On Start the Week Tom Sutcliffe asks if one day we might know everything. The mathematician Marcus du Sautoy and the physicist Roger Penrose explore the far reaches of knowledge, questioning whether certain fields of research will always lie beyond human comprehension. They ask how much fashion and faith shape scientific theories. The experimental physicist Suzie Sheehy attempts to build machines to test the latest theories, while Joanna Kavenna plays with a philosophical Theory of Everything in her latest novel A Field Guide to Reality. Producer: Katy Hickman.