String theory Definition and 833 Threads

Are interpretations that are non linear with respect to the wave function (eg. GRW, transactional) compatible with string theory?

Maybe this is more quantum, but I'm not sure. I was watching Susskinds first String lecture on youtube, and he was talking about how, within each particle family, you get a straight line called a regge trajectory if you plot spin vs. mass^2. He also mentioned that there was some slight insight...

Hello everybody! I hope you are having a great day ! My question: is the strings theory a REAL theory ... is it really the final answer to the relationship between relativity and quantum mechanics! ? [emoji54]

It seems that the latest data out of CERN suggest a mass of the Higgs Boson that is smack in the middle of what would be suggested by parallel universes/string theory and SuSy. Do you think Edward Whitten, Savas Dimopoulos, and probably others could get together in a room to unify these two...

For a string in string theory, Energy = string tension * length So I'm wondering if it can increase its length with increasing its energy.

Does the length of a string depend on its energy, or does its energy depend on its length? Similarly, does the area of a d brane depend on its energy, or does its energy depend on its energy? Are these stupid questions?

Urs Schreiber submitted a new PF Insights post Why Higher Category Theory in Physics? Continue reading the Original PF Insights Post.

In string theory, if we have NN BCs along ##X^i, i = 1, \ldots, n-1## and DD BCs along ##X^a, a = n, \ldots, 25## then you get, from ##\alpha^{i,a}_{-1}|0,p\rangle ##, ##n## massless vectors and ##24-n## massless scalars. I understand that for the first excited level, ##M^2=0## and so we have...

Do higher dimensional branes, like the super membrane (which is a 2D brane) or the NS5/M5 brane, have wave functions? I know that they become unstable once they are quantized, but does that mean that they do not have wave functions? You will never here about any thing regarding an M2 wave...

Dear all, recently I'm reading up some string/M-theory, especially the role of branes, because I'm writing a popular science book in Dutch. Every textbook states the issues one encounters when you try to quantize p-branes for p>1, as is discussed e.g. here...

can string theory reproduce hawking radiation in non-extremel black holes in 4D? i.e physically realistic black holes. do they exactly match hawking's calculations? what is the interpretation of hawking radiation in string theory?

Could someone explain or point me in the right direction on how string theory explains the leptons? TIA, Kevin

I was doing some reading on String Theory...I'm not a scientist, but i enjoy it (so forgive me if my question is stupid) and i was wondering: Being time a dimension, could it be the dimension the strings exist in? And interaction between all particles and all forces determine how they vibrate...

Hello, I have a question about the the difference between mathematical physics and theoretical physics in general and about the difference between the MSc Theoretical and Mathematical Physics courses at Edinburgh in particular. I am planning to apply, however I am not sure which of the two...

Let's consider superstring theory on a 10 dimensional Minkowski background. And assume there is a D3-brane on which the open strings end and closed strings wander around freely in the background. I want to know, in what limit this gives a supergravity theory in which I can study it by using the...

Is supersymmetry part of string theory or does it have a place in the standard model

Urs Schreiber submitted a new PF Insights post Spectral Standard Model and String Compactifications Continue reading the Original PF Insights Post.

Move over, M- theory and F-theory! http://arxiv.org/abs/1609.06863 A brief review of E theory Peter West (Submitted on 22 Sep 2016) I begin with some memories of Abdus Salam who was my PhD supervisor. After reviewing the theory of non-linear realisations and Kac-Moody algebras, I explain...

In this note, the author says: with the following footnote: But I don't understand how that can be true. All the evidence for the cojecture arises from string theory: Similarity of Large N expansion and the perturbative expansion of a string theory and the equivalent low energy description of...

Roger Penrose’s http://press.princeton.edu/titles/10664.html']Fashion,[/PLAIN] Faith and Fantasy in the New Physics of the Universe "Arguing that string theory has veered away from physical reality by positing six extra hidden dimensions, Penrose cautions that the fashionable nature of a...

I was wondering why Quantum loop theory is still being followed FAIK it does not predict any thing yet, the same for string theory which seems to have lost its predictability, if these theories fail being tested where will we be It seems to me like super symmetry is the theory that every one...

I do not know why can they classify 5 theories of superstring.Is that correct that they base on different symmetries?

Hello, I hope this is not a stupid question as I am not a physicist. But I was curious about how contenders for the so-called Theory of Everything view the shape of the elementary particles. I know that the basic idea of string theory is related to the shape of elementary particles as one...

String Theory implies that the universe has 11 dimensions. If the 3 Dimensions represents space and the other one is time, what about the 7 dimensions??

Back when I was studying at Princeton University, J.A. Wheeler introduced me to Ed Witten while we were having lunch at the Institute for Advanced Study (IAS). I knew Feynman’s and Wheeler’s views on “String Theory,” and I had looked into it a bit as a field of research, but I couldn’t seem to...

Loosely, in terms of string theory, an electron moving back and forth in a radiating antenna is a string moving in space-time. Far away, the electromagnetic radiation of the antenna is made of strings moving in space-time. Can I think of the near electric and magnetic fields surrounding the...

If so, how.

If we study the high temperature limit (near Hagedorn) of a string gas, most of the energy is concentrated in a single long string. If we model the string by a fixed number of rigid links of length ls and calculate the number of possible configurations, we get the density of states: $$\omega(E)...

Currently I am working on a manga/comic of mine which imvolves science, especially stuff related to quantum mechanics. The theme of my manga is based on the 'collapsing of realities'...i.e, realities from different timescales would collapse at one place and try to exist at once, which would...

Derive Vacuum permittivity and permeability using Quantum Field theory or String theory! If QFT or String theory is real fundamental theory, it can be derived the permittivity and permeability of vacuum. << Moderator's note: personal contact details deleted>>

Didn't someone invent a bunch of dimensions in order to make the theory compatible with other theories but are the extra dimensions right or correct.

Hello, As I understand there is a problem in physics where point-like massive (or charged, etc.) particles would have infinite mass/energy (or charge, etc.) density. I'm curious how in the context of String Theory how we address the same problem? I have come to understand Strings as...

I am finishing high school this year and i want to be a theoretical physicist. My academic result in mathematics is not good throughout last 5 years. But physics is my dream. I want to overcome every obstacles. I think i am not bad at mathematics but the reason behind my bad result was lack of...

Hello all! I am a senior in high school with a love for physics. In English, we were assigned an argumentative research paper with a topic of our choice. So, naturally, I chose String Theory, since it is a semi controversial topic in theoretical physics today. My only problem is that I have a...

string theory is a scalar-tensor theory of gravity, with higher order corrections. in light of the result discovery of gravitational waves of 2 black holes merging, matching GR in the strong field regime, how much deviation should strong theory differ from GR in the strong field regime and can...

What are some of the top graduate programs in Europe (excluding the UK) on theoretical physics specializing in string theory, fields or mathematical physics?

So I saw that claims are being made that LIGO may have detected gravitational waves. http://www.nature.com/news/has-giant-ligo-experiment-seen-gravitational-waves-1.18449 My question is, if the universe were in fact multidimensional as string theory predicts, would gravitational waves propagate...

Is Brown a good university for string theory? I've checked out their website but was wondering about the general reputation and strength of the researchers in string theory at Brown. It does seem like a small school and guessing their acceptance rate would be low. Thanks

What does it mean that a Killing vector and a total differential of a certain theory are related to bilinears? In other words, why would bilinears (e.g. of the forms ##<\gamma_0\epsilon, \gamma_5\gamma_{\mu}\epsilon>## and ##<\gamma_0\epsilon, \gamma_{\mu}\epsilon>## tell us anything about...

Spinors in $N=2, D=4$ supergravity can be simplified using gauge transformation and thus canonical spinors can be found. In the case of $N=2, D=4$ supergravity the gauge transformation Spin (3,1) is used. My question is how do we know which transformation can be used in a certain theory in order...

I believe I've read that null geodesics can reach the boundary of AdS space within finite affine parameter and that this allows for a causal connection between the bulk AdS spacetime and the boundary on which the CFT lives and that this is very important for AdS/CFT. I can't find a reference...

Links for [1] and [2] are below. Please have a look here section 12.6 [1]. It says here that Given the action of a supergravity theory, it is generally useful to search for solutions of the classical equations of motion. It is most useful to obtain solutions that can be interpreted as...

The following article debates whether string theory is testable. https://www.quantamagazine.org/20151216-physicists-and-philosophers-debate-the-boundaries-of-science Even though they mention philosophy, this is not merely a philosophical debate. It a serious question for physicists as to how...

Homework Statement I'd like to better understand why the central charge is assumed to be equal to the number of dimensions in the spacetime background. Homework Equations By definition of Virasoro algebra and its operators: [Lm,Ln]=(m−n)Lm+n+c/12(m3−m)δm+n,0 The Attempt at a Solution The...

Why hello there my fellow science lovers, I'm some what new to the forums, and I'm loving it here. If this is being posted in the wrong section, I am very sorry. Anyways, I'm aware of the whole idea of the string theory. General relativity governs motion at a macroscale and quantum field theory...

Various types of friction operate in all relative motion of materials. Boundary layers in the flow over on wings, Fatigue in metals subject the oscillatory bending. Friction between a car tire and the road. these are just some examples of the holistic impact on operations here on Earth. Does...

Hallo. So the other day I reviewed a bit of quantum field theory and went through the Compton scattering calculation. To no ones surprise it was fairly simpel if you have a nice list of identities for rewriting the base results from the Feynman diagrams. See for exaxmple section 5.3 in...

When I was studying complex manifolds in a Freedman's SUGRA book, I ran across this. In a complex manifold, the metric is...

The scalar fields of supersymmetric theories in 4 spacetime dimensions are a set of complex fields (usually denoted by ##z^{\alpha}##). How can this be physically translated? More precisely, we know that in 5D, those scalars are real, so what is that makes them real here but complex there?

I have heard that ST can calculate the masses of the particles species of some vacuum and also its decay rate, charge and so on, but I have not seen any clear paper on the subject. Can anyone point me to one? Are "hbar" and "c" the same in all the vacuums?why or why not? Can ST predict the...