Introduction

Imagine a universe with extremely strong gravity. Stars would be able to form from very little material. They would be smaller than in our universe and live for a much shorter amount of time. But could life evolve there? It after all took human life billions of years to evolve on Earth under the pleasantly warm rays from the Sun. 

Now imagine a universe with extremely weak gravity. Its matter would struggle to clump together to form stars, planets and – ultimately – living beings. It seems we are pretty lucky to have gravity that is just right for life in our universe.

Featuring Fred Adams, professor of physics, University of Michigan, and Paul Davies, professor of physics, Arizona State University.

This episode was presented by Miriam Frankel and produced by Hannah Fisher. Executive producers are Jo Adetunji and Gemma Ware. Social media and platform production by Alice Mason, sound design by Eloise Stevens and music by Neeta Sarl. A transcript is available here. Sign up here for a free daily newsletter from The Conversation.

Further reading: 

• The multiverse is suspiciously unlikely to exist unless it is one of many