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submitted 2 days ago by fossilesque@mander.xyz to c/science_memes@mander.xyz

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[-] dwindling7373@feddit.it 50 points 2 days ago

Tell me you don't understand black holes using a lot of words.

As far as gravity goes they are equivalent to the star that they collapsed from and just as deadly.

The difference is that you can get that much closer before "impacting" with it, but you and superman would be fucked pretty much at the same distance from it.

And I think you need a lot less than 300 writers to conjure an idea that leverage our fantasy in more and better ways.

[-] Wirlocke 23 points 2 days ago

Nothing you said about black holes really contradicts what they were saying? Even if a star and black hole can have the same gravity, there is still a shell of space that once you pass you cannot ever return. I'm sure Superman could go into a star and come back out, not so much with a black hole.

[-] dwindling7373@feddit.it 1 points 19 hours ago

No. You can't ever get out of a lot of shit.

From a common star, if you can make your mass somehow be almost 0 and your speed being almost c, you can get out.

[-] sem 32 points 2 days ago* (last edited 2 days ago)

And an infinitely dense point in spacetime doesn't necessarily exist: it's just what general relativity predicts is at the center of a black hole.

The last time our physical model of the universe predicted an infinite value, we ended up discovering new physics eventually (the ultraviolet catastrophe). (Edit: ultrasound was a typo).

[-] Wolf@lemmy.today 3 points 1 day ago

And an infinitely dense point in spacetime doesn’t necessarily exist: it’s just what general relativity predicts is at the center of a black hole.

If the singularity at the center of a black hole didn't exist, and was just extremely dense instead, would all of the other properties that we know is true about black holes be able to exist? For example we know that Sag A* and that one other black hole we 'imaged' give off no light, would that still be possible without a singularity?

[-] sem 3 points 21 hours ago* (last edited 21 hours ago)

In General Relativity, the way to get gravity so strong that not even light can escape is with a singularity: a point of infinite density. So, either this infinity physically exists, and maybe we'll understand how better, or General Relativity may be incomplete: a model that works well most of the time, but doesn't represent reality correctly at the extremes of heavy mass and small space.

Or at least that's how I understand it. This has more info: https://physics.stackexchange.com/questions/18981/why-singularity-in-a-black-hole-and-not-just-very-dense#18987

This is similar to the ultraviolet catastrophe. Physicists predicted black body radiation using their current physical models, with high accuracy at low wavelengths of light, but at high wavelengths, the predictions diverged towards infinity, which disagreed with measurements.

(Source: Wikipedia)

Breakthroughs in quantum physics later reconciled theory with measurements.

One big difference with black holes is we cannot yet measure the actual density in the interior of the black hole. We just have the prediction that there is a point of infinite density.

Any physicists around here may have a better understanding than me.

[-] Wolf@lemmy.today 3 points 19 hours ago

I appreciate your detailed answer, thank you for taking the time :D

[-] Ageroth@reddthat.com 20 points 2 days ago

I think you're referring to the ultraVIOLET catastrophe

https://en.m.wikipedia.org/wiki/Ultraviolet_catastrophe

[-] BussyGyatt@feddit.org 6 points 2 days ago

yeesh, what was the ultrasound catastrophe then?

[-] sem 4 points 2 days ago* (last edited 2 days ago)

That whole comment was a struggle to type on my phone at the time because the screen was wet, so at the end that one slipped though.

[-] BussyGyatt@feddit.org 1 points 2 days ago

still, kind of funny wondering what an ultrasonic catastrophe might have been

[-] VoterFrog@lemmy.world 1 points 1 day ago

It's what OP's parents call the first day they saw him.

[-] BussyGyatt@feddit.org 1 points 1 day ago

aw thats kinda mean

[-] drosophila 16 points 2 days ago* (last edited 2 days ago)

I mean, the gravitational gradient is much higher. To me this kind of sounds like saying "there's nothing that special about a 10 watt laser, an LED lightbulb puts out the same amount of light", but a 10 watt laser is enough to instantly and permanently blind you.

Its true that there's nothing that special about orbiting a black hole, but I think its not really logically inconsistent (inasmuch as a superhero can be logically consistent) to say "even if superman could survive dipping into a sun he probably wouldn't be too happy if he stuck his arm into an event horizon".