If the universe, like a box of gas, can exist in only a finite number of available states, theory predicts that we are Boltzmann brains, which conflicts with observations, not to mention common sense. If, on the contrary, the universe has an infinite number of available states, then our usual statistical techniques are not predictive, and we are stuck. The multiverse appears to offer a middle way. The universe has an infinite number of states available, avoiding the Boltzmann brain problem, yet approaches a steady-state behavior, allowing for a straightforward statistical analysis. But then we still find ourselves making absurd predictions. In order to make any of these three options work, I think we will need a revolutionary advance in our understanding of physics.
— Read on cosmos.nautil.us/feature/120/the-crisis-of-the-multiverse