Warsaw Spacetime Colloquium: John Norton (25 February on Zoom)

On Friday, 25 February, John Norton (University of Pittsburgh) will give a talk titled “Eternal Inflation: When Probabilities Fail” (abstract below).

The meeting will be online on Zoom (17:00-19:00 CET). If you have not registered yet, you can do so here.

You can address any inquiry to antonio.vassallo@pw.edu.pl.


In eternally inflating cosmology, infinitely many pocket universes are seeded. Attempts to show that universes like our observable universe are probable amongst them have failed, since no unique probability measure is recoverable. This lack of definite probabilities is taken to reveal a complete predictive failure. Inductive inference over the pocket universes, it would seem, is impossible. I argue that this conclusion of impossibility mistakes the nature of the problem. It confuses the case in which no inductive inference is possible, with another in which a weaker inductive logic applies. The alternative, applicable inductive logic is determined by background conditions and is the same, non-probabilistic logic as applies to an infinite lottery. This inductive logic does not preclude all predictions, but does affirm that predictions useful to deciding for or against eternal inflation are precluded.