Antimatter was once as abundant in the universe as matter is today. Now almost entirely confined to science fiction, where has all the antimatter gone?

The multiverse is wild, but scientifically very serious. What kinds of multiverses might there be, what implications might they have? Which theories in physics and mathematics entail them?

Betelgeuse is a red supergiant star in the constellation of Orion, doomed to a short life and a violent death – and in cosmic terms, it could go supernova at any time. But what would happen if it does?

Are objects identical with regions of spacetime, or do objects exist separately and occupy regions of spacetime? I defend the former thesis, known as supersubstantivalism.