- #1
- 2,970
- 1,513
- TL;DR Summary
- How does the BGV-theorem fit in with Penrose's Conformal Cyclic Cosmology?
Dear all,
Some time ago I stumbled upon the famous BGV-theorem,
- https://en.wikipedia.org/wiki/Borde–Guth–Vilenkin_theorem
- https://arxiv.org/abs/gr-qc/0110012
which states that on spacetimes which have, on average, a positive Hubble constant, one can find timelike geodesics which cannot be completed indefinitely in the past. This is often rephrased as "expanding universes must have had a beginning", although this statement is a bit subtle. My simple question is: How does the BGV-theorem fit in with Penrose's Conformal Cyclic Cosmology (CCC)? Does it imply that this CCC is also not past-complete? Can someone point to references in which this is explicitly treated? :) I can't find any references in Penroses' Cycles of Time.
Some time ago I stumbled upon the famous BGV-theorem,
- https://en.wikipedia.org/wiki/Borde–Guth–Vilenkin_theorem
- https://arxiv.org/abs/gr-qc/0110012
which states that on spacetimes which have, on average, a positive Hubble constant, one can find timelike geodesics which cannot be completed indefinitely in the past. This is often rephrased as "expanding universes must have had a beginning", although this statement is a bit subtle. My simple question is: How does the BGV-theorem fit in with Penrose's Conformal Cyclic Cosmology (CCC)? Does it imply that this CCC is also not past-complete? Can someone point to references in which this is explicitly treated? :) I can't find any references in Penroses' Cycles of Time.