∃ a Good Book on Alternative Theories to SR and/or GR?

Why do you want alternatives? These are two of the most accurate and best validated theories that we have.

 

I'm not aware of any good BOOKS on alternate theories but the Internet is full of crackpot sites that will give you plenty of them. It won't be actual science, but if alternate theories are what you are after, there will be plenty of them.

 

Just to make sure you're clear, there are no alternatives that are more accurate than either of these theories. If there were, they would be adopted.

 

There are also modern theories such as String Theory and Loop Quantum Gravity that aim to extend GR beyond it's domain of applicability. They don't compete with GR, but that might be what the OP is interested in.

 

http://www.aapt.org/doorway/TGRUTalks/Weiss/WeissTalk1of9.htm
"GR is one of several possible covariant theories of gravity. It is only from observation and experiment that we conclude that GR is the valid theory."

An historically important alternative to GR was Nordstrom's theory of gravity, the first theory of gravity consistent with special relativity. It is not consistent with observation, because it predicts the wrong sign for the perihelion precession. Nordstrom's theory is formulated as a field in flat spacetime. Einstein and Fokker showed that Nordstrom's theory could be equivalently formulated as a curved spacetime theory. Later Einstein formulated GR, which is a different theory, but also based on curved spacetime, and which can be reformulated (under some conditions) as a field in flat spacetime.

Deviations from Lorentz invariance are discussed, including the use of alternative theories, by Mattingly http://relativity.livingreviews.org/Articles/lrr-2005-5/ [Broken] .

You can also see alternative theories to GR discussed in section 3.2 of http://relativity.livingreviews.org/Articles/lrr-2006-3/fulltext.html [Broken] .

Clifford Will has a good popular book "Was Einstein Right?".

 

There seems to be ignorance here surrounding what an alternative theory to GR actually is. OP if you're interested, take a look at the end of chapter 4 of "Spacetime and Geometry"-Carroll and the references given therein.

You might also be interested in GR equivalent theories such as teleparallel gravity, in which case start here: http://arxiv.org/pdf/gr-qc/0011087v1.pdf

GR is to teleparallel gravity as Newton-Cartan theory is to standard Newtonian gravitation theory.

 

Gauge Theory of Gravity

A major alternative to GA is the gauge theory of gravity as presented in

"Geometric Algebra for Physicts" by Doran and Lasenby

https://www.amazon.com/Geometric-Algebra-Physicists-Chris-Doran/dp/0521715954

This is a first order theory including spin (there are two gauge fields) and it is formulated on flat space time. All measurable predictions (so far) agree with GA. However, if the gauge theory of gravity there are no wormholes.