That's the thing about black holes that always blows my mind. I don't understand how the larger a black hole is, the less dense that it is. In my mind, I always think of black holes as super dense objects containing so much matter in such a little space that the gravity is crazy strong. How can something so not dense be a black hole? It doesn't make sense to me!
To be fair, the density is calculated from the event horizon, which is a somewhat arbitrary boundary. All the mass is still concentrated at the singularity which is still infinitely dense, just... a bit more so.
Ah, I didn't realize that. I guess that's a little more terrifying. Sounds like you could pass the event horizon and not be instantly crushed, but would have no way of ever escaping. You'd just eventually get sucked into the singularity.
Not really. If more material falls in, its mass and size increases (the volume increases faster than the mass, which is why it's so unexpectedly low density in the first place), but otherwise it just sort of sits there.
Over the very long term, it will evaporate away by Hawking radiation. But that's a very very slow process. Like, long after everything else in the universe has ended.
Is there a banana for scale or does Lemmy use a different model for scale? Beans?
I think all the bananas (and beans) are already in the picture
Well, even the picture is in the picture..
And it has a density of only about 3g per cubic meter. It's not much denser than a vacuum made with a mechanical pump.
That's the thing about black holes that always blows my mind. I don't understand how the larger a black hole is, the less dense that it is. In my mind, I always think of black holes as super dense objects containing so much matter in such a little space that the gravity is crazy strong. How can something so not dense be a black hole? It doesn't make sense to me!
To be fair, the density is calculated from the event horizon, which is a somewhat arbitrary boundary. All the mass is still concentrated at the singularity which is still infinitely dense, just... a bit more so.
Ah, I didn't realize that. I guess that's a little more terrifying. Sounds like you could pass the event horizon and not be instantly crushed, but would have no way of ever escaping. You'd just eventually get sucked into the singularity.
Hiw stable is this kind of density? Is it going to shrink over time?
Not really. If more material falls in, its mass and size increases (the volume increases faster than the mass, which is why it's so unexpectedly low density in the first place), but otherwise it just sort of sits there.
Over the very long term, it will evaporate away by Hawking radiation. But that's a very very slow process. Like, long after everything else in the universe has ended.
And then what’s left?
Heat death
...and thennnn??
Normally black holes are considered to be everything up to the event horizon. E.g., from the Wikipedia page:
The term "black hole" derives from the fact that beyond a certain point light can't escape, that point being the event horizon.
That's actually smaller than I would have thought. I wouldn't have expected our solar system to even be visible in comparison.
What the hell are you talking about, that thing is beyond comprehension.
We shouldn't downvote people when they realize they have been thinking about something the wrong way and admit it.
Did I miss something? I didn't down vote them
Not you I'm sure, but they were at 0 when I posted, so thought I'd note it.
Lucky for us, it is to far away.
How big is this, in real numbers?
More than 1 AU.
That's technically correct.
About 1600 AU, according to wikipedia.