Black Hole Question

[Loren Pechtel]

Ceases to exist?

If somebody walks behind a wall so that you can no longer see them, have they ceased to exist?

If you turn the lights out in a deep slate mine, so no photons bounce off your hands, have your hands ceased to exist?

No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.

 

[Loren Pechtel]

He is only immortal in its mass 3 and 4 isotopes. The longest lived unstable He isotope has a half life of about 800ms (⁶He).

You're assuming the proton doesn't decay.

 

[bilby]

He is only immortal in its mass 3 and 4 isotopes. The longest lived unstable He isotope has a half life of about 800ms (⁶He).

You're assuming the proton doesn't decay.

Well, given long enough, probably nothing is stable.

 

[bilby]

Ceases to exist?

If somebody walks behind a wall so that you can no longer see them, have they ceased to exist?

If you turn the lights out in a deep slate mine, so no photons bounce off your hands, have your hands ceased to exist?

No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.

There's no visible light at all in a deep slate mine without illuminating sources. The operative word is 'deep' - in an accessible lava tube I would expect you to still be close enough to the outside world to get some ambient light.

There are, perhaps unsurprisingly, visual hallucinations of various kinds even in the complete absence of photons in the visible range. The brain really HATES to interpret retinal input as zero. And even in the complete absence of light, retinal cells and optic nerves will occasionally fire.

 

[Loren Pechtel]

No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.

There's no visible light at all in a deep slate mine without illuminating sources. The operative word is 'deep' - in an accessible lava tube I would expect you to still be close enough to the outside world to get some ambient light.

There are, perhaps unsurprisingly, visual hallucinations of various kinds even in the complete absence of photons in the visible range. The brain really HATES to interpret retinal input as zero. And even in the complete absence of light, retinal cells and optic nerves will occasionally fire.

It was long enough with enough turns that no ambient light got in.

I also feel there were some dots that glowed as a reaction from our lights, but this was so long ago I'm not completely certain of what the lights were, only that they did exist.

 

[SLD]

The tidal forces will depend on the mass of the black hole. A supermassive black hole won’t have nearly as large a tidal force as a small one.

As long as you're falling "straight in" you might survive a while ... but otherwise you'll go into close orbit, accelerate to near lightspeed and become part of the superheated glowing aura around the supermassive black hole where magnetic fields are so strong that the very atoms of your body are ripped into their constituent subatomic particles... fun times!

I think that’s from the perspective of the observer. The observer will basically see you slowly merge into a glowing aura that surrounds the black hole, but getting redder and dimmer as time goes on. But don’t confuse the singularity with the Schwarzschild radius. You can cross that boundary at any particular speed <c. You will not realize it, unless there’s a firewall of Hawking radiation, which is unknown at this time. You can then orbit the singularity forever. You just can’t leave.

Wait. Are there other levels to the black hole out of which light can’t leave? Further Schwarschild radii within the hole?

 

[Bomb#20]

If you turn the lights out in a deep slate mine, so no photons bounce off your hands, have your hands ceased to exist?

Photons continue to bounce off your hands. There's no escaping blackbody radiation.

 

[T.G.G. Moogly]

No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.

There's no visible light at all in a deep slate mine without illuminating sources. The operative word is 'deep' - in an accessible lava tube I would expect you to still be close enough to the outside world to get some ambient light.

There are, perhaps unsurprisingly, visual hallucinations of various kinds even in the complete absence of photons in the visible range. The brain really HATES to interpret retinal input as zero. And even in the complete absence of light, retinal cells and optic nerves will occasionally fire.

It was long enough with enough turns that no ambient light got in.

I also feel there were some dots that glowed as a reaction from our lights, but this was so long ago I'm not completely certain of what the lights were, only that they did exist.

I had a cave experience. There is no visible light. It's all gone. If your hand is a tenth of an inch in front of your eyeball it might as well be on the other side of the moon. You cannot "see" it. It's not like in the movies.

 

[Loren Pechtel]

It was long enough with enough turns that no ambient light got in.

I also feel there were some dots that glowed as a reaction from our lights, but this was so long ago I'm not completely certain of what the lights were, only that they did exist.

I had a cave experience. There is no visible light. It's all gone. If your hand is a tenth of an inch in front of your eyeball it might as well be on the other side of the moon. You cannot "see" it. It's not like in the movies.

Yeah, there was no seeing your hands other than by occluding the points of light. They were very, very dim.

 

[SLD]

I did a lot of caving during college. There is no light at all down there.