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

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[-] 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.