. But this is just normal scientific progress. You try, you check, you fail, you improve, and then you try again.<br />
<br />
And, in fact, this does not mean that GUTs are wrong. Just that we need to consider somewhat different GUTs, and make the predictions more carefully next time. Which GUTs we need to look at we still need to figure out, and that will not be simple. But, fortunately, the improved methods mentioned beforehand can use much of what has been done so far, so most technical results are still unbelievable useful. This will help enormously in finding GUTs which are applicable, and yield a consistent picture, without the one-to-one identification. GUTs are not dead. They likely just need a bit of changing.<br />
<br />
This is indeed a dramatic development. But one which fits logically and technically to the improved understanding of the theoretical structures underlying particle physics, which were developed over the last decades. Thus, we are confident that this is just the next logical step in our understanding of how particle physics works.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-8573782994183401372017-11-30T09:15:00.002-08:002017-11-30T09:15:20.510-08:00Reaching closure – completing a review
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">I
did not publish anything here within the last few months, as the
<a href="http://axelmaas.blogspot.dk/2017/01/writing-review.html">review I am writing</a>
took up much more time than expected. A lot of interesting project
developments happened also during this time. I will write on them as
well </span><span lang="en-US">later</span><span lang="en-US">, so
that nobody will miss out on the insights we gained and the fun we
had with them.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">But
now, I want to write about how the review comes along. It has now
grown into a veritable </span><span lang="en-US">almost </span><span lang="en-US">120
page document. And actually most of it </span><span lang="en-US">is
</span><span lang="en-US">texts and formulas, and </span><span lang="en-US">only
very</span><span lang="en-US"> few figures. This makes for a lot of
content. Right now, it has reached the status of a release candidate
2. This means I have distributed it to many of my colleagues </span><span lang="en-US">to
comment on it</span><span lang="en-US">. I also used the draft as
lecture notes for a lecture on its contents at a winter school </span><span lang="en-US">i</span><span lang="en-US">n
Odense/Denmark (where I actually wrote this blog entry). </span><span lang="en-US">Why?
Because I wanted to have feedback. What can be understood, and what
may I have misunderstood? After all, this review not only looks at my
own research. Rather, it compiles knowledge from more than a hundred
scientists over 45 years. In fact, some of the results I write about
have been obtained before I was born. </span><span lang="en-US">E</span><span lang="en-US">specially,</span><span lang="en-US">
I could have overlooked results. With by now dozens of new papers per
day, this can easily happen. I have collected more than 330 relevant
articles, which I refer to in the review.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">A</span><span lang="en-US">nd,
of course, I could have misunderstood other people’s results or
made mistakes. This needs to be avoided in a review as good as
possible.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">I</span><span lang="en-US">ndeed,
I had many discussions by now on various aspects of the research I
review. I got comments and was challenged. In the end, there was
always either a conclusion or the insight that some points, believed
to be clear, are not as entirely clear as it seemed. There are always
more loopholes, more subtleties, than one anticipates. </span><span lang="en-US">By
this, the review became better, and could collect more insights from
many brilliant scientists. And likewise I myself learned a lot.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">I</span><span lang="en-US">n
the end, I learned two very important lessons about the physics I
review.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">The
first is that many more things are connected than I expected. Some
issues, which looked to my like a parenthetical remark in the
beginning became first remarks at more than one place and ultimately
became an issue of their on.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">The
second is that the <a href="http://axelmaas.blogspot.dk/2009/10/let-me-introduce-players-in-standard.html">standard modelof particle physics</a> is even more special and more balanced than I
thought. I was never really thinking that the standard model is so
terrible special. Just one theory among many which happen to fit
experiments. But really it is an extremely finely adjusted machinery.
Every cog in it is important, and even slight changes will make
everything fall apart. All the elements are in constant connection
with each other, and influence each other.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">Does
this mean anything? Good question. Perhaps it is a sign of an
underlying ordering principle. But if it is, I cannot see it (yet?).
Perhaps this is just an expression of how a law of nature must be –
perfectly balanced. At any rate, it gave me a new perspective of what
the standard model is.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">So,
as I anticipated writing this review gave me a whole new </span><span lang="en-US">perspective</span><span lang="en-US">
and a lot of insights. Partly by formulating questions and answers
more precisely. But, and probably more importantly, I had to explain
it to others, and to either </span><span lang="en-US">successfully
</span><span lang="en-US">defend or adapt it </span><span lang="en-US">or
even correct it</span><span lang="en-US">.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">In
addition, t</span><span lang="en-US">wo</span><span lang="en-US"> of
the most important lessons </span><span lang="en-US">about
understanding physics </span><span lang="en-US">I learned were the
following:</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">One:
Take your theory seriously. Do not take a shortcut or use some
experience. Literally understand what it means and only then start to
interpret.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">Two:
</span><span lang="en-US">Pose your questions (and answers) clearly.
Every statement should have a well-defined meaning. Never be vague
when you want to make a scientific statement. Be always able to back
up a question of “what do you mean by this?” by a precise
definition. </span><span lang="en-US">This seems obvious, but is
something you tend to be cavalier about. Don’t.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">So,
writing a review not only helps in summarizing knowledge. It also
helps to understand this knowledge and realize its implications. And,
probably fortunately, it poses new questions. What they are, and what
we do about, this is something I will write about in the future.</span></div>
<div class="western" style="margin-bottom: 0cm;">
<br />
</div>
<div class="western" style="margin-bottom: 0cm;">
<span lang="en-US">So,
how does it proceed now? In two weeks I have to deliver the review to
the journal which mandated it. At the same time (watch my <a href="https://twitter.com/axelmaas">twitteraccount</a>) it will become available on the preprint server <a href="http://arxiv.org/">arxiv.org</a>,
the st</span><span lang="en-US">a</span><span lang="en-US">ndard
repository of all </span><span lang="en-US">elementary </span><span lang="en-US">particle
physics knowledge. Then you can see for yourself what I wrote, </span><span lang="en-US">and
wrote about</span></div>
Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-18406082284206630792017-07-20T08:38:00.001-07:002017-07-20T08:38:12.281-07:00Getting betterOne of our main tools in our research are <a href="http://axelmaas.blogspot.de/2012/02/simulating-universe.html">numerical simulations</a>. E.g. the research of the <a href="http://axelmaas.blogspot.co.at/2017/07/tackling-ambiguities.html">previous entry</a> would have been impossible without.<br />
<br />
Numerical simulations require computers to run them. And even though computers become continuously more powerful, they are limited in the end. Not to mention that they cost money to buy and to use. Yes, also using them is expensive. Think of the electricity bill or even having space available for them.<br />
<br />
So, to reduce the costs, we need to use them efficiently. That is good for us, because we can do more research in the same time. And that means that we as a society can make scientific progress faster. But it also reduces financial costs, which in fundamental research almost always means the taxpayer's money. And it reduces the environmental stress which we exercise by having and running the computers. That is also something which should not be forgotten.<br />
<br />
So what does efficiently mean?<br />
<br />
Well, we need to write our own computer programs. What we do nobody did before us. Most of what we do is really the edge of what we understand. So nobody was here before us and could have provided us with computer programs. We do them ourselves.<br />
<br />
For that to be efficient, we need three important ingredients.<br />
<br />
The first seems to be quite obvious. The programs should be correct before we use them to make a large scale computation. It would be very wasteful to run on a hundred computers for several months, just to figure out it was all for naught, because there was an error. Of course, we need to test them somewhere, but this can be done with much less effort. But this takes actually quite some time. And is very annoying. But it needs to be done.<br />
<br />
The next two issues seems to be the same, but are actually subtly different. We need to have fast and optimized algorithms. The important difference is: The quality of the algorithm decides how fast it can be in principle. The actual optimization decides to which extent it uses this potential.<br />
<br />
The latter point is something which requires a substantial amount of experience with programming. It is not something which can be learned theoretically. And it is more of a craftsmanship than anything else. Being good in optimization can make a program a thousand times faster. So, this is one reason why we try to teach students programming early, so that they can acquire the necessary experience before they enter research in their thesis work. Though there is still today research work which can be done without computers, it has become markedly less over the decades. It will never completely vanish, though. But it may well become a comparatively small fraction.<br />
<br />
But whatever optimization can do, it can do only so much without good algorithms. And now we enter the main topic of this entry.<br />
<br />
It is not only the code which we develop by ourselves. It is also the algorithms. Because again, they are new. Nobody did this before. So it is also up to us to make them efficient. But to really write a good algorithm requires knowledge about its background. This is called domain-specific knowledge. Knowing the scientific background. One reason more why you cannot get it off-the-shelf. Thus, if you want to calculate something new in research using computer simulations that means usually sitting down and writing a new algorithm.<br />
<br />
But even once an algorithm is written down this does not mean that it is necessarily already the fastest possible one. Also this requires on the one hand experience, but even more so it is something new. And it is thus research as well to make it fast. So they can, and need to be, made better.<br />
<br />
Right now I am supervising two bachelor theses where exactly this is done. The algorithms are indeed directly those which are involved with the <a href="http://axelmaas.blogspot.co.at/2017/07/tackling-ambiguities.html">research</a> mentioned in the beginning. While both are working on the same algorithm, they do it with quite different emphasis.<br />
<br />
The aim in one project is to make the algorithm faster, without changing its results. It is a classical case of improving an algorithm. If successful, it will make it possible to push the boundaries of what projects can be done. Thus, it makes computer simulations more efficient, and thus satisfies allows to do more research. One goal reached. Unfortunately the 'if' already tells that, as always with research, there is never a guarantee that it is possible. But if this kind of research should continue, it is necessary. The only alternative is waiting for a decade for the computers to become faster, and doing something different in the time in between. Not a very interesting option.<br />
<br />
The other one is a little bit different. Here, the algorithm should be modified to serve a slightly different goal. It is not a fundamentally different goal, but subtly different so. Thus, while it does not create a fundamentally new algorithm, it still does create something new. Something, which will make a different kind of research possible. Without the modification, the other kind of research may not be possible for some time to come. But just as it is not possible to guarantee that an algorithm can be made more efficient, it is also not always possible that an algorithm with any reasonable amount of potential can be created at all. So this is also true research.<br />
<br />
Thus, it remains exciting of what both theses will ultimately lead to.<br />
<br />
So, as you see, behind the scenes research is quite full of the small things which make the big things possible. Both of these projects are probably closer to our everyday work than most of the things I have been posting before. The everyday work in research is quite often grinding. But, as always, this is what makes the big things ultimately possible. Without such projects as these two theses, our progress would be slowed down to a snail's speed.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0tag:blogger.com,1999:blog-3289825502161718378.post-56240709333453287862017-07-19T01:00:00.005-07:002017-07-19T01:00:51.798-07:00Tackling ambiguitiesI have recently published a <a href="https://arxiv.org/abs/1705.03812">paper</a> with a rather lengthy and abstract title. I wanted to enlighten in this entry a little bit what is going on.<br />
<br />
The paper is actually on a problem which occupies me by now since <a href="http://axelmaas.blogspot.de/2012/04/groundwork.html">more than a decade</a>. And this is the problem how to really define what we mean when we talk about <a href="http://axelmaas.blogspot.de/2009/10/let-me-introduce-players-in-standard.html">gluons</a>. The reason for this problem is <a href="http://axelmaas.blogspot.de/2013/09/blessing-and-bane-redundancy.html">a certain ambiguity</a>. This ambiguity arises because it is often much more convenient to have auxiliary additional stuff around to make calculations simple. But then you have to deal with this <a href="http://axelmaas.blogspot.co.at/2015/10/being-formal.html">additional stuff</a>. In a <a href="http://axelmaas.blogspot.co.at/2016/10/redundant-ghosts.html">paper</a> last year I noted that the amount of stuff is much larger than originally anticipated. So you have to deal with more stuff.<br />
<br />
The aim of the research leading to the paper was to make progress with that.<br />
<br />
So what did I do? To understand this, it is first necessary to say a few words about how we describe gluons. We describe them by mathematical functions. The simplest such mathematical functions makes, loosely speaking, a statement about how probable it is that a gluon moves from one point to another. Since a fancy word for moving is propagating, this function is called a propagator.<br />
<br />
So the first question I posed was whether the ambiguity in dealing with the stuff affects this. You may ask whether this should happen at all. Is a gluon not a particle? Should this not be free of ambiguities? Well, yes and no. A particle which we actually detect should be free of ambiguities. But gluons are not detected. Gluons are, in fact, never seen directly. They are <a href="http://axelmaas.blogspot.de/2012/04/why-colors-cannot-be-seen.html">confined</a>. This is a very peculiar feature of the <a href="http://axelmaas.blogspot.de/2010/01/lthe-forces-of-nature-iii-strong-force.html">strong force</a>. And one which is not satisfactorily fully understood. But it is experimentally well established.<br />
<br />
Since therefore something happens to gluons before we can observe them, there is now a way out. If the gluon is ambiguous, then this ambiguity has to be canceled by whatever happens to it. Then whatever we detect is not ambiguous. But cancellations are fickle things. If you are not careful in your calculations, something is left uncanceled. And then your results become ambiguous. This has to be avoided. Of course, this is purely a problem for us theoreticians. The experimentalists never have this problem. A long time ago I actually already wrote together with a few other people a <a href="https://arxiv.org/abs/1007.3901">paper</a> on this, showing how it may proceed.<br />
<br />
So, the natural first step is to figure out what you have to cancel. And therefore to map the ambiguity in its full extent. The possibilities discussed since decades look roughly like this:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp4B3t4VwOFRz6mKCpOtMp-k-5I5oKSVnWd4thCnAUrGzrP1aKjeGOXKmjjk_edBRko3_3z8rTkCZrI_cNH2d3Hoz4CUkr_jKv6NOf25yKZFE988qyVrmAe4C-FlDeZhmgUixP2gY7MTGv/s1600/gribov1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="400" data-original-width="640" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp4B3t4VwOFRz6mKCpOtMp-k-5I5oKSVnWd4thCnAUrGzrP1aKjeGOXKmjjk_edBRko3_3z8rTkCZrI_cNH2d3Hoz4CUkr_jKv6NOf25yKZFE988qyVrmAe4C-FlDeZhmgUixP2gY7MTGv/s320/gribov1.png" width="320" /></a></div>
<br />
As you see, at short distances there is (essentially) no ambiguity. This is actually quite well understood. It is a feature very deeply embedded in the strong interaction. It has to do with the fact that, despite its name, the strong interaction makes itself less known the shorter the distance. But for weak effects we have <a href="http://axelmaas.blogspot.de/2012/01/perturbation-theory.html">very precise tools</a>, and we therefore understand it.<br />
<br />
On the other hand at long distances - well, there we knew for a long time not even qualitatively what is going on for sure. But, finally, over the decades, we were able to constrain the behavior at least partly. Now, I tested a large part of the remaining range of ambiguities. In the end, it indeed mattered little. There is almost no effect left of the ambiguity on the behavior of the gluon. So, it seems we have this under control.<br />
<br />
Or do we? One of the important things in research is that it is never sufficient to confirm your result just by looking at a single thing. Either your explanation fits everything we see and measure, or it cannot be the full story. Or may even be wrong and the agreement with part of the observations is just a lucky coincidence. Well, actually not lucky. Rather terrible, since this misguides you.<br />
<br />
Of course, doing all in one go is a horrendous amount of work, and so you work on a few at the time. Preferably, you first work on those where the most problems are expected. It is just ultimately that you need to have covered everything. But you cannot stop and claim victory before you did.<br />
<br />
So I did, and looked in the paper at a handful of other quantities. And indeed, in some of them there remain effects. Especially, if you look at how strong the strong interaction is, depending on the distance where you measure it, something remains:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQF8bHY8F7A2KO7ZfhZgERsgnpYIfsg8JwN0YqMoZ_OlxY1hgMf0lMiMhqv6fv38iUdCio7qhtXWGksfR0cCxM9w3NnA12eRoPH02h5S8kG0qIZNL55azC7QG2lLC4orQqJsxEiRJF8Pya/s1600/gribov2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="400" data-original-width="640" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQF8bHY8F7A2KO7ZfhZgERsgnpYIfsg8JwN0YqMoZ_OlxY1hgMf0lMiMhqv6fv38iUdCio7qhtXWGksfR0cCxM9w3NnA12eRoPH02h5S8kG0qIZNL55azC7QG2lLC4orQqJsxEiRJF8Pya/s320/gribov2.png" width="320" /></a></div>
<br />
The effects of the ambiguity are thus not qualitative. So it does not change our qualitative understanding of how the strong force works. But there remains some quantitative effect, which we need to take into account.<br />
<br />
There is one more important side effect. When I calculated the effects of the ambiguity, I learned also to control how the ambiguity manifests. This does not alter that there is an ambiguity, nor that it has consequences. But it allows others to reproduce how I controlled the ambiguity. This is important because now two results from different sources can be put together, and when using the same control they will fit such that for experimental observables the ambiguity cancels. And thus we have achieved the goal.<br />
<br />
To be fair, however, this is currently at the level of an operative control. It is not yet a mathematically well-defined and proven procedure. As with so many cases, this still needs to be developed. But having operative control allows to develop the rigorous control easier than starting without it. So, progress has been made.Axel Maashttp://www.blogger.com/profile/16708869827696572827noreply@blogger.com0