Is General Relativity Really About Physics on Curved Spacetimes?

[waterfall]

Yes, that's true, but not what I meant. I meant that there may be spin 2 fields that produce "gravity" that is different from that of GR, even below the Planck scale.

http://arxiv.org/abs/1007.0435

I actually read the paper above. It's talking about higher spin (more than 2) that produce "gravity" that is different from that of GR. It's not talking about spin 2.. so maybe you are mistaken above?

Also your analogy "A chair can be made of wood, but not everything made of wood is a chair." is not related to the above paper but as an answer to my other question, isn't it?

 

[waterfall]

Yes, that's true, but not what I meant. I meant that there may be spin 2 fields that produce "gravity" that is different from that of GR, even below the Planck scale.

http://arxiv.org/abs/1007.0435

I think what you meant was that since spin-3 or spin-4 describe GR. Then spin-2 describe "gravity" that is not 100% GR. This is very important to distinguish because it means spin-2 over flat spacetime is not equivalent to GR even those describe by harmonic coodinates.

The meaning of equivalent is "=". So when something is not matched 100%. They are not equal. So when you said before it is equivalent and later said spin-2 is not sufficient to produce GR. Then your statements conflict. Try to be consistent in descriptions especially when dealing with such complicated subject. Thanks.