In the context of general relativity, space almost is a substance. It can bend and twist and stretch, and probably the best way to think about space is to just kind of imagine a big piece of rubber that you can pull and twist and bend.

In the context of general relativity, space almost is a substance. It can bend and twist and stretch, and probably the best way to think about space is to just kind of imagine a big piece of rubber that you can pull and twist and bend.

Space is certainly something more complicated than the average person would probably realize. Space is not just an empty background in which things happen.

It’s hard to build models of inflation that don't lead to a multiverse. It’s not impossible, so I think there’s still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking [the idea of a] multiverse seriously.

The Big Bang theory says nothing about what banged, why it banged, or what happened before it banged.

Despite its name, the big bang theory is not really a theory of a bang at all. It is really only a theory of the aftermath of a bang.

The recent developments in cosmology strongly suggest that the universe may be the ultimate free lunch.