George Ellis and the multiverse

George Ellis

George Ellis is a South African cosmologist who rose to fame almost half a century ago when he wrote a book together with Stephen Hawking (The Large Scale Structure of Space-Time, 1973), today considered a classic.

In an earlier post in this blog, published in November 2014, I mentioned that there are six independent theories about the multiverse, almost all of them incompatible with each other. In a recent article titled Theory Confirmation and Multiverses published in the book Why Trust a Theory?, edited by Radin Dardashti, Richard David and Karim Thébault (Cambridge University Press, 2019), George Ellis updates the different multiverse theories. He does not mention six, as I did five years ago, but nine, although he has left out one of the six I mentioned in my post (Smolin’s), perhaps because this theory has been abandoned in the meantime. The nine theories are: