String theory Definition and 782 Threads

Hey all, I started reading up on string theory the other day, and a colleague told me that string theory is already being applied in communications. He said that it is being used to account for the effect of gravitation on electromagnetic waves. This seems a little too hard to believe...

I'm unsure if this is the right place for this question or not but hopefully I'll still get some helpful responses even if I'm in the wrong place! I was discussing a potential string theory research project with a potential supervisor and he was asking me whether I was more interested in...

Hi, All: I am a fiction writer and am interested in writing a short story that ties actual music with physicists' string theory. I have (very) rudimentary knowledge based on layman readings and shows like Brian Greene's TV series. If I have it correct, at the very core of everything are tiny...

I've been hearing that String Theory tied to eternal inflation seems to be providing support for the multiverse. But, I'm missing something with this connection. (1) Eternal inflation seems to "predict" a truly infinite number of other Universes or, at least as time progresses, a limit...

String Theory is basically the idea involving an indefinite amount of invisible "strings" vibrating at a large spectrum of frequencies, thus creating sub-atomic particles that compose everything we experience and ourselves. It would make sense if you could test this theory by creating something...

ever since i heard about how string theory clames to be able to describe particles through string vibrations, i have been looking for the equation that relates particles to string vibrations, i.e., by using this equation i could as a example:"see what string vibration is a electron". do any of...

Hey guys! Which research departments are best? I was hoping to get the top 3-4 institutions names. Basically I am into mathematical string theory and geometry/topology-physics in general.

Can string theory or quantum gravity theory predict faster than light neutrinos ?

What is the relationship between quantum field theory and string theory?

I read an interesting article http://www.scientificamerican.com/article.cfm?id=how-does-the-higgs-boson which says that string theory seems to require our world to have a property called supersymmetry and also, I have heard that the supersymmetry requires the eexistence of at least 5 Higgs...

I'm an engineer trying to get a reasonable laymen's/conceptual understanding of string theory. I've finally gotten a general understanding of developing classical equations of motion, but I'm a little stuck on relativistic equations. As I understand it, relativistic equations of motion are...

Hello, like I said in the topic title I am interested in what mathematics is needed for string theory to be studied. I am in faculty of electrical engineering, sub-filed nanoelectronics. I have good knowledge of math but not good in comparison with what is needed for superstrings, which I...

If spacetime is composed of tiny quantum "grains," the gamma-ray photons' polarization should change from random polarization (at the GRB source) to biased toward a certain polarization when received by the Integral spacecraft . The Integral polarization results depend on spacetime being...

"Loop variables for string theory" That is the title of a http://arxiv.org/abs/hep-th/0207098" . I know quite a few people have wondered what string theory would look like in the framework of loop quantum gravity. Well, this is a glimpse of how it would be. Only a glimpse, because no-one...

I am currently an undergraduate majoring in honors physics and mathematics. I am also doing pre-med studies. If I don't make it into medical school, I am thinking about what field I should continue to study. The field of physics that I actually like is mathematical physics, including gauge...

Was Super String theory (theory that attempts to unite General Relativity and the Standard Model of particle physics) specifically designed to explain singularities; ie: phenomena such as black holes and the big bang? Does all other phenomena obey, and can be explained, by either classical...

because there are these "weird" spatial geometries on the elementary distance level (PS. sorry, this is unlear) PS. I mean physically 1 meter + 1 meter != 2 meters, because there is not that kind of precision on any of of these numbers regardless, as long as it is grounded in our universe PS...

http://www.sciencedaily.com/releases/2011/06/110630111540.htm What do you guys think?

could you explain why quantum mechanics and general relativity don't mix. please help! Dr. Candy:biggrin:

Does Super String theory (attempt to) unite Quantum Mechanics and General Relativity using one master equation? Will this equation explain one grand physical principle behind all physical events? Is this equation called the Standard Model? I would like a basic answer before a more detailed...

http://arxiv.org/abs/1105.6359 Is string theory a theory of quantum gravity? Steven B. Giddings (Submitted on 31 May 2011) Some problems in finding a complete quantum theory incorporating gravity are discussed. One is that of giving a consistent unitary description of high-energy scattering...

What ist better to study, for making string theory, high energy physics and so on. Maths or Physics I think its better to study Maths, but Iam not sure, is there anyone, who has experience. Thx

http://arxiv.org/PS_cache/arxiv/pdf/1105/1105.5283v1.pdf Abstract We provide a simple transfer function that considers the impact of an early matter dominated era on the gravitational wave background and show that string theory can be tested by observations of the gravitational wave...

Hello everyone. I'm not a physicist however have been doing some research on the concepts behind dark energy and string theory and it has presented me with a question: Is it possible that dark matter could be the components of quarks that haven't pulled together to form the quarks. We can't...

Edit: Here is the short (but more confusing and less rigorous) version of what I wrote below: For something to be considered a "law" it needs to make predictions which can then be tested, and if they are proven then it is considered law. However, scientists have been looking at the nature of...

This came up in another thread, but I have seen the statement many times in various places. The statement is that string theory implies general relativity i.e Einstein's field equations in some kind of a classical limit. So my question is how does that go? I am curious to see the details.

I'm a layman trying to get a conceptual understanding of string theory. It's my understanding that SO(32) & E8 are used to compactify the 16 extra bosonic dimensions in heterotic theory, is that correct? Also, it's my understanding that SO(32) is used in Type I for group symmetry. Does that...

Hi PF Does the discovery of the Higgs Boson mean anything to string theory ? Does it falscify or verify the theory, or is it completely irrelavant for the theory? \Schreiber

http://online.kitp.ucsb.edu/online/qcdscat11/ You can see it happening in these talks. For now it's just d=4 N=4 super-Yang-Mills and d=4 N=8 supergravity, but there is every reason to think that the relationships being discovered there will be extended (in more complex forms) to other gauge...

I'd like to hear what people have to say about the following paper, which is way beyond my level knowledge, but could be exciting(?): http://arxiv.org/abs/1104.2302

Instead of thinking of non - critical and critical strings, why not thinking about those as 1 aspect of the same theory, where the non - critical character provides a kind of virtual dimensions. Maybe this could somehow guide a preferential choice of the vaccuum? For example, this theory...

In post #549 here I answered: And then I was surprised by the comment of Tom, asking how the pairing was done. Well, I thought that I had discussed it in some thread in BSM, but after looking at it, it seems that I did only a few sparse remarks here and there. On other hand, people was not...

First off, I've always been under the impression that string theory was crackpot (with absolutely zero reasoning on my part, just from authority) but the way I've seen it discussed here in the last years (and I've heard the LHC has some experiments pertaining to it) maybe my impression was...

Okay so if we assume strings (as described in superstring theory or M theory) are about the size of plank length, then if you divide the estimated size of a quark or atom by planks length, shouldn't that give you the total amount of estimated strings in a quark/atom?

I always hear that these two things are incompatible but I never really hear why. The most I know is that QM assumes a quantized spacetime whereas GR assumes a dynamic one, but I don't really understand if this is correct (nor do I get what that really means). I don't see how GR would fail...

Apparently, it is difficult to reconcile a champion of this theory and the opposition. I would enjoy hearing views on this, since I am convinced the general scientific community is above condemning those with different approaches/beliefs to those of the mainstream. So, who believes string...

Is it proved that the bosonic string and superstring partition functions are modular-invariant for arbitrarily high loop order? If not, how many loops have been analyzed?

Hi all, I have been reading a bit upon LQC and from what I understand this theory of QG makes some fundamentally different assumptions from string theory but has there any work been done that relates these two theories? I tried to look on google but no good results turned up there, ergo, I...

So I have a few questions about a string theory course I am taking, although I guess the questions are largely on indices/QFT stuff! (i) Consider the expression \bar{\psi}^a \gamma^\mu \partial_\mu \psi^b \eta_{ab} we were going to take the transpose of this and it was said that the transpose...

If string theory asserts that a particle can be in more than place and theoretically there are different realms / universes etc. where this occurs but each one is different, how do these differences occur? If it's based the assertion that complete hard determinism does not exist (for every realm...

Hi all, I remember in the Elegant Universe (the documentary), at some point the following lines were said: "So what exactly, in nature, sets the values of these 20 constants so precisely? Well the answer could be the extra dimensions in string theory. That is, the tiny, curled up...

I'm reading this: ==quote== Einstein's theory of gravity, General Relativity, and our theory which governs the sub-atomic world, Quantum Theory, give seemingly inconsistent accounts of the nature of time. According to General Relativity, each observer will have a separate notion of time...

A summary of connections between String theory and Relativity. Can you please explain it in a paragraph or post a link of a webpage that explains this concept specifically (High School Physics Level Please!)

Considering that the smallest particles in nature are supposed to be strings, which are donut and line shapes. And the poincare conjecture says the simplest shape in nature is a sphere. wouldn't it make sense that the true fundamental particles are sphere shaped and that if they combine to form...

since the strings are no longer points, the UV divergences are avoided from calculations, but what happens with IR divergences ? ,

The answers will probably be "it ain't as simple as that" but here's trying, anyway. 1. Is current thinking that strings have to wind "around" something? If so, must the compactified space have at least one hole? 2. With just a single hole, presumably there can be just one topologically...

Brilliant forum, wish i'd spent time browsing it years ago. In my layman's "understanding" of string theory six dimensions are compactified and usually presumed to be of very small size. My questions are: 1. Is there any mathematical or (better still) physical reason why this space does...

I have a few questions on non-critical string theory... terminology: 1: Are "Gepner models" a subset of non-critical string theory? technical: 2: Given a set of spectrum, are there ways to construct a non-critical string theory with enough symmetries so that the CFT becomes minimal and...

Hi people I have 2 questions about string theory 1-I've read that string theory tells us that we can ignore the fluctuations of space time in sub Planck scale and so enables us to use general relativity in such small scales.Also we know that GR says Gravity is not a force but a cause of...

I often hear people talk about string theory being the hardest branch of theoretical physics, and require a PhD to even understand the basics. I've even heard of people saying it's getting too hard for humans, much like quantum mechanics is too hard for cats. So to put things into perspective...