Is there a point where the matter goes from trying to expand to being a black hole?

Imagine a box with two characteristics:

1. It is indestructible, it can't be deformed or torn apart.
2. It can shrink to any precise size regardless of the opposite forces.

Let's assume the box starts with a size of 10 m³ and contains gas molecules. As you shrink the box, molecules increasingly push against the walls of the box. At some point, the matter in the box is so compressed that it becomes a black hole.

I'm thinking that since the matter went from trying to expand to generating its own gravity toward a compact point, there must be a point where the matter was neither trying to expand nor was it a black hole, so it was in a neutral state.

Is this assumption wrong? If so, what does the matter go through before being a black hole? Is there even a point where an object goes from not being a black hole to being a black hole?

• 1) an un-deformable box violates special relativity. See: Born Rigidity.
– JEB
Commented Sep 13, 2021 at 20:29
• You have to put a lot of gas into your box. A black hole with the radius of a proton (0.85 fm) has a mass ~572 million tonnes. See vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator Commented Sep 13, 2021 at 20:30
• Can't any object become a black hole if compressed enough ? Commented Sep 13, 2021 at 20:37
• @SamuelFyckes "Can't any object become a black hole if compressed enough ?" - A black hole is a concept in General Relaticity, which is a classical theory inapplicable at subatomic sizes. Commented Sep 14, 2021 at 2:02
• @safesphere Fair point. Relativity doesn't "know" what matter is made of. OTOH, we don't know at what scale quantum gravity effects become significant, but it's probably within a few orders of magnitude of the Planck length, i.e., much smaller than a proton. Commented Sep 14, 2021 at 5:04