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Comment by btcindivist | Hacker News Reader

Are discoveries about black holes legit?

Isn't it still the case that they have not been experimentally confirmed to exist, and all talk of discoveries is just conceptual?

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We have recorded a video[1] of the black hole at the center of our galaxy.

[1] - https://www.youtube.com/watch?v=k7xl_zjz0o8

Amazing video!

That’s incredible! Definitely love to see / hear more about this if anyone has any pointers?

The video came from this study - "Monitoring stellar orbits around the Massive Black Hole in the Galactic Center" - https://arxiv.org/abs/0810.4674

the wiki article - https://en.wikipedia.org/wiki/Sagittarius_A*

They are actually quite visible - their accretion disks (matter falling into the black hole) are very hot and radiate on a broad range of frequencies.

An accretion disk is not a black hole. Current physics have no other explanation for the disks, but it does not mean that the black holes are really there.

There is also some lack of precision on the LIGO experiment that does not invalidate all reasonable alternative explanations.

As people already said, the evident is overwhelming on the side of black holes existing. But we don't have any definitive measurement of them.

We have direct proof of:

* extremely large masses

* in very small volumes

* that are not, themselves, emitting anything

It could be many things, but they pretty much all fit the definition of "black hole".

I think this is as definitive a proof we'll get until we get close enough to directly measure Hawking radiation. Of course, by that time we should also be close enough to "see" the black hole directly...

No, they definitely exists, for example:

https://en.wikipedia.org/wiki/Cygnus_X-1

It's a bit a matter of definition or interpretation but I would count the LIGO observations as direct observations of black holes. But as others pointed out there's lots of evidence for their existence.

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