Paul Zak: Trust, morality. Philip Zimbardo shows how people become monsters ... or heroes. Tim Ferriss: Smash fear, learn anything. Dan Gilbert asks, Why are we happy? Beau Lotto: Optical illusions show how we see.
David Gallo shows underwater astonishments. John Hodgman: Aliens, love. Rives on 4 a.m. Michael Shermer on strange beliefs.