John Carlos Baez on Nostr: As you're freely falling through the air you don't feel any force except the wind - ...
As you're freely falling through the air you don't feel any force except the wind - but in fact you're getting *stretched* slightly because gravity is a bit stronger near your feet. This is called a 'tidal force' because it creates the tides: water on the sunny side of the Earth is pulled toward the Sun more than water on the night side.
As a star falls toward a black hole it can get stretched and even destroyed by this tidal force - we've seen it happen! It can create a huge flare of radiation.
But surprisingly, the bigger the black hole, the smaller the tidal force is right near the event horizon. We could be falling through the event horizon of a truly enormous black hole right now, and we'd never notice - though I consider this very unlikely.
More importantly, a star like the Sun will only get disrupted *before* it crosses the event horizon if the black hole is < 100 million solar masses. Otherwise it will get sucked in and be lost to sight without any drama!
The big black hole in the center of our galaxy is only 4 million solar masses, so this 'silent death' doesn't happen here. But it happens elsewhere. The biggest black hole known is 66 *billion* solar masses!
Black holes emit flares of light that we don't understand. Some must be from stars falling in. But some flares show very little light in hydrogen's spectral lines! This talk is pretty fun, and it's all about these mysteries.
https://www.youtube.com/watch?v=m6cFy34wsyM
As a star falls toward a black hole it can get stretched and even destroyed by this tidal force - we've seen it happen! It can create a huge flare of radiation.
But surprisingly, the bigger the black hole, the smaller the tidal force is right near the event horizon. We could be falling through the event horizon of a truly enormous black hole right now, and we'd never notice - though I consider this very unlikely.
More importantly, a star like the Sun will only get disrupted *before* it crosses the event horizon if the black hole is < 100 million solar masses. Otherwise it will get sucked in and be lost to sight without any drama!
The big black hole in the center of our galaxy is only 4 million solar masses, so this 'silent death' doesn't happen here. But it happens elsewhere. The biggest black hole known is 66 *billion* solar masses!
Black holes emit flares of light that we don't understand. Some must be from stars falling in. But some flares show very little light in hydrogen's spectral lines! This talk is pretty fun, and it's all about these mysteries.
https://www.youtube.com/watch?v=m6cFy34wsyM