In this podcast George Ellis explains why the study of the cosmos poses some deep philosophical questions.

Why (some) physicists want to modify Einstein's general theory of relativity.

The Astronomer Royal examines the evolution of our Universe and the important role of the constants of nature in this filmed public talk.

Cormac O' Raifeartaigh recently made a surprising discovery – an unpublished paper by Albert Einstein that sheds light on how Einstein's thinking about the Universe changed as he tackled some of the big questions in cosmology at the time.

David Sloan calculates how likely it is that our Universe exists. He explains to us how, and why the answer can help shape our theories of physics.

A 1 in 14 million chance to win the lottery, a 5% risk of cancer, a 50:50 chance of heads on a coin — we deal with probabilities all the time, but do they actually mean anything? We explore the philosophy of probability and ask whether the probabilities that come up in physics differ from those in every day life.

Are there objective chances in the world?

Is the Universe finite or infinite? Is there infinity inside a black hole? Is space infinitely divisible or is there a shortest length? We talk to philosophers and physicists to find out.

Is the Universe finite or infinite? Is there infinity inside a black hole? Is space infinitely divisible or is there a shortest length? Can infinity occur at all in the cosmos or is it a mathematical construct? Find out more in our podcast with Anthony Aguirre, John D. Barrow and George Ellis.

This podcast comes to you from a conference on the nature of time. We talk to philosophers of physics Jeremy Butterfield and David Wallace, as well as the eminent Roger Penrose about the puzzle time poses to physicists and what it has to do with the Big Bang and the second law of thermodynamics.