String theory Definition and 833 Threads

Hello, before I start off, I apologize for asking a question which I am sure has been asked hundreds of times before: but I felt there is just way too much information out there which is a little confusing, so I am here with the hope of getting some personalized suggestions. I am currently a...

If you could magically go back in time, and spend two hours with Einstein shortly before he died in 1955, could you explain to him current modern superstring theory? If so, what would he think of it?

Can somebody please explain to me how the S-Matrix of Heisenberg and others helped influence the birth of String Theory. I keep hearing people say that String Theory came as a result of S-Matrix but I don't see the connection. Please keep maths to a minimal. Thanks.

Like what does the higher dimensional branes mean what what do branes do.

I heard that in order for something to become a theory it must be tested.

hey can somebody suggest me some good books on string theory ...i am looking forward to join this field and i have no knowledge about this theory ... and some information about some colleges which are good for quantum physics and what's the future in this field of quantum physics... by the way i...

I have been trying for a while to read a precise definition of a Vector Multiplet (to whom ##N=2## Supergravity theories couple to in ##4D##) but was not lucky in finding a self-contained one. The best I got was that on https://en.wikipedia.org/wiki/Supermultiplet though it was on...

Crossing over the following paragraph: There are three types of special manifolds which we shall discuss, related to the real scalars of gauge multiplets in D = 5, the complex scalars of D = 4 gauge multiplets and the quaternionic scalars of hypermultiplets. Since there are no scalars in the...

Hello everyone! As an admirer of string theory, I have strong interest in the theories that purport to unify general relativity with quantum mechanics. In the case of string theory, the goal is to find a form of describe the force of gravity according to the principles of quantum mechanics, ie...

I heard that the LHC was supposed to do some testing on supersymmetry but i didn't hear anything from them and is string theory still possible or not.

Did string theory come about as a possible solution to quantum mechanic's "something being in several places at the same time" paradox so to speak? I am not a math-guy or pretend to know anything about physics. I m just curious. I was thinking that what appears as something being in multiple...

Is there an existing equation, or set of equations, that directly links the specific vibration of a superstring filament with the resultant particle mass? A brief explanation of any mathematics would be helpful. Thank you.

String Theory speculates that extra dimensions may exist. Obviously, it would be difficult to describe or imagine that, but is it possible that there are objects or particles that exist observing LESS dimensions. For example, photons travel at c meaning that time travels infinitely slow in for...

I'm Indian and I've heard stuff that it is difficult to get into a good PhD program in the US/UK for string theory because the competition is more fierce than other fields. Furthermore,the likelihood for getting academic positions is even tougher(added to the fact that I'm from a different...

How are fermions, like electrons, described by m theory? Are they closed strings like gravitons, or are they open strings attached to a D2/M2, D4, or M5 branes?

I've read in a few string theory documents that have 10d spacetime that a baryon is a D4 brane with three strings (each being a quark), but what about in M theory?

In M Theory, can an elementary open 1d string attach its ends on an M5 brane? According to M theory, the elementary string are created when an M2 brane is wrapped tightly around a circular dimension. When the open string is created can its end point attach on an M5 brane??

Can the 5brane turn into a fundamental string?

A lot of people quote 10^ 500 as the number of different ways of compactifying the extra dimension in string theory. But I recall somoene saying at a talk that its now much larger than that. What's the current estimate?

Hi fellow physicists, Suppose a spring with a stiffness k, is attached to wall and with the other side a block with a mass, m, a force F, then pulls the block away from the wall. How do you derive a function for acceleration of the block as a function of time, a(t)? When trying to solve this I...

I have been following along the problem on SO(32) st. in Zwiebach's "A first course in String theory" and my question concerns this problem. I have no problem with the mathematics of SO(32), at least not at the simple level Zwiebach discusses it, rather the "why" behind a particular concept of...

Can someone explain string theory? and how it works please? I am really interested thanks :D

Hello, Before starting, I would like to apologize for any errors in the use of symbols. This is my first time :sorry:. I am studying the wonderful book of Barton Zwiebach, "A First Course in StringTheory". In chapter 02, I am experiencing for the first time with the mathematics of special...

In one book of Susskind I found the following claim and I wanted to ask for its basis. Susskind says that each kind of boson gives positive contribution to the cosmological constant (the lighter, the better). Each kind of fermion gives negative contribution to the cosmological constant. Thus...

Can the M theory/ string theory coexist with the penrose interpretation of quantum mechanics?

Strings are said to be one dimensional, due to the math. And I understand that there are problems in the math when they put the strings in 3 or 2 dimensions. According to string theory, lengths smaller than Planck length have no physical significance. Could it be that strings are 3...

When they say strings are one dimensional, do they mean that the height and width are really small that its only the length that matters? And if not, how can a one dimensional object exist if it has no height or width?

Are strings really just one dimensional? Is it possible that strings are 3 dimensional? Or even 10 dimensional?

This question, at the moment, is ridiculously difficult or even impossible to answer. Some prefer string theory, and some think that it is overly speculative and LQG may be a better fit, and some say the opposite. I would like to ask; In your opinion, what could be the right theory of quantum...

Assume String Theory is headed in the right direction, can one understand electron (or any Standard Model particle spin for that matter) spin roughly in terms of some small spinning string? If so, would you consider that a selling point of the theory as it provides an explanation for intrinsic...

String theory is what I'm currently studying. The dominant form is the action formulation of it. A classical string Lagrangian is submitted and quantized to produce the equations of motion of a string. Is there a purely quantum formulation of string theory that doesn't start with a classical...

I was recently watching a talk by Witten and he mentioned that one of the magical things about string theory is that it forces us to accept certain symmetries of nature, as opposed to choosing them as we do in QFT. Can anyone give an enlightening explanation of this? I do have very basic...

Is it allowed to travel to the past in ST?. I've always thought about paradoxes in the regular framework (4D space-time). What about ST framework?. I need a little guidance here. Thank you in advance, AGZ

Please hint me the order in time to read those String Theory books:Zwiebach,Polchinski,Hatfield,Kaku,Green-Schwarz-Witten,West,Johnson(D-Branes),David Tong(lecture on String Theory dampt).

Is there quantum foam between strings?

I was watching a sixty symbols video on Stephen Hawking: , and it got me thinking. Is there any practical value for theoretical physicists, if what they are doing is simply speculation not backed by any data? I understand observing a physical phenomena, and from understanding it predicting new...

Hi. 4 years ago my child asked to me a question... What will be happen, if the light is stop? I tried to answer it ... But my knowledge is insufficient. (I had been educated at social science, specially labor laws) . So I searched, tried to learn something new... So I liked physics. Of course it...

Layman question here: When discussing the difficulties in merging GR and Quantum theory, it is often mentioned that a main issue is that GR is continuous while quantum theory is discrete. A less commented point is the fact that GR is a deterministic theory while quantum theory is probabilistic...

This is a stupid question (good that I ask). String theory treats bosons and fermions in different ways e.g fermion potential are differ from boson potentials,actions differ and so on... My question is simply : why? Yes I know fermions and bosons are different groups of particles (integer and...

Hi, So in an informal sense, we hear about string theory requiring small, curled up dimensions locally at every point of spacetime. In my very, very limited knowledge of geometry, I would like to think of this as a fibre bundle structure over each point of Minkowski space. However, analogous...

As I understand it the proposed SUSY model is based on an "expectation of symmetry", which also happens to nicely solve specific problems with the SM. If the LHC does find evidence of SUSY structures - is string theory a candidate for a fundamental theory that would "explain the harmony" of the...

I'm not sure where to post this but it is technically homework but it doesn't follow the template and its less of a math question and more of a conceptual thing anyways. I have to write an English paper on a problem in a future career and it has to be big. I'm thinking about physics so I wanted...

To prepare for a meeting I'm having with a prof in 2 weeks I've been told to compute things in string perturbation theory. During this process I have come to performing the calculation of the vacuum amplitude at one loop directly from Polyakov's action, as performed by Polchinski in 1986. I can...

What is the prerequisite to learn string theory ? I know Quantum Field Theory at the level of David McMahon, i don't konw General Relativity

I wasn't sure whether I should post this question in this category or "High Energy, Nuclear, Particle Physics", but I decided to post here, since I want to get opinions from the people who are studying the topics discussed in this category, not the experts on standard model or particle physics...

In his 2001 Three Roads to Quantum Gravity, on its p.l66, Smolin says, "M theory, if it exists, cannot describe a world in which space is continuous and one can pack an infinite amount of information into any volume, no matter how small." As a lay person, I'm hoping to get an informed opinion...

Are the general principles of string theory “the properties of fundamental particles are due to their unique vibrational pattern of strings in 10 or 11 or 26 dimensions” incompatible with both general and special relativity? due to an observer would be able to detect changes in properties of...

I've been tasked with giving a presentation on any subject i like to my undergraduate physics class. Inspired by a recent lecture i attended by David Tong i have chosen to do a quick (10 minute) overview of the current state of theories beyond the standard model, obviously aimed at being...

I read somewhere that the Monster Group appears is related to String Theory as 26D String theory on a 24D Leech Lattice gives a vertex algebra whose symmetries are the Monster Group. Just wondering if the size of a big group like that appears in the actual Universe? For example, there are lots...

Well, the string theory talks about multiverse, unlike the Big Bang theory. Michio Kaku explains it by comparing it with bubbles. There are many universes. These universes are like bubbles floating around, and when they collide, they form a single bubble- a universe. When a single bubble...