Re:Physicists Debate Hawking’s Idea That the Universe Had No...
by pdonis on Thursday June 06, 2019 @05:38PM
(#20119515)
> Is the hypothesis still that the limit as time goes to zero still exists
Note that in other models of the universe, the ones that have an "initial singularity" which can be thought of as "the limit as time goes to zero", the initial singularity itself is not part of the universe; it can be approached as a limit but never reached. (The reason is that spacetime curvature increases without bound as the singularity is approached, and the equations of GR break down at the singularity.)
One of the nice things about Hawking's model is that it totally avoids this problem; spacetime curvature is finite everywhere and there are no singularities and no points where the equations break down.
Note that in other models of the universe, the ones that have an "initial singularity" which can be thought of as "the limit as time goes to zero", the initial singularity itself is not part of the universe; it can be approached as a limit but never reached. (The reason is that spacetime curvature increases without bound as the singularity is approached, and the equations of GR break down at the singularity.)
One of the nice things about Hawking's model is that it totally avoids this problem; spacetime curvature is finite everywhere and there are no singularities and no points where the equations break down.