What if? Exploring the multiverse through Euclidean wormholes

Area of Science:

• Cosmology
• Theoretical Physics
• Quantum Gravity

Background:

• The multiverse concept suggests a vast collection of universes.
• Third quantisation provides a framework for studying universe creation and evolution.
• Scalar fields are fundamental in cosmological models, including inflation.

Purpose of the Study:

• To investigate Euclidean wormhole solutions as potential bridges between universes.
• To model the multiverse using a scalar field within third quantisation.
• To calculate the probability of transitions between baby universes and de Sitter universes.

Main Methods:

• Utilising Euclidean wormhole solutions in the context of third quantisation.
• Modelling matter content with a scalar field.
• Computing tunnelling probabilities for universe transitions.

Main Results:

• Euclidean wormhole solutions connect baby universes to asymptotically de Sitter universes.
• Tunnelling probabilities for these connections were computed.
• The likelihood of specific universes undergoing inflation was determined based on current inflationary energy scale bounds.

Conclusions:

• The study provides insights into the dynamics of baby universes within a multiverse.
• It highlights which universes are more prone to nucleating and inflating.
• Findings contribute to understanding the conditions for a standard inflationary era.