Can an object grow past the schwarzschild radius?
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Lots of answers. I’ll try a different approach and see if it sheds any light for you (or not). <– 2 puns! Maybe a superpositioning of puns?
Don’t think of light having an escape velocity – think of space-time being an escalator pulling everything down – space & time, and thus matter & energy & light, everything.
Imagine a neutron star like others have written here. With a radius of 10km and a schwarzschild radius of 15km.
Now imagine you’re a god who can alter the schwarzschild radius for this object like a human can adjust the lights with a dimmer switch.
Slowly crank down the schwarzschild radius to 14km – what would happen? 12km? 10.5km? 10.1km?
Eventually space-time is being warped more and more at that ever changing schwarzschild radius. Causing more and more of the surface of the star to be visible from your distant (we hope!) location. Check out https://www.youtube.com/watch?v=LSDNNfXYPq4#t=1m25 for a good idea.
But also, the light from the star will be traveling against space-time up the gravity well. It will get more and more red-shifted.
Until it’s infrared. Until it’s long radio waves. Until, there’s nothing left many many years from now.
Like an astronaut falling in, their light would get red shifted the closer they got to the event horizon and never totally cross it. Weird.
When an object “falls beyond” the schwarzschild radius of a blackhole (even if it’s the object itself) it goes red shifted into oblivion so to say.
Blackholes don’t form slowly by slowly getting more and more matter. But it’s fun it image what it would be like – it can help understand what effects are at play.
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