The Borde-Vilenkin-Guth Theorem states that if any universe, which has, on average, a rate of expansion greater than zero then that system had to have a finite beginning. This would apply in any multiverse scenario as well. There are four exceptions to the theorem.*
1. First Exception: Initial Contraction (Havg<0) … (The average rate of the Hubble expansion is less than zero)
- Main Problem: Another problem this raises is that this requires acausal fine-tuning. Any attempt to explain the fine-tuning apart from a fine-tuner is left bereft of any explanation.
2. Second Exception: Asymptotically static (Havg=O)
- Main Problem: The exception is that it does not allow for an expanding or evolutionary universe. This model cannot be true. The best evidence and empirical observations indicate that the universe is not static; rather, it is expanding and evolving. This might have been a great model under Newton but not since Einstein’s field equation concerning the energy-momentum of the universe.
3. Third Exception: Infinite cyclicity (Havg=0)
- Main Problem: The universe splits into non-interacting patches. The universe has expanded so much at this point that nearly all of these patches are empty of matter and radiation and only contain phantom energy.
4. Fourth Exception: Time reversal at singularity
- Main Problem: Rejects an evolutionary universe
Also, be sure to read Alexander Vilenkin and Audrey Mithani’s paper, “Did the Universe Have a Beginning?”
Here’s their abstract:
We discuss three candidate scenarios which seem to allow the possibility that the universe could have existed forever with no initial singularity: eternal infation, cyclic evolution, and the emergent universe. The first two of these scenarios are geodesically incomplete to the past, and thus cannot describe a universe without a beginning. The third, although it is stable with respect to classical perturbations, can collapse quantum mechanically, and therefore cannot have an eternal past.
*This information is primarily from and available in William Lane Craig and James Sinclair’s “The Kalam Cosmological Argument,”
inThe Blackwell Companion to Natural Theology Eds. William Lane Craig and J.P. Moreland (Oxford, UK: Blackwell, 2009), 143-147. Diagram on 146.