String theory Definition and 833 Threads

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 guys, I am ready to apply for PhD and one of my targets is STONY Brook (actually the only one in the USA since it won't require me to take any tests). Background: a) Undergrad at Lancaster University, BSc Theo. Physics b) Master's degree in Theo. Physics UAM/IFT in Madrid under...

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"...

In covariant quantization of the string, say as in David Tong's http://arxiv.org/abs/0908.0333 (p28), time is an operator. Is the time operator Hermitian, and does it correspond to an observable?

Right, Hello, I am new to this, and do not have much understanding, but can someone here help explain the Dimension Models and String theory to me?

LQG, strink theory and Penrose's spinor theory, or maybe it's twistor theory, I don't know, all I know is that all three theories achieve mathematical miracles in their attempts to go beyond the Standard Model - how can all three theories do this but be mutually exclusive at the same time. Or...

Hi everyone, I've always wondered what's that fuss for unifying general relativity and quantum mechanics all about. I stumbled upon things like string theory(or M theory) and even loop quantum gravity( which I think is as good as string theory despite rumors). My...

Hi! Reading some string theory books I always find that the introductory chapters discuss the relativistic free particle. Then they go on about showing that the action S=-m\int^{t_1}_{t_2} dx = -m \int^{t_1}_{t_2}d\tau\sqrt{-\frac{dx^\mu}{d \tau} \frac{dx^\nu}{d \tau} \eta_{\mu\nu}} is...

"Foundations of physics" Special Issue: Forty Years of String Theory http://www.springer.com/physics/history+&+philosophical+foundations+of+physics/journal/10701 If this has already been mentioned feel free to delete this post. Articles free through march, A Critical Look at Strings (Carlo...

I have been following Dr. Michio Kaku and his ideas on string theory. My question is, with the addition of other dimensions, what types of experiments and/or results could possibly provide evidence that this theory is correct. If we currently can't perceive these "discrete" dimensions, what...

From whst I have read, anything smaller than Plancks length, you need to account for quantum gravity.. also, it is assumed strings in string theory are Plancks length.. so how could anything be smaller than Plancks length if strings are Plancks length(or greater than)? I thought strings made...

Background-independence is the requirement that the theory be formulated based only on a bare differentiable manifold but not on any prior geometry. General relativity is the first example of such a theory. This is a radical shift as all theories before General relativity had part of their...

hello, I find both quantum mechanics and string theory to be a bit iffy. Mabey it's just because I don't understand it but I think the best way to understand the iffy stuff is to post it on here. Mentors might see this as a debate or going against mainstream physics but how are you able to make...

Can Someone Explain What String Theory Is? (Simple Terms With Examples) Ive been hearing a lot of references to this new string theory, what is it?

There was a thread about how to describe the proton in string theory that was deleted while I was writing an answer, so I will post my answer here in a new thread. How the proton, and processes inside the proton, are described in string theory, is an open research question, part of the area...

Hey guys, who can tell me briefly about the 10+1 dimensions in the string theory? I am going to deliver a short presentation on string theory ,but i am not very clear about the reason that we have to introduce 11dimendion to string theory ...

I just recently seen an article that the recent findings at the LHC seem to disprove supersymmetry. I would like to know how supersymmetry and string theory are connected and what the implications would be if the LHC totally disproves supersymmetry all together?

I had an exchange with Lubos Motl about this topic, in the comments here. Very briefly, there is a 2004 paper in which the author (Kjell Rosquist) considers the old idea that the electron is actually a spinning, charged (i.e. Kerr-Newman) micro black hole. Using a purely classical model for...

Just about few hours ago,my friend and i argued about which theory is the best theory nowadays ever existed. I claim that string theory is the only game in town as what i heard from Dr. Michio Kaku's TV shows, while my friend strongly disagree with it. He claimed that quantum theory is the best...

Consider me physics illiterate since my last class was advanced placement physics in high school (over 20 years ago). I am trying to understand what the title says, How does quantum entanglement, string theory, and the BB fit together? Skipping to the meat of the subject, everything revolves...

I was watching a video on string theory and they claim that its all vibrating strands of energy. I thought energy was just a property of the system, not a physical entity. So do they mean something else by "energy"?

I understand that suitable compactified strings in AdS correspond to conformal field theories (w/o gravity) living on the boundary space. What I do not get is the exact relationship between non-perturbative gravitational phenomena in the bulk and the CFT. All what I have seen are...

Could someone give me a short summary(if possible) of how discovering matter is made of vibrating energy will give explanation to all four fundamental forces?

I mean we really don't know what they are, right? We just know they can be positive or negative, north or south, but we really don't know why they exist. Will string theory give a definite answer to this? And also gravity. Will it confirm Einsteins theories?

Hi, I have a question concerning simple bosonic string theory governed by the Polyakov action. Under which assumptions/requirements is the corresponding worldsheet theory a conformal field theory? Is this always true or does it depend on the topology of the worldsheet? Conformal symmetry of...

Can anyone explain to me what is string theory mathematically?

Hi all, Would like to start off by letting you all know i am new to the PF and the reason for joining is due to constant ideas and thoughts flooding my brain to no end, i do not have any physics degree's but i do share an intense interest in Physics. According to a friend of mine the only...

I have recently been reading up on the basics of string theory and my question is this. How exactly are strings "allowed" to vibrate? In particular, do they have to be in all ten dimensions of space as predicted by M-theory at once? Or can they just "reside" in several of those dimensions...

It's really difficult as a layman trying to find out who is right and wrong in this debate as far as string theory. I find it kind of hard to believe that string theory is just simply completely wrong and has no relevance whatsoever to reality. After all so many theorists and so many papers...

Hi. I am fairly new to physics. I have recently read the first half of a book by Michio Kaku called “Beyond Einstein”, and I am really struggling to get my head around the superstring theory. The superstring theory seems illogical for the following reasons... 1. Nature demands symmetry. So...

Gerard 't Hooft just dropped this interesting paper. http://arxiv.org/abs/1207.3612 Discreteness and Determinism in Superstrings Gerard 't Hooft Ideas presented in two earlier papers are applied to string theory. It had been found that a deterministic cellular automaton in one space- and one...