Measures on transitions for cosmology from eternal inflation

Area of Science:

• Cosmology
• Theoretical Physics
• Particle Physics

Background:

• Eternal inflation models propose a vast landscape of possible vacuum states.
• Predicting observable quantities in such a landscape is a significant challenge.
• Existing measures focus on counting vacua, which may not fully capture cosmological history.

Purpose of the Study:

• To propose a new framework for making predictions in the context of eternal inflation.
• To address the limitations of existing measures that focus solely on vacua.
• To develop measures that account for cosmological histories and transitions between vacua.

Main Methods:

• Reviewing existing measures for counting vacua in inflationary cosmology.
• Developing novel measures specifically designed to count transitions between metastable vacua.
• Analyzing how cosmological observables are determined by the history after the last vacuum transition.

Main Results:

• Demonstrating that a measure on cosmological histories is necessary for robust predictions.
• Introducing new measures that quantify the transitions between different vacua.
• Showing that observables are often determined by the post-transition history.

Conclusions:

• A measure on cosmological histories is crucial for predictions in eternal inflation.
• The developed measures for counting transitions offer a more accurate approach.
• This work provides a foundation for future investigations into cosmological predictions.