For the context, the video this is a follow up to is helpful (they're both short) - https://www.youtube.com/watch?v=ZlHvW6k2bcM
John Carlos Baez thinks Sabine has a point.
https://mathstodon.xyz/@johncarlosbaez/113285631281744111
>Despite the silly clickbait title of this video, Sabine says a lot of interesting stuff in it: her criticism of claimed deviations from Lorentz invariance in loop quantum gravity is about as good as you'll get from anyone who hasn't actually worked on loop quantum gravity. I worked on it for about 10 years, and the situation is even a bit worse than she makes it sound.
I know people have strong reactions to her and her sensational style, but that is a serious recommendation from a knowledgeable person, so I think we can give this thread a second chance. (Someone emailed and asked us to.)
All: please let's keep the comments on topic and substantive (and avoid the sensationalism and personality aspects).
Edit: this subthread was getting too off-topic so I moved the replies to https://news.ycombinator.com/item?id=41814764. Feel free to reply there if you want.
> John Carlos Baez
For those like me who didn't know, https://en.wikipedia.org/wiki/John_C._Baez
> John Carlos Baez (/ˈbaɪ.ɛz/;[2] born June 12, 1961) is an American mathematical physicist and a professor of mathematics at the University of California, Riverside (UCR)[3] in Riverside, California. He has worked on spin foams in loop quantum gravity, applications of higher categories to physics, and applied category theory. Additionally, Baez is known on the World Wide Web as the author of the crackpot index.
He was also a long-time maintainer of the Usenet Physics FAQ and has been writing about physics and mathematics on the internet for decades. So not only is he the real deal in terms of knowledge, he also has a long history of communicating that knowledge to the public, albeit typically for a more advanced audience.
And https://news.ycombinator.com/user?id=johncarlosbaez!
Perhaps he'll contribute to this thread (or perhaps it would waste his time)
He is better known within physics as the author of This Week's Finds in Mathematical Physics, an archive of which is at https://math.ucr.edu/home/baez/TWF.html. His more current blog is available at https://johncarlosbaez.wordpress.com/.
And he was known on Usenet and sci.physics before the World Wide Web was invented...
30 years ago I spoke to a fairly well known and regarded physicist who said something rather interesting along the same lines. Quoting as accurately as I can "physics looks sexy from the outside due to some celebrities but inside it's mostly worse than anyone wants to admit.". He also suggested I go and study mathematics instead because at least there will likely be some applications for it. I did and I am glad I did.
Sounds like this criticism would be valid for fundamental physics but there are many other physics fields with experimental results that become technology.
Yes, there's definitely some interesting fields that are making progress that are still in the purview of "physics". Materials science, or condensed matter physics, is doing a lot of fascinating work with quasiparticles: https://en.wikipedia.org/wiki/Quasiparticle There's a number of fields you could call "quantum engineering" where physics and engineering work together on the cutting edge. Some of the output of that is why our TVs are so good.
There's a lot of work to be done on how big systems, where "big systems" can be as small as hundreds or even dozens of atoms, behave, where you can't "just" throw the whole wavefunction into a computer and crunch away on it.
It's particle physics that seems to be stuck in a rut. Fundamentally, they're starved for useful data. Until that is resolved, the science really isn't going anywhere. Since people on the internet frequently seem to operate on the silly theory that someone pointing out a problem has some sort of obligation to propose a solution, let me say outright I have no more clue how to resolve this than anyone else does, except to hope that some sort of other progress in other fields creates new opportunities for new experiments.
> Since people on the internet frequently seem to operate on the silly theory that someone pointing out a problem has some sort of obligation to propose a solution
The issue with Sabine is she tends to yell about anyone proposing any solution. CERN would like to build a bigger particle accelerator, but since it's not her favored variant of accelerator they are obviously lying to the public and wasting your tax payer dollars which could be spent instead on the (implied) guaranteed discoveries if people would just listen to her.
(note also that this is a false dichotomy: any realistic analysis any set of potentially competing projects would generally conclude they're unlikely to be in competition if they are in fact viable - we usually have plenty of money to do both things provided they're likely to pay off. But the under-developed, under-timelined thing is a lot easier to promise the world with, yet far more likely to wind up just as "clearly blown out it's budget!" as the project being built).
if you want to do applications, engineering will get you a 10% higher salary for the same job.
I know that this will probably be down-voted to death but I don't like these hyperbolic takes. I know that Sabine did use this title for click-bate purposes that she is now mostly doing YouTube videos (she had horrible experience that unfortunately not rare in scientific community [1]). I understand that the field of particle physics which is the corner stone in fundamental physics is not showing the great advances that it used to have a couple of decades ago. But I think people really don't understand that the field is still advancing and although these advances are less catchy to be reported in mainstream (and don't get traction if posted on HN) it is not dead or dying. There is a reason why we had a particle data group updating the PDG [2] each two years (you can order physical copies for free but please don't do if you don't need one). People were writing about that since after the big discovery of Higgs boson (that was 12 years ago). We still have a lot of measurement and puzzles that is less about unification theory that people usually would talk about. Theory people are coming up with all different ideas even if some are not testable now but that job of theorist is mainly come up with ideas and help bridge the gap later. I would suggest everyone interested in this topic to read the electroweak current chapter of the book called "How experiments End" [3] to understand a historical example to how we approached the standard model when it was first proposed. Most of the particle physicists will not work on supersymmetry, string theory and these catchy theories that people will hear about. Most of the work is advancing and answering (and raise questions) piece by piece. Here is an example of interesting results that help us answer some questions [4]. Also I'm not saying that the field had its own problems and can improve on many aspects. I'm just against these extreme and hot takes that claims it is in a crisis or dying.
Disclaimer: I'm a particle physicist and have a skin in the game.
[1]https://www.youtube.com/watch?v=LKiBlGDfRU8
[3] https://press.uchicago.edu/ucp/books/book/chicago/H/bo596942...
[4] https://www.symmetrymagazine.org/article/new-results-from-th...
[5]
My understanding of the situation (which may be wrong, in which case please let me know) is that physics is stuck at a local optimum.
There are two obvious ways to get out
(1) Surprising physical observations, or
(2) Mathematical advances
Way (1) is what kicked off quantum mechanics. Way (2) is what kicked off Newtonian mechanics.
I see string theorists and loop quantum gravity people as working on (2). Their models are mathematically interesting and aren't totally understood from a mathematical perspective. But they're different enough that studying them may break the impasse.
I see (1) as largely limited by the budgets and technology needed to build things like particle accelerators and spacecraft.
For (2) you have to decide whether to only explore mathematics that defines physical reality, or whether to also allow exploration of non-physical systems. For example, you might explore a universe that is almost physical but has time machines. Restricting the search space to only physically realistic systems is a significant constraint, so there's a debate to be be had about how much weight to give it.
> physics is stuck at a local optimum.
I think I heard somewhere that the trouble with string theory is it can describe anything if you tune it just in a right way. It reminds me of epicycles, they also had this property, you can add more and more epicycles to describe literally any observation data.
> Way (1) is what kicked off quantum mechanics. Way (2) is what kicked off Newtonian mechanics.
Hmm... What was the way that kicked Copernicus to redraw epicycles with the Sun in the center? I mean, is there some notes on these? For example, Newton took as granted that celestial bodies move by elliptical orbits, and somehow he guessed that the gravitation law has r^2 in its denominator, and so he invented calculus to prove, that if you have r^2 in the denominator then you'll get elliptical orbits. The question where Newton got his guess it remains open for me, but back to Copernicus, what was his way?
Maybe he thought how movements of planets will look if seen from the Sun, and so he had redrawn epicycles to take a look, and he got circles? (I'm not sure that it could work this way, I propose this answer to my question just to give an example of the kind of an answer I'd like to have).
I ask this question for two reasons.
1. I believe that Copernicus advanced the science not with surpising physical observation and not with mathematical advances, to me it seems more like surprising mathematical observation. I'm not sure what was that observation exactly.
2. Can one apply techniques of Copernicus to the modern physics? I suspect that it will not. I'm sure physicist already tried everything and there were (is) a lot of them and they are pretty smart people, so it is highly unlikely that Copernicus can help them in any way. But I'm still curious, what Copernicus would do? Would he tried to imagine how electron flying through a double-slit might observe scientists-observers? Or maybe it would try to feel the pain of a black that may believe that the whole universe is falling on it? I bet that the true Copernicus idea would require to use some pretty hard mind-altering substances, and I like such ideas.
My understanding as a layman:
1. Copernicus figured out that if you put the sun at the center, then epicycles weren't necessary, and the math got easier --- because epicycles were based on a mis-understanding of the actual state of the universe --- I don't believe that anyone has identified such a non-alignment of fact and reasoning and observation for contemporary physics.
2. The problem is, modern physics is arguably getting boxed into a corner by approaching an end game state where the fundamental particles are getting identified, but are so small and difficult to separate out, that measurements are challenging to the point that while one can speculate and do math, actually proving out the speculations experimentally and taking actual measurements is expensive or so difficult to reason about that there doesn't seem an obvious path to an experiment, e.g., it looks as if the electron may be a fundamental particle, which is a sufficiently difficult concept to parse that it led to "The one-electron universe"/"The single electron hypothesis" and if that is the case, it walls off a not insignificant portion of particle physics at a size/state which can't be gotten smaller than.
Those mathematical advances weren't developed in a vacuum, but made to solve some very specific problems which came from better measurements. So even Newtonian mechanics originated in solving problems trying to explain measurements, not that someone sat in their chamber and dreamed up cool math that happened to be very useful.
Number theory and algebraic geometry were developed for their own sake (i.e. "it is cool"), but later people found practical applications in cryptography.
So "useful math must be motivated by practice" is empirically false
I agree.
Generally, the scientific method has mutually recursive turns of theory and observation. And I don't mean to imply that exist independently.
I'm just saying that if you get stuck, the two clearest ways out are to provide more observations or perturb the theory.
(1) is also limited by imagination
Isn't it (2) that's limited by imagination? Nobody imagined quantum theory, they observed it first.
If LQG turns out to be unworkable, we're back at string theory as the only renomalizable description of quantum gravity.
Quantum gravity research amounts to one professor per university faculty on average. Even in the worst case this would not be the crisis of unmet expectations it is made out to be... QG researchers are very brave because they are risking everything on the possibility that existing data constrains quantum gravity in a way that hasn't yet been understood. I doubt there is even a single person making that gamble unaware that the Planck energy density is something like 20 orders of magnitude above present-day experiments.
Physicist here.. I will not give Sabine more YouTube views, justifying clickbait titles. Below is just my opinion. There are certainly issues in theoretical physics. I think particularly string theory was a massive waste of effort in physics and to some degree illustration of failure of the whole system. Despite that most of other physics I would say in sensible shape, it is just harder to make progress given that we have to push to higher energies, more accurate measurements etc. The question whether there will be major advance in fundamental physics to some degree depends on new discoveries. Many people are pushing, but it is not guaranteed.
The fundamental reason for this is simple. Humans are prone to cognitive dissonance. Meaning, we do absurd things to avoid painful thoughts. And anything that questions our sense of identity, is a painful thought.
So if my self-image is, "I've advanced our understanding of the fundamental nature of reality," then the idea that my contributions weren't useful becomes painful. So we avoid thinking it, challenge people who question our past contributions, and so on.
The natural result of this cognitive dissonance is a feeling of undue certainty in our speculations. After all certainty is merely a belief that one idea is easy to believe and its opposites are hard to believe. We imagine that our certitudes are based on fact. But they more easily arise from cognitive biases.
And this is how a group of intelligent and usually rational people descend into theology whose internal contradictions can't be acknowledged.
This is beautifully articulated.
And reinforces my general below-the-line (layperson) fear about the state of physics today (as reinforced ofc by the likes of Sabine Hossenfelder & Eric Weinstein).
Thank you for the compliment.
I've been working on how to formulate that idea clearly for a while. It is a problem that goes well beyond physics. For example I believe that the same cognitive error is behind the fact that experts do significantly worse than chance in actually predicting the world, and the more certain the expert sounds, the less likely they are to be right. See https://www.amazon.com/Expert-Political-Judgment-Good-Know/d... for data demonstrating that fact.
Depressingly, this means that we consistently put public policy in the hands of people who are demonstrably incompetent.
>> I've been working on how to formulate that idea clearly for a while. It is a problem that goes well beyond physics.
It's a really fundamental thing in psychology. The solution is something like the destruction of the ego, and many people who push hard enough to be a PhD tend toward larger ego to start with. Meditation and practicing martial arts can help. Apparently psychedelics can as well.
It's a real pain because if you try to tell someone their ego is preventing them from seeing things clearly... Well that's going to trigger the same problem. So yes, it's good to find ways to articulate the message so it can get through to those that suffer from it the most.
The problem is that we need an ego to be healthy. Attempts to destroy it can wind up compromising your mental health.
The first part of the solution is to be careful what's in your ego. See https://paulgraham.com/identity.html on this topic. See https://blog.codinghorror.com/the-ten-commandments-of-egoles... for how careful choices in what we value in ourselves, can lead to thinking better.
This of course still leaves us with an identity. For that I've found that gratitude can help us deal with pain. And so targeted gratitude can help us avoid cognitive dissonance when we otherwise would be overrun by it.
Sadly, neither skill is widely taught in our society.
> So if my self-image is, "I've advanced our understanding of the fundamental nature of reality," then the idea that my contributions weren't useful becomes painful.
Only if one believes the logical fallacy that the dependent steps of a process of elimination weren't useful.
Even if you believe that they are useful, you're also not going to wind up as a hero in the history books. And so people wind up acting in the same way.
Besides, the argument that all of the bad ideas contributed to discovering the right one, is as strong as the empirical argument that white chairs are evidence that all ravens are black. Logically you're right. Discovering the right idea requires disproving all of the wrong ones. Similarly "all ravens are black" is logically the same as its contrapositive, "all non-black things are not ravens". It's just that you've just decided to focus on a search space that is so much bigger, that each data point in it becomes much less important.
[flagged]
"Don't be snarky."
"Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith."
https://news.ycombinator.com/newsguidelines.html
(I'm sure you could rephrase your point here as a substantive thought in a respectful way and then it would be fine)
It's in the video: LQG is not a promising, or even a plausible, physical theory. That's the idea.
As a non-physicist, it’s hard to understand if she has a point or not.
Any physicists care to weigh in?
Follow the links to John Baez's thoughts ("the situation is even a bit worse than she makes it sound"): https://news.ycombinator.com/item?id=41808143
I think in this an other videos, what she says is "they are not even wrong" and she does have a point there.
long ago i coin: scientific physics
an analogy with astrology and astronomy fits perfectly.
Remember those great men who did groundbreaking work that completely changed the fabric of society? Consensus my a, their work is self evident. If you need someone to tell you something is a great accomplishment it apparently isn't obvious.
If there is no revolution triggered by [say] relativity theory it doesn't qualify for the list of great discoveries. You need people to tell you how great it is.
funny as hell
I have a pet conspiracy theory for why there has been so little progress in physics for so long. The invention of the nuclear bomb scared a lot of people, it made them scared of physics. What else might physicists turn up that could change the world in dramatic ways? Anti-gravity? Ray guns? Other dimensions? Travel to other worlds? All bad for business, no one is going to buy your airplanes or air craft carriers if they can buy an anti-gravity machine. So physics was suppressed by both business and government. Physicists were given "safe" work to do (ITER, quants) that would occupy them and keep them from exploring wild stuff. Grant financing was controlled so that only safe research would be conducted. It would be fairly invisible to the world, just a few high level decisions would determine how the funding was directed. I get the impression that if this was indeed a conscious decision that it's starting to fall apart as younger generations take over and become frustrated with the direction of physics. They weren't there when the A-bomb was invented, and nuclear weapons have not been on peoples minds much for a long time, most people have not lived in a time when one was used. So they see interesting topics and want to explore them and encounter resistance from more established scientists. It's a conspiracy theory because it would involve some buy-in from a fair number of physicists to make it work, but a lot of physicists when I was getting my BA in physics were very loudly saying "never again" about atomic weapons and felt it had tarnished the whole profession. It's very difficult to say what humanity would be capable of handling in terms of radical new inventions. Anti-gravity could solve many large problems, but it might make it even easier to destroy Earth. Once new knowledge exists it is hard to suppress it. Stopping it from from ever existing seems easier. I guess we'll find out if physics has been suppressed if the dam breaks and new ideas start proliferating. The nature of the new physics would be a big clue as to whether research in it was suppressed. I'm reminded of Elon Musk, he seems to have had really radical success in some very stagnant industries, just by trying instead of accepting limits, and being able to fund his ideas himself.
The theory stops working imho if you take competition into account. The world is not aligned as a single bloc of power. While it’s not completely unthinkable (but extremely unlikely, imho) that some scientists plus some decision makers from, say, the liberal west might collude to achieve this kind of suppression, their counterparts from one or multiple other blocs might not, because they want to dominate and anti-gravity guns surely give you some nice advantage.
You'd be amazed how quickly powerful discoveries find military purpose.
An important thing to consider here is that the first engineering project which had to make use of Einstein's Theory of Relativity was GPS --- the time/position calculations to triangulate location based on satellites is so exacting that it has to take into account gravimetric distortions based on the receivers being further down in the gravity well than the GPS satellites:
Perhaps this is of interest to you.
What time frame are you talking about here? Starting in 01950, 01995, 02010?
If we're talking about 01995, it's conceivable that, say, the US and CERN could coordinate to suppress research into hafnium bombs, AVLIS, antigravity, or whatever. If we're talking about research much prior to that point, though, you'd have to include the Russians in the conspiracy. Probably not just any Russians, either; probably Khrushchev, Brezhnev, Andropov, Tsar-Bomba-era Sakharov, and his successors. And, on the other side, people like J. Edgar Hoover, JFK, McNamara, Kissinger, Johnny von Neumann, and Teller.
I don't want to say it's literally impossible for Brezhnev or his underlings to have made a secret agreement with Kissinger and Teller to suppress the development of theoretical physics in order to keep the world predictable. But I do think it's pretty implausible, and there would have been an enormous incentive to cheat on any such secret agreement.
In the 01990s, though, it could have become plausible. But, remember that that's also when Pakistan became a nuclear weapons state, shortly followed by North Korea in 02006. And the People's Republic of China has had nuclear weapons since 01964, so they evidently had significant physics capabilities that they were willing to use for warfare (which was a huge priority; Mao reorganized the country's economy to resist an anticipated US invasion), and they dominated the TOP500 supercomputer list until this year, when they withdrew from it in apparent protest against the efforts of the USA to reverse their technological progress with a worldwide system of export controls.
So I think there's maybe a ten-year window when this could have happened somewhat, about 01992 to 02002. Both before and after that, there are too many countries with strong physics communities that are too bitterly opposed to make such cooperation plausible.
If you want to reply to https://news.ycombinator.com/item?id=41811140 or say something Sabine-adjacent, please do it here.
(This is so https://news.ycombinator.com/item?id=41808143 doesn't get too offtopic)
I don't like Sabine Hossenfelder's videos because they're too short. When I want to relax after work by playing a game while listening to someone drone on on youtube on a deep and esoteric subject, her videos end way too soon, and with an advertisement for her sponsor.
I just want to hear some rambling boffin expound for an hour in the background on some matter that can't possibly raise more than a few hundred views. I decided I don't like popular science videos any more. Boo.
Sean Carroll is my go to guy for long form physics and philosophy discussions that have some depth but are still accessible. His October AMA on the Mindscape podcast is over 4 hours, but I haven't listened to it yet.
When I read the submission title here I immediately wondered if it was Sabine again and, well, there she was.
"sensational style" is one part but another is that it is hard to extract truth from Sabine's videos, at least for me, not without doing some serious research as someone with a PhD in physics.
Example starting at ~1:00 "Carlo Rovelli is fine with the theory being untestable for practical purposes. So now the situation is that either the theory is falsified or its not falsifiable..."
Is Carlo Rovelli fine with it not being testable, in that he is fine with research continuing even though it can not be tested with up coming experimental set ups? That is reasonable lots of research goes on for long periods of time with out experimental verification. From a funding point of view it makes sense to allocate more money to things that have a tighter feedback loop though. If Sabine was going to expose howe much money was going to these topics and where it could be better spent that would be worth watching.
Or is Carlo Rovelli ok with the theory being unfalsifiable in the sense that that he is ok with the research not being science? This is the straight forward meaning of Sabine's words, but are a negative attack, and one that would come off as a personal attack to many scientists I have known, one that she does not back up with anything immediately and then goes on to make more negative comments like "and Carlo complains to me because he thinks I do not understand his genius".
Ok if Sabine was going to expose Carlo Rovelli as someone who was not really practice science but was getting paid to be a scientist that would be awesome to watch and learn about. That does not happen.
"everyone who works on this just repeats arguments that they all know to be wrong to keep the money coming" - accusation of scientific fraud and defrauding the government.
Ok what percentage and total amount of founding is going to this? Is there anyone who has come forward? It would be awesome to watch something that exposed something like this. That does not happen either.
~3:19 - Arguments saying loop quantum gravity require space to be quantized, but they can not be lorentz invariant without having the quantization go to zero volume, according to Sabine, and no one has done that and extracted back out loop quantum gravity.
I am experimentalist and this is not my area. I would want to see a link to a paper/book etc. The analogy to the angular momentum operator comes off as a good place to start investigation/research but is treated dismissively, anologies like this often do not apply in the end but can still be useful.
3:53 ~ "length contraction should make that minimal area smaller than minimal proof by contradiction"
Ok that does not seem like the gottcha that it is laid out to be. Interesting stuff happens where their are apparent contradictions in physics. If experimental/observational evidence about A produces theory TA and experimental/observational evidence about B produces theory TB and they contradict each other in conditions C that is an interesting point to study look in to etc. This may not be interesting for other reasons, but the apparent contradiction does not make it obviously non interesting.
~4:27 ~ "this can't work because these deviations would inevitably so large we'd have seen them already" -
Why did Sabine talk about it being a mathematical contradiction if you can make the theory work, but it leads to physical phenomenon that we do not observe?
I can not make those two arguments jive in to a cohesive whole. Not that it can not happen, but I can not from this video and that is the conclusion, or similar, I normally reach when watching Sabine's videos and why I do not watch or recommend them generally.
I do not see any of the interesting things I mentioned above being discussed or dug into in comments so far or other new interesting takes. The issue for Sabine's videos, at least for me, is not the "sensational style".
Well, if you want a simple argument from authority, John Carlos Baez's confirmation that she's right is pretty good. If you want a better one, she very rarely gets any of her facts wrong.
Now let's go point by point.
Is Carlo Rovelli fine with it not being testable, in that he is fine with research continuing even though it can not be tested with up coming experimental set ups? He is arguing for a version of the theory that can't be tested, is continuing to do research on it, and presumably thinks that he is doing science.
If Sabine was going to expose howe much money was going to these topics and where it could be better spent that would be worth watching. Discussing how these things wind up getting funded would be a very different video. And would not likely be interesting to most of her audience.
Or is Carlo Rovelli ok with the theory being unfalsifiable in the sense that that he is ok with the research not being science? Presumably he thinks that he is doing science. Sabine's opinion clearly is that this isn't really science. However she only claims her opinion as her opinion, not established fact.
Ok what percentage and total amount of founding is going to this? Again, that would be a very different video. In 10 minutes for a general audience, you have to make decisions about what you will and will not cover. It's not a valid criticism of her that she made a choice. Particularly in a video that she disclaims as a personal rant.
Arguments saying loop quantum gravity require space to be quantized, but they can not be lorentz invariant without having the quantization go to zero volume, according to Sabine, and no one has done that and extracted back out loop quantum gravity. This is not according to her, this is according to an argument that comes from Lee Smolin. A region of space that has a specific amount of area will, according to special relativity, have a smaller area according to an observer that is traveling fast enough. By having the velocity as close as you want to C, you can make the area arbitrarily small. So your choice is to violate Lorentz invariance, or have arbitrarily small areas. If you violate Lorentz invariance, the speed for light will depend on the wavelength.
As her previous video at https://www.youtube.com/watch?v=ZlHvW6k2bcM said, this prediction of Lee Smolin has been tested to extremely high precision, and the predicted effect was not seen. That version of LQG has been falsified. The alternative supported by Carlo Rovelli is that you need to average out over quantum areas in all reference frames. This is a neat idea, but in several decades, nobody has made it work. Until someone can make it work, LQG can't produce any testable predictions.
Please note that John Baez, who worked on LQG for 10 years, specifically complimented her presentation of this particular issue. Her description of where research stands is accurate.
I am experimentalist and this is not my area. I would want to see a link to a paper/book etc. Rants generally do not come with properly cited references. That said, the previous video that this refers back to is based on https://arxiv.org/abs/2402.06009?utm_source=substack&utm_med..., which is one of the experimental tests showing that Lee Smolin's prediction is false.
The analogy to the angular momentum operator comes off as a good place to start investigation/research but is treated dismissively, anologies like this often do not apply in the end but can still be useful. It was a good place to start. After 20 years of research that has failed to turn that idea into anything workable, most people would conclude that this is an analogy that will not apply in the end. But apparently Rovelli gets mad at anyone who doubts that it will work out. One of the triggers for this rant was whatever Rovelli said to her in private. Personally, I excuse her for being human here in her reaction.
Ok that does not seem like the gottcha that it is laid out to be. Interesting stuff happens where their are apparent contradictions in physics. No, it really is the gotcha it claims to be. It's directly inside of the math. This demonstration is no different than, say, proving that sqrt(2) is irrational by proving that if you start with the smallest fraction that equals it, you can find a smaller one.
The conclusion of that gotcha is exactly what she said: if there's a minimal area then you can't have Lorentz invariance. And conversely, if you have Lorentz invariance, then you can't have a minimal area. Experimentally, we have tested for the Lorentz invariance to be expected from a minimum area based on the Planck length. It does not exist. And therefore there isn't Lorentz invariance.
Why did Sabine talk about it being a mathematical contradiction if you can make the theory work, but it leads to physical phenomenon that we do not observe? Her previous video (that triggered the nasty emails)_made this point more clearly. She's saying that there is a mathematical contradiction between having minimal areas and Lorentz invariance. This forces us to choose to have one or the other. Minimal areas leads to a testable and now falsified theory. Lorentz invariance has yet to lead to a theory that doesn't blow up with unnormalizable infinities, let alone one which can produce a testable prediction.
I can not make those two arguments jive in to a cohesive whole. Not that it can not happen, but I can not from this video and that is the conclusion, or similar, I normally reach when watching Sabine's videos and why I do not watch or recommend them generally. Is that Sabine's fault, or yours? This video is much lower quality than her normal ones. And yet absolutely none of what you think are flaws, do I think is one. Every one of your objections has an answer that jives. And the conclusion is agreed with by John Baez, whose background on this specific topic is much stronger than yours.
Perhaps, rather than looking for things to complain, you should try figuring out what she actually said. In my experience it is logically internally consistent. Even though it skewers some sacred cows.
> Well, if you want a simple argument from authority, John Carlos Baez's confirmation that she's right is pretty good. If you want a better one, she very rarely gets any of her facts wrong.
It is not what I want. I read the linked comment by John Carlos Baez[1] and do not agree with the wording of your conclusion "that she's right". There is some alignment, but you have removed any nuance.
> Again, that would be a very different video. In 10 minutes for a general audience, you have to make decisions about what you will and will not cover. It's not a valid criticism of her that she made a choice. Particularly in a video that she disclaims as a personal rant.
My specific comments are about why I do not find value in Sabine's video not about not about a general audience. The over all arch is a point that I do not find her videos or the discussions in the comments valuable on hacker news in response to Dang's comment:
> so I think we can give this thread a second chance
[2]
So my comments are not about how she decides to reach her general audience.
I think this covers some of your pervious comments too.
> This is not according to her, this is according to an argument that comes from Lee Smolin.
"What I said in my pervious video" is what she said in her video. So this idea may not have originated from her, but my word choice is correct by saying according to her. This does no assert she came up with the idea or is 100% sure of it.
> A region of space that has a specific amount of area will, according to special relativity, ...
> ...
> Please note that John Baez, who worked on LQG for 10 years, specifically complimented her presentation of this particular issue. Her description of where research stands is accurate.
My comment about about the video and why it is not useful to me or useful seeing it on HN, not about the correctness or incorrectness of Sabine's statements which is what you seem to be addressing here.
> It was a good place to start. After 20 years of research that has failed to turn that idea into anything workable, most people would conclude that this is an analogy that will not apply in the end. But apparently Rovelli gets mad at anyone who doubts that it will work out. One of the triggers for this rant was whatever Rovelli said to her in private. Personally, I excuse her for being human here in her reaction.
You are making some assumptions here and empathizing with Sabine, which is understandable. Arrogant Physics professor gets mad when someone questions their pet theory is not unrealistic but is not headline worthy either. Does it matter if he was mad? Is this any different than any other celebrity spat? If not, that is not what I read HN for.
> Rants generally do not come with properly cited references.
I know it was a rant, I saw the labeling. That does not help make it good material for HN or lead HN commenters to interesting and curious comments though. The reverse is often true regardless of the source of the rant.
> No, it really is the gotcha it claims to be. It's directly inside of the math. This demonstration is no different than, say, proving that sqrt(2) is irrational by proving that if you start with the smallest fraction that equals it, you can find a smaller one.
Physics is not practiced like math though, so it is different. A contradiction in physics theories is not the same as saying true = false in math. Experimental evidence and observation rule the day until we find the fundamental laws of physics, after that it will be more like math(well at least some physics will).
> Her previous video (that triggered the nasty emails)_made this point more clearly. She's saying that there is a mathematical contradiction between having minimal areas and Lorentz invariance. This forces us to choose to have one or the other. Minimal areas leads to a testable and now falsified theory. Lorentz invariance has yet to lead to a theory that doesn't blow up with unnormalizable infinities, let alone one which can produce a testable prediction.
Comments like this, and much of what you said before this, lead me to think Sabine's pervious video would be less likely to cause me to write a comment like I did.
> Is that Sabine's fault, or yours?
Nothing I have said is about Sabine being at fault of something. I can stand corrected if something I wrote was too misleading though.
> This video is much lower quality than her normal ones.
This seems like it would argue against Dang giving this Sabine video an exception.
> Perhaps, rather than looking for things to complain,
That is not what happened here. My response was to Dang about giving this video a exception and the comment on "sensational style".
> you should try figuring out what she actually said.
And if I was having a conversation with Sabine or if I was corresponding with her then both people are responsible for reaching out to cover any communication gaps. That is not what this is, this was Sabine's rant as labeled by her and you.
> Even though it skewers some sacred cows.
I do not think Sabine's videos "skewer sacred cows". At least not any in the physics community at large, maybe some sub disciplines. The physic's community at large does not seem to have many if any sacred cows, that is my experience at least.
[1] https://mathstodon.xyz/@johncarlosbaez/113285631281744111
[2]
> so I think we can give this thread a second chance
Your complaint is that it is hard to extract truth from her videos.
However extracting truth from what you said is trivial if you believe that what she reports as fact, is fact. And what she reports as her opinion, is her opinion. If you pick any 5 videos you want, I'd be happy to help you spot check them. Just like I did with this one.
Now I'd like to pull out three specific issues.
1. Your point about settling physics with experiment is not applicable here. The result is about what the math will predict if you make a specific assumption in a specific mathematical model. Testing that is like trying to test the frequency with which 1+1 gives you 3. It's a question of logic. What becomes a question of experiment is whether a particular model is a good description of reality.
2. She may not be skewering cows that are sacred to all of physics. But a lot of her videos skewer cows that are sacred to some group, and she's constantly getting an earful about it.
3. Why this video? The reason why I voted for it was not quality, but topic. I think it is very important to be aware how easily branches of science become pseudoscience. And with John Baez' support, it's clear that her complaint is more than simple sour grapes. See https://news.ycombinator.com/item?id=41808404 for some of my thoughts that are specific to this topic.
> Your complaint is that it is hard to extract truth from her videos. > > However extracting truth from what you said is trivial if you believe that what she reports as fact, is fact. And what she reports as her opinion, is her opinion.
So the level of doubt and or critical thinking I apply to Sabine's videos is not much different than what I would apply to a physic paper out of journal and I feel like I can often apply less than what I apply while reading many popular science articles. That is no where close to the level of trust I would put in to a well grounded physics text book though.
This sort of doubt is critical to most people while reading journal articles, double checking, verifying, not assuming ground truth for what a paper says to uncover hidden assumptions, mistakes, and differing interpretations.
~"Just believe" is not conductive to learning science and is not going to make for curious or simulating conversation.
> If you pick any 5 videos you want, I'd be happy to help you spot check them. Just like I did with this one.
You did not extract the value from this video though. You reference other resources to try and get the value. I am not interested in doing something similar with her other videos.
> 1. Your point about settling physics with experiment is not applicable here. The result is about what the math will predict if you make a specific assumption in a specific mathematical model. Testing that is like trying to test the frequency with which 1+1 gives you 3. It's a question of logic. What becomes a question of experiment is whether a particular model is a good description of reality.
If physical reality does not, can not matter to resolving a question, your question may not be about physics. This one point is not enough, like I said original, by itself, to make the apparent contradiction obviously non interesting.
> 2. She may not be skewering cows that are sacred to all of physics. But a lot of her videos skewer cows that are sacred to some group, and she's constantly getting an earful about it.
Is the earful about any sacred cows though? Are their other viable explanations You may have evidence for you conclusion, but it is not here.
> I think it is very important to be aware how easily branches of science become pseudoscience.
Sabine asserts this has happened to quantum loop gravity but doe snot show it. If I thought what she said was true and I wanted to make convincing case I would have to go out and do considerable research and put together a case, I could not simply reference this video.
> And with John Baez' support, it's clear that her complaint is more than simple sour grapes.
Sour grapes normally means that when someone can not have something they want they go negative on it instead. Does this saying even apply here? Nothing in the video made me think she was sour about anything.
she said some outlandish stuff in one video - I don't remember which. I refuse to watch any more of her videos.
She was ripping on the valuations and economics of quantum computing companies the other week, and her critiques were such that they could be levelled against capitalism itself and basically any company in the market. Was an obvious and clear step way out of her area of expertise.
That doesn't have anything to do with her criticism of Loop Quantum Gravity, and is precisely the derailing of the topic that dang is asking you to avoid.
When people don’t have expertise in an area they are prone to making really dumb comments. She has a history of this on other topics. As such I think it’s appropriate to mention so that people can evaluate how much weight/time they want to spend on her video and views.
Do you have expertise in the area of deciding source trustworthiness or relevancy in certain fields?
I do not. I do have a sense of the notion and make decisions for myself on whether or not something is worth my time. While her video might be accurate in this case her past casts doubt in my mind and as such I’ve decided not to watch it. Other people might find it useful to know about her past errors when deciding whether or not to watch this video.
> What's even more insane is that the only two people I can think of who have pushed back against this are Peter Woit and Eric Weinstein, and both of them are trying to sell you their own theory of everything
Sabine forgot Stephen.
https://writings.stephenwolfram.com/2021/11/the-concept-of-t...
Not exactly. She's just admitted that he isn't someone she thought of. And that's likely because she's far more aware of the contributions of physicists to this field, than the attempted contributions of non-physicists. It's not that she's not aware that they exist - in fact she's painfully aware that there are a great number of them saying all sorts of things - its that she's not individually aware of them.
That said, if she had thought of him then she would have merely increased her sample size from 2 to 3, and still had the exact same conclusion.
What absurd definition are you using that makes Stephen Wolfram not a physicist?
Wolfram is more of a physicist than most physicists.
Wikipedia:
He entered St. John's College, Oxford, at age 17 and left in 1978[17] without graduating[18][19] to attend the California Institute of Technology the following year, where he received a PhD[20] in particle physics in 1980.[21] Wolfram's thesis committee was composed of Richard Feynman, Peter Goldreich, Frank J. Sciulli and Steven Frautschi, and chaired by Richard D. Field.[21][22]
In the mid-1980s, Wolfram worked on simulations of physical processes (such as turbulent fluid flow) with cellular automata on the Connection Machine alongside Richard Feynman[29] and helped initiate the field of complex systems.[citation needed] In 1984, he was a participant in the Founding Workshops of the Santa Fe Institute, along with Nobel laureates Murray Gell-Mann, Manfred Eigen, and Philip Warren Anderson, and future laureate Frank Wilczek.[30] In 1986, he founded the Center for Complex Systems Research (CCSR) at the University of Illinois at Urbana–Champaign.[31] In 1987, he founded the journal Complex Systems.[31]
From 1992 to 2002, Wolfram worked on his controversial book A New Kind of Science,[4][33] which presents an empirical study of simple computational systems. Additionally, it argues that for fundamental reasons these types of systems, rather than traditional mathematics, are needed to model and understand complexity in nature. Wolfram's conclusion is that the universe is discrete in its nature, and runs on fundamental laws which can be described as simple programs. He predicts that a realization of this within scientific communities will have a revolutionary influence on physics, chemistry, biology, and a majority of scientific areas in general, hence the book's title
Wofram was a child prodigy but he quit physics.
It's not like you can stop doing something as a young person and be relevant or be competent just because you are smart. "A New Kind of Science" is not very deep book. It's graphically beautiful, but it contains lots of hand waving.
He has gradually descended into crackpot regime.
You are right.
But let's reduce it down to physicists working in quantum gravity, who publish in journals that such physicists typically publish in. Give that this is Sabine's background, this is who she will be aware of. For all that he's done, I'm pretty sure that Wolfram's works have not been published in such journals.
Roger Penrose is an even better example. His claims to be a physicist include a Nobel prize. But people working in quantum gravity dismiss his theories, so he doesn't publish in the right places, and so Sabine didn't think of him.
In short, Sabine is only likely to think of people in this context because their scientific work intersected hers.
i love sabine. she's speaking the lived experience of quite a few of us who lost faith in the academy.
I like her message, but some of her recent videos have me a little worried about her. She seems on the edge of a breakdown at times.
> She seems on the edge of a breakdown at times.
Academia does this to you. She's a really well controlled case.
yeah. she does seem like she's on the edge of throwing down f-bombs, flipping tables and screaming "i'm out of here." guess it's to her credit she hasn't done that.
I've said this before in not the same words, and I am always downvoted here on hackernews: people need to understand theory of knowledge before they understand science. Physics and physicists are the worst offenders.
If by "theory of knowledge", you mean they need to have read a bunch of philosophical musings on epistemology, then I strongly agree with the downvoters, because that's utter nonsense. If you mean anything else by that, then you're being way too vague to contribute to a technical discussion, so again I agree with the downvoters. Try defining what you mean by "theory of knowledge" and explain why you think that's required to "understand science" (and you might want to explain what you mean by that too) and I suspect you'll see a lot fewer downvotes.
Amusingly, the International Baccalaureate Diploma Programma - an A-Levels like uni-prep course - has a subject called TOK: Theory of Knowledge with these intentions.
This strongly depends on what you mean by "theory of knowledge".
If you mean the practical importance of self-honesty, and a historical awareness of how easily we slip into self-delusion, then I agree. See, for instance, https://calteches.library.caltech.edu/51/2/CargoCult.htm for a very famous speech on exactly this topic. A lot of Feynman's writing touches on the same issue.
If you mean the musings of philosophers on epistemology, then I emphatically disagree. The philosophers in question generally have failed to demonstrate that they understand science. And when they venture into science, they generally fail to live up to the ideals that they proclaim that scientists should follow. As an example I direct you to the sight of Karl Popper arguing to the end of his days that quantum mechanics cannot be a correct scientific theory. An opinion that began because a probabilistic theory cannot in principle be falsified.
In fact QM is a scientific theory, and it stands as an example falsifying Popper's criterion for science!
I find it very ironic that Feynman is so disliked by philosophers for having been honest about how irrelevant they are to science. And philosophers in turn have failed to recognize Feynman's explanations of how to do science as a key topic that should be included in any proper philosophy of science.
Theoretical physics are theoretical; that seems to be the crux of her problem. And in that light it makes sense that she's become an influencer who makes content instead of someone who devotes most of their time to advancing the science. Yes, oftentimes people will be paid to work on problems, and they'll end up in a cul-de-sac. That will be the case for the majority of the field in the case of something like quantum physics. But if we pay enough of these people to sit in rooms and work on problems, maybe one of them will figure something out. That's how science progresses.
> enough of these people
There’s more than enough already. (And, historically, you only need less than a dozen.)
> (And, historically, you only need less than a dozen.)
This seems initially like a pretty outlandish claim to me. Could you clarify what you're referring to here?
I'm not the one you're replying to, but the claim seems very reasonable to me.
Fundamental breakthroughs in how to think about scientific subjects usually are created by fairly small groups of people. A lot more people are involved in popularizing it, and then filling out the details. But it is rare for it to start with a large number of people.
For example that list in the case of quantum mechanics was Max Planck, Albert Einstein, Niels Bohr, Louis de Broglie, Max Born, Paul Dirac, Werner Heisenberg, Wolfgang Pauli, and Erwin Schrödinger.
You can think of this as the scientific version of the 2 pizza rule.
Humans sure love this story. A dozen Founding Fathers created the United States. A dozen physicists invented quantum mechanics. A dozen innovators caused the Industrial Revolution. It's always wrong.
Ask any of those dozen people where they got their ideas and (if they're honest) they'll each have another dozen people to name, and so on. Ask them who made minor contributions and suggestions and they'll again have dozens of people to name. Science is an ever-expanding body of work that always builds on its past successes and it's the height of naivete to reduce humanity's effort in a subject down to its few most visible people. It makes for good stories and trivia questions, but it's extremely far from the actual truth.
And even if it were true: how could you possibly identify those dozen people beforehand? It'd be like walking into a publishing house and proclaiming that everyone there is stupid because they waste all this money on books that don't end up best-sellers. Why don't they just only invest in the future best-sellers? Are they stupid?
I partly agree. A conceptual breakthrough always rests on a foundation to which many contributed. All of whom, in some sense, contributed. But my reading of history says that the reconceptualization that leads to intellectual breakthroughs themselves usually only involve small numbers of people.
If you've read The Structure of Scientific Revolutions, what I'm saying is that new paradigms are usually created by very small numbers of people. But they have both a foundation and their further success from the contributions of many.
I'm very much not offering an opinion on a great man theory of history in fields outside of science. Your example of the American Revolution is entirely off topic.
I'm also very much not saying that who will contribute what is in any way predictable. At best, the necessary collision of circumstances to make the breakthrough possible is chaotic, and therefore cannot be predicted. Nor did anyone else. The original point a few posts up was that, even if though there might be a haystack of clearly wasted effort, there may still be a needle powerful enough to make up for the rest.
All good points, but remember the claim in question was:
> But if we pay enough of these people to sit in rooms and work on problems, maybe one of them will figure something out.
and the response that you called "very reasonable" was:
> There’s more than enough already. (And, historically, you only need less than a dozen.)
So you were agreeing with someone who said we are paying too many physicists. There are too many people studying this problem. Okay, let's get rid of some then. Which ones?
> I'm also very much not saying that who will contribute what is in any way predictable
Uh oh, then how do we know who to get rid of? Which physicists should we not be paying? The claim that we should fire a bunch of scientists because we "only need less than a dozen" is nonsense, and you called this claim "very reasonable", with more examples. But maybe I should have replied to that person instead. It's a little awkward trying to have an N-way conversation when you can only reply to one response at a time.
The statement that there's more than enough, is not the statement that we should be firing them. It's a statement that we don't want more.
But if we had to fire some, I'd recommend ones who are not willing to do research outside of oversubscribed ideas. That's because the lack of success of existing lines of research means that additional effort there is less likely to work out than looking at less overpopulated approaches.
>> For example that list in the case of quantum mechanics was Max Planck, Albert Einstein, Niels Bohr, Louis de Broglie, Max Born, Paul Dirac, Werner Heisenberg, Wolfgang Pauli, and Erwin Schrödinger.
Those were not the only people working in that field at the time. Not by a long shot. In order to have pioneers in a field, there has to BE a field with a bunch of people in it.
You're right that these were not the only people working on the set of problems that lead to QM. Lots of people were thinking about the same problems at the same period of time. And lots more added to it later.
But what key concept underlying how we now think about QM doesn't go back to this list of people? OK, add Richard Feynman if you want to include the second breakthrough to QED.
Ideas that look like conceptual breakthroughs can usually be traced back to small numbers of people. Ideas that look like progress usually trace back to much larger groups.
Eh, there is theoretical and then there is intentionally untestable, like string theory.
Just because you pay a bunch of people to sit in a room and think of things, doesn’t mean they’re doing science. It could just as easily be theology.
I think that you have half a point. You're absolutely right that just because people are paid to think about things, doesn't mean that they are making progress. And there is a lot of evidence that this is true today in the foundations of physics.
However string theory was not intentionally untestable. In https://www.youtube.com/watch?v=eRzQDyw5C3M she gives a good history of why it was originally invented, what testable predictions it made, how it failed those tests. And then how string theorists who were trying to find relevance for their work tried to keep it going as it stumbled into being untestable.
This is a very cruel reading of string theory. Intentional? What?
Exactly. Consistently untestable and unfalsifiable claims for decades has to be seriously questioned at some point, and I think we're well beyond that point. This is especially true for string theory. I'm particularly fond of how Angela Collier laid out the timeline of string theory in her video on it[0] as well as the consequences that science communication is now facing as a result.
The same could've been said of atomic theory, neutrinos, gravitational waves, the higgs boson, cmb radiation, plate tectonics, and quantum mechanics at various points in time.
That statement is only true for a few of the things on your list..
Yes, it took a couple of decades to test the existence of neutrinos. But, for example, general relativity was successfully tested within 5 years of being published. Gravitational waves were a prediction that took decades before we could test them, but the theory itself had lots of other verifications.
To date string theory has had many predictions that leads to failed tests. But not a single successful test in its favor.
Weren't those all arrived at from a series of falsifiable predictions? What does string theory even predict that can be tested?
As a non string theorist my understanding was that string theory actually makes quite a lot of empirically verifiable statements, just that those statements are only interesting at either never or extremely high energies.
I think ppl are asuming that sting theory comes from the meme about turning 1+1 = 2 into some massive integro differential equation. The world is rarely so simple.
I’ve heard that it also predicts at very low precision, some values that are practically measurable, and, unsurprisingly for how little precision these predictions have, these predictions are correct (I.e. the experimental results are within the predicted range).
(Or, maybe “a prediction” rather than “predictions”? I only heard about one, and I forget what it was.)
I think the prediction you may be referring to is supersymmetry, which was apparently empirically disproved by the LHC, or at least the supersymmetric extension to the standard model was disproved.
https://www.sciencenews.org/article/supersymmetrys-absence-l...
I am aware of no case where it clearly made an advance prediction of any behavior that later turned out to be true.
I'm aware of quite a few where they managed to "predict" something we already knew.
That said, they've made so many "predictions" that I'm sure that some likely worked out by sheer coincidence.
Oh, yes, I meant predict a value we had already measured at the time the "prediction" was made. I should have made that clear in my original comment. I would add it now except that the editing time has run out. Maybe I should have said "postdicted".
Actually, I think the value might have been something like, the electron mass? Or something like that. (Which, obviously, had been measured before string theory made a "prediction" of it.)
You are making it sound as though string theorists are asserting some kind of flying spaghetti monster theory. Do you think these people are not genuinely interested in advancing science? That's an ad hom fallacy. There is a difference between a hypothesis being conceptually unfalsifiable and a hypothesis that is incredibly difficult to test from a practical standpoint, or impossible with present energy constraints.
I don’t think the mistake made is exactly an ad hom fallacy? I agree with the rest of your comment though.
No, not really. All of those had reasonable, technically addressable methods for testing.
How is it "intentionally untestable"? I get that it is practically untestable, but as far as I know, there are people working to try to find some possible tests.
There is no evidence to suggest that string theorists designed the theory to be untestable.
That proves it!
I mean, you should prove they didnt. If that sounds unreasonable we've made progress. Prove we didn't?
Ill let myself out
After this much time and that much work, how is it possible for a physics theory to not have a single testable/falsifiable prediction without it being intentional? It has been over 80 years. [https://en.m.wikipedia.org/wiki/History_of_string_theory].
The evidence is in the absence.
It predicted supersymmetry, which has been experimentally disproved.