We have quantum theories about three of the four forces of nature - electromagnetism, the strong nuclear force and the weak nuclear force - but not of gravity, theoretical physicist Leonard Mlodinow says in this IdeaFestival Conversation. He'd like to change that.
But why should anyone care? Because as theory, it could describe all known physical interactions - from the vanishingly small to the colossally big, unifying quantum theory and relativity - and lead to a better understanding of the state of nature a mere fraction of a second following the Big Bang.
Once you're done here, go watch Mlodinow's The Moth story about his father, a Holocaust survivor, and how that relationship shaped his life. As with quantum theory, some physics can only be known in retrospect.