/sci/ - Science & Math

[Anonymous No.9951607]

What's /sci/ opinion on string theory?

[Anonymous No.9951656]

Useless horseshit.

It's all E8 nigga

[Anonymous No.9951771]

>>9951607
gave us some interesting mathematics to chew on
could be true, but is aggressively untestable right now

[Anonymous No.9951783]

>>9951607
99% confident it is at least a limit of a correct theory.

[Anonymous No.9951814]

>>9951607
i think it’s become a very detrimental aspect of physics: a theory that’s been worked on for 50 years but has yet to make any connection with experiment.

and it’s looking a bit contrived, now, considering there are tight limits on SUSY which rule out a natural MSSM

[Anonymous No.9951827]

>>9951607
Useful mathematically and philosophically; useful physically only if you pretend all experiments that contradicted the model didn't happen.

[Anonymous No.9951830]

>>9951827
wrong image

[Anonymous No.9951832]

>>9951607

Let's be real, very few people here have even a superficial understanding of string theory.

The topologies make sense if that compactified dimensional logic and it's a possible (albeit NOT BACKGROUND INDEPENDENT) framework for reality.

[Anonymous No.9952056]

I like strings.

[Anonymous No.9952071]

String theory is a recursive circle. Each corresponding to a level of human intelligence. We are tenth dimensional beings. But we can be influenced by any of the other rungs on the dimensional ladder. We are two beings. The rational mind, and the irrational emotional side that is a conduit

[Anonymous No.9952073]

>>9951607

Intellectual masturbation, i.e. useless bs

[Anonymous No.9952113]

>>9951656
1) String theory has E8 symmetries in it, either as the E8 x E8 gauge symmetry of the heterotic string, or as the E8 symmetry of the end-of-the-world branes in M-theory compactified on S^1/Z2 (this is actually the same thing viewed two different ways).
2) You can't particle physics as we know it using just E8, because E8 only has real representations, and you need complex representations to describe chiral matter. This is why GUTs use E6: it's the only exceptional group with complex representations.
3) You definitely can't embed gravity in an E8 gauge field. Lisi's paper literally rests on adding together tensors, and spinors, fermions and bosons. Do you remember learning, very early on in your mathematical career, that you can't add a vector to a scalar? Lisi seems to have forgotten this basic point.

As an aside, string theory/M-theory can get you from E8 to chiral matter in a way field theory cannot. One way of doing this is using orbifolds: field theory can't be defined on singular spaces, but strings/membranes are happy living on an orbifold, rather than a smooth manifold. By compactifying M-theory on an orbifold, you can create chiral spinors that transform as a complex representation of E6 ⊂ E8.
The symmetry is broken by stringy effects.

[Anonymous No.9952120]

>>9952071
The emotional side of us exists to ensure our survival/security. Simply because it is a mechanism few of us are aware of and can easily be preyed upon does not make it irrational.

[Anonymous No.9952136]

>>9951832
In a sense string theory is background independent: a small deformation of the spacetime metric is equivalent to the insertion of a graviton on the worldsheet, so any any metric can be produced from any other by appropriately modifying the worldsheet theory. In other words, adding some (coherent) particles of gravity is the same as changing the metric, and string theory can then compute scattering amplitudes by a perturbative expansion around this background.

[Anonymous No.9952141]

>>9951607
Based and redpilled.

[Anonymous No.9952162]

>>9951607
>/sci/ opinion on string theory
Is irrelevant because no one here is a relevant hep-theorist.

[Anonymous No.9953279]

>>9951607
Any theory of higher physics is basically arcane nonsense at this point. They may as well be hermeticists babbling to made up demons.

[Anonymous No.9953631]

>>9951607
Esoteric bullshit

[Anonymous No.9953636]

>>9952162
Nima, we’re tired of your shitposts. Douche.

[Anonymous No.9953641]

quantum loop gravity > string theory

[Anonymous No.9953651]

>>9951607
It would be correct if our universe was in 11 dimensions

[Anonymous No.9953688]

>>9953641
woof, she did not age well after the 90's

[Anonymous No.9953814]

>>9951607

I predict that the wheels are going to start coming off for string theory as it becomes apparent that it is incapable of describing universes like ours which have early time slow-roll inflation and late time acceleration.

[Anonymous No.9953816]

>>9953636
Thanks, keep up the good vibes.
>>9953641
Obviously wrong.

[Anonymous No.9954431]

>>9953641
String theory is basically S-Matrix theory with the postulate that the particles are strings and not points

It's not some phenomenally implausible construct like LQG that is a massive reinterpretation of the universe

[Anonymous No.9954642]

>>9954431
except it requires a bunch more dimensions...

[Anonymous No.9955033]

>>9954431
>11 dimensions

[Anonymous No.9955414]

>>9954642
>>9955033
Compact dimensions change nothing though. Space and time being quantized goes against all of classical mechanics. Other theories are even more fantastical in their postulates

[Anonymous No.9955459]

I've been doing a reading course on it. So far I'm pretty skeptical. Here's some stuff that I've found suspicious so far,

>The supposed existance of D-branes is a convenient way to get rid of boundary conditions that stop you from making a relativistic theory of strings
>The number of extra dimensions in the theory is cherry picked so that the theory hasn't been ruled out experimentally yet, kind of like a "God of the Gaps" argument.

Then again, I haven't learned superstring theory, maybe these issues are resolved in superstring theory, I dunno.

[Anonymous No.9955645]

>>9951827
>physically only if you pretend all experiments that contradicted the model didn't happen
????

[Anonymous No.9955693]

>>9955459
>>The supposed existance of D-branes is a convenient way to get rid of boundary conditions that stop you from making a relativistic theory of strings
No, there is no problem neither in the case of closed string nor for open strings with Neumann boundary conditions (so you didn't read it carefully). Only when you try to formulate open strings with Dirichlet boundary condition you realize the existence of D-branes. And although that is the original formulation of D-branes, they are understood now as non-perturbative objects of the theory.

>>The number of extra dimensions in the theory is cherry picked so that the theory hasn't been ruled out experimentally yet, kind of like a "God of the Gaps" argument.
No, the number of extra dimensions is chosen so the conformal symmetry of the two-dimensional theory is not anomalous, so it can be treated in a quantum way without problems. What kind of course are you doing?

[Anonymous No.9955695]

F = ma explains it, right?

[Anonymous No.9955711]

>>9955693
Kyrghyz yak-milking forum shitposting course.

[Anonymous No.9956777]

>>9954431
>>9955414
This guy gets it.

[Anonymous No.9956788]

>>9955459
>The number of extra dimensions in the theory is cherry picked so that the theory hasn't been ruled out experimentally yet.
you somehow missed one of the most important parts of an introduction to ST, the fact that the basic axioms of ST forces you to have a specific number of dimensions.

[Anonymous No.9956836]

>>9951827
being indian truly is suffering

[Anonymous No.9956908]

>>9955645
well string theory is not consistent without SUSY, and SUSY in its “natural” manifestations are ruled out.

so if you want string theory to explain why the standard model looks fine tuned, then you have to accept that susy is fine tuned

>grumble grumble but ST predicts a spin 2 graviton
meh, not convincing. what if gravity is emergent

[Anonymous No.9957155]

>>9951607
It's an incomplete model we poured to much time into.

[Anonymous No.9957606]

>>9956788

Yes, the wrong, specific number of dimensions!

[Anonymous No.9957693]

>>9957606
Would you rather have a theory where you can pick the number of dimentions, or a theory that forcves a specific number which can them be experimentally veriviied?

[Anonymous No.9957729]

>>9957693

'Four dimensions' is very special. It is very difficult to have chiral fermions in a higher dimensional theory.
I am aware that the string theorists are optimistic that this is not a problem, but I am fairly sure that inability to produce a universe with late-time acceleration and early time slow-roll inflation will be the end of String Theory.

[Anonymous No.9957754]

>>9956908

Emergent gravity seems interesting; I've heard some talk about weighted tensor product decompositions of quantum mechanical Hilbert spacs having sufficient structure to mimic geometry. It's not too outlandish to suppose this might lead to an emergent space-time structure.

[Anonymous No.9957872]

>>9957729
>end of string theory
there wont be an end unless we find a better theory. String theory as a real theory of how the world works is very unlikely, even the people who developed it admit its not a good fit with reality, the only people who seem to push that are popsci retards. But the value of string theory comes from the fact that its a very good toy model that shows non trivial effects of a quantum theory applied to more complex situations that in QFT. The math is whats important, and a load of the breakthroughs in string theory have already been ported back into QCD and used in actual physics. Just like how phi-4 field theory in QFT can be proven to be useless, but is still discussed in every single QFT textbook, so will string theory continue on.

[Anonymous No.9957898]

>>9955033
>>11 dimensions
>Four dimensions we interact with
>Three dimensions in heaven, sharing our "time"
>Three dimensions in hell, sharing our time

[Anonymous No.9957900]

>>9957872
>theorists at IAS
>popsci retards

[Anonymous No.9957904]

>>9957900
>IAS
you mean the MENSA of physics?

[Anonymous No.9957909]

>>9951607
A useful interpretation tool. Too narrow for the full scope of things though.

[Anonymous No.9957923]

>>9957904
more like MENSA of STEM
not that anyone beyond undergrad sees it as that

[Anonymous No.9957933]

>>9957900

Exactly! This is some crazy revisionism. For many years, a lot of the best minds in high energy physics were not just working on this stuff (at the best universities too) but very publicly pushing it as the theory of everything.

If it completely fails as a theory of physics then that is a huge thing in the history of science, I would say.

[Anonymous No.9957935]

>>9957933
>a lot of the best minds in high energy physics were very publicly pushing it
Like who? everyone ive seen who publicly push it gave up on being a physicist decades ago and went full popsci. Except maybe edward witten.

[Anonymous No.9957939]

>>9957935
Vafa, Maldacena, Witten, Nima, Polchinski, ...
All the big names in hep-theory "push" it as the theory of everything. It would be retarded not to, as it is the best (only) candidate we have.

[Anonymous No.9957940]

>>9957935
The Guy in the Pic for one...

[Anonymous No.9957941]

>>9957939

If it is incompatible with our universe, it is not a candidate for a theory of everything. Have a think about that!

[Anonymous No.9957943]

>>9957940
Green hasnt done anything worth while in physics for almost 20 years, hes too busy writing popsci and starting in the big bang theory now.

[Anonymous No.9957946]

>>9957941
Prove that it is incompatible with our universe then. So far, people much smarter than you or me deemed it THE candidate for theory of everything.

[Anonymous No.9957954]

>>9957939
>Vafa
He made his own theory and is pushing that as a theory of everything, not string theory.

>Maldacena
He is known for saying that string theory gives us math that's important in other areas of physics, not just string theory, so that falls within my claim above.

>Nima
Nimas claim is that string theory is the only valid theory under very specific conditions, not that its the actual theory reality obeys.

>Polchinski
Hes supported Susskinds view that string theory is just a toy model as far back as I can remember.

[Anonymous No.9957985]

>>9957943
delet this

[Anonymous No.9958006]

>>9957954

>Vafa
>He made his own theory and is pushing that as a theory of everything, not string theory.

F-theory is considered part of string theory.

[Anonymous No.9958028]

>>9957939
i don't really care what they say, honestly. it's a combination of two things:
1) theorists are wishful thinkers, duh. they want their theories to be right, cuz then they get awards and better job offers. string theory is largely motivated by "look how pretty the math is" which means jack in the end, pic related

2) if they didn't shill their theories, then they wouldn't get funding. they shill their theories and their buddies' theories so they mutually reinforce each other's justifications to the funding agencies.

[Anonymous No.9958203]

>>9957946

It's not about that. It's just that there doesn't seem to be any reason to expect that this theory has anything to do with our universe.

I get that there are these nice reasons that attracted so much interest to String Theory, but the pile of what needs to be 'hidden' grows bigger and bigger: Supersymmetry, extra dimensions, (possibly) dynamics of whatever is accelerating our universe. The list goes on.
All these problems aren't coming from within the the formalism but from experimental constraints, and I think that should be a worry.

[Anonymous No.9958284]

>>9958203
REEEEEEEEEE

>t. Nima

[Max Tesla No.9959613]

>>9951607
String Theory tastes like Plum Pudding.

[Anonymous No.9959767]

>>9952136
>by a perturbative expansion
Is that literally the only thing fagysicists can do nowadays do?
Imagine being this cucked

[Anonymous No.9959770]

>>9952136
>by a perturbative expansion
Is that literally the only thing fagysicists can nowadays do? Imagine beyond this cucked beyond redemption

[Anonymous No.9961086]

>>9951827
*Not useful at all.

[Anonymous No.9961092]

As useful as any original theory Einstein made."Thalmudic, materialist bullshit