Paul Rozin has been studying the psychology and culture of food for more than 40 years. And he's come to appreciate that food fills many of our needs, but hunger is just one.

"Food is not just nutrition that goes in your mouth or even pleasant sensations that go with it," he says. "It connects to your whole life, and it's really a very important part of performing your culture and experiencing your culture."

Virgin Galactic says it has reached a rather lofty milestone.

During a test flight Thursday morning in Mojave, Calif., a pair of pilots flying the company's SpaceShipTwo spacecraft hit an altitude of 51.4 miles. That height clears the 50-mile threshold that is sometimes considered the boundary of space.