This week on the show Chris speaks to world renowned theoretical physicist Sean Carroll about multiple worlds, the possibility of time travel, and whether the last Avengers film got the science right.Also,  Claire chats to geochemist Hayden Dalton about his research looking at the chemistry of diamonds that have travelled from the mantle to the surface via volcanic explosion, and what these can tell us about what our planet is made from.And Stu reports about the long awaited breakthrough for a male contraception that is both easy to use and highly efficient.