Soon after the Large Hadron Collider (LHC) came online, the news and the Internet were abuzz with fears that an LHC-spawned black hole would destroy the Earth. Here's why you should buy those green bananas anyway: According to Einstein, the LHC cannot create microscopic black holes. Even if it could, as some have hypothesized, they would disintegrate instantly or, if not, would pass through the Earth into space. How do we know? Because if these microscopic black holes exist, then cosmic rays already make them when they collide with the Earth so, if they were dangerous, they would have already destroyed us [source: LHC].
The End of the World, or Through the Looking Glass
You climb into your indestructible pod, knowing it will spare you only briefly, but hoping at least to survive long enough to experience the black hole's interior. Launching into space, you plot a gentle, decaying orbit inward.
Luckily for you, but unluckily for the solar system, this is a supermassive black hole. Yes, we're changing the rules, but everything would happen far too quickly if we didn't. Here's why:
In a small black hole -- say, around 30 solar masses -- the tidal forces caused by the steep intensification of gravity over distance would tear you apart long before you reached the event horizon. In fact, at the event horizon, the tidal force between your head and your feet would be around 1 million G's (Earth gravities). Even if you could survive, there would be no time to enjoy your victory, for you would encounter the singularity 0.0001 seconds after crossing the event horizon [source: Hamilton].
In a supermassive black hole sporting the mass of 5 million suns, like the one at the center of our galaxy, the experience is much different. Any black hole that bulks up to more than 30,000 solar masses exerts head-to-toe tidal forces of less than 1 G at its event horizon. There's also more time for sightseeing on the way to your doom: On a curved descent, it will take you 16 seconds (and change) to reach the singularity after crossing the event horizon (this "infall" time is a function of the black hole's mass; the more mass, the longer it takes) [source: Hamilton].
Falling through the event horizon of a black hole is a bit like falling asleep or falling in love: It's hard to pinpoint when it happens, but once it does, your sense of reality is significantly compromised. In the case of the black hole, you can still see the starfield (light can get into a black hole, it simply cannot leave), but the view reminds you of the whorls of color inside a soap bubble, and there is something else wrong, too: The curved space-time garbles and twists light, confusing your binocular vision; it's like peering through a kaleidoscope with your eyes crossed [source: Hamilton].
Tidal forces stretch your craft downward like taffy and crush inward on you from every side. As you near the singularity, you witness an extraordinary sight: The outside universe appears to compress into a bright, thin, blueshifted band around your waist, as the views above and below dim and redshift. After that, what's left of your shredded matter enters a point of infinite curvature, where known space and time end.