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/sci/ - Science & Math

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10108827 No.10108827 [Reply] [Original]

What are the most bleeding-edge subjects in physics?

>> No.10108835

Not string theory.

>> No.10108846

>>10108835
Why not though? It's probably the most difficult branch of theoretical physics, or physics in general.

>> No.10108856
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10108856

>>10108846
all the string theorists now study dualities between ST and field theories, like AdS/CFT and that triangle that sabrina is always shilling (pic related)

>> No.10108866

https://journals.aps.org/about
select the topic you want

>> No.10108891

>>10108835
wrong, ST dominates quantum gravity research as usual, and there are still no real challengers to take its crown

>> No.10108903

>>10108891
the point is that there hasn't been much progress on string theory in-and-of itself for the past 20ish years. only the sad realization that the landscape is making it look nearly impossible to get a working theory out of it

the cutting-edge research is on studying dualities like is mentioned here: >>10108856
which is not really the study of string-theory in a standalone form, but rather its relationships with other kinds of theories

>> No.10108910

>>10108827

states of matter

topological insulators

string theory is just brain masturbation

>> No.10108945

String theory is actually schizophrenia tier by my book. My money is on a metaphysically real universe in which form begets function at all scales, in that the motion of energy in all forms is determined, and each passing moment at any given point in the universe is a determined state, causality preserved. Change my mind ~ uwu baka

>> No.10108956

>>10108891
>there are still no real challengers to take its crown
Why?
And why is nobody trying to come up with another theory of quantum gravity?

>> No.10108966

>>10108956
Literally everybody is trying to do that just use google scholar

>> No.10109002

>>10108910
>states of matter
What, plasma?

>> No.10109074

>>10109002
plasma is pretty hot with fusion right now, but he was probably just talking generic condensed matter

>> No.10109171

>>10109074
ITER is a scam, it needs to be dismantled for fusion research to advance

>> No.10109174

>>10109171
why do you think so?

i wonder what you have to say about the Webb telescope....

>> No.10109229

Why is /sci/ so critical of string theory? Surely people like Witten wouldn’t be working so hard on it if they thought it couldn’t lead anywhere interesting.

>> No.10109246

>>10109229
see here: >>10105867

>> No.10109253

>>10109246
Yeah, I read that thread, but what's the bottom line? Are string theorists just that far up their own ass? I have a hard time believing that they single-handedly ruined HEP

>> No.10109266

>>10109253
bottom line is that the theory has gone for 50 years without giving us even one experimental prediction that came true. it's one promising outgrowth was supersymmetry, and that has failed to show up even though for decades, the stringy guys were saying "for sure, it will definitely turn up at LEP/Tevatron/LHC" and they were wrong

fine, wrong theories don't bother me, but string theory is so nebulous that it can't be killed. it's "not even wrong." usually things like that fall out of favor, but it's just become such a self-reinforcing culture in academia that it just keeps going and going and going and leading nowhere. and it's taken over hep-th groups -- they're all filled to the brim with string theorists or their close allies that it crowds out other physics (that might actually prove productive, unlike ST). and that's what bothers me

>> No.10109270

>>10109266
Which parallel theories do you think have more merit and are more interesting than ST?

>> No.10109287

>>10109270
well, i don't think physics "needs" a ToE for any reason, even though that would be nice. Einstein worked on it for the latter half of his life without any success, and didn't contribute much to physics at all while spending decades working on that; meanwhile particle physics brought us the modern age by staying in contact with experiment

so i would suggest placing more emphasis on _testable_ predictions for experiments we _can_ do, like good theories of dark matter, neutrino physics (which is full of things we don't understand), and even more work just on SM physics like QCD, where LHCb is returning results that suggest there is new physics showing up in the world of quarks and gluons

i like Jesse Thaler a lot, look at what he's doing. Alexei Kitaev has done a good job at coming from the condensed matter world and BTFOing all the string theorists by making a really nice toy quantum model that shows e.g. gravity and black holes and hawking radiation, with none of that string crap.

also, if i had to name one other possible quantum gravity theory i think deserves attention, i would mention higher spin gravity. it's a super niche theory but i had a professor give me a really good lecture on it once, so i think it deserves some attention

>> No.10109308

>>10109287
String Theory IS the TOE until something better comes along. Like you said it not even wrong.

>> No.10109319

>>10109308
"not even wrong" is worse than wrong, i shouldn't have to explain this, but if something is not falsifiable, then it's not science, which is worse than plain wrong.

string theory might be the TOE, if we could prove first that it's the theory of _anything_. currently nobody has been able to turn it into a theory of the universe, it's currently a theory of nothing with a few mathematical applications in unrelated fields to high energy physics. so before you can call it a ToE, it needs to at least be able to describe reality, which it currently cannot, and that's why experimentalists in high energy physics use the standard model instead (since it just werks)

>> No.10109327

Why are people obsessed about a theory of everything anyways? Half of my undergrad was doing nothing but using taylor approximations and ignoring terms to actually get results. Theories that are practical and work, even if only in certain regimes seem more than OK to me.

>> No.10109904

>>10109229
Because string theory requires a strong math background and the physics people on /sci/ typically have very little of it. At the same time the math people on /sci/ resent physics people and don't like scienceplebs contaminating their threads. Unfortunately /sci/ is too small to split it into separate science and math boards.

>> No.10110163

>>10109904
>physics people on /sci/ typically have very little of it.
Any halfway respectable physics program will give you good foundational knowledge of mathematics. And if you're smart you'll minor in math anyway.

>> No.10110167

>>10110163
A minor in math and the sort of math that physics students do is still very little math compared to what a pure math major does.

>> No.10110181

>>10108827

black holes

>> No.10110192

>>10110167
It's not like physicists aren't given the tools to deepen their understanding of mathematics by themselves. Witten isn't from a math background despite receiving the Fields medal.

>> No.10110199

>>10110192
>It's not like physicists aren't given the tools to deepen their understanding of mathematics by themselves.
Of course, this isn't unique to physics students either. That said the majority of physics students on /sci/ don't do that and I get the sense that except for a few specifics the majority of physics students in general only study the bare minimum amount of math and only the special cases that apply to physics.

>> No.10110201

>>10110199
>the majority of physics students in general only study the bare minimum amount of math
Which is never sufficient when planning to go to grad school anyway.
Anything theoretical is going to involve high level math.

>> No.10110294

let me remind everyone chatting about “physicists are bad at math, that’s why people dislike string theory” are wrong. before string theory, all the best physicists were trained in physics but taught themselves or derived the math themselves. einstein, dirac, feynman, fell-mann, etc

feynman himself said “string theorists only make excuses” or something like that. peter woit is no schlub at math and is an outspoken critic of string theory.

even witten himself has been focusing a lot on condensed matter lately

>> No.10110298

>>10110294
*gell-mann

>> No.10110303

>>10108956
>And why is nobody trying to come up with another theory of quantum gravity?
Every attempt fails, but string theory keep working

>> No.10110316

>>10109266
>it's one promising outgrowth was supersymmetry, and that has failed to show up even though for decades, the stringy guys were saying "for sure, it will definitely turn up at LEP/Tevatron/LHC" and they were wrong
String theory is supersymmetric at the string scale (i.e about the Planck scale). It's true that SUSY at lower energy would help particle physics, but the lack of SUSY at TeV scales does not imply ST is incorrect.
>string theory is so nebulous that it can't be killed
ST is unique. It has many classical backgrounds, but there is only one fundamental theory -- even then, the number of vacuua is finite, unlike field theory
>>10109287
>i don't think physics "needs" a ToE for any reason, even though that would be nice
You're right that there is no need for all the forces to be combined into one, but nonetheless there is a need for a quantum theory of gravity, because coupling classical gravity to quantum matter is impossible.
>Alexei Kitaev has done a good job at coming from the condensed matter world and BTFOing all the string theorists by making a really nice toy quantum model that shows e.g. gravity and black holes and hawking radiation, with none of that string crap.
Bullshit! Nothing he's produced can actually explain quantum gravity even as a toy model. He might make some crazy speculations, but I've never seen him make any sensible claim about quantum gravity that could replace ST.

>> No.10110339

>>10110294
>peter woit is no schlub at math
Yeah, that's why he's published so many great maths and theoretical physics papers...

>> No.10110347

>>10108945
Is it being causal by allowing itself then? Or is it only multi modal under scrutiny? Sounds like it learned something the wrong way cause even a virus wont sit in the light facing a predator and theyre all instinct. Causality preserved and all that.

>> No.10110466

>>10108856
nice try sabrina

>> No.10110468

>>10108956
As it turns out its exceedingly difficult to produce a theory that is consistent with all previous data in every relevant field of physics and makes new predictions while being in someway testable.

Shocker.

>> No.10110640

>>10110167
side note: witten isn’t really from a physics background either. he was a history major in undergrad.

i’d be shocked if he ever took a lab course

>> No.10110723

What about plasma/nuclear physics? Are we really close enough to fusion for it to be a specialty worth getting into?

>> No.10111569

>>10110316
>but the lack of SUSY at TeV scales does not imply ST is incorrect.
but it implies you guys tried to predict something and failed miserably. so why should we trust you?

> but nonetheless there is a need for a quantum theory of gravity
what need? does it pertain to experiment in any way?

>Bullshit!
oh sure, typical stringfag thing to say. somebody comes in and demonstrates that your theory is unnecessary for describing a model with quantum gravity, and you write it off with a one-word reply: "bullshit". pretty weak

it's pretty amazing how many string theorists lurk /sci/, really, since nobody besides your clique really tries to defend your failed theory besides you guys

>> No.10111592

>>10110723
We're very close to fusion energy. no one knows how safe it'll be though

>> No.10111605

>>10110640
Witten's brain makes baffles me he supposedly went to get a master in economics after he realized he didnt wanna do political campaigns or teach then switched to math then switched to physics and was at the top of his field immediately. I dont understand how he taught himself everything so quickly

>> No.10111606

The only way to prove what everything is made up of is to build a LHC the diameter of the milky way

>> No.10111614

>>10111592
I'll take the reasonable bet darpa already has it

>> No.10111615
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10111615

>>10111605
>I dont understand how he taught himself everything so quickly
it's easy when you have the [math]\mathbb{PHENOTYPE}[/math]

>> No.10111928

>>10111569
Jesus Christ, just stop posting

>> No.10111969

>>10111615
Truly his
\mathbb{PHENOTYPE}
Is more potent than anyones in the entire world!

>> No.10112059

>>10110303
It's more like it doesn't not work

>> No.10112069

>>10108827
if you want bleeding then biophysics

>> No.10112077

>>10111615
I wish my phenotype was even a quarter as powerful as his

>> No.10112080

>>10109229
Because the phenotypes of sci are second rate at best