Formal definition of the Equivalence Principle(s)

[lalbatros]

Considering how the various forms of equivalence principle can lead to ambiguous discussions, I would like to know if more formal definitions for the various forms of the Equivalence Principles are available.

I would consider as "formal" all definitions that could be used (formally) to check if a theory satisfies this principle and eventually under which conditions it does.

For example, to avoid useless discussions about alleged contradictions between the EP and GR, a formal definition would make a formal and general proof crystal clear. I would also be interrested to see such a formal proof, although I consider it is rather obvious (WEP + sufficient smoothness of the equations).

Thanks for your help,

Michel

 

[robphy]

One might start here:
http://relativity.livingreviews.org/open?pubNo=lrr-2006-3&page=articlesu1.html
"The Confrontation between General Relativity and Experiment"
by Clifford M. Will

 

[lalbatros]

Thanks Robphy, this is a very interresting reference.
I also just received a book by the same author on the same subject.
A little more difficult to read.

However, there is no formal definition to be found there.

What I am looking for is not necessarily a big and complicated mathematical formulation.
It could be just a little bit more precise than casual english.
Some statement about trajectories or physical variables in the context of the various forms of EP.

Michel

 

[Crosson]

The equivalence principle states that what we normally think of as the force of gravity is actually the absence of force: a freely falling observer does not feel his own weight, a freefalling frame is equivalent to an inertial reference frame, flat spacetime.