Replication Regulates Volume Weighting in Quantum Cosmology

Understand

Probabilities for observations in cosmology are conditioned both on the universe's quantum state and on local data specifying the observational situation.

• We show the quantum state defines a measure for prediction through such conditional probabilities that is well behaved for spatially large or infinite universes when the probabilities that our data is replicated are taken into account.
• In histories where our data are rare volume weighting connects top-down probabilities conditioned on both the data and the quantum state to the bottom-up probabilities conditioned on the quantum state alone.
• We apply these principles to a calculation of the number of inflationary e-folds in a homogeneous, isotropic minisuperspace model with a single scalar field moving in a quadratic potential.