Anthropic Bounds on Lambda from the No-Boundary Quantum State

TL;DR

This paper demonstrates that anthropic reasoning naturally arises in quantum cosmology, with the no-boundary wave function predicting a flat distribution for Lambda and favoring small Q, aligning with observed values.

Contribution

It shows how the no-boundary quantum state leads to anthropic predictions for Lambda and Q in an inflationary landscape, restoring Weinberg's Lambda prediction.

Findings

No-boundary wave function predicts a flat distribution of Lambda.

It strongly favors small values of Q.

Results align with observed cosmological parameters.

Abstract

We show that anthropic selection emerges inevitably in the general framework for prediction in quantum cosmology. There the predictions of anthropic reasoning depend on the prior implied by the universe's quantum state. To illustrate this we compute the probabilities specified by the no-boundary wave function for our observations at the present time of the values of Lambda and Q in an inflationary landscape model in which both quantities vary. Within the anthropic range of values the no-boundary state yields an approximately flat distribution on Lambda and strongly favors small values of Q. This restores Weinberg's successful prediction of Lambda.