5 ms·
I've been wondering - if the black hole was very small (I've read elsewhere that it would be grapefruit sized), would it be possible to build some kind of box a
by geoffmunn 6y ago
I've been wondering - if the black hole was very small (I've read elsewhere that it would be grapefruit sized), would it be possible to build some kind of box around it so you couldn't accidentally go into the event horizon?
- Sharlin 6y agoThere's no material that you could make the box or shell out of that could withstand the gravitational forces near the black hole. Even the gravity differential (tidal forces) is strong enough to rip anything apart (the so-called spaghettification). And if you made the shell large enough (planet-diameter), it would collapse into a spherical body just from its self-gravity, never mind the additional gravity of the PBH.
- geoffmunn 6y agoBut given that it's so small, what would the gravitational forces be if you made a shell with a 100km radius? Or pick a number - surely at some point it might be practical to build something.
- xingyzt 6y agoSize of the object doesn’t matter. Gravitational force depends on its mass and how far away you are from the black hole. Standing on a shell ~6300 km above a black hole with the mass of the Earth is equivalent to standing on the Earth itself.
- jborichevskiy 6y agoI have a hard time really accepting this concept given how unintuitive it is to me but I found your comment helpful in that regard.