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The "squashed into spaghetti" occurs in "normal space" before you get to the black hole, for most black holes. It is not an effect of anything special about bla

by jerf 4y ago

The "squashed into spaghetti" occurs in "normal space" before you get to the black hole, for most black holes. It is not an effect of anything special about black holes, it's just plain ol' normal tidal effects, turned up to eleven, then turned up until the knob breaks, then turned up some more. Neutron stars will give you a bad day with tidal effects too long before you reach their surface. Very large black holes turn out not to have this, though it's going to be a long time cosmologically before there are any large black holes also quiet enough for you to get anywhere near.

syllablehq 4y ago
To an outside observer it would look like you were torn apart by tidal forces, but would it feel that way to you? Or would you feel normal? If it's just space being curved, would you feel nothing just like you feel nothing in freefall? I'm sure this question is wrong...
- yencabulator 4y ago
  The "tidal effect" here is due the difference in gravity experienced by parts of you at different distances from the gravity source. Imagine your feet pulled downward hard enough that your bones stretch and/or snap, while you are squished in from the sides. And then more. You'd become a long thin strand of matter, no longer in the shape of a human and no longer feeling anything. It's not "just a ride down" where things feel locally normal, and it's not a phenomenon about black holes, as some stars can do that to you too. https://en.wikipedia.org/wiki/Spaghettification https://en.wikipedia.org/wiki/Spaghettification
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- jerf 4y ago
  Position is relative, velocity is relative, acceleration is actually absolute. Tidal forces are not relative, they are agreed upon by all observers, who would all agree that you got torn apart by those forces. You can remember this by considering the effect acceleration has on objects; there is no trajectory an object can take in which it will observe the surface of the earth being at 25G and consequently everything being crushed on it. They'll still see 1G, they just won't agree about the velocities being modified and in sufficiently extreme cases, won't agree about how long the forces were applied for, but they'll still see 1G. Being able to witness varying accelerations would actually be a very strange theory, having instead a twin paradox in which one astronaut takes off and comes back home to a twin (and civilization) crushed to death, whereas the stay-at-home twin sees his twin take off, get crushed to death, and never return home at all. The YouTube videos trying to explain this universe would certainly be epic. Again, this all happens in normal space too; the black-hole-ness of the black hole is not in play yet. Non-black hole objects can "spaghettify" too.
selfmodruntime 4y ago
What? Any reading material on the last part?
- jerf 4y ago
  I don't have a specific link. But the larger the black hole, the lesser the tidal forces at the event horizon. Tidal forces are created by gravity gradients, the differences, and the differences become less extreme as the black hole sizes up. You can see it just by thinking about how the gravity field changes around an object as it gets larger; think about where the 1G line as you make the Earth denser and denser, and note how quickly the field is changing at that point. Hypothetically, a large black hole would permit you to actually survive entry into the event horizon. It's still hypothetical because the environment around any such black hole in the current era is still far too violent for you to get that close, and it will be for cosmologically-meaningful periods of time.

by jerf 4y ago

syllablehq 4y ago

To an outside observer it would look like you were torn apart by tidal forces, but would it feel that way to you? Or would you feel normal? If it's just space being curved, would you feel nothing just like you feel nothing in freefall? I'm sure this question is wrong...

yencabulator 4y ago
The "tidal effect" here is due the difference in gravity experienced by parts of you at different distances from the gravity source. Imagine your feet pulled downward hard enough that your bones stretch and/or snap, while you are squished in from the sides. And then more. You'd become a long thin strand of matter, no longer in the shape of a human and no longer feeling anything. It's not "just a ride down" where things feel locally normal, and it's not a phenomenon about black holes, as some stars can do that to you too. https://en.wikipedia.org/wiki/Spaghettification https://en.wikipedia.org/wiki/Spaghettification
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jerf 4y ago
Position is relative, velocity is relative, acceleration is actually absolute. Tidal forces are not relative, they are agreed upon by all observers, who would all agree that you got torn apart by those forces. You can remember this by considering the effect acceleration has on objects; there is no trajectory an object can take in which it will observe the surface of the earth being at 25G and consequently everything being crushed on it. They'll still see 1G, they just won't agree about the velocities being modified and in sufficiently extreme cases, won't agree about how long the forces were applied for, but they'll still see 1G. Being able to witness varying accelerations would actually be a very strange theory, having instead a twin paradox in which one astronaut takes off and comes back home to a twin (and civilization) crushed to death, whereas the stay-at-home twin sees his twin take off, get crushed to death, and never return home at all. The YouTube videos trying to explain this universe would certainly be epic. Again, this all happens in normal space too; the black-hole-ness of the black hole is not in play yet. Non-black hole objects can "spaghettify" too.

selfmodruntime 4y ago

What? Any reading material on the last part?

jerf 4y ago
I don't have a specific link. But the larger the black hole, the lesser the tidal forces at the event horizon. Tidal forces are created by gravity gradients, the differences, and the differences become less extreme as the black hole sizes up. You can see it just by thinking about how the gravity field changes around an object as it gets larger; think about where the 1G line as you make the Earth denser and denser, and note how quickly the field is changing at that point. Hypothetically, a large black hole would permit you to actually survive entry into the event horizon. It's still hypothetical because the environment around any such black hole in the current era is still far too violent for you to get that close, and it will be for cosmologically-meaningful periods of time.