What's Going Wrong in Particle Physics? (This is why I lost faith in science.)

if you follow news about particle physics then you know that it comes in three types it's either that they haven't found that thing they were looking for or they've come up with something new to look for which they later report not having found or it's something so boring you don't even finish reading the headline how come that particle physicists constantly make wrong predictions and what will happen next that's what we'll talk about today the list of things that particle physicists said should exist but that no one's ever seen is very long no supersymmetric particles no proton decay no Dark Matter particles no wimps no axioms no sterile neutrinos thus about as much evidence for any of those as for bigfoot though Bigfoot would probably have got me more views some particle physicists even predicted unparticles and those weren't found either it's been going like this for 50 years ever since the 1970s in the 1970s particle physics has completed what's now called the standard model the standard model of particle physics collects all the fundamental particles that matter is made of and their interactions when the model was completed not all these particles had yet been measured but one after another they were experimentally confirmed the W and that bosons were discovered in 1983 at CERN the top Quark was discovered in 1995 at formula and the last one was the Higgs boson which was founded soon in 2012. it was the final nail in the coffin of the standard model there are no more particles left to look for but particle physicists believe they'd be more to find indeed I'd guess most of them still believe this today or at least they tell you they believe it already in the 1970s they said that the standard model wasn't good enough because it collects three different fundamental forces that's the electromagnetic the strong and the weak nuclear force particle physicists wanted those to be unified to one force why because that'd be nicer theories which combine these three forces are called Grand unified theories you get them by postulating a bigger symmetry than that of the standard model grandiian fight theories guts for short reproduced the summit model in the range that it had been tested already but led to deviations in in untested ranges I'd say at the time Grant unification was a reasonable thing to try because symmetry principles had worked well in physics in the past the standard model itself was born out of symmetry principles and even though Einstein himself yes that guy again didn't use symmetry arguments we today understand his theories as realizations of certain symmetries but this time more symmetries didn't work Grand unified theories made a prediction which is that one of the constituents of atomic nuclei the proton is unstable starting in the 1980s experiments looked for proton decay they didn't see it this ruled out several models for Grant unification but you can make those models more complicated so that they remain compatible with observations that's what particle physicists did and that's where the problems began next there was the Axion the standard model contains about two dozen numbers that must be determined by experiment one of them is known as the Theta parameter experimentally it's been found to be zero or so small it's indistinguishable from zero if it was non-zero then the strong nuclear force would violate a symmetry known as CP symmetry that the Theta parameter is zero or very small is known as the strong CP problem it isn't really a problem because the standard model works just fine with simply setting the stutter parameter to zero but particle physicists don't like small numbers it's a feeling that I'm sure most of us have experienced when looking at our bank statements but particle physicists are somewhat more accepting they accept small numbers if there's a mechanism keeping it small the standard model has no such mechanism this is why to make the small theater parameter acceptable particle physicists added a mechanism to the standard model that it forced the parameter to be small but a consequence of this modification was the existence of a new particle which Frank wilcheck called the Axion in 1978 the names upon on the Symmetry axis of the mechanism and the name of an American laundry detergent because the Axion particle was a particularly clean solution unfortunately the Axion turned out to not exist if the Axion existed neutron stars would cooled very quickly which we don't observe with this argument the Axion was experimentally ruled out almost as quickly as it was introduced in 1980 but physicists didn't give up on the Axion like with Grant unification they changed the theory so that it elevate the experimental constraints the new type of Axion was introduced in 1981 and was originally called the harmless Axion it was then for someone called The Invisible Axion but today it's often just caught the Axion lots of experiments have looked and continued to look for these invisible axioms none was ever detected but physicists still look for their invisible friends we'll check by the way invented another particle 1982 which he called the femalon no one's found that either yet another flawed idea that particle physicists came up with in the 1970s is supersymmetry supersymmetry postulates that all particles in the standard model have a partner particle this idea was Dead on Arrival because those partner particles have the same masses as the standard motor particles that they belong to if they existed they'd have shown up in the first particle colliders which they did not supersymmetry was therefore amended immediately so that the supersymmetric partner particles would have much higher masses it takes High energies to produce heavy particles so it would take big particle colliders to see those heavy supersymmetric particles the first supersymmetric models made predictions that were tested in the 1990s at the large electron positron collider at CERN those predictions were falsified super symmetry was then amended again to prevent the falsified processes from happening the next bigger collider the tevatron was supposed to find them that didn't happen then they were supposed to show up at the Large Hadron Collider and that didn't happen either particle physicists continued to change and demand those super symmetric models so that they don't run into conflict with new data the reason particle physicists liked supersymmetry besides that it neatly abbreviates to Susi was that they claimed it itself what's known as the hierarchy problem that's the question of why the mass of the Higgs boson is so much smaller than the Planck Mass you may say well why not and indeed there's no reason why not the mass of the Higgs boson is the constant of nature it's one of those three parameters in the standard model this means you can't predict it you just go and measure it supersymmetry doesn't change anything about this the Higgs boson mass is still a free parameter in supersymmetric extensions of the standard model and you still can't predict it supersymmetry therefore does not explain the mass of the Higgs boson you measure it and that starts then there are all kinds of Dark Matter particles a type that's particularly popular is called weekly interacting massive particles wimps for short experiments have looked for wimps since the 1980s they haven't found them each time an experiment came back empty-handed particle physicists claimed the particles were a little bit more weakly interacting and said they needed a better detector there are more experiments that I've looked for all kinds of other particles which contain you to not find them there are headlines about this literally every couple of weeks the panda x40 experiment looked for light fermionic dark matter they didn't find it the stereo experiment looked for sterile neutrinos they didn't find them CDX didn't find light wimps Hess didn't find any evidence for wimp Annihilation the microscope experiment didn't find the fifth Force an experiment called Sensai didn't find sub GV dark matter and so on the pattern is this particle physicists invent particles make predictions for those invented particles and when these predictions are falsified they changed the model and make new predictions they say it's good science because these hypotheses are falsifiable I'm afraid most of them believe this but just because the hypothesis is falsifiable doesn't mean it's good science and no no papa didn't say that a hypothesis which is falsifiable is also scientific he said that a hypothesis which is scientific is also forsifiable in case you're a particle physicist here's a diagram that should help example tomorrow you will receive one thousand dollars from my friend the prince of Nigeria falsifiable but not scientific the best way to see that what particle physicists are doing isn't good science is by noting that it's not working good scientists should learn from their failures but particle physicists have been making the same mistake for 50 years but why is it not working I'll try to illustrate this with a simple sketch if you understand the following two minutes you can outsmart most particle physicists and you don't want to miss that opportunity do you suppose you have a bunch of data and you fit a model to it the model is this curve you can think of the model as an algorithm with input parameters if you like or just a set of equations that you work out by hand either way it's a bunch of mathematical assumptions if you make a model more complicated by adding more assumptions you can fit the data better but the more complicated the model becomes the less useful it'll be eventually the model is more complicated than the data at this point you can fit anything and the model is entirely useless this is called overfitting the best model is one that reaches a balance between Simplicity of the model and accuracy of the fit let's suppose it's this one if you get new data and the data do not agree with what was previously your best model then you improve the model this is normal scientific practice and this is probably what particle physicists think they are doing but it's not what they are doing the currently best model is the standard model and all the data agree with it so there's no reason to amend it here's what they are doing instead let's imagine that this curve is the standard model and this is all the existing data and imagine we have a particle physicist let's call him Bob Bob says that's nice but we haven't checked the model over here and he says I could make this model more complicated so that the curve goes insert this way or that way or any other way I'll pick this one call this my prediction and hey I'll publish it in PRL why do I predict it because I can because you see my model agrees with all the data so this prediction could be correct right right and it's falsifiable therefore I'm a good scientist and all of Bob's friends with all their different predictions say the same they are all good scientists every single one of them and as a result of all that good science we get any possible prediction then they do an experiment on the data come in and would you know it they agree with the standard model and Bob and all his friends say oh well no worries we'll update our prediction now the deviations are in this range where we still haven't measured it we need bigger experiments and also I'll write a new paper about it what's the problem with that procedure the problem is that those models with all their different predictions are unnecessarily complicated they should never have been put forward they are not scientific hypotheses they are made up stories like my friend the prince of Nigeria who'd send you money tomorrow though if you send me one hundred dollars today I'll have another word with him there are only two justifications for making a model more complicated the first is if you already have data that requires it we can call this an inconsistency with data the second is if the model isn't working properly it makes several predictions that contradict each other or no predictions at all we can call this an internal inconsistency and that's what's going wrong in particle physics they have no justification for making the standard model more complicated when they do it nevertheless it isn't working because that's just not how science works if you change a good model then that change should be an improvement not a complication I believe the reason they don't notice what they're doing is that they have invented all these pseudo problems that the complicated models are supposed to fix like the absence of unification or some parameters being small these aren't real problems because they don't prevent them from making predictions with the standard model they are just aesthetic misgivings in fact if you look at the list of unsolved problems in the foundations of physics on Wikipedia most problems on the list are pseudo problems I have a list in which I distinguish real from pseudo problems to which I'll leave you a link in the info below and there are a few real problems in the foundations of physics but they are difficult to solve and particle physicists don't seem to like working on them but then I repeat myself I've been giving many talks about this it hasn't made me friends among particle physicists but it's not like I'm against particle physics I like particle physics that's why I talk about those problems it bothers me that they're not making progress there are some common replies that I get from particle physicists the first is to just deny that anything is wrong because hey they are writing so many papers and holding so many conferences or they'll argue that it's sometimes just takes a long time to find evidence for a new prediction for example it took more than 30 years from the hypothesis of the neutrino to its confirmation it took took half a century to directly detect gravitational waves and so on but both of those objections are beside the point the issue isn't that it's taking a long time the issue is that particle physicists make all these wrong predictions and that they think that's business as usual the next objection they bring up is normally that yes there are all those wrong predictions but they don't matter the only thing that matters is that we haven't tested the standard model in this or that range and we should the problem with this argument is that there are thousands of possible tests we could do in physics and all of them cost money sometimes a lot of money we must decide which tests are the most promising ones and the ones most likely to lead to progress this is why we need good predictions for where something new can be found and that's why all those wrong predictions are a problem particle physicists know of course that predictions are important because that's why they always claim that some new experiment will be able to rule out this or that particle though they usually don't mention that there wasn't any reason to think those particles existed in the first place besides in which other discipline of science do we excuse thousands of wrong predictions with saying it doesn't matter another common reply I get from particle physicists is that it doesn't matter that those models are all wrong because us why they're working on it they might stumble over something else that's interesting and that's possible but it's not a good strategy for knowledge Discovery as I've already said a few times it does as a matter of fact not work also if that's really the motivation for their work then I think they should put this into their project proposals hey I don't actually think that those particles I'm going on about here exist but please give me money anyway because I'm smart and maybe while I write useless papers I'll have a good idea about something else entirely I'm sure that'll fly another objection that particle physicists often bring up is that this guessing worked in the past but if you look at past predictions in the foundations of physics which turned out to be correct and that did not just confirm an existing Theory then it was those which made a necessary change to the theory the Higgs boson for example is necessary to make the standard model work empty particles predicted by The Rock are necessary to make quantum mechanics compatible with special relativity neutrinos were necessary to explain observations three generations of quarks are necessary to explain CP violation and so on but the physicists who made those predictions didn't always know that doesn't matter the point is that we can learn from this it tells us that a good strategy is to focus on necessary changes to a model those that resolve an inconsistency with data or an internal inconsistency one final objection I want to mention usually doesn't come from particle physicists but from people in other fields who think that we need all these models to explain dark matter but that's mixing up two different things we need either dark matter or a modification of gravity to explain observations in astrophysics and cosmology but if it's dark matter then the only thing we need to explain observations is how the mass is distributed data is about the particles if they exist are unnecessary what particle physicists do is guess these unnecessary details they guess for example that those particles will be produced at some particle collider which then doesn't happen so what will happen to particle physicists well if you extrapolate from their past Behavior to the Future then the best prediction for what will happen is nothing they'll continue doing the same thing they've been doing for the past 50 Years it'll continue to not work governments realize that particle physics is eating up a lot of money for nothing in return funding will collapse people will leave the end a lot of people are intimidated by physics don't be it isn't Magic and if you didn't understand it at school maybe the way they teach it in school wasn't the right approach for you if you want to try a new approach to learning have a look at the courses at brilliant who have been sponsoring this video brilliant has a large variety of courses on Science and Mathematics it's a fresh and fun method to learn something new or freshen up Knowledge from long ago all their courses come with interactive visualizations so you really get a feeling for what is going on and they'll challenge you with questions along the way so you can check your understanding and don't worry no one will give you bad grades if you don't get it right it's all about the process of learning I found Brilliance courses to be really effective at getting new information into my head and convince it to stay there I now even have my own course on brilliant it accompanies my videos on quantum mechanics and it'll introduce to to all the basics superpositions entanglement interference wave functions and probabilities and after that you can continue maybe with their course on Quantum objects or Quantum Computing if you're interested in trying brilliant out use our link brilliant.org Sabina and sign up for free you'll get to try out everything brilliant has to offer for a whole week and the first 200 subscribers using this link will get 20 off the annual premium subscription thanks for watching see you next week

Channel: Sabine Hossenfelder

Views: 1,628,878

Keywords: physics, particle physics, large hadron collider, dark matter, dark matter particles, new particles physics, what is going wrong in particle physics, particle physics problems, progress particle physics, hossenfelder, particle physics crisis, physics crisis, physics stagnation, science without the gobbledygook

Id: lu4mH3Hmw2o

Length: 21min 45sec (1305 seconds)

Published: Sat Feb 11 2023