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This is easily Sabine Hoffstader’s fringiest video. Please don’t get the wrong idea that this is a point of controversy within physics! As a physicist I’d estim
by superposeur 3y ago
This is easily Sabine Hoffstader’s fringiest video. Please don’t get the wrong idea that this is a point of controversy within physics! As a physicist I’d estimate 99.9% of her colleagues would disagree and I would too. She has no real argument, just vaguely gestures at “maybe the comoving frame makes relativity invalid” and then vaguely gestures at “quantum gravity spoiling everything we know so far about physics”.
As to the second point, quantum gravity is a thing but almost certainly will not upend the special relativistic account of the large scale causal ordering of events. This is for the same reason that it almost certainly won’t change the calculation of the amount of time it takes an apple to drop from a tree —- within the domain of validity of the old theory, its predictions will agree.
- aaron695 3y ago[dead]
- elcritch 3y agoWell then again theoretical physics was dominated by "string theory" for decades despite a lack of any physical or experimental evidence, so we should take consensus about speculative physics with a grain of salt. This sort of speculation is precisely what physicists should be doing, within measure. At least Sabine appears to recognize her "out there" aspect, unlike say the string theorists that stifled physics for decades. At worse maybe she'll annoy another theoretician to analytically disprove her. That said of course whatever quantum gravity would bring it'll need to reduce to match known physics. However at the fringes of known physics what will happen as you get nearer to the singularities in special relativity? Generally speaking in the past singularities in physics have been due to incomplete knowledge of the physics in these regions.
- superposeur 3y agoYes, at the fringes of known physics, as you say. My point is that this question is not at the fringes known physics. Earth and Alpha Centauri are not near the singularity of a black hole and special relativity is perfectly adequate to predict that events now on Earth will take some time to influence events on Alpha Centauri.
- singularity2001 3y agoSince Sabine Hoffstader labeled the whole string theory (and some particle accelerator physics) as unscientific she shouldn't engage in the very fringes she appalls.
- taylodl 3y agoBoth String Theory and Brane Theory have been shown to yield equivalent results to the Standard Model (QFT). Nowadays physicists choose the model yielding the simplest computation for the problem at hand. No contradictions have been found after years of doing this.
- Valgrim 3y agoSo you're saying they're the same theory disguised as different, or another facet of the same solid, only useful as a computational shortcut. Maybe it's time to look for contradictions?
- taylodl 3y agoI'm not a physicist, just a knowledgable enthusiast. To your point, people are trying to look for contradictions. So far, none have been found. Physicists therefore use the model that simplifies the computation. If a contradiction is ever found then that will provide information as to which model is correct.
- nextaccountic 3y agoIsn't that just because there are enough free parameters that can be plugged in to make string theory agree with the standard model?
- flangola7 3y agoWhat is wrong with string theory?
- planck01 3y agoSome issues that string theory has: - We have not found any evidence for it. - Some predictions have been made from it that weren't found (e.g. no supersymmetric particles in the LHC). - It can be tuned to fit almost fit any universe and any observation, which doesn't really make it scientific. - The reasons for inventing it might have been misguided or flawed. (universe must be beautiful / simple / etc). The lack of results are turning a growing part of the scientific community off, while there is still a core amount of scientists holding on to it.
- ftxbro 3y ago> As a physicist I’d estimate 99.9% of her colleagues would disagree and I would too. What would be your estimate of disagreement with her other takes?
- superposeur 3y agoHard to say, but other videos I've seen are in areas where things are genuinely murkier; for instance, the status of fine-tuning arguments and the interpretation of quantum mechanics. Not so for this video, which is settled territory (and presents no extraordinary counter evidence). Generally, I do enjoy her off-kilter takes.
- snapplebobapple 3y agoIf she was wrong all it would take is one......
- comboy 3y agoNo argument? She has shown that within widely accepted theory FTL could be possible. You need to poke a hole in that to say that she has no real argument. I think many physicist may dismiss it as, well, yes, given certain assumptions.. but it's a really good argument. Personally my biggest question would be why didn't we observe anything FTL in the Universe yet. But it could be, just like with many scientific discoveries, what has been a great data point has been dismissed as some measurement problem.
- superposeur 3y agoThe form of argument "maybe X invalidates theory Y, so we shouldn't trust prediction of Y" isn't terribly useful since it could be applied to any prediction of science; "Maybe quantum gravity so let's not worry about conservation of energy." "Maybe comoving frame, so maybe we can build antigravity devices", etc. Of course, it could be true. Most anything could be true. It's just not a useful basis for adjusting one's priors.
- voxl 3y agoActually it is. There is no good reason scientists should all follow the same course of action. In fact, per your own appeal to statistical reasoning, such reasoning is only meaningful if you have an actualization of the samples. If no scientists ever try the unlikely scenarios then you will always reach local optimum. What is at stake is "Some scientists should consider FTL travel possible, and give it a go." for such a statement, the argument definitely holds water.
- Maursault 3y ago> Personally my biggest question would be why didn't we observe anything FTL in the Universe yet. If something was FTL, and we need light to see things, how could anything FTL be seen, as light could not move fast enough to reach it then reach our eyes. Further, assuming we could travel FTL, while traveling we'd be nearly blind, and anything we did see wouldn't make any sense.
- comboy 3y ago
- cuteboy19 3y agoI suppose she's just saying possible in the sense that it's not impossible. She's not saying it's probable
- hgsgm 3y agoYeah, it's possible to modify physical theory in a way that is compatible with our current bounded observations, that allows FTL with higher energies then ever controlled or perhaps ever practical to create. One of SH's hobbyhorses is that the Universe has no obligation to conform to the most elegant symmetrical theory. (See C/P/T symmetries.)
- cuteboy19 3y agoShe's not saying that it should be possible, only that we shouldn't automatically rule it out based on a theory that we already know to be incomplete
- ImPostingOnHN 3y agoit is reasonable to "rule out" (read: effectively treat as not true, see Russel's Teapot) any theory which lacks sufficient evidence to treat it with any greater weight
- MattPalmer1086 3y agoI agree with you. I enjoyed her talk. She pointed out the subtle flaws in the commonly held view that the speed of light is an absolute limit. At no point does she say this means it is not a limit, only that this conclusion is not fully warranted from the theory we have now, which we also know to be incomplete.
- layer8 3y agoThat’s vacuously true, though. Nothing is strictly impossible, from a Bayesian perspective.
- ShamelessC 3y ago
- revscat 3y agoYes, I am sure that 99% of your colleagues would agree with you. But modern astrophysics seems to be stuck in a rut, wasting decades on string theory, and now steadfastly determined that no advancements beyond relativity quantum mechanics can ever be accomplished. Even discussing such is met with disdain, dismissiveness, and ridicule. And absolute confidence that this is the correct take. Now, I understand that the experimental evidence underpinning modern astrophysics is very, very sound. But if that is truly the end, and no further discoveries of any note are ever to be had beyond Solvay 1927… well, perhaps the modern astrophysics community should just collectively hang it up and start a landscaping business.
- Mistletoe 3y agoThey could always switch fields to where we need help. People are still dying from cancer and Covid won’t be the last pandemic the human race encounters. We also need plumbers and air conditioner repairmen.
- ianburrell 3y agoString theory is not astrophysics but particle physics.
- taylodl 3y agoWasting decades on String Theory? We've learned String Theory and Brane Theory both yield the same results as the Standard Model (QFT). Nowadays physicists use the model that makes the computations easiest for the problem at hand. My own thoughts as a well-learned armchair physicist is GR is the wrong model and Einstein's field equations aren't the right model allowing us to include gravity in QFT. This is what most actual physicists believe, and for good reason. Of course it's entirely possible that QFT is also the wrong model and we need a completely different model from everything we have today in order to form a theory of everything. That's what String Theory and Brane Theory attempted to do. The problem being is thus far the new models don't predict any different results than does the existing model - they all appear to be equivalent. But you can't know that unless you tried, so it's not a waste of time.
- bmacho 3y ago> Please don’t get the wrong idea that this is a point of controversy within physics! As a physicist I’d estimate 99.9% of her colleagues would disagree and I would too. I am pretty sure 99.9% of her colleagues won't state that "this is impossible" when presented a consistent model. Why would they? Why do you do that?
- superposeur 3y agoBecause she doesn’t present a consistent model or indeed any model at all.
- bmacho 3y agoAlso please note, that either relativity or quantum (or both) is total wrong. None of the laws and equations hold quantitatively, also the basic objects do not exist, and the basic axioms don't hold either. All of the qualitative results, conservation laws, negative laws that forbid things are total useless. There is a chance that relativity is wrong, there is no spacetime, there are no frames, E, m and c are useless numbers, and albeit they are definable and measurable, E=mc^2 never ever holds. (< or > holds instead) Or the same can happen with quantum, there are no states, you can't add states together, Dirac equation never ever holds quantitatively, etc etc.
- i-use-nixos-btw 3y agoIt’s quite rare for a theory to be dismantled so thoroughly that we look back on it and say “oops, all of that was just coincidence”. Rather, the existing theory is a special case of the one that replaces it. For instance, Newtonian physics wasn’t demolished by Einstein et al. It was refined, such that Newtonian physics applies very well in scenarios and scales that we would consider ordinary. But you are completely right. When the theories are unified then people could very well be saying “you can’t just add these states together”, just like I’d often say that when talking about adding speeds together (it doesn’t convince the traffic officer). What I do think, though, is that a perfectly good response to that will be “ah, yes, that isn’t a problem though because this isn’t in the presence of a magnetic, rotating, supermassive black hole with a funny hat on, so the flopookle correction we learned about in physics 201 is negligible”
- hilbert42 3y ago"Please don’t get the wrong idea that this is a point of controversy within physics!" I was a little surprised by her comment but perhaps generating controversy is her actual point. It seems to me that with the long-standing and seemingly insurmountable gulf between QM and GR there needs to be more controversy—not less. I've always considered >c discussions and arguments speculative and hypothetical and my view hasn't changed but with the QM/GR elephant in the room perhaps it's time to remind ourselves of a similar controversy. When Galileo proposed his controversial theory that likely >99.9℅ of the establishment was against him or thought him crazy.
- PrufferFrish 3y agoI don't have anything to add to the topic, but I wanted to ask you about your usage of this character: ℅ Obviously, you meant to use the percent sign (%), but instead have used the "care of" sign (℅). This is the second time in a month I've seen this error, and I'm curious how it can occur. I did just notice that it's possible to type it on an Android keyboard by long pressing the percent sign. That seems challenging to do by accident. I'm curious if there's another way to easily type it by accident. Screenshot: https://ibb.co/YdGKwZd https://ibb.co/YdGKwZd
- hilbert42 3y agoThank you for pointing that mistake out, I just didn't notice it (the phone is set to small font). The message was sent from the same Android phone I'm using now. Moreover, I'm still not sure how it happened because the KB app I'm using is OpenBoard and its long-press is '‰'. I'm curious too because OpenBoard only has the one long-press option (as above) unlike GBoard which has two—the first being '‰' and the second the "care of" sign. Trouble is that GBoard is normally disabled [not just deselected] on this phone and I had to re-enable it to check. I've noticed occasionally that I've had 'strange' characters appear that do not seem to be long-presses when I've been typing in a hurry so there must be some option for selecting them that I'm unaware of. It's late here now so I'll investigate later and get back to you when or if I find the answer.
- hilbert42 3y ago
- taylodl 3y agoI think Dr. Hoffstader enjoys making these controversial, click-bait videos. They probably go a long way toward paying the bills! She is well-aware that until we reconcile GR and QFT then we don't have the final word on anything. Even so, we've yet to observe anything traveling faster than the vacuum speed of light - and we've been looking!
- pieter_mj 3y agoIt's Sabine Hossenfelder but I get the mistake.
- naikrovek 3y ago> I get the mistake. I don't.
- bogdanstanciu 3y agoprobably mix up with https://en.wikipedia.org/wiki/Douglas_Hofstadter https://en.wikipedia.org/wiki/Douglas_Hofstadter
- naikrovek 3y agoah, now I get it. sorta.
- GistNoesis 3y agoI would have guessed https://en.wikipedia.org/wiki/Leonard_Hofstadter https://en.wikipedia.org/wiki/Leonard_Hofstadter fictional character of the TV show Big Bang Theory that usually attract physics enthusiasts, but your guess is better.
- throwaway81523 3y agoI thought of Robert Hofstadter, who won the Nobel physics prize in 1961 and was Douglas Hofstadter's father.
- martincmartin 3y agoThere's a sense in which worm holes allow information to travel faster than light. However, since the worm hole itself has a reference frame, you can't use it to create a grandfather paradox.
- deleted 3y ago[deleted]
- wruza 3y agoWhy Hofstader, isn’t she Hossenfelder?
- WithinReason 3y agoNow the misspelling has spread across this whole thread