String theory Definition and 782 Threads

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?

Does these strings have mass? So, everything's made of these strings. Obviously, dark matter would also be made of strings, vibrating to give them certain properties? What makes them vibrate? Are photons made of strings? If strings have mass, then the mass can't just vanish, if photons...

Are changes in the frequencies of vibrating strings the cause of entropy? Does entropy also count in the case of changes in the frequency of vibrating strings?

I am currently an freshman physics major taking my second semester physics class, E&M. If I eventually want to become a theoretical physicist specializing in string theory, how would I go about doing this? I really do not know what happens once you get all the general physics classes out of...

Hi, in my sparetime I've been reading lots about physics and more recently string theory/m-theory. I think I am understanding most of the concepts and implications of the theory and I was just wondering if anyone knew where I could get some books explaining the math behind the theory in detail...

What type of background (both in Physics and mathematics) is needed for learning string/M-theory upto topics recently developed? I will appreciate detailed and specific answers.

Are the stings in string theory, considered to be matter? Are the fundamental particles of the universe cnsidered to be matter?

Is the number of lepton generations in string theory restricted to 3? Or is this "landscape dependent"? I don't really see what could limit the number of eigenmodes on a continuous object like the string.

In a recent lecture on String Theory, we encountered the divergent sum 1+2+3+... when calculating the zero mode Virasoro operator in bosonic String Theory. This divergent sum is then set equal to a finite negative constant - the argument for doing so was a comparison with the definition of the...

I was just wondering what string theory says, if anything, about mass energy equivalence...anyone have any insights...?? For example, I was wondering if there are mathematics formulated that can transform, say, an electron form of vibration into a massless energy vibration form...or how an...

I am currently searching for what I am interested in as far as future job possibility and what to major in. I have always been intrigued with science and learning about new discoveries. Physics is one of my favorite thing to read about because it constantly gives us new outlooks on the world...

Can anyone point me in the direction of a paper, website, etc. which essentially discusses the current state of theory - I think its defunct; however, my ToK instructor wants some evidence of it - or any predictions, if any, the theory made? Suggestions are much appreciated. Thanks.

Don't really want to go into much detail here :P, was just wondering during a crappy elctro/physics lesson today; I find it hard to understand the concept of spin at all in string theory, but assuming it's the same as the standard model (it's physically spinning) as opposed to vibrating or...

Cargese lectures on string theory with eight supercharges Monica Guica, Andrew Strominger http://arxiv.org/abs/0704.3295 The authors state "Ultimately the most interesting and most physically relevant case is no supersymmetry at all. But at the moment analytic control in this case is quite...

I have just read the book Three Roads to Quantum Grabity... but my mind has gone blank, the three methods are string theory (M-Theory), loop quantum gravity and one other. I can't remember the last :(:( Any help would be great.,..

Hello! Does anyone know whether in the current phase of String Theory, there are any equations that would enable us to calculate half-lives of a given a particle or isotope?

what is string theory? thanks guys

Neutrinos are elementary particles that have the ability to pass through any matter. Billions of them pass through our bodies every second. Billions of them pass through the Earth and exit on the other side unaffected. They can pass through stars and travel to the other side of the universe...

Does string theory state that space-time is made of strings? And if so, how can "empty space" be made of strings if string theory says that a single string is a particle? Also, would space-time being made of strings be an explanation as to why it behaves so erratically at very tiny scales...

To make it short, any recommandation for a good book on string theory? Something with a good introduction and cover a good part of what one should know at the beginning ?

I have a question concerning the mathematical predictions for space-time under String Theory. Physicist David Gross of University of California said in an interview that String Theory will change the way think about space-time. Then another physicist, Sylvester Gates of University of Maryland...

I was reading this: https://www.physicsforums.com/showthread.php?t=181830 I was wondering if there is any up to day info about the speed of gamma ray burst that could confirm or debunk these claims. Or are LQG and String Theory in troubles?

How does one justify in String theory that 1+2+3+4+5+6+...=-1/12?

Hi there, I'm searching for an argument according to which fundamental strings cannot carry RR charge. I'm aware of the couplings between, say, the Maxwell field and the point particle, the string and the B_{\mu\nu}, and the D-branes and the various RR potentials. One should form Lorentz...

First question: Since a neutral Higgs boson is its own anti-particle, and has zero spin, it appears to have zero for all quantum numbers (in the standard model). This is what one would expect as well for the smallest neutral black hole with no angular momentum. What "new" quantum numbers...

I am kind of a newbie to string theory. I just read Brain Greene’s “The Elegant Universe”. I thoroughly enjoyed it -- almost a "String Theory for Dummies". Greene certainly has a way of dumbing down theoretical physics (substituting analogy for mathematics) so that even someone like myself...

I was wondering if anyone has ever tried to formulate a string theory with a 3D string rather than a 1D string. Has this been done? Is this much more complicated?

This may be a stupid question, but I have been curious about it for awhile. Before string theory, extra dimensions seem not to be taken seriously. But if gravity warps space doesn't it need another dimension to warp into? I saw Brian Green on TV and I thought he suggested that you don't, but he...

quantum mechanics has many interpretations, though a lot of them don't disagree in the maths. i would like to know how each interpratation of quantum mechanics effects string theory, and viceversa: how do the string equations effect the individual interpratations of quantum mechanics. which...

The fundamental part of string theory is that particles are in fact made up of vibrating strings. So this means that the lowest form of unit is a vibrating string? It goes like this Human - made up of atoms - atoms made up of subatoms (electrons, protons and neutrons)- quarks. And then...

Hi: I've heard that Susy is a central prediction of string theory, is that true?, and if that is true, does that mean that if susy isn't found, then string theory will be wrong? Thanks

Hello Physics Forum members, I have got a question that really got into my head and i don't seem to get the answers. I tried to look for some extra information over the internet and couple of books but nothing. So my question is whether the hypothetical Higgs field incorporates with the...

Special Theory predicts that if we could accelerate an object to the speed of light, it would become 2 dimensional in the direction of motion. I'm not sure how many dimensions that String Theory predicts, but my question is this. Does String Theory have a satisfactory way of squeezing all their...

I am reading Michael Hines new book, Supersymmetry and String Theory. He keeps referring to "tree-level". What is this?

Hello everyone I create this thread as a copy of one thread with the same title in the subforum dedicated to string theory because nobody there answered my following question: I have a question regarding string theory (ST) predictions: I am not interested (in this thread) about the...

Hello everyone I have a question regarding string theory (ST) predictions: I am not interested (in this thread) about the predictions related to what is specific about (ST) (what is not predicted by Quantum theory (QT) or General Theory of Relativity (GTR)) I want to know only if (ST) by...

In https://www.physicsforums.com/showthread.php?t=235006 there is a reference to Peter Woit's blog, which has one entry regarding the paper “So what will you do if string theory is wrong?” by Moataz H. Emam -- http://arxiv.org/PS_cache/arxiv/pdf/0805/0805.0543v1.pdf I didn't want to...