What Is Time?

Wired Science has posted a thought-provoking interview with Caltech theoretical physicist Sean Carroll about the arrow of time, which points from past to future. We all perceive this arrow and can measure its passage with clocks, but very little is understood about how and why it works that way. Carroll explains:

We remember the past but we don't remember the future. There are irreversible processes. There are things that happen, like you turn an egg into an omelet, but you can't turn an...