By The Daily Galaxy
For me, at least, says John Donoghue, theoretical physicist at the University of Massachusetts at Amherst, the multiverse is the idea that physically out there, beyond where we can see, there are portions of the universe that have different properties than we see locally. We know the universe is bigger than we can see. We don’t know how much bigger. So the question is, is it the same everywhere as you go out or is it different?
A multiverse of realms with different ground states would support the view that the universe’s habitability can be explained by the anthropic principle—we live in the realm where conditions are suitable—and not by a single theory that specifies the same properties everywhere.
What we can know, observes Donoghue, may depend on things that may end up being out of our reach to explore. The idea that we should be searching for a unified theory that explains all of nature may, in fact, be the wrong motivation. It’s certainly true that multiverse theories raise the possibility that we will never be able to answer these questions. And that’s disturbing.
Knowable Magazine interviewed Donoghue about the meaning of the multiverse, the issues surrounding anthropic reasoning, and the argument that the idea of a multiverse is not scientific.