On Friday, a Russian Soyuz rocket will send an unmanned cargo ship with more than 3 tons of food, water and fuel for astronauts aboard the International Space Station. Russian Federal Space Agency hide caption

itoggle caption Russian Federal Space Agency

Theoretical Physicist Sean Carroll asks why does time exist? Marla Aufmuth/Courtesy of TED hide caption

itoggle caption Marla Aufmuth/Courtesy of TED

"Human beings are works in progress that mistakenly think they're finished," says psychologist Dan Gilbert. Ryan Lash/Courtesy of TED hide caption

itoggle caption Ryan Lash/Courtesy of TED