As the sun sets on the longest day of the year, Matthew Sweet talks to an eclectic group of guests about the illusion of time, the summer solstice and the philosophy of comedy. They are:Materials scientist & engineer; Director of the UCL Institute of Making; Author of Stuff Matters and other book Mark Miodownik.Philosopher Emily Herring who is about to publish the first English biography of the french philosopher Henri Bergson who was famous for his theory of time as well as his views on the meaning of comedy. Emily's book Herald of a Restless World: How Henri Bergson Brought Philosophy to the People is out in October.Comedian Rob Newman who made his name with the Mary Whitehouse Experience in the 90s and has presented two series on BBC Radio 4 including Rob Newman's Half-full Philosophy Hour.Also Professor of theoretical physics at Imperial College London Fay Dowker who is an expert in Causal Set Theory and Quantum Relativity.And Author K A Laity will talk about the Women in Magick Conference being held in Birmingham this weekend.Producer: Lisa Jenkinson