String theory Definition and 833 Threads

I don't know if String Theory solves all of our problems, or whether it is nothing more than a mathematical model for understanding things at the Planck Scale, but I appreciate the simplicity of the theory, and the beauty it introduces to the universe. But I have two major problems with it that...

Hi! When quantum mechanics was established it allowed us to do things that we could not do before. What would string theory allow us to do? Let's say that string theory was confirmed -- tests showed the projections string theory made were correct and now string theory was accepted. What...

Hi, I just joined this forum a few minutes ago because I'm thinking of joining my high school science research program to research string theory. For those of you who don't know about the programs, basically you research something for three years and then you enter it in the Intel Talent...

What is the best review article, published in a peer-reviewed journal, introducing string theory?

How do String Theory and Quantum Entanglement mix?

At what level (graduate, PhD, etc...) do people start learning theories, such as String Theory and Loop Quantum Gravity?

Hi, What is the absolute best grad schools in the US or Europe for String Theory, M-Theory and LQG? I tend to learn better in a classroom environment, so I'm sort of looking for a grad school which actually has relevant courses, and not just a European-style research university where I...

Since now time is 2-dimensional, coordinates of points X\mu are dependent on both (\tau1, \tau2), and if \tau2 is infinite, it's a open string; if \tau2 is finite, it's a closed string. How do you think so?

My teacher told me that in my essay I need to briefly describe string theory (because I'm talking about how the LHC is a good test for string theory) and by briefly she told me 1 sentence. If anyone could tell me how THEY would describe string theory in 1 sentence that would be much...

Hi, I am trying to understand relations between Homology/CoHomology and Homotopy group..I am familiar with Hurewicz Theorem but I need something more general. I hope that you can help. Thanks, Lala

Does string theory imply time as a dimension that can run in more than one direction or is it asymmetric?

I have watched numerous shows about physics and I am curious if I understand gravities apparent weakness due to 11 dimensions correctly. The way I made sense of it was by picturing myself at the bottom of a steep hill. At the top of the hill I saw a huge amount of water coming down hill. It...

so i came across string theory and i don't understand (if your going to go along with it) why it is tiny strings that make up the universe and why exactly do they have to exist in more then 4 dimensions?

Topological string theory is a description devoid of metric and hence is background independent and everything emerges from pure topological considerations. This should put it at the front of all other candidate string theories, but that is not the case (it is certainly considered important, but...

I'm a physics undergraduate (2nd year), and I'm just learning the basics of Quantum Mechanics. As you would expect, I've been fascinated by the elegance and...paradoxes involved. My question here is about the phenomenon of entanglement. I know the mathematics of it, but when I asked my...

I have a computer science background, so I don't know about this. Can somebody give me some recommendations on good introductory books about -String Theory - Wormholes -Black holes etc. I'm looking something for academics, not for general public. So maybe books for 1st year graduate...

The Coming Revolutions in Fundamental Physics--as seen by string-master David Gross http://seminput.aei.mpg.de/more_info.php?which=2478&talk=index ==quote== Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut The Coming Revolutions in Fundamental Physics Wed 7 Oct 2009...

Does string theory predict additional long range forces gravity EM? One of the most touted features of String theory is that it correct predicts and even requires 2 infinite long range forces, gravity and E&M. I've heard that string theory though also predicts additional non-observed long...

Firstly i am under educated in physics, that said i have a great interest in physics, this interest sends me a drift with many questions. As many questions in philosophy i seek to start at the beginning and develop a theory from there (or at least what i thin k is the beginning). For...

If you have a guitar string and you pluck it nothing happens. Not unless it is tensioned by pulling both ends tightly. In string and brane theory do the strings have something that keeps them tensioned? Or don't they need tension to maintain vibrating; unlike normal strings? Are they free...

Is gravity a particle field on spacetime or is it the geometry encoded in spacetime itself? Since strings is 10-11 D, does a mass-energy object curve all 10 dimensions of spacetime or only 4 dimensions? Is there a problem of time in string theory as there is in canonical quantum gravity? What...

What does string theory have to say about this and how has string theory changed cosmology in terms of verifiable observational predictions?

http://www.forbes.com/forbes/2009/0921/opinions-peter-woit-physics-ideas-opinions.html Princeton's Witten declines to discuss Woit, saying in an e-mail that he prefers to debate these issues only with "critics who are distinguished scientists rather than with people who have become known by...

Spacetime is 3D + 1T = 4D Is spacetime in string theory 4D as a result of compactification, or 12D, 11D+1T?

Would someone please give me the rundown on the String Theory? I have The Elegant Universe novel and I've been stressing to understand this theory but I've hit a few dead ends. Could someone please enlighten me? Thank you kindly

Am I correct in thinking string theory has an infinite number of terms so to prove finiteness to the first order means proving one (or the first) term to be finite? If so, then how can we ever prove an infinite number of terms? And what exactly does it mean to say, or prove, something is...

I have, for a couple of weeks, been looking up what string theory is all about but i can never actually really grip it. Is there anyone one out there who can give me a simple explanation of it?

"String theory is not science!" So there seems to be a lot of people bashing String Theory for not being real science (real science being theories with predictive/explanatory power). For instance: https://www.amazon.com/dp/061891868X/?tag=pfamazon01-20...

The historic roots of string theory are in an explanation of the strong force. Nowadays QCD is the accepted theory of strong force. But having heard several lectures on the large N limit (SU(N)) of gauge theories it seems these theories start to looklike string theories in this limit. I believe...

http://www.eurekalert.org/pub_releases/2009-07/lu-pro070309.php Well, according to this article, at least. http://www.sciencemag.org/cgi/content/abstract/1174962 Just thought I'd share. Problem is, they didn't entirely describe high temp superconductivity. O well.

I've heard it said that to include a quantum theory of gravity in string theory that the model must include extra dimensions to explain the apparent weakness of gravity. First off, why? couldn't you just as easily say the universe is bigger than we thought and that's why gravity is so weak? And...

Hey all, first post here. I had the opportunity recently to ask Steven Weinberg a question that the physics professors at my university didn't have an answer to. In short, Weinberg said he couldn't understand where I was going with my question. My heart broke as I obviously wasn't able to convey...

I am reading The Elegant Universe...and I have bumped to possibly the first part of the book that I can not understand. When an electron and a positron pop out of existence, they soon annihilate each other with a "bang"...emitting a photon. If fundamental substance of universe are...

Up to now I have learned that matter particles (aka Leptons) were point particles with no physical size/extension. As a matter of fact, it appears that most (including many here based on responses to one of my earlier threads: https://www.physicsforums.com/showthread.php?t=301495") apparently...

How useful is the framework of minimal Conformal Field Theory (ie. CFTs with finite primary fields) in String Theory? From what I have come across, I have only seen its usefulness in studying toy models of minimal string theory.

Hidden dimensions of string theory "hiding" in 4D spacetime? Could the hidden dimensions of string theory be "hiding" in 4D spacetime? Thank you for any thoughts.

Hello to all: I heard Michio Kaku talk on string theory recently and I thought I heard him say that the theory had no free parameters. But in thinking about the matter, I could not decide what that meant -- if it is true. Could someone please tell me what ingredients go into string theory...

Combining quantum mechanics with general relativity supposedly yields infinite gravitation, between the gravitons if I have understood this correctly (correct me if I'm wrong). String theory supposedly does away with this infinite gravitation -- my question is, how does it do this...

Hi I was wondering if anyone knows a good book which contains problems and solutions to string theoretical physics for beginners.

I'm guessing string theory might get a lot simpler if there were only electrons, positrons, photons, and gravitons around? Mathematically could there be a Universe with only electrons, positrons, and photons? If so, how many dimensions would such a string theory need?

Can anybody explain to me what string theorists mean when they are talking about background independence in string theory? I understand this concept in the context of general relativity and loop quantum gravity; there it means invariance with respect to active, local diffeomosphisms. In...

"These are -- as their name suggests -- string-like objects that some scientists believe were formed in the early universe. These strings may line the entire length of the universe and are under immense pressure -- millions upon millions of tons. These cosmic strings, which are thinner than...

Recently I have read some non-technical publication and books on strings (ex. The elegant universe by B. Greene). Greene says that the string theory unifies all interactions and explains their nature. In fact I haven’t found any explanation why do particles / strings interact. I mean – why do...

Is there any lattice model for String Theory? If there is such models, can anyone any good literature? Many Thanks.

Can anyone please comment on this? Any new progress in extending String theory to QFT & SM other than AdS/CFT?

Homework Statement Zwiebach's A First Course in String Theory Quick Calculation 2.5: Consider the plane (x,y) with the identification (x,y)\rightarrow (x+2\pi R,y+2\pi R). What is the resulting space? Homework Equations A one dimensional line with identification x\rightarrow x+2\pi...

General relativity Theory, spacetime and string theory question.. Please Help! Alright, I am a high school student and my teacher just introduced "the General theory of relativity, spacetime and the Super string theory" to us, but he explained those in some weird way that none of us understood...

Can someone give me a Pop science explanation of what do strings and Branes have got to do with black hole entropy. The no of degrees of freedom or the no of microstates of the black hole corresponding to a given macrostate is given by exp(S),where S is entropy of black hole which is related to...

I've watched a few documentaries about string theory, read about it, heard people talk about it. But I cannot visually grasp what the heck strings look like. Physicists (maybe not all of them but the ones I only hear) like to say stuff like that if you pluck a guitar string you get a certain...

http://www.pbs.org/wgbh/nova/elegant/program.html" Did a search and didn't see any posts about it, so if you haven't seen this, check it out, it's pretty cool and will let you know the basics about string theory if you're not familiar with it. Any opinions on it?