[vorticalbox]

I was always under the impression there was only 1 black-hole in our galaxy, at it's centre.

[tomrod]

There are many, many more, probably ranging in size to tinier than a period (.) to the 33 Sol mass (so far).

The one at the center of the galaxy is along for the ride! A good video: https://www.youtube.com/watch?v=e-P5IFTqB98

[The_Colonel]

> probably ranging in size to tinier than a period (.)

"Probably" is a strong word, these are very hypothetical, the lightest observed black hole has a mass of 3 Suns.

[robin_reala]

A three solar mass black hole is still only ~13km across. Not full-stop-sized, but closer to that than the diameter of the sun.

[volkadav]

I'm guessing the 13km diameter refers to the event horizon rather than the singularity itself, which I gather could be considered as zero-sized, or maybe one Planck length in size because we can't definitively measure anything smaller, or ...

Admittedly, it gets a bit philosophical. The sphere of no return isn't the thing, but it might as well be for any outside observer, but it isn't, but it could be viewed as such, but... :) Suffice to say I'm glad the closest thing to black holes I have to contend with in my daily life is a 2+ million line php codebase dating from the late Clinton administration.

[floxy]

"Do Black Holes have Singularities?" by Roy Kerr (Yes, that Roy Kerr)

https://arxiv.org/abs/2312.00841

https://www.pbs.org/video/what-if-singularities-do-not-exist...

[papichulo2023]

There is even a theory about a mini black hole in our solar system pulling Uranus.

[xpe]

See e.g.

"What If Planet 9 Is a Primordial Black Hole?" by Jakub Scholtz and James Unwin [1]

[1] Phys. Rev. Lett. 125, 051103 – Published 29 July 2020 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...

[Sharlin]

Well, your impression was wrong then.

[vorticalbox]

very wrong and I am a little sad I am getting down voted for not knowing something but here we are.