Editing Openai/6921ae73-3700-8000-8ab7-90012976bb8a (section)

=== Assistant: If you somehow compressed all the mass–energy of the observable universe into the size of a penny, you’d basically crea… ===
If you somehow compressed all the mass–energy of the observable universe into the size of a penny, you’d basically create:

: 

Let’s walk it through in human terms.

===== Rough ballpark: =====
* Mass of observable universe ≈ 10⁵³ kg (that’s 1 with 53 zeros).
* A penny’s radius ≈ 1 cm = 0.01 m.

That’s like trying to cram all galaxies, stars, planets, gas, dark matter… everything into something smaller than your fingernail.

===== For a mass MMM, the Schwarzschild radius is: =====

rs=2GMc2r_s = \frac{2GM}{c^2}rs=c22GM
For the mass of the observable universe, rsr_srs is way bigger than even the current size of the observable universe, not smaller.

That means:
* Even now, if you treat all that mass as a single object, its “black hole radius” would be larger than the universe itself.
* Compressing it to the size of a penny would mean the whole thing is deep, deep inside its own event horizon.

So yes:

: 

===== If you could keep compressing: =====
* Density goes to unimaginable levels (way beyond anything in neutron stars or normal black holes).
* General relativity predicts you’re headed toward a singularity: - A region where curvature of spacetime becomes infinite - Physics as we know it stops giving sensible answers

At that point:
* Space and time stop behaving like “space” and “time.”
* Talking about “what it looks like” from the outside doesn’t even make sense, because: - No light or info can escape. - There is no “outside” universe left—everything is the black hole.

===== If we imagine some hypothetical observer outside this setup (not really possible, but for the story): =====
* They’d see a gigantic black hole with a Schwarzschild radius larger than the observable universe.
* Nothing from inside (no light, no signals) ever gets out.
* To them, the collapse might appear to “freeze” at the event horizon due to time dilation—but locally everything continues inward.

===== Kind of: =====
* Big Bang (in some models): universe starts extremely dense and hot, then expands.
* This scenario: taking today’s universe and forcing it into an ultra-dense state → sort of a Big Crunch idea.

But we don’t really know what happens at such extremes:
* Quantum gravity (the real theory of spacetime at those scales) is still unknown.
* It might be a singularity, a bounce, new physics, extra dimensions, who knows.

===== If you compress the entire universe into the size of a penny: =====
* You’d create an insanely massive black hole far beyond anything imaginable.
* The density would be so extreme that spacetime itself breaks down.
* From any reasonable external viewpoint, the universe ends—there is only the black hole.

If you want to push this further, we can try:
* “What if only our galaxy were compressed to a penny?”
* or “What if a penny suddenly had the mass of the Earth?”