1. What is Space?

Space. It separates you from me, one galaxy from the next, and atoms from one another. It is everywhere in the universe. But to most of us, space is nothing, an empty void. Well, it turns out space is not what it seems. From the passenger seat of a New York cab driving near the speed of light, to a pool hall where billiard tables do fantastical things, Brian Greene reveals space as a dynamic fabric that can stretch, twist, warp, and ripple under the influence of gravity. Stranger still is a newly discovered ingredient of space that actually makes up 70 percent of the universe. Physicists call it dark energy, because while they know it's out there, driving space to expand ever more quickly, they have no idea what it is.

Probing space on the smallest scales only makes the mysteries multiply. Down there, things are going on that physicists today can barely fathom—forces powerful enough to generate whole universes. To top it off, some of the strangest places in space, black holes, have led scientists to propose that like the hologram on your credit card, space may just be a projection of a deeper two-dimensional reality taking place on a distant surface that surrounds us. Space, far from being empty, is filled with some of the deepest mysteries of our time.