Recent content by naunzer

I never claimed that the worldsheet is moving when the string moves. It's clear to me that is the history of the string. I know that the X^mu are scalar fields when viewed from the worldsheet and that they are the embedding functions of the string when viewed from the spacetime. Of course...

What I understand mathematically: The Polyakov action has three symmetries of the world sheet(reparametrization-inv.,Weyl inv.). These can be used to take the worldsheet metric into the form diag(1,-1), i. e. it is a flat space. But I don't understand that when I try to visualize the...

Yes, I agree that he is free to use their strategies and I didn't want to complain too much about that. I just wanted to state that now that we apparently know a (the?) correct form of the energy-momentum tensor further investigations about it's (the definitions) origin are needed. Another...

Padmanabhan finds so to say the "correct rule" (Eqn (15)) to define the transition from the flat metric to a curvilinear one (in order to be able to use functional derivation) which leads to the correct definition of the energy-momentum tensor of a spin 2 field. Correct means here that when one...

Consider the following: Postulate as FEW as possible things that seem to be necessary to make (intelligent) life possible, e.g. causality (one should be able to kill one's dad) at least at "large" scales,...?... Let there be mathematical logic and demand that all laws of nature can be written...

Another eqn which admits stable (no dispersion) wave-like solutions is the Sine-Gordon-Eq: D'Alembert(theta) + Sin(theta) = 0 (using suitable units) [theta = theta(space,time), of cours] This theta can be visualized as follows: Consider a chain of pendulums, each being elastically...

But the energy of a photon depends on its frequency by E=hf, so we are finally back at the starting relation p=hf/c.

Thank you very much. I will check it.

I've read a bit in Nakahara' s "Geometry, Topology and Physics" and at the end there is a chapter string theory where he uses Atiyah's index theorems and those Chern class things etc. I found that very mathematical, too. So maybe you can tell me, what are the mathematical preliminaries for...

Yes, I think it was A. Connes who thought about it first. But is it now called nc-geometry or nc-quantum field theory(nc-qft).

I've sometimes heard that there are string theory results that are quite similar to some of non-commutative qft. What are these?