String theory Definition and 782 Threads

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?

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...

Where can I learn string theory online with the math and everything? ANY help appreciated. Tanks in advance. Ps I'm looking for links, I really can't afford books. I'm a high school student. I know the principles but haven't attempted any math above the Schrödinger equation for a quantum...

Hi there! S-matrix is Path Integral with Vertex Operators inserted. I know how to compute Shapiro-Virasoro amplitude. So I don't have problems with calculations but with understanding. In this calculations formalism of 2-dimensional CFT is used. But there is no S-matrix in CFT, only...

Hey everybody, I have a few questions about membranes in string theory, so here it goes. What is meant by the membrane in the cyclic model, from my understanding it means that branes in an ultiverse collide, and create there own universes, would this mean that branes could collide in our...

Hi all! I am ready for applying for my PhD which I want to be on String Theory and in Europe. I am finishing my master's degree in Theoretical Physics and currently I am researching Holographic Renormalization for asymptotically non-AdS space-times. I am interested in all aspects of String...

Why string field theory doesn't explane a black singularity but its called the theory of everything? It just explanes quantum gravity not why the universe exists or why we exist, what I am tring to say is that it should not be called the theory of everything.

... due to whatever. What has the effort provided besides showing that the universe doesn't work a certain way? Assuming it has aided in other areas of physics and mathematics. Any examples? Thanks.

This was just posted on arxiv. It seems to be of general interest so here's a thread in case anyone wants to discuss it. http://arxiv.org/abs/1308.1977 Holography without strings? Donald Marolf (Submitted on 8 Aug 2013) A defining feature of holographic dualities is that, along with the bulk...

what are the research prospect of doing a phd on string theory in India

Laurent Freidel is working on string theory again. His earlier paper, with Krasnov and Livine, which had a remark on the subject was Holomorphic Factorization for a Quantum Tetrahedron http://arxiv.org/abs/1307.7080 Born Reciprocity in String Theory and the Nature of Spacetime Laurent Freidel...

From looking at the Wikipedia entry on string theory I gather that it is found that any given physical model implies two Calabi-Yau spaces. Perhaps one space gives rise to a sector of particles with left-handed weak interactions and the other gives rise to a sector with right-handed weak...

Does the math in string theory tell us anything about the size of any of the extra dimensions?

The notion field of Quantum Field Theory is deduced from the combination of Quantum Mechanics and Special Relativity.The local characteristic of field is led from Cluster Decomposition Principle. String Theory is also a combination between Quantum Mechanics and Relativity Theory.Then I wonder...

In another thread Ben indicated that string theory formulated as non-linear sigma model using world-sheet action is - in some sense - background independent. To discuss this I start with a generalization of the Polyakov action ##S_G[X] = \frac{1}{4\pi\alpha}\int d^2\sigma \, \sqrt{g} \, g^{ab}...

There is still, to this day, absolutely no empirical proof that string theory is correct, or even that it can predict anything , but I know it's mathematically elegent ,here's feynman view on it:''I don’t like that they’re not calculating anything. I don’t like that they don’t check their ideas...

One of my goals in life is to get a reasonable understanding of string theory. This is done as a hobby of mine so I will not have a professor to ask. My question is: which route would you recommend for learning this? My thoughts: I understand many people think highly of "A First Course...

Hey everyone, I've been trying to get a rough idea of what types of classes I should be taking for my upper level undergrad courses, and get an early idea of what type of graduate elective courses I should be taking. I'm a double major in physics and math, and plan to go to grad school for...

Hi As far as I understand, that teleportation using quantum entanglement is only partially instantaneous, because a classical channel has to be used to send the two qbits from Point A to B. So the speed of light is the boundary as how fast teleportation can happen one day using this...

Hi everyone. I'm interested in computational science but have an interest in string theory as well as I'm sure a few people here do. My question is does computational science have a place in the research for string theory? Would a physicist simply give some numbers for a computational...

Probably a bit abstract,but I was thinking if 4D closed strings could form knots? I mean if a closed string in 4-dimensional spacetime can be considered an unknot and a knot polynomial be associated with every closed string. I also wondered that if the fundamental strings vibrate in the knotted...

I have a question about the paper: C. G. . Callan, R. C. Myers and M. J. Perry, “Black Holes In String Theory,” Nucl. Phys. B 311, 673 (1989). I have attached the relevant section. I am having trouble using equations (2.1) and (2.4) to derive (2.5) and (2.6). When I do the calculation...

Does string theory, in principle, answer why matter comes in "chunks"? Does string theory, in principle, answer why matter comes in "chunks" of the same amount (say the mass of an electron or muon), and why the energy in the electromagnetic field of a given frequency also comes in a "chunks"...