# Written in the Stars

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Sunday, December 16, 2007

Excerpts from "Death by Black Hole: And Other Cosmic Quandaries":

Including the space shuttle and Superman, a few things in life travel faster than a speeding bullet. But nothing moves faster than the speed of light in a vacuum. Nothing. Although as fast as light moves, its speed is decidedly not infinite. Because light has a speed, astrophysicists know that looking out in space is the same as looking back in time. And with a good estimate for the speed of light, we can come close to a reasonable estimate for the age of the universe.

These concepts are not exclusively cosmic. True, when you flick on a wall switch, you don't have to wait around for the light to reach the floor. Some morning while you're eating breakfast and you need something new to think about, though, you might want to ponder the fact that you see your kids across the table not as they are but as they once were, about three nanoseconds ago. Doesn't sound like much, but stick the kids in the nearby Andromeda galaxy and by the time you see them spoon their Cheerios they will have aged more than 2 million years.

. . . Without a doubt the most spectacular way to die in space is to fall into a black hole. Where else in the universe can you lose your life by being ripped apart atom by atom?

Black holes are regions of space where the gravity is so high that the fabric of space and time has curved back on itself, taking the exit doors with it. Another way to look at the dilemma: the speed required to escape a black hole is greater than the speed of light itself. . . . [L]ight travels at exactly 299,792,458 meters per second in a vacuum and is the fastest stuff in the universe. If light cannot escape, then neither can you, which is why, of course, we call these things black holes.

All objects have escape speeds. Earth's escape speed is a mere 11 kilometers per second, so light escapes freely, as would anything else launched faster than 11 kilometers per second. Please tell those people who like to proclaim, "What goes up must come down!" that they are misinformed.

© 2007 The Washington Post Company