Posted: Sep 25, 2011 4:59 pm
cavarka9 wrote:well, I would like to consider this from conservation of energy point of view in the universe, there light gets red shifted, does it disappear ?.Or virtual particles popping into existence. If so, one wonders what we mean by a particle.
Is energy conserved for the entire universe ?
Noether => time symmetry ~ energy conservation
Universe not time symmetric (no timelike Killing vector).