7 ms·
The crisis (if it exists) is not triggered by a belief in beauty, but by the simple fact that LHC hasn't yet seen anything "new" (beyond the very-important succ
by ISL 8y ago
The crisis (if it exists) is not triggered by a belief in beauty, but by the simple fact that LHC hasn't yet seen anything "new" (beyond the very-important success of the Higgs discovery).
The observation of the apparent non-existence of something (supersymmetry, in this case) is at least as important as the existence of something. Supersymmetry is one of high-energy physics' best guesses as to the nature of the universe. If that turns out not to be true, we have learned something very important.
"Thirty spokes share the wheel's hub;
It is the center hole that makes it useful.
Shape clay into a vessel;
It is the space within that makes it useful.
Cut doors and windows for a room;
It is the holes which make it useful.
Therefore profit comes from what is there;
Usefulness from what is not there."
Tao Te Ching - Lao Tzu - Chapter 11
(translation by Gia-fu Feng and Jane English)
Physics is alive and well; there are plenty of big open problems with strong experimental backing:
How does gravity connect with the rest of physics?
What is the nature of dark energy?
What is the nature of dark matter?
Where is the rest of the CP violation?
What gives neutrinos mass?
(And, the doozies that are so hard to answer that nobody touches them: Why does time have a direction? Is there something underlying quantum mechanics?)
- myWindoonn 8y agoI agree with you, and I would add that, from a Popperian view, the LHC has helped falsify some of the possible string-theoretic universes from being our universe, by failing to pick the lower-hanging particle-fruits of supersymmetry from its relatively low-powered tests.
- sgt101 8y agoNothing is falsified by the failure of an experiment to observe the expected.
- jsweojtj 8y agoCan you give an example of a falsified result?
- sgt101 8y agoAll swans are white. I can sit for day after day not observing a black swan. This proves nothing, it does not prove the theory "there is no non white swan". But if I see a black swan then the theory that all swans are white is up the chute.
- madhadron 8y agoThere's a distinction here. An experiment may measure a parameter to be zero instead of some nonzero value that everyone expected. That isn't subject to the black swan fallacy. Only when you are sampling is the black swan fallacy relevant.
- sgt101 8y agoYes agree, although the mechanism of measurement is important.
- pbhjpbhj 8y agoHypothesis 0 - all adult swans have largely white plummage. Expectation - all observed swans "are white". Observation - some swans "are black". >"Nothing is falsified by the failure of an experiment to observe the expected." // The experiment failed to observe the expected. The hypothesis was falsified. Hypothesis 1 - all swans are white or black. --- Even with something like "we expected to find a Top quark at ~100GeV and found nothing" then the experiment has falsified that there is Top that would appear in such an experimental framework. We usual project that result beyond it's technical bounds, to say there is no top below that limit, is that what you're trying to get at? If you mean experiments aren't perfect then I don't see how that truism is useful. There have been a couple of potentially massive results in recent years that have fallen to poor experimental process.
- sgt101 8y agoWhen a particle is observed at some energy the theories that predict that no such particle can exist are invalidated. It fault of the experiment to see something is just that, the experiment has failed. The causality of the failure is unknown, also if you do make the observation then the causality of the observation if unknown; Newton's observations and all the observations made by people who believed in a Newtonian universe were not unobserved when relating came along. I believe that the probabilistic approach to observation and observe to rule out approach in HEP now is a big error.
- repsilat 8y agoPerhaps not absolutely, but in a Bayesian sense it should make us less sure of the theory's truth. "Falsification" is really just severe scepticism, after all, nothing can be absolutely proven in any direction.
- sgt101 8y agoI think that Bayesian reasoning applies to a different category of knowledge; there are things for which we have no predictive theories that we have to reason about probalistically and Bayes is good for that. But thinking about how things are and probability seems a poor duo - after all, we can end up 99.999% sure that something is true, observe one counter example and now know that 100% it is false... Bayes doesn't do that.
- ISL 8y agoAny theory that predicts something other than the "expected" can be falsified by observing the "expected". To use the swan argument from down-thread: If a theory predicts a) All swans are drawn from a single distribution of colors and b) 1% of swans will be black, then the observation of a few thousand white swans will be sufficient to rule out said theory.
- sgt101 8y agoIn an idealised world the thousand white swans and 10 black swans will be mixed randomly, and you would be right. In the real world bird move in flocks, the presence of one group of birds frightens off different birds. You may live in the hemisphere with only white swans and never as long as you live see a black one, but just over the hill there is a big population, it just lives in a place you haven't looked. In natural systems observations are biased. You reasoning is based on ideal assumptions.
- Retra 8y agoFundamental physics is not like flocks of birds. It is much more like a system which makes ideal assumptions.
- lisper 8y agoHuh??? What was the Michelson-Morley result then?
- noobermin 8y agoMM is a great historical example that the field should remember. However, culturally for the current and previous generations, physicists aren't keen on their history and even if they are they definitely can't place themselves in it.
- mcnamaratw 8y agoI'm sorry but that's silly. Everybody in physics knows the Michelson-Morley experiment.
- sgt101 8y agoYes, and it's results confused everyone in physics and made people wonder what was really going on, but it could have been that another "amended" version of aether could have worked out, or it could have been that there was some mess with the experiment, or something else (perhaps) a bit like gravity now (cdm, or something else?) - when Einstein came up with relativity then all of that was blown away because Relativity came with positive predictions that aether didn't come with and these predictions were then observed ("look ma that swan is black, I told ya"). Now, who out there actually believes that cold dark matter is wrong because no one has had a good direct observation so far? It might be wrong, but it isn't ruled out at all.
- lisper 8y agoYou're losing the plot here. Recall the original claim: > Nothing is falsified by the failure of an experiment to observe the expected. MM definitively falsified the then-prevalent theory that space and time are absolute, and that the earth is moving with respect to the medium through which light waves propagate. The fact that it did not falsify all possible theories of the luminiferous aether does not change this fact.
- beojan 8y agoNot by the result directly, no. But you can take the same data and use it to state that we are this sure the theory is wrong.
- frumiousirc 8y agoThe term "failure" is loaded. The lack of observation of proton decay has falsified several otherwise acceptable theories.
- andrepd 8y agoThere's plenty of research about the problem of the arrow of time, so o don't think it's fair to say nobody touches them. And what did you mean by "Is there something underlying quantum mechanics?"
- Certhas 8y agoNone of what you say contradicts that HEP Theory is in a crisis. That word was thrown around before the LHC confirmed the Standard Model, it's become more acute since. The crisis is that the foundational ideas about how to make progress in physics: Elegance, beauty, naturalness, symmetries... are not yeilding any insights on the questions you raise. And yet CERN still argues that HL-LHC is important for detecting supersymmetry in their press release today. The technical core of Hossenfelders argument is here: https://arxiv.org/abs/1801.02176 https://arxiv.org/abs/1801.02176
- theoh 8y agoPasting block quote for mobile users: "Thirty spokes share the wheel's hub; It is the center hole that makes it useful. Shape clay into a vessel; It is the space within that makes it useful. Cut doors and windows for a room; It is the holes which make it useful. Therefore profit comes from what is there; Usefulness from what is not there." Tao Te Ching - Lao Tzu - Chapter 11 (translation by Gia-fu Feng and Jane English) --- (YC people: it is very telling that you can't find the will/resources to fix this blockquote on mobile problem. I would say it is damning of the whole ethos of YC/HN, in fact, but I'm marginal.)
- shawn 8y agoThe blockquotes are fine. It’s for code, not quotes. And they have better things to focus on.
- repsilat 8y agoOn mobile you can read about 20 characters before hitting the edge of an iframe. It isn't even good for code.
- theoh 8y agoOne dev intern could tinker with HN's codebase to improve it. It's not as if YC is a startup that has to have a laser focus on one main chance. This is big business now.
- Zanni 8y agoThe crisis that Hossenfelder is addressing is that there has been no significant progress that's been experimentally verified in fundamental physics since the birth of string theory in the 1980s. Yes, there are a lot of big open problems, but they remain open. Yes, we have recently found experimental evidence for things like the Higgs boson, but that was first predicted in the 1960s. Yes, we can rule out some versions of string theory thanks to LHC results, but there are a vast multitude of string theories, and that's not a lot to show for nearly 40 years.
- gus_massa 8y agoSome results that I remember just now: * There is a recent 4.5+4.8 sigma excess in neutrinos oscillation that hints a new neutrino https://arstechnica.com/science/2018/06/weird-neutrino-excess-wont-go-away-hints-at-new-physics/ https://arstechnica.com/science/2018/06/weird-neutrino-exces... [technical note, you can't add sigmas naively, 4.5+4.8=6.1] * The value of the magnetic moment of the muon (g) is too high. IIRC this result has only a 2.5 or 3 sigma, so it's far from confirmed. * There are some experiment to prove that the neutrino is a majorana particle and that the neutrino and the anti-neutrino is the same particle. I don't remember any good announcement, so I think that the experiments have still too early results or the results are not interesting. [I don't like this theory, but many people that knows more than me like it.]
- noobermin 8y agoDo you have a link for the majorana bit?
- gus_massa 8y agohttps://www.symmetrymagazine.org/article/august-2013/neutrinoless-double-beta-decay https://www.symmetrymagazine.org/article/august-2013/neutrin... https://en.wikipedia.org/wiki/Double_beta_decay#Neutrinoless_double_beta_decay https://en.wikipedia.org/wiki/Double_beta_decay#Neutrinoless...
- jerf 8y ago
- sampo 8y ago> The observation of the apparent non-existence of something (supersymmetry, in this case) is at least as important as the existence of something. Human imagination can create a large number of theories. It isn't as valuable to prove the non-existence of something you have imagined up than proving the existence of something you have imagined up. Sure, in this case, it was pretty important to prove an idea (supersymmetry) wrong because it was so widely accepted. But, insofar as physics is an empirical science, not it's important to reflect, how did it happen in the first place that an idea with no empirical support became so widely held? What can be improved in the culture and habits of physics and physics funding. Which traditions should be reconsidered.
- vorg 8y agoSupersymmetry was "beautiful" (i.e. it was produced by the conscious mind) and hence in a sense more "likely", so disproving it is as valuable as proving other "beautiful" theories (e.g. GR and Mercury's orbit).
- noobermin 8y agoThe fact that the LHC hasn't seen anything new is the entire point here because it yields evidence against SUSY. That puts almost all of mainstream HEP theory in bad position because it has been built around SUSY being real and an accepted hypothesis. As usual, theoretical physics is taking the wrong message from this, sticking to their guns and claiming SUSY evidence is yet above 10 TeV instead of stepping back and re-evaluating their fundamental assumptions. Of course they won't because many have built their careers on this hypothesis. I forsee a reckoning for the whole field (which will take on economic dimensions) in the future.