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The event horizon is the point where the gravitational pull is pulling you at nearly the speed of light so that there is no possible escape velocity for any par

by kyllo 14y ago

The event horizon is the point where the gravitational pull is pulling you at nearly the speed of light so that there is no possible escape velocity for any particle that has mass, correct? I'm no physicist, but if gravity were to act on a human body with that much force, wouldn't the force alone kill you? I imagine the force of the pull would be stronger than the force holding together the atoms that make up the tissue of your body, and you would disintegrate into a stream of particles accelerating toward the singularity. Am I way off here? If a smaller object approached an object of such great mass that not even light can escape its gravitational pull, wouldn't the smaller mass's particles inevitably be funneled into a single-file line until they are absorbed into the singularity?

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pdonis 14y ago
if gravity were to act on a human body with that much force, wouldn't the force alone kill you? No, because you don't feel this "force" of gravity; you are in free fall, just like astronauts on the International Space Station. Your body will be subject to tidal gravity because it has a finite size; the effects you talk about in the rest of your post (your body's atoms being pulled apart, etc.) are due to tidal gravity, not "the force of gravity" per se. But for a large enough black hole, tidal gravity is small enough to be bearable at the horizon.
jbri 14y ago
How much gravitational force does the Sun exert on you? Do you feel any of it? A constant gravitational field doesn't change anything - everything is accelerating the same amount, in the same direction. What can cause problems is the difference between the gravitational field at two different points (for example, when a planet gets too close to a star, it can be torn apart due to the force exerted on the near side being much greater than the force exerted on the far side). But this isn't the same as the overall strength of the field, and a sufficiently large black hole could have a very survivable field gradient at the event horizon.
- kyllo 14y ago
  Oh ok, so what I described (the atoms of your body being stretched apart by tidal force) will eventually happen, but not necessarily until quite a while after you cross the event horizon, if the total mass of the black hole is great enough. Thanks for the explanation.

by kyllo 14y ago

deleted 14y ago

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pdonis 14y ago

if gravity were to act on a human body with that much force, wouldn't the force alone kill you? No, because you don't feel this "force" of gravity; you are in free fall, just like astronauts on the International Space Station. Your body will be subject to tidal gravity because it has a finite size; the effects you talk about in the rest of your post (your body's atoms being pulled apart, etc.) are due to tidal gravity, not "the force of gravity" per se. But for a large enough black hole, tidal gravity is small enough to be bearable at the horizon.

jbri 14y ago

How much gravitational force does the Sun exert on you? Do you feel any of it? A constant gravitational field doesn't change anything - everything is accelerating the same amount, in the same direction. What can cause problems is the difference between the gravitational field at two different points (for example, when a planet gets too close to a star, it can be torn apart due to the force exerted on the near side being much greater than the force exerted on the far side). But this isn't the same as the overall strength of the field, and a sufficiently large black hole could have a very survivable field gradient at the event horizon.

kyllo 14y ago
Oh ok, so what I described (the atoms of your body being stretched apart by tidal force) will eventually happen, but not necessarily until quite a while after you cross the event horizon, if the total mass of the black hole is great enough. Thanks for the explanation.