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/sci/ - Science & Math

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7748478 No.7748478 [Reply] [Original]

Why are you still resisting the beauty that is String Theory?

>> No.7748495

>>7748478
Because it uses meme equations like 1+2+3+... = -1/12

>> No.7748509

>>7748495
What classifies an equation as a "meme equation"?

>> No.7748510

>>7748495
g8 b8 m8

>> No.7748595

>>7748478
I mean, like, what am I even looking at? Fuuck

>> No.7748734
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7748734

>>7748478
Is that categorical notation?

>> No.7749021

>>7748478

because it is only an unverified hypothesis.

>> No.7749025

>>7748734
Obviously not. Why even ask such a stupid question?

>> No.7749030

>>7748478
Are there any predictions that String Theory makes?

>> No.7749044

>>7748478
>pertubative theory
>background dependent

Thanks, but no thanks.

>> No.7749046

>>7749044
>Doesn't like pertubative theories
>Doesn't like QED, apparently

>> No.7749049

>>7749046
Pertubative theories are generally shit. Many solved problems (like that of the harmonic oszillator) give false predictions when "solved" by an pertubative ansatz.

>> No.7749068

>>7749049
>Pertubative theories don't work well if you don't apply perturbation theory correctly
>Therefore any pertubative theory is shit.

Yeeeeah.

>> No.7749074

>>7749049
>Many solved problems (like that of the harmonic oszillator) give false predictions when "solved" by an pertubative ansatz.
>predictions is what matter in science
>he has no idea why predictions matter.

>> No.7749107

>>7748595
Irreducible Representations of Spin(8)

>>7749030
Yes, a lot. We just can't test any of them.

>>7749044
Perturbation theory is used in pretty much every theory of physics and makes calculating things actually possible. There are non-perturbative ways to study String Theories (and M-theory too). i.e. D-Brane World-Volume Theories, Through the Ads/CFT, String Dualities, Matrix String Theory, etc.

>> No.7749110

>>7748478
Ramond-Ramond best field.

>> No.7750409

>>7748509
For one, any equation where you sum up divergent infinite series into a finite value is a meme equation.

>> No.7750545

>>7750409
Infinite values have no physical meaning though. So there is no way the answer could be infinite.

>> No.7750554

>>7750545
>Infinite values have no physical meaning though
But they do.

>> No.7750587

>>7748478
I'm not resisting it. I'm just too stupid to understand it.

>> No.7750613

>>7750554
like?

>> No.7750643

>>7750545
Fucking physicists

>> No.7750647

>>7750643
It is the whole reason we have processes like regularization and renormalization in QFT.

>> No.7750905

>>7749025
Are they using tensors?

>> No.7750923

>>7750905
Something like [math] {{\mathbf{8}}_V} \otimes {{\mathbf{8}}_V} = {\mathbf{1}} \oplus {\mathbf{28}} \oplus {\mathbf{35}} [/math] means that the product of two eight dimensional representations of Spin(8) can be decomposed into the sum of 1,28, and 35 dimensional representations.

[math] \varphi \oplus {B_{\mu \nu }} \oplus {G_{\mu \nu }} [/math] just means that the dilation field, [math]\varphi[/math], corresponds to the 1-dimensional representation. The antisymmetric gauge field [math] {B_{\mu \nu }}[/math] corresponds to the 28-dimensional representation. And the spacetime metric (graviton field), [math] {G_{\mu \nu }} [/math], corresponds to the 35-dimensional representation.

>> No.7750924

>>7750923
>dilation
dilaton*

>> No.7750930

>>7749107
I guess it's not even worthwhile asking anything about these equations since my background in physics goes as far as integrating to find magnetic fields.

>> No.7750987

>>7748478
Theor. physics lecturers have severe autism so I'd probably end up learning everything by myself and waste loads of time for mental masturbation. Better study related math and ignore memes.

>> No.7750999

>>7750987
>Theor. physics lecturers have severe autism so I'd probably end up learning everything by myself

I don't think most schools typically even offer a course on String Theory. At that level if you can't pick up a book and teach yourself then you have a problem.

>> No.7751034

>>7748478

Because in physics, the object of a theory is that it should both actually and verifiably correspond to phenomena which take place in the physical world.

There is another field of human endeavor, full of both beauty and autism, where theories often do, but need not necessarily correspond to phenomena in the physical world. That field is known as pure mathematics, and activities such as writing Principia Mathematica, publishing a proof of a single theorem which goes on for several hundred pages, having conferences on Interuniversal Teichmuller Theory, and spilling 10,000 pages by a hundred different authors over several decades to classify a certain family of finite groups --- all these types of activities are welcome there. In physics? Not so much.

>> No.7751175

>>7751034
>Because in physics, the object of a theory is that it should both actually and verifiably correspond to phenomena which take place in the physical world.

Hence why it is "Theoretical Physics" .

>> No.7751336
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7751336

>>7750545
>Infinite values have no physical meaning
>so the answer can't be infinite
Fucking physicists

>> No.7751410

>>7749107
>we just can't test any of them
THIS IS WHY WE DONT TAKE STRING THEORY SERIOUSLY

>> No.7751420

>>7750923
What is meant by "28-dimensional representation" and "35-dimensional representation"? What are the anti-symmetric gauge fields and the graviton fields doing in their respective 'dimensions'?

>> No.7751436

>>7751410
It's not untestable in principle. We just don't have the technology needed to reach the type of energies needed to test the interesting predictions of string theory. This is going to be a problem with any alternative to ST. Are you one of those people who thinks we should simply stop working on HET and beyond-SM physics altogether?

>> No.7751442

>>7751420
Physically, the dimension of the representation corresponds to the number of physical polarization states (or degrees of freedom) of the field.

>>7751410
See >>7751436

>> No.7751807

>>7748478
string theory is meme science

>> No.7751809

>>7748495
u diserve midiclorians

>> No.7751810

>>7748595
Don't worry, this is math of meme science, so it means nothing

>> No.7751813

>>7750545
WHAT IN THE FUCK????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

>> No.7751850

>>7751810
The picture is just products and sums of group representations. As an elementary particle corresponds to a irreducible representation of the respective symmetry group. The math, and notation, is standard throughout particle physics.

>> No.7752422

>>7749030
General relativity falls out of M-theory.

Now keep in mind that Einsteins obtained his equations of motion by taking the classical limit so it it still a fit.

M-theory gives the equations of motion for the metric without making any assumptions other than the main string theory assumption :p

>> No.7752424

>>7750409
First year calculus spotted

>> No.7752432

>>7748478
Nothing studying Zwiebach at the moment...

>> No.7752493

>>7748478

If we evolved from strings, why are their still guitars?

>> No.7752539

>>7752422
>General relativity falls out of M-theory.
Yeah that is pretty easy to (non-rigorously) show.

The low energy effective action of M-theory is that of D=11 SUGRA, which looks something like [math] S = \frac{1}{{16\pi {G_{11}}}}\left[ {\int {{d^{11}}x\sqrt { - G} } \left( {R - \frac{1}{2}{{\left| {{F_4}} \right|}^2}} \right) - \frac{1}{6}\int {{A_3} \wedge {F_4} \wedge {F_4} + i{{\bar \Psi }_M}{\Gamma ^{MNP}}{\nabla _N}{\Psi _P}} } \right] [/math].

GR is not SUSY so it is ok to break any SUSY involved in this action. Also in vacuum GR does not involve any fields except the gravitational one.

When we remove all fields except for the gravitational field from the action we are left with just an 11-dimensional version of the Einstein-Hilbert action. [math] {S_G} = \frac{1}{{16\pi {G_{11}}}}\int {{d^{11}}x} \sqrt { - G} R [/math].

So if we perform some type of dimensional reduction under the previous constraints, and a few extra, we should end up with GR.

>> No.7752554

>>7752539
>SUGRA
>SUSY
what do these mean?

>> No.7752558

>>7752554
Supergravity
Supersymmetry

>> No.7753403

>>7752558
What's so "super" about them?

>> No.7753412

>>7753403
"Super" is physicist slang for Z2-graded.

>> No.7753418

>>7749107
>spin(8)
Do you mean SU(8)? Because im not sure the mathematicians have defined a Spin group.

>> No.7753424

>>7753418
>im not sure the mathematicians have defined a Spin group.
They have. Lurk more, newfag.

>> No.7753425

>>7753418
Actually nevermind. I am only familiar with the standard model gauge groups, so hadnt seen any of this before.

>> No.7753426

>>7748495
>engineers

>> No.7753570

>>7753418
Spin(8) is the universal covering group of SO(8), related to it through the exact sequence [math] 1 \to {\mathbb{Z}_2} \to Spin\left( 8 \right) \to SO\left( 8 \right) \to 1 [/math].

>> No.7753581

>>7753570
>spoonfeeding a brainlet who refuses to use wikipedia before making stupid posts
Why are you such a pleb enabler?

>> No.7753582

>>7753418
Also, if you want to learn more take a look at these notes.

https://empg.maths.ed.ac.uk/Activities/Spin/SpinNotes.pdf

>> No.7753993

>>7753403
They are theories with an equivalent number of bosonic and fermionic degrees of freedom.

>> No.7754154

>>7748478
Because physics is for cucks that think we happen to live in the universe with the most interesting mathematics
>pure maths is TRUE beauty

>> No.7754176

String theorists of /sci/, are there any string theory graduate programs someone could get into without having a 4.0 GPA, 990 physics gre, graduate courses already done, etc.?

>> No.7754214

>>7749030
String theory is nothing but a puzzle for nerds to determine if your intelligence is above average, because you need above average intelligence to make sense of any of that gibberish. Besides giving autistic savants a reason to do pointless maths, it doesn't have any practical purposes.

>> No.7754657

>>7754214
>it doesn't have any practical purposes.
Yet. If we ever gain a better understanding of the Ads/CFT, it could have huge applications.