Twenty-five years ago in a German bar, neuroscientist Christof Koch bet philosopher David Chalmers that we’d understand the neural basis for consciousness by 2023. Last month, the winner of the bet received a case of wine. Ian Sample talks to Christof and David about why they made the bet, who won, and where we are now in our understanding of this most fundamental aspect of existence.. Help support our independent journalism at theguardian.com/sciencepod