http://physics.princeton.edu/~steinh/lambda16.pdf In this research article the authors suggest a cyclic universe, specifically one involving collisions of higher dimensional branes (an idea taken out of string theory), could indirectly explain why the observed cosmological constant is so small. I personally like this idea because I find it much more logical than the random anthropic interpretation which posits that fine-tuned universes are very rare; mostly as it provides a mechanism for which the cosmological constant can be fine-tuned so life can exist. However cosmological theories involving higher dimensions and stuff outside of what we can observe seem to be notoriously hard to verify. I am curious whether a cyclic model would leave a smoking gun; something we could use to prove that the actual universe is much older than the observable universe. Not necessarily just for the string theory cyclic model. Also, this may sound like a dumb question, but supposing the universe is infinitely old, would it be possible to see 'before' the big bang.