Could a black hole just be a planet?

[JLemp]

TL;DR Summary

Just a thought that came to me after hearing any object or material, if compressed enough, could become a singularity.

So the theory is the center of a "black hole" is nothing more than a planetoid of incredibly dense material, and the black hole is just this planet's atmosphere for lack of a better description. Thoughts?

 

[Ibix]

No. There's nothing wrong with the concept of planetary mass black holes (one with the mass of the Earth would be about 1.5cm across). However, the point about a black hole is that there is no mechanism that can stop collapse once you overcome neutron degeneracy pressure, so you can't have a solid lump of matter in a black hole - it collapses because nothing is strong enough to stop it. Furthermore, the interior of a black hole is a complicated place - it doesn't have a center per se. The singularity (despite popular description) is not a point, but rather like a moment in time.

Note that all of the above is predicated on general relativity. At some point between here and the singularity we expect quantum gravitational effects to become apparent. Since we don't have a working theory of quantum gravity we can't say what those effects would be. Allowing planets in the core of black holes seems unlikely, though.

 

[PeroK]

Summary: Just a thought that came to me after hearing any object or material, if compressed enough, could become a singularity.

A singularity is not a physical thing. It's a deficiency in the mathematical model.

 

[Drakkith]

So the theory is the center of a "black hole" is nothing more than a planetoid of incredibly dense material, and the black hole is just this planet's atmosphere for lack of a better description. Thoughts?

Sorry to be harsh, but it makes absolutely no sense in regards to being a plausible possibility with our current understanding of science.

 

[malawi_glenn]

No

 

[Bandersnatch]

People did propose something along those lines, albeit in more rigorous terms - the Planck stars:
https://arxiv.org/abs/1401.6562
At this point firmly in the hypothesis bucket, though.

(this is more like an evolving stage in a star's life, rather than a permanent planet-like object)

 

[russ_watters]

However, the point about a black hole is that there is no mechanism that can stop collapse once you overcome neutron degeneracy pressure, so you can't have a solid lump of matter in a black hole - it collapses because nothing is strong enough to stop it.

Note to OP; "neutron degeneracy pressure" is what keeps a neutron star/pulsar from collapsing if it's not quite massive enough to collapse into a black hole. That would be the "last"/densest known object that isn't a black hole.