Contents

# Contents

## Idea

In the context of cosmic inflation one speaks of eternal inflation if the inflationary expansion process perpetuates, in space and/or time.

Many classes of models of cosmic inflation in fact exhibit eternal inflation, notably the observationally preferred plateau-models, such as the Starobinsky model of cosmic inflation (Barenboim-Kinney-Park 16). (Also models of chaotic inflation do, but these are now strongly disfavoured by observation).

## Implications

The idea of eternal cosmic inflation has been argued to provide a possible way to conceptualize the measured values of dimensionless “physical constants”, such as the fine structure constant, the Yukawa couplings and notably the cosmological constant: for if in the fundamental theory these parameters are not really constants but are dynamical fields that just happen to have constant value (“moduli fields”) over large scales, then they might, so the argument, still vary from one “inflationary bubble” to the next. Thereby the idea of eternal inflation combined with that of a fundamental theory that has moduli fields (such as string theory with its landscape of string theory vacua) has been argued to put “physical constants” on the same footing as other more or less random phenomenological parameters, such as for instance the distance of our planets from the sun, etc.

For more on this see at multiverse.