there is a relationship between conseration laws and symmetries.

Conseration of energy and momentum are related to the isotropy of spacetime.

However, spacetime is NOT isotropic:

CP symmetry is violated: http://en.wikipedia.org/wiki/CP_symmetry

Based on the CPT theorem: http://en.wikipedia.org/wiki/CPT_theorem

T-symmetry is violated

Hence, our spacetime is not isotropic: there is prefered direction in time

Hence, stress energy tensor is not conserved.

Any comments?