What Keeps Physicists Up At Night?

No, it's not the great pumpkin, Charlie Brown. Physicists are kept up by questions about the very nature of space, time, and reality itself ... and New Scientist has broken these concerns down into the "Seven questions that keep physicists up at night." These questions come out of a panel discussion among physicists speaking at the "Quantum to Cosmos" festival, which took place at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, last week. Videos from the festival are available on the website.