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Journey into a Black Hole

Imagine a trip into a black hole. This tantalizing thought has excited much creative speculation.

There are two ways to consider the issue. One is to "watch" someone or something -- say a small robot spacecraft -- fall into the black hole. The odd thing is it never seems to get there. The closer it approaches the hole's event horizon, the slower it seems to travel. But for the crew inside, there would be no warning of its impending doom.

An accretion disk might warn of an event horizon beyond, but the horizon itself would remain invisible. And for the crew, time seems to flow normally. Nevertheless, to you, the observer, the spacecraft appears to halt, seemingly forever suspended at the boundary of the black hole. The spacecraft begins to turn orange, then red, then fades imperceptibly from view. Though it is gone, you never saw where or how it disappeared.

Now brace yourself! Imagine that you are venturing into the black hole yourself. As you travel toward it you may notice nothing out of the ordinary, except an inability to steer yourself in any but one direction -- which is toward the "invisible" hole. You would never know when you had crossed the event horizon were it not for the increased gravitational tugging that draws your body longer and longer, squeezing in from the sides. You wouldn't last long, which is too bad, because theorists believe that inside a black hole, time and space are scrambled up strangely, such that even time travel, or travel to different universes via so-called "wormholes" might become possible, if (and a big IF!) you could survive the extreme gravity inside the hole.

Einstein's Theory of General Relativity predicts that though the gravitational field around a massive black hole is stronger on the large scale, it will exert weaker tidal forces than its smaller counterpart, at least outs ide the event horizon. These forces are what would stretch and squeeze you into spaghetti. So, if you insist on exploring the vicinity of a black hole and want to play it safe, pick a big one!

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NCSA. Last modified 11/7/95