String theory Definition and 833 Threads

Hello everyone. I am an international student from China. Currently I received offers of a PhD position from both Caltech and Stanford. I applied for Hep-th and my main interests are formal field theories and string theory. I know both Caltech and Stanford are great schools in physics. And it...

Hi guys, To the experts of particle physics and of course to anyone else who knows and wants to share, what is the current status of string theory? Is there any progress? regress? are we stuck at a point (if so, I'd love to know which and why)? Thanks.

Hello, if you have ever heard of the TOE then you may be able to answer my question on this theory. The theory explains that there are tiny little strings in all atoms. Imagine the universe being an atom, the stings in this atom would be the size of a tree here on Earth. That is how small they...

If a function f'(u) has Fourier coefficients anμ and bnμ, by integration one can make new coefficients Anμ ,Bnμ which include constants of integration. My question how can I verify that : Anμcos nτ + Bnμ sin nτ= -i/2 ((Bnμ) -Anμi) einτ- (Bnμ-iAnμ) e-inτ I assume this is the complex form of...

Hi guys, So I'm a bit confused about why strings can't move at the speed of light. I understand that the end points do if the string is open, but the rest of it doesnt. To paraphrase, really I want to know why you must have timelike and spacelike tangent vectors to a point on the world sheet...

In string theory/M theory, there are two types of strings, open and closed strings. What kind of strings are fermions(electrons, quarks) made out of? Closed or open strings?

Dears, What do you think, hypothetically, Einstein should think about String Theory?. Obviously, if he was here to study it.

I'm a beginning graduate student in string theory and I'm in the process of teaching myself algebraic geometry. I'm using lecture notes that go without mention of physics. I'm curious if there is a introductory book, or paper, or set of lecture notes that describes the application of alg...

Hello guys. I am fortunate that I have found this website and I have created an account just to ask one question. I asked this on yahoo answers as well but no luck. So here goes. I'm 14 years old and I love astrophysics. I have learn most of the basic stuff and I've also read A brief history...

Hello folks, I want to starting learning the subject this Christmas (Merry Christmas :D) and I am wondering what would be the best way to introduce me to Strings. I am a masters student in Theoretical Physics. Best wishes, and many thanks in advance. Breo.

My question is rather simple: How can I derive the equation for the change in action "delta S" ? If S is the Nambu gotto action.Thanks for any clarifications.

Hello Everyone, I want to know if it's a good time to study string theory from the basics? Or is it wiser to wait till next year, after the 2015 LHC run, if indeed we find any evidence for it? I have done a course in mathematical physics, classical and quantum field theory, electrodynamics and...

Hi. I am no physicist but I am trying to know something about the holographic principle. As I understand, everything is happening in a surface and our three-dimensionality is an illusion of our senses. On the other side, string theory assume the existence of 11 dimensions. Are the two theories...

I've applied physics in nuclear weapons work, finance, biochemistry, molecular dynamics, space physics, and other areas. High school students, and even young Air Force officers with technical degrees often have little idea of the value of physics. And physics loses. Linked here to a Prezi...

In string theory, the Neveu-Schwarz B-field appears in the action: S_{NS}=\frac{1}{4\pi\alpha^\prime}\int d^2\xi\;\epsilon^{\mu\nu}B_{ij}\partial_\mu X^i\partial_\nu X^j. In Polchinski's text, the antisymmetric tensor appears in the form of \frac{1}{4\pi\alpha^\prime}\int...

I'm beginning to apply to grad schools (primarily in observational or computational cosmology and extragalactic astronomy) but have a deep interest in M-theory and quantum gravity although I haven't been able to study it. I very much enjoy theory and think that I would find studying M-theory or...

Greetings, I am intending on learning bosonic string theory in self study before new years eve and I nead a ruff and short introduction on the basics and the idea of gauge theory. The introducton is preferably in PDF form, yet books are fine to.

Consider the feynman diagramms for two freely propagating particles...Correction from one graviton exchange. Correction from two graviton exchange.The problem at hand is the divergence (of the math) at arbitary energys and each additional graviton exchange. So there are several resoultions and...

I am looking for introductiory books on gauge theory and conformalfield theory and polyakov integrals for research in Bosonic string theory. Any other material recommendations for String theory that are necessary for bosonic string theory or heterotic string theory are definelty apreciated. To...

This will, no doubt, sound like a silly question but I am just getting my feet wet in string theory. It seems from what I know so far, that string theory is very far removed from our observable universe. What I mean by that statement is that it seems we just say "well, maybe our universe is a...

Hi, so I'm new to this forum and wanted to ask for some advice. I REALLY am interest in string theory and I've read around the topic a lot without actually learning about it. In my school we can do an independent study project or ISP. When students do ISPs they have to have a project that can be...

Im a trying to understand how the string entity relates to its underlying field. Is the field a brane and the string the partice?

As Steven Weinberg put it, "the idea of quantum field theory is that quantum fields are the basic ingredients of the universe, and particles are just bundles of energy and momentum of the fields." At least, this is one way to look at QFT. The other approach is to imagine that these particles are...

Here's an idea that I came up with. I've heard over and over again that there is no test yet available to confirm string theory. So what I say is... What if you could derive some fundamental physics equation from string theory principles? Then wouldn't that be a test so to speak...

String effective action: S=-\frac{1}{2\lambda_{\text{s}}^{d-1}}\int d^{d+1}x\sqrt{|g|}e^{-\phi}\left[R+(\nabla\phi)^2+2\lambda_{\text{s}}^{d-1}V(\phi)-\frac{1}{12}H^2\right]+S_m where H^2=H_{\mu\nu\alpha}H^{\mu\nu\alpha}\\ H_{\mu\nu\alpha}=\partial_\mu B_{\nu\alpha}+\partial_\nu...

This is a question currently pondered by many Quantum physicists and theoretical physicists. I was just wondering how many of you prefer ST(string theory) as opposed to LQG(loop quantum gravity.) Please provide points and reasons regarding your answer. I will provide an opinion when a few...

I'm watching a lecture by Edward Witten here: In it, he mentions that String/M-theory seems to be hinting toward a new kind of geometry where you don't talk about space/time points, but the interactions between quantum world sheets (around 37:00 minute mark.) Does this new geometry have...

Hi, I've been looking for a string theory review for a beginner graduate student. However, there is a vast number of reviews so it's easy to get lost. Does anyone know about a review article or any kind of material to begin with String Theory? Thanks.

Hello, Can anybody please explain me how magnetic monopoles, fine structure constant and string theory are related to each other? Thanks

I have recently visited CERN, and in the Globe they showed an equation from string theory. My knowledge about it goes only as far as 'The elegant universe', so no mathematics, but i would say that the sketch beneath is about the string coupling constant. Could anyone please explain the...

I've heard that the strings in String theory are vacuums, is that right? And if so then how is it expected they form?

Just as particles move through the theoretical Higgs field and gain energy which gives them mass, do the strings in String theory get their energy to vibrate from the Higgs Field as well? And does that mean that the Strings have mass?

Hi, if you remember back a decade ago we had a discussion on solutions to the first edition of Zwiebach's undergraduate textbook in string theory. (I have a copy of the solutions in my computer). Does someone have solutions to the updated second edition of the textbook? I tried looking for...

Can string theory explain dark matter and dark energy?

What are you thoughts about Laura Mersini Haughton´s theory of the multiverse? She predicted a CMB cold spot, power suppression at low multipoles, preferred direction associated with the quadrupole octupole alignment, dark flow, and the deviation of the CMB amplitude. While dark flow remains...

I have been given a project in my ap physics class where I am to explain how Bose-Fermi equivalence, tachyon, dilaton, green-schwarz anomaly cancellation and kahler manifolds relate with string theory. After an hour of research, I realized that I could not find even the slightest information on...

Hello, Is string theory or M theory wrong ? Isn't it the theory of everything ? Should we continue our research to reach the true theory of everything ? If so, why physicists still research on string theory ?!

I am looking for literature on a certain topic in mathematics inspired by string theory of which I have heard bits and pieces. Since I am not at all familiar with string theory and haven't found anything online, I was hoping someone more knowledgeable might recognize some of the keywords I...

Are there any solutions (ways to avoid/get rid of) to the string theory landscape besides the anthropic principle and comological natural selection?

Anything that exists has to exist/interact with at least 4 dimensions, right? Stuff existing/interacting with other dimensions too (even if they can't be/haven't been observed) have to exist/interact with our 4D as well, right?

Hello everybody. I have a BSc in physics, I tried hardly recent two years to get high scores in GRE/TOEFL exams to get accepted in U.S. and continue my education in physics,however, I rejected badly. First I thought by myself to leave physics, I gambled whole my future for physics and now I'm...

I am trying to understand the connection between eternal inflation and the the string theory landscape of 10^520 possible universes Where is the original scientific article that proposed so many false vacua solutions If anyone can point me to the underlying equation and article that...

If dark energy is caused by quantum fluctuations, where does this energy come from? Also according to string theory mass is determined by the sum of a string's positive, vibrational energy and its negative energy from quantum fluctuations. Could it be possible to create a particle with negative...

When do these two fields of physics overlap other than when we discuss entropy of supersymmetric black holes? Does statistical mechanics or statistical physics support any aspect in string theory or vice verse? I have read some place that the string theory reduces to the standard model by doing...

Which do you think are the most promising alternatives?

Hi, I have a couple questions from chapter 2 of Zwiebach's A First Course In String Theory, second ed. 1) Zwiebach says [in the context of compact extra dimensions] "it seems very difficult, if not altogether impossible, to construct a consistent theory with more than one time dimension". Why...

I am familiar with String theory and the Multiverse theory, but I didn't know that apparently String Theory points to a multiverse? Can anyone give insight to this? Also what do you guys think about the Multiverse theory? Personally it is far-fetched, but I am not dismissing it. I don't want to...

Not sure what section to put this in, so I'll put it here. Are there any good books on string theory that are good for someone who is a bit more than a layman (i.e. no extremely superficial, dumbed-down stuff), but still doesn't know more than single variable calculus and Newtonian mechanics?

It seems many people in Science have gravitated towards some form of a multiverse. Whether it's a Cyclical Universe or some version of the Many Worlds Interpretation. The question is where's the evidence? I do think there's some evidence that points to this conclusion. If you look at the work of...

I'm a 10th grade high school student, but before you judge me I would like to inform you that I have a 127% (thanks extra credit) in my Advanced Physics class. I was reading the textbook as I usually do in my free time and I stumbled across a section on String Theory, I read through the chapter...