If you stuck your hand into a black hole what would happen?
You can't just park outside a black hole and do this because there are no stable orbits possible for objects within an 'arms length' of the black hole's event horizon. Your only option to get close enough is to plot a course that lets you fall into the black hole. General relativity says that as you approach the event horizon, nothing unusual is going on at all. All you would be feeling are the tremendous tidal forces of the black hole, and these could be very substantial across a distance equal to your arm's length. In fact for a black hole produced by a star, by the time you are 40 miles from its horizon, the difference in the gravitational pull between your chest and hand is a thousand Earth gravities. Your hand would be torn from your body. But by then that will be the least of your problems. For the gargantuan black holes that lurk in the cores of many galaxies, the tidal forces near their event horizons are so minor that you might not even realize you had reached the event horizon at all, provided of course that the black hole was not surrounded by a lethal accretion disk spewing out x rays and gamma rays. You would gently pass across the horizon with your body intact, but with a very dismal future awaiting you as you continue to fall into the Singularity (See Glossary) located a few billion miles away. In either case because of relativity, distant observers would see your hand 'wink out' followed moments later by the rest of you!
