A new kind of symmetry shakes up physics(quantamagazine.org)
quantamagazine.org
A new kind of symmetry shakes up physics
https://www.quantamagazine.org/a-new-kind-of-symmetry-shakes-up-physics-20230418/
90 comments
They've corrected the story (angular momentum, not momentum) and added a note at the end.
At least in some formulations (e.g. using bivectors and geometric algebra) you can treat a spatial translation as being a rotation about a point at infinity.
(A line at infinity, of course, as rotations are about axes, not points, and in three dimensions an axis is a line.)
As long as dimension n = 3 and so [dimension of R^n] n = n(n-1)/2 [dimension of so(n)]. Not to disregard these low-dimensional isomorphisms; there’s quite a few of them (they run out at about n = 10 IIRC), each one different from the next, and most are important in one way or another. But expressing momenta and angular momenta in those terms gives the impression that their existence is due to the (numerous and sometimes very complex) particulars of three-dimensional space, which it isn’t.
As long as dimension n = 3 and so [dimension of R^n] n = n(n-1)/2 [dimension of so(n)]. Not to disregard these low-dimensional isomorphisms; there’s quite a few of them (they run out at about n = 10 IIRC), each one different from the next, and most are important in one way or another. But expressing momenta and angular momenta in those terms gives the impression that their existence is due to the (numerous and sometimes very complex) particulars of three-dimensional space, which it isn’t.
>rotations are about axes, not points
Well, in 2D it's about the same. In 3D it can be the same, as long as the rotation happens on a 2D plane.
Well, in 2D it's about the same. In 3D it can be the same, as long as the rotation happens on a 2D plane.
Rotations always happen in a plane, in n-dimensions. In 3D there's a coincidence where planes and lines can be put in exact correspondence.
This is the root of the whole "axial" and "pseudo" vectors that plague physics -- there's a (Hodge) duality being hidden, and we're stuck with Gibbs & Heaviside's vector calculus.
But a plane (bivector) will always be the natural way to define a rotation.
This is the root of the whole "axial" and "pseudo" vectors that plague physics -- there's a (Hodge) duality being hidden, and we're stuck with Gibbs & Heaviside's vector calculus.
But a plane (bivector) will always be the natural way to define a rotation.
You can rotate around a line, it doesn't necessarily need to be an axis.
Rotations of a point happen in a plane around some point in the plane, not around a line or axis. In two dimensions there is no line perpendicular to the plane to rotate around, in four and higher dimensions there is no unique plane perpendicular to any given line. It is only in three dimensions that rotating in a plane and around a line coincide.
Disclaimer: I'm not a physicist and am must approaching this with a very basic understanding of the matter
Isn't it generally said that the earth is rotating around the sun, or is that scientifically inaccurate?
Isn't it generally said that the earth is rotating around the sun, or is that scientifically inaccurate?
The planets all orbit in approximately the same plane, the ecliptic. So it’s fine to say that they rotate around the Sun—except that, really, they orbit in (approximate) ellipses with the Sun at one focus. But these ellipses are pretty circular (low eccentricity), so, again, we can say that we’re orbiting around the Sun without hurting anyone.
> really, they orbit in (approximate) ellipses with the Sun at one focus
Don't they technically orbit the center of mass, assuming a simplified two-body system?
In the case of Sol and a planet, given the massive (pun intended) disparities, the center of mass is very, very close to the center of Sol - but not coincident.
Don't they technically orbit the center of mass, assuming a simplified two-body system?
In the case of Sol and a planet, given the massive (pun intended) disparities, the center of mass is very, very close to the center of Sol - but not coincident.
We can also say the Sun is orbiting the Earth thanks to being able to choose our frame of reference. GPS makes good practical use of the Earth as the preferred frame.
I don’t really see your point, sorry? In arbitrary dimension, you rotate in an oriented plane (aka a bivector up to a positive constant) around a fixed point, if anything; I meant to call that an “axis” by abusing the terminology a bit (it’s an oriented line in three dimensions and a point plus an orientation, i.e. either “clockwise” or “counterclockwise”, in two).
Not all isometries with a fixed point will be “rotations” in that sense, though—some will be products of them, as in
Not all isometries with a fixed point will be “rotations” in that sense, though—some will be products of them, as in
/ cos u sin u 0 0 \
| -sin u cos u 0 0 |
| 0 0 cos v sin v |
\ 0 0 -sin v cos v /
[deleted]
The word axis can be used to mean various things. One of those is the line that a rotation happens around.
Is that like saying sin(x)=x?
It is more like saying 1/∞ = 0.
"Translations are rotations around infinity" is what you get if you compactify the real plane with projective geometry, 1/∞ = 0 is what you get when you close the complex field with an holomorphic-friendly point at infinity.
"Translations are rotations around infinity" is what you get if you compactify the real plane with projective geometry, 1/∞ = 0 is what you get when you close the complex field with an holomorphic-friendly point at infinity.
sort of... A line is a circle (more precisely, a cline ("circle-or-line") with infinite radius and center on the "horizon" (In 1D, the horizon is the 2 points at +/infinity. In 2-D, the horizon an infinite circular boundary around the plane. In 3-D, it's an infinite circular sphere). The center's position determines the slope/angle of the line.
For a translational "rotation" in 3D, the axis of rotation is the line that is tangent to the infinite "celestial" sphere and perpendicular to the line of translational motion.
For a translational "rotation" in 3D, the axis of rotation is the line that is tangent to the infinite "celestial" sphere and perpendicular to the line of translational motion.
You mean, for small x, sin(x) ~= x?
I've been thinking for a while and I can't see a way that it's like that
Like if you zoom in on a circle close enough it looks like a straight line.
This is basically it, yes, along with cos(x) = 1. If the axis of rotation is much further than the distance that you move through upon rotation, the angle of rotation is very close to zero, so the approximations are very good. In the limit that the axis of rotation is infinitely far away, it is exact.
Coincidentally, a recent relevant XKCD: https://xkcd.com/2761/
Looks to be related to projective geometry in some way in which every point symmetry has a matching “dual” or line symmetry.
https://en.m.wikipedia.org/wiki/Projective_geometry#Duality
https://en.m.wikipedia.org/wiki/Projective_geometry#Duality
It is not. Sorry to disappoint. :)
The "dualities" mentioned in the article are about two seemingly different quantum field theories actually being equivalent. See here, for example:
https://en.wikipedia.org/wiki/S-duality https://en.wikipedia.org/wiki/Seiberg_duality
The "dualities" mentioned in the article are about two seemingly different quantum field theories actually being equivalent. See here, for example:
https://en.wikipedia.org/wiki/S-duality https://en.wikipedia.org/wiki/Seiberg_duality
I'm sorry, "non-invertible symmetry"? In what way is that still a symmetry?
Think of a symmetry as "something that remains the same" when you do something to a system.
Imagine a pair of denim pants, one could say it has the property of being made of denim, and when you bend the pants or move them around the room, they keep being made of denim. Anything you do to the pants that you can undo, like moving them around or bending them, those are invertible symmetries. Now imagine I rip the pants in half: they're still made of denim, but this action is not so easy to invert. So there are actions I can perform on these pants that are hard or impossible to undo, but still maintain the property of them being made of denim, these are non-invertible symmetries.
The example given in the article is a system being split into a superposition in a way that's hard or impossible to undo, sort of like the pants being torn in half, but just because the system is now in a superposition doesn't mean there weren't properties preserved along the way.
Imagine a pair of denim pants, one could say it has the property of being made of denim, and when you bend the pants or move them around the room, they keep being made of denim. Anything you do to the pants that you can undo, like moving them around or bending them, those are invertible symmetries. Now imagine I rip the pants in half: they're still made of denim, but this action is not so easy to invert. So there are actions I can perform on these pants that are hard or impossible to undo, but still maintain the property of them being made of denim, these are non-invertible symmetries.
The example given in the article is a system being split into a superposition in a way that's hard or impossible to undo, sort of like the pants being torn in half, but just because the system is now in a superposition doesn't mean there weren't properties preserved along the way.
That just looks like a conserved property. I know those are linked to symmetries, but they're not identical.
Is this something like the physical operation to invert it doesn't exist, even though it's logically possible? The "pants" example, and maybe the superposition example, makes it sound like they're uninvertible for entropy reasons, which seems interesting if it's not an illusion.
Is this something like the physical operation to invert it doesn't exist, even though it's logically possible? The "pants" example, and maybe the superposition example, makes it sound like they're uninvertible for entropy reasons, which seems interesting if it's not an illusion.
Right, they're not identical, but they're generally paired up so neatly via Noether's theorem that they're treated as the same thing.
In seems like physicists are finding more general conserved quantities associated with more general spaces of physical operations such that not every action is reversible, but there are still conserved quantities associated to the underlying systems, AKA symmetries.
I don't have any solid physical intuition as to what makes an operation irreversible in this context, though, whether it's related to entropy or not.
In seems like physicists are finding more general conserved quantities associated with more general spaces of physical operations such that not every action is reversible, but there are still conserved quantities associated to the underlying systems, AKA symmetries.
I don't have any solid physical intuition as to what makes an operation irreversible in this context, though, whether it's related to entropy or not.
Interesting. Thanks!
Great explanation, thanks.
Yeah, it's a reference to how "category theory" generalizes "group theory". So if transformations in a group are called "symmetries" then you might call the transformations in a category "generalized symmetries" or "non-invertible symmetries" as in this article.
Erm the whole idea of a symmetry is that it is a group invariant. If they're using the term in some more general way, it would help if they said what the new way was. The article is otherwise almost completely uninformative. What on earth is a "generalized symmetry", especially one that still has something like a conservation law? Does it have applications in math as well as physics? E.g. topologists are always looking for new invariants.
I can understand that popularizations have to gloss over the math, but they usually at least identify the important points even if they don't get into the weeds of explaining the details. This seems like more of a sleight of hand.
I can understand that popularizations have to gloss over the math, but they usually at least identify the important points even if they don't get into the weeds of explaining the details. This seems like more of a sleight of hand.
Read the original paper: https://arxiv.org/abs/1412.5148
Apparently the QM and condensed matter people use the term "defect" for a (possibly non-invertible) transformation (semigroup or similar), and a "symmetry" is an "invertible" "defect".
https://physics.stackexchange.com/questions/561118/why-shoul...
https://physics.stackexchange.com/questions/561118/why-shoul...
> the symmetries apply to higher-dimensional objects such as lines, rather than lower-dimensional objects such as particles at single points in space.
Does this relate the String Theory?
Does this relate the String Theory?
FTA:
> And within these theories it’s often necessary to go beyond points and particles to think about one-dimensional lines, or strings (which are conceptually distinct from the strings in string theory).
Super Asymmetry?
Is this some flavour of groupoids symmetry?
Cue incoming Sabine Hossenfelder YT video takedown.
> “I have not yet seen shocking results that we didn’t know before, but I have no doubt it’s quite likely this will happen, because this is clearly a much better way of thinking about the problem,” Seiberg said.
This bothers me. What about the empirical evidence from experimentation? Shouldn't that be more important?
> “I have not yet seen shocking results that we didn’t know before, but I have no doubt it’s quite likely this will happen, because this is clearly a much better way of thinking about the problem,” Seiberg said.
This bothers me. What about the empirical evidence from experimentation? Shouldn't that be more important?
What is it about theoretical physics that makes people on the internet (with zero understanding of the context) feel entitled to snarkily attack results such as this?
The research in the article is about as innocuous as it gets — uncovering another possible way to get a handle on the math of quantum field theories. It’s not like millions of dollars went into the research (just the modest salaries of the four theorists). No major applications as yet — the Quanta title “…shaking up physics” is certainly not true. But it’s another stone in the edifice of science.
And my god when you see the esoterica in some (most?) other academic fields, the unrelenting complaints about the solipsism of physics seem totally misdirected. When an upper bound on some complicated measure on the distribution of prime numbers is lowered, no chorus of jackals assembles on the internet to mock the proof for its lack of real world relevance. The other day I spoke with a classics professor whose primary research was on a possible alternative interpretation of one line in a Latin poem. I found it interesting and worthwhile, but wow another level of remove from the so-called real world of engineering application and commerce.
Also, to be clear, whether or not mathematical physics work winds up elucidating experiments, it is still correct and “useful” math. It’s not for nothing that the math community gave Edward Witten a Fields medal.
The research in the article is about as innocuous as it gets — uncovering another possible way to get a handle on the math of quantum field theories. It’s not like millions of dollars went into the research (just the modest salaries of the four theorists). No major applications as yet — the Quanta title “…shaking up physics” is certainly not true. But it’s another stone in the edifice of science.
And my god when you see the esoterica in some (most?) other academic fields, the unrelenting complaints about the solipsism of physics seem totally misdirected. When an upper bound on some complicated measure on the distribution of prime numbers is lowered, no chorus of jackals assembles on the internet to mock the proof for its lack of real world relevance. The other day I spoke with a classics professor whose primary research was on a possible alternative interpretation of one line in a Latin poem. I found it interesting and worthwhile, but wow another level of remove from the so-called real world of engineering application and commerce.
Also, to be clear, whether or not mathematical physics work winds up elucidating experiments, it is still correct and “useful” math. It’s not for nothing that the math community gave Edward Witten a Fields medal.
acchow(1)
I've observed that this exists in all domains. Unsubstantial critique is cheap and at everyone's disposal. Generously, I think it can be interpreted as an appeal to common sense due to ignorance / lack of specialization. There's probably some heuristic like, "the more specialization required to understand information, the easier it is to invite empty critique."
I'm not very generous though. I personally think the majority of people are more interested in being right or sounding clever than arriving at truth or understanding.
I'm not very generous though. I personally think the majority of people are more interested in being right or sounding clever than arriving at truth or understanding.
> I personally think the majority of people are more interested in being right or sounding clever than arriving at truth or understanding.
there's a term-of-hate for this "poser" like in parent's username. regardless of whether HN or the internet at large has a poser problem, drawing attention to it is off topic at best and hateful at worst - otoh we could be happy that the zeitgeist holds theoretical physics in high enough regard as to draw posers (iow we could have worse problems!)
there's a term-of-hate for this "poser" like in parent's username. regardless of whether HN or the internet at large has a poser problem, drawing attention to it is off topic at best and hateful at worst - otoh we could be happy that the zeitgeist holds theoretical physics in high enough regard as to draw posers (iow we could have worse problems!)
I thought a superposeur was someone who prepares superposed quantum states. It's one of the steps on the way to getting the entangleur credential. You need the latter before you can build quantum computers. ;-)
yes pun intended
Sabine is a theoretical physicists who works on the foundations of quantum mechanics. And she's not the only critic inside the field. The debate is over whether math should be elevated to the status that observation has in science, when it becomes difficult to make progress doing experiments.
GP didn't say anything about Sabine.
> What is it about theoretical physics that makes people on the internet (with zero understanding of the context) feel entitled to snarkily attack results such as this?
This is about you.
> What is it about theoretical physics that makes people on the internet (with zero understanding of the context) feel entitled to snarkily attack results such as this?
This is about you.
Sabine was in my initial comment. She makes videos criticizing physics which relies more on math and beauty over observation. This sounds like more of the past several decades of string theory related research.
This has literally nothing to do with string theory except for one object sharing the same name.
> And within these theories it’s often necessary to go beyond points and particles to think about one-dimensional lines, or strings (which are conceptually distinct from the strings in string theory).
And for that matter, they literally discuss observations in TFA, what are you on about.
Anyway, if you don't know the role symmetries have played in physics for well over a century at this point, you aren't qualified to discuss the subject.
> And within these theories it’s often necessary to go beyond points and particles to think about one-dimensional lines, or strings (which are conceptually distinct from the strings in string theory).
And for that matter, they literally discuss observations in TFA, what are you on about.
Anyway, if you don't know the role symmetries have played in physics for well over a century at this point, you aren't qualified to discuss the subject.
> But last May, three physicists proved that the 1969 verdict was only half the story. It wasn’t just that the presupposed symmetry wasn’t there — it was that higher symmetries were. And when those symmetries were incorporated into the theoretical picture, the predicted and observed decay rates matched exactly.
…
> [The] fractional quantum Hall effect, involves the spontaneous reorganization of electrons, but without any apparent symmetry being broken. This made it an uncomfortable outlier within the theory of phase transitions. That is, until a paper in 2018 by Xiao-Gang Wen of the Massachusetts Institute of Technology helped establish that the quantum Hall effect does in fact break a symmetry — just not a traditional one.
…
> [The] fractional quantum Hall effect, involves the spontaneous reorganization of electrons, but without any apparent symmetry being broken. This made it an uncomfortable outlier within the theory of phase transitions. That is, until a paper in 2018 by Xiao-Gang Wen of the Massachusetts Institute of Technology helped establish that the quantum Hall effect does in fact break a symmetry — just not a traditional one.
Theoretical results allow you to make experiments in the first place and to interpret empirical results.
Sometimes experimental results aren’t even the important part. Lorentz Ether Theory and Special Relativity make the exactly same predictions. Yet only one of them is considered revolutionary. And it isn’t the one that was invented first.
Sometimes experimental results aren’t even the important part. Lorentz Ether Theory and Special Relativity make the exactly same predictions. Yet only one of them is considered revolutionary. And it isn’t the one that was invented first.
> Theoretical results allow you to make experiments in the first place
How so?
> Sometimes experimental results aren’t even the important part.
When are experiments ever not important? What is a theory without experimental results?
I know you've mentioned Special Relativity but let me illustrate my point using General Relativity:
When Einstein came up with General Relativity, few people believed him – until experiments proved him right[0]. But the hype was over soon after because there were not many things one could predict (beyond rather simple things in cosmology). While hype came back briefly during the Golden Age of Relativity between 1960 and 1975[1], afterwards everyone lost interest in GR once more because there were still barely any experiments you could do. That is, until recently, when people found gravitational waves and started taking "photos" of black holes.
So do you think that Special Relativity would be as well-known and popular today if people hadn't proven it right in countless experiments and found applications in many other areas? Personally, I think SR would probably be known only among physicists today, as a correct but somewhat arcane theory some patent clerk from the early 20th century came up with.
Don't get me wrong. Some theories are impressive. But they're much more impressive if they turn out to be correct. :)
[0]: https://en.wikipedia.org/wiki/General_relativity#cite_ref-14
[1]: https://link.springer.com/article/10.1007/s10714-017-2203-1
How so?
> Sometimes experimental results aren’t even the important part.
When are experiments ever not important? What is a theory without experimental results?
I know you've mentioned Special Relativity but let me illustrate my point using General Relativity:
When Einstein came up with General Relativity, few people believed him – until experiments proved him right[0]. But the hype was over soon after because there were not many things one could predict (beyond rather simple things in cosmology). While hype came back briefly during the Golden Age of Relativity between 1960 and 1975[1], afterwards everyone lost interest in GR once more because there were still barely any experiments you could do. That is, until recently, when people found gravitational waves and started taking "photos" of black holes.
So do you think that Special Relativity would be as well-known and popular today if people hadn't proven it right in countless experiments and found applications in many other areas? Personally, I think SR would probably be known only among physicists today, as a correct but somewhat arcane theory some patent clerk from the early 20th century came up with.
Don't get me wrong. Some theories are impressive. But they're much more impressive if they turn out to be correct. :)
[0]: https://en.wikipedia.org/wiki/General_relativity#cite_ref-14
[1]: https://link.springer.com/article/10.1007/s10714-017-2203-1
> How so?
A theory created after an experiment is just fudging. A new theory allows you to come up with new experiments to test it. Or to come up with new theoretical extensions. Or to build a research agenda.
> So do you think that Special Relativity would be as well-known and popular today if people hadn't proven it right in countless experiments and found applications in many other areas?
There is no empirical evidence that supports SR over LET. There can’t be any, mathematically.
A theory created after an experiment is just fudging. A new theory allows you to come up with new experiments to test it. Or to come up with new theoretical extensions. Or to build a research agenda.
> So do you think that Special Relativity would be as well-known and popular today if people hadn't proven it right in countless experiments and found applications in many other areas?
There is no empirical evidence that supports SR over LET. There can’t be any, mathematically.
> A theory created after an experiment is just fudging.
So you're saying people came up with Maxwell's equations, quantum mechanics, the standard model of cosmology, et cetera, by… fudging?
How do you even devise a new theory without indications from experiments? There is a reason why there's a "crisis" in theoretical high-energy physics these days. Everyone is waiting for "new physics" to show up in experiments.
So you're saying people came up with Maxwell's equations, quantum mechanics, the standard model of cosmology, et cetera, by… fudging?
How do you even devise a new theory without indications from experiments? There is a reason why there's a "crisis" in theoretical high-energy physics these days. Everyone is waiting for "new physics" to show up in experiments.
> So you're saying people came up with Maxwell's equations, quantum mechanics, the standard model of cosmology, et cetera, by… fudging?
Partly, yes, though I am not really familiar with the exact context behind them. People fudge theories so those theories would fit known data. That alone doesn't guarantee that those theories would fit future data.
> How do you even devise a new theory without indications from experiments?
It's a two-way process. You need experiments to improve theory, and you need theory to create experiments.
Partly, yes, though I am not really familiar with the exact context behind them. People fudge theories so those theories would fit known data. That alone doesn't guarantee that those theories would fit future data.
> How do you even devise a new theory without indications from experiments?
It's a two-way process. You need experiments to improve theory, and you need theory to create experiments.
> That alone doesn't guarantee that those theories would fit future data.
Sure, but that's sort of a triviality. It's true for any theory.
> It's a two-way process. You need experiments to improve theory, and you need theory to create experiments.
I agree that it's a two-way process but I wouldn't say you need theory to create experiments and I think I've given sufficiently many counter examples to illustrate this.
What we (as humans) do need theory for is to make sense of our experiments (or of the world, really) and discover new experimental setups that might uncover something interesting (not explained by the current theory). On the other hand, without theory there's no concept of "unexplained by theory" in the first place. Our experiments would probably resemble random walks (in the sense that they're not driven by theory) but that doesn't mean we couldn't uncover interesting phenomena, let alone run experiments at all.
Getting back to the "making sense of the world" point: Take an AI for instance. It could probably be trained on experimental data alone and make suggestions for future experiments and give predictions, without a simple, coherent and human-understandable theory behind them[0]. This, too, illustrates that experiments would be possible (and worthwhile) even without theory.
Note that I'm not at all trying to play down the role of theory. To the contrary, I'm saying all this as a former theoretical physicist myself. I just see experiment and theory as equals.
[0]: Isn't this more or less what a human baby does as it learns?
Sure, but that's sort of a triviality. It's true for any theory.
> It's a two-way process. You need experiments to improve theory, and you need theory to create experiments.
I agree that it's a two-way process but I wouldn't say you need theory to create experiments and I think I've given sufficiently many counter examples to illustrate this.
What we (as humans) do need theory for is to make sense of our experiments (or of the world, really) and discover new experimental setups that might uncover something interesting (not explained by the current theory). On the other hand, without theory there's no concept of "unexplained by theory" in the first place. Our experiments would probably resemble random walks (in the sense that they're not driven by theory) but that doesn't mean we couldn't uncover interesting phenomena, let alone run experiments at all.
Getting back to the "making sense of the world" point: Take an AI for instance. It could probably be trained on experimental data alone and make suggestions for future experiments and give predictions, without a simple, coherent and human-understandable theory behind them[0]. This, too, illustrates that experiments would be possible (and worthwhile) even without theory.
Note that I'm not at all trying to play down the role of theory. To the contrary, I'm saying all this as a former theoretical physicist myself. I just see experiment and theory as equals.
[0]: Isn't this more or less what a human baby does as it learns?
> Sure, but that's sort of a triviality. It's true for any theory.
It is not a triviality. OP and many other people insist that nothing is important unless there is empirical evidence. Was there any empirical evidence that the Higgs boson is real and all competing theories are wrong before physicists spent billions of dollars to find it? Yet it was one of the most convincing theories, even if most of the evidence was theoretical, intuitive and aesthetic rather than empirical. I think you, as a former theoretical physicist, can come up with a dozen theories that are uglier but could fit old data just as well. The most trivial way to do it is just to say that in those experiment we should’ve expected those results and so on without any generalization. But of course numerous more sophisticated wrong theories would be possible. There is no theory that is so bad that it can’t be “fixed” with a few epicycles. By the way, Ptolemaic vs Copernician model is another good example of two different theories with similar or exactly the same fit w.r.t. to old experiments and observations.
> This, too, illustrates that experiments would be possible (and worthwhile) even without theory
That just illustrates that you can build a theoretical model with lots of free parameters and low interpretability.
> Note that I'm not at all trying to play down the role of theory.
Right. And I was just responding to OP who completely downplayed it.
It is not a triviality. OP and many other people insist that nothing is important unless there is empirical evidence. Was there any empirical evidence that the Higgs boson is real and all competing theories are wrong before physicists spent billions of dollars to find it? Yet it was one of the most convincing theories, even if most of the evidence was theoretical, intuitive and aesthetic rather than empirical. I think you, as a former theoretical physicist, can come up with a dozen theories that are uglier but could fit old data just as well. The most trivial way to do it is just to say that in those experiment we should’ve expected those results and so on without any generalization. But of course numerous more sophisticated wrong theories would be possible. There is no theory that is so bad that it can’t be “fixed” with a few epicycles. By the way, Ptolemaic vs Copernician model is another good example of two different theories with similar or exactly the same fit w.r.t. to old experiments and observations.
> This, too, illustrates that experiments would be possible (and worthwhile) even without theory
That just illustrates that you can build a theoretical model with lots of free parameters and low interpretability.
> Note that I'm not at all trying to play down the role of theory.
Right. And I was just responding to OP who completely downplayed it.
They do mention condensed matter physics. If it really makes maths easier there, that means instant practical relevance.
Facepalm. That's exactly the first thing I thought. I don't know if I am more tired of those blatant statements without any basis or of Sabine's expected reaction.
Theoretical particle physics is in a tough spot. I really hope in my lifetime I will get the change to learn new theories.
I am hopeful, still. But we either invent or we fail.
Theoretical particle physics is in a tough spot. I really hope in my lifetime I will get the change to learn new theories.
I am hopeful, still. But we either invent or we fail.
(Even?) Sabine understands following the beauty. Formalisms are thinking tools. Let them think.
Good for her. Before her there were people like Lee Smolin. They eventually get cancelled by the physics community, like short sellers in investment, no one wants to hear the sad trumpet but the "market" doesn't function without skeptics.
Theoretical discoveries are good, but some ego, some hype for funding, and some clickbaiting have made reporting on science even from the better sources like Quanta too focused on finding aliens and the grand unification or commercial fusion or whatever at least just by what gets written and posted, it seems like that.
Theoretical discoveries are good, but some ego, some hype for funding, and some clickbaiting have made reporting on science even from the better sources like Quanta too focused on finding aliens and the grand unification or commercial fusion or whatever at least just by what gets written and posted, it seems like that.
Smolin was not "cancelled".
He runs a prestigious institute (Perimeter) and has published several books and papers since his 2006 polemic "The Trouble with Physics"
http://leesmolin.com/wp-content/uploads/2019/04/cv_Lee-Smoli...
He runs a prestigious institute (Perimeter) and has published several books and papers since his 2006 polemic "The Trouble with Physics"
http://leesmolin.com/wp-content/uploads/2019/04/cv_Lee-Smoli...
It was just a freakin' expression. I didn't think it would trigger 5000000000 reply guys.
>people like Lee Smolin. They eventually get cancelled by the physics community
Could you tell me more about this or lead me where to read about it? All I know of him is that I came across some of his talks/interviews on youtube and found them incredibly refreshing. I am a physics graduate that left entirely dissatisfied and feel he's the lecturer that I wish I could have had. Is he viewed as a crackpot?
Could you tell me more about this or lead me where to read about it? All I know of him is that I came across some of his talks/interviews on youtube and found them incredibly refreshing. I am a physics graduate that left entirely dissatisfied and feel he's the lecturer that I wish I could have had. Is he viewed as a crackpot?
It’s news to me, but that doesn’t mean it’s not true. Maybe “people like” Smolin but not Smolin. I mean, he has a very good job, and has recently published books and papers, and interviews. I’m not sure I even understand what “cancelled by the physics community” would mean. Journal editors have secret instructions to throw out your manuscripts instead of sending them out for review?
garbagecoder(1)
Smolin isn't viewed as a crackpot, but anyone who brings up foundational issues, or who tries to moderate the conclusions drawn from research gets labeled a certain way, especially if the criticism is directed "outside."
Sabine is getting too famous to not ultimately get resentment.
Apparently, something in my comment there really made a lot of people mad (or one person with several accounts), and I'm unsure why. I would love someone to explain to me how they think science should function without skeptics.
Especially in the clickbait era.
Sabine is getting too famous to not ultimately get resentment.
Apparently, something in my comment there really made a lot of people mad (or one person with several accounts), and I'm unsure why. I would love someone to explain to me how they think science should function without skeptics.
Especially in the clickbait era.
> I would love someone to explain to me how they think science should function without skeptics.
No one thinks this. People dislike Hossenfelder and Smolin because they're peddling their own hot takes as established fact to a lay audience utterly unequipped to tell the difference.
No one thinks this. People dislike Hossenfelder and Smolin because they're peddling their own hot takes as established fact to a lay audience utterly unequipped to tell the difference.
"No one thinks this"
YOU don't think this, but there are clearly people out there who don't want to hear their wild speculation isn't real. It's human nature.
YOU don't think this, but there are clearly people out there who don't want to hear their wild speculation isn't real. It's human nature.
I don't understand why you're downvoted, I appreciate your response to my question
I thought any trouble Lee Smolin got in was because of Epstein.
I have nothing smart to say about the topic, but it is awesome as always to read about these kind of efforts to crack open murky but promising concepts that are posed. Also, the writer did a great job presenting it all.
Physics "breaks up" 4-5 times every year judging from such articles.
Reality being that there have been no major new developments for decades...
Reality being that there have been no major new developments for decades...
Is symmetry between left and right brain what allows consciousness to exist?
Clearly not, since you can have consciousness with only half a brain. Even a full hemispherectomy doesn't make you not conscious. In fact, there may be little change to the personality or cognition at all.
The symmetry between right and left brain doesn't really correspond to the types of symmetries they're talking about in the article. They're usually expressed as "The laws of physics are independent of X; you can substitute X with Y and the laws work the same." There isn't any kind of substitution here, so no place to apply the symmetry.
The symmetry between right and left brain doesn't really correspond to the types of symmetries they're talking about in the article. They're usually expressed as "The laws of physics are independent of X; you can substitute X with Y and the laws work the same." There isn't any kind of substitution here, so no place to apply the symmetry.
Given that the left and right brain aren't exactly symmetrical and will receive and process different inputs that seems like a no.
If some experimentator will destroy a half of his brain in such a way to not harm anything else - does he have a chance to keep being consciouness? That experiment kind of answers the question.
https://www.uclahealth.org/medical-services/pediatric-neuros...
It's literally a medical procedure that children (or adults[1]) with extreme seizures or epilepsy undergo so that they can live more normal lives.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281896/
It's literally a medical procedure that children (or adults[1]) with extreme seizures or epilepsy undergo so that they can live more normal lives.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281896/
In my opinion, one is between "this needs to be remembered, I will need this later" and "I have already remembered this, immediately recover!".
Conservation of angular momentum.
Conservation of momentum corresponds to spatial translation symmetry, not rotational.