Susskind's Challenge to the Hartle-Hawking No-Boundary Proposal and Possible Resolutions

TL;DR

This paper discusses Susskind's challenge to the Hartle-Hawking no-boundary proposal, arguing it favors a nearly empty universe and explores potential resolutions, including the possibility of extremely large inflationary expansion.

Contribution

The paper amplifies Susskind's argument against the no-boundary proposal and examines novel potential resolutions, including an extraordinarily large inflationary universe.

Findings

Susskind's challenge suggests the universe should be nearly empty.

Possible resolutions include inflation expanding the universe beyond 10^{10^{10^{122}}} Mpc.

The paper proposes that certain resolutions could reconcile the no-boundary proposal with observations.

Abstract

Given the observed cosmic acceleration, Leonard Susskind has presented the following argument against the Hartle-Hawking no-boundary proposal for the quantum state of the universe: It should most likely lead to a nearly empty large de Sitter universe, rather than to early rapid inflation. Even if one adds the condition of observers, they are most likely to form by quantum fluctuations in de Sitter and therefore not see the structure that we observe. Here I present my own amplified version of this argument and consider possible resolutions, one of which seems to imply that inflation expands the universe to be larger than 10^{10^{10^{122}}} Mpc.