Melvyn Bragg and guests Frank Close, Jocelyn Bell Burnell and Ruth Gregory discuss the Vacuum of Space. The idea that there is a nothingness at the heart of nature has exercised philosophers and scientists for millennia, from Thales's belief that all matter was water to Newton's concept of the Ether and Einstein's idea of Space-Time. Recently, physicists have realised that the vacuum is not as empty as we thought and that the various vacuums of nature vibrate with forces and energies, waves and particles and the mysterious phenomena of the Higgs field and dark energy.