Signature change in loop quantum cosmology

Understand

The Wick rotation is commonly considered only as an useful computational trick.

• However, as it was suggested by Hartle and Hawking already in early eighties, Wick rotation may gain physical meaning at the Planck epoch.
• While such possibility is conceptually interesting, leading to no-boundary proposal, mechanism behind the signature change remains mysterious.
• We show that the signature change anticipated by Hartle and Hawking naturally appear in loop quantum cosmology.