Singularities and Scalar Fields. Matter Theory and General Relativity

Philosophers of physics should be more attentive to the role energy conditions play in GR. I review the changing status of energy conditions for quantum fields – presently there are no singularity theorems for semiclassical GR. So we must re-evaluate how we understand the relationship between GR, QFT and singularities. Moreover, on our present understanding of what it is to be a “reasonable” field, the standard energy conditions are violated classically. Thus the singularity theorems are unavailable for classical GR. Our understanding of singularities in GR turns on delicate issues of what it is to be a matter field – issues distinct from the content of the theory.