Bookmark this for the next airhead invasion of your local Great Ideas discussion group.
Eternal inflation is an extrapolation of inflation, which is an extrapolation of the concordance model, which is an extrapolation of the present-day universe back in time. Eternal inflation, like inflation, works by inventing a new field (the “inflaton”) that no one has ever seen because we are told it vanished long ago. Eternal inflation is a story about the quantum fluctuations of the now-vanished field and what these fluctuations did to gravity, which no one really knows, but that’s the game.
There is little evidence for inflation, and zero evidence for eternal inflation. But there is a huge number of models for both because available data don’t constraint the models much. Consequently, theorists theorize the hell out of it. And the more papers they write about it, the more credible the whole thing looks.
And then there’s the string theory landscape, the graveyard of disappointed hopes. It’s what you get if you refuse to accept that string theory does not predict which particles we observe. More.
Hossenfelder sounds like an extraordinarily honest person for the field she’s in. Hope she’s not taking too big a risk.
See also: Theoretical physicist: Multiverse not based on sound science reasoning Good points But what if multiverse theory is simply a means of fending off the impasses that fully naturalist theoretical physics is in? It doesn’t need to make sense, any more than bollards do.
Picture the multiverse controversy if real evidence were demanded for a multiverse…
Post-modern physics: String theory gets over the need for evidence
Cosmic inflation theory loses hangups about the scientific method
The multiverse is science’s assisted suicide