Where is the relativity principle?

[arivero]

At a naive level, one really has problems to understand the relationship between all these modern approaches and gravity.

LQG is supposed to contain gravity because it is a quantization of geometry a-la-Asthekar. Strings are supoosed to contain gravity because there is a spin 2 particle. It sounds me as to say that electromagnetism contains Newton gravity because it contains a 1/r potential.

Which one expects is to be told how the relativity principle appears in these theories. That is gravity: the postulate that every reference frame is locally equivalent to a minkowskian one. In usual GR, "locally" means "infinitesimally". Here it could have another meaning, to be quantized, restricted, patched, who know. But it should be clearly related to the GR principle.

 

[MathematicalPhysicist]

Originally posted by arivero
Strings are supoosed to contain gravity because there is a spin 2 particle.

are you referring to graviton?

 

[arivero]

Hmm yes I am. Or, if you prefer, to a particle which induces atractive forces between equal charges. Strings are supposed to contain such beast, aren't it?