A nanometre is to a normal metre as a CD is to the earth! The infinitely small scale at which scientists are working is difficult to grasp - even for a scientist like presenter Prof Iain Stewart. In Bristol he sees how researchers are working on nano diamonds as a way of creating new solar panels that work well in temperate climates, and how the ears of mosquitoes are being studied in 'the world's quietest room' to help minaturise and improve microphones. He also sees how, most remarkable of all, scientists can now work with human tissue at the level of individual cells. This has huge implications for the development of regenerative medicine and therapies in future. Producer: Susan Marling A Just Radio production for BBC Radio 4.