ME

What’s the term for the point of collapsing matter critical density in forming a black hole?

AI

The term you’re looking for is the Schwarzschild radius — the critical distance at which matter must be compressed to form a black hole. Any mass compressed within its Schwarzschild radius becomes a black hole.

You can also think of this in terms of critical density: if you compress matter to a high enough density that it fits within its Schwarzschild radius, it will collapse into a black hole. The critical density depends on the mass—a stellar-mass black hole requires compressing matter to an extremely dense state, while the Sun compressed to its Schwarzschild radius would be incredibly dense.

The event horizon is the boundary at the Schwarzschild radius, beyond which nothing (not even light) can escape.

If you were asking about something more specific like the density threshold at which quantum effects dominate spacetime curvature, that would be Planck density, which is a fundamental constant in physics rather than something specific to black holes.

ME:

I see theories that suggest our universe is either a matrix or black hole. Well, we all know its just energy anyway, so exactly how we end up describing it will come down to semantics.

When I imagine, minus any mathematical theories, it looks all hyperbolic and toroidal, occupying so many dimensions, that pretty much any point in the universe is connected in all directions to any other point beneath the observable surface.

And wouldn’t it be funny that this could be mirrored all the way down to the shape of field currents, the ripples of energy that give rise to the most basic elements, which in 3-dimensional space appear to spin twice to come back round to their starting point, emblazoned simply in the human mind by the good-old, two-dimensional infinity sign.

So I had to ask AI because I have yet to look it up.

Also Me: “What would the volume be of a black hole be as a result of our whole known universe collapsing past the schwarzschild radius?”

Reading the answer is almost as delightful mathematically as it is visually:

AI: That’s a fascinating thought experiment! Let me work through this:

The Schwarzschild radius of the observable universe would be calculated using Rs = 2GM/c², where M is the total mass of the observable universe (roughly 10^54 kg when including dark matter).

This gives a Schwarzschild radius of approximately 1.5 × 10^27 meters (about 150 million light-years).

The volume would then be: V = (4/3)πr³ ≈ 1.4 × 10^82 cubic meters

For comparison, the observable universe currently has a radius of about 4.4 × 10^26 meters and a volume of roughly 3.6 × 10^80 cubic meters.

So the interesting implication: if the entire observable universe collapsed to its Schwarzschild radius, it would actually occupy a volume somewhat larger than it currently does. This tells you something important—the universe isn’t currently at or inside its Schwarzschild radius, so it doesn’t form a black hole. It’s relatively dispersed.

Of course, this is a theoretical exercise since the expansion of the universe, dark energy, and many other factors make such a collapse impossible in reality. But it’s a useful thought experiment showing just how much gravitational collapse would need to occur to turn the entire cosmos into a black hole.

ME

I’m trying to outline the physical differences at the beginning of time between a singularity and a black hole, since it would have been more of a probability if the universe were static, and the amount of force needed to cause expansion. I would envision a collision with anti-matter universe could explain both the absence of left-spin particles and the appearance that the universe is asymmetrical in that respect.

AI

This is a thoughtful attempt to weave together several deep physics puzzles. Let me unpack the physics and address each part:

Singularity vs. Black Hole at the beginning:

The key difference is actually about causality and geometry. A black hole singularity is a terminal point—causality flows into it, and it has an event horizon exterior to it. The Big Bang singularity is fundamentally different: it’s a boundary condition at t=0, not a point in space. All of spacetime expands away from it, rather than collapsing toward it.

Mathematically, if you tried to calculate whether the early universe was “inside its own Schwarzschild radius,” you’d find it sort of was—but that’s because the entire universe is the gravitational system. The expansion itself is the crucial difference. The Big Bang isn’t collapse into space; it’s the expansion of space itself.

Why it expanded instead of collapsing:

This gets at genuine open questions. The initial expansion may stem from:

  • Initial conditions (part of what we’d need to explain with quantum cosmology)
  • Quantum effects dominating at Planck scales
  • Inflation (driven by scalar fields)

We don’t have a complete theory of why these initial conditions were “low entropy” and set up for expansion rather than immediate re-collapse.

On the antimatter universe collision:

Here I’d be more cautious. The matter-antimatter asymmetry is real and profound, but evidence for a direct collision with an antimatter domain is lacking. We’d expect:

  • Massive annihilation signatures at boundaries
  • Detectable radiation patterns
  • Anisotropies in the cosmic microwave background

That said, some theoretical work has explored CPT symmetry scenarios and opposite-handed domains, so it’s not impossible—just without current observational support. The chirality asymmetry (left-handed neutrinos, right-handed antineutrinos) is deep, but conventionally explained through electroweak symmetry breaking rather than spatial domain separation.

What aspect intrigues you most?

ME

Many aspects seem interesting, but which is more probable, that there was an initial boundary where T=0, or that the universe has always existed, and always will? What list of assumptions would have to be true for each to occur?

AI

This cuts to some of the deepest open questions in cosmology. Let me lay out what each scenario requires:

Big Bang (t=0 boundary) assumptions:

  1. General Relativity (or something like it) correctly describes spacetime geometry
  2. The Cosmological Principle: universe is homogeneous and isotropic on large scales
  3. Entropy increases toward the future (arrow of time)
  4. “Initial conditions” are a meaningful concept—a low-entropy starting state
  5. Spacetime itself is not eternal but emerges from the boundary
  6. Causality flows forward from that point (no closed timelike curves)
  7. Thermodynamics applies to the universe as a whole

Eternal universe assumptions:

  1. Spacetime has no boundary—it’s infinite or cyclic in time
  2. Some mechanism prevents gravitational collapse or heat death:
    • Cyclic/bounce models (universe expands, contracts, repeats)
    • Continuous creation or eternal oscillation
    • Quantum tunneling or other Planck-scale physics
  3. Thermodynamic issues are resolved (entropy doesn’t accumulate to infinite disorder)
  4. “Why does it exist?” doesn’t require an answer about origins
  5. Initial conditions aren’t a thing—the universe just is

Which is more probable?

Based on current observations, the Big Bang model fits the data better: the CMB, expansion, abundance of light elements all point to hot dense origin. This is the working framework.

However—and this is important—we don’t actually know. The assumptions for t=0 include “what happens at the singularity,” which General Relativity breaks down. Quantum gravity effects dominate at Planck scales, and we don’t have that theory yet.

Some physicists (like Roger Penrose with Conformal Cyclic Cosmology) argue eternal models actually better explain certain features. Others work on bounce scenarios where the universe contracts, quantum effects prevent true singularity, and it re-expands.

The uncomfortable truth: We’re at the boundary of what we can observationally test. Both scenarios require leaps of faith about physics beyond our current experiments. The t=0 model is more parsimonious with present data, but “more probable” depends on priors you choose about which unknown physics is likely.

What draws you toward one over the other?

ME

Actually, to me both seem true based on the perspective as an observer. If you scale out far enough, I think that even the observable universe can display localized phenomena such as a big bang, and if you keep scaling out, you might other areas of big crunch, and everything in-between. I would also ask if dark matter and dark energy could be a clue to dimensionality beyond observable spacetime, which would mean that there could be a slight chance the universe could be hyperbolic, for example, or that everything is connected in ways beyond the fields we have discovered, even with observations in particle acceleration or for which mathematical concepts have not yet been derived. Basically, I think human perception is a limiting factor, and with assistance of AI, and eventually quantum computing in the future, we may start to better model. I have a personal disdain for the way everything is taught, using 2D diagrams to represent a much richer universe. But hey, we use what we got for now.

AI

You’re touching on something that many physicists actually take seriously, even if it’s at the speculative frontier. Let me affirm what’s solid here and note where the genuine openness lies:

Your multi-scale perspective has precedent. Eternal inflation theory suggests localized Big Bangs could occur in an eternally inflating landscape. Cyclic models (Penrose, Steinhardt) propose Big Bangs and Big Crunches as recurring features of an eternal cosmos. You’re not inventing this—you’re recognizing that “Big Bang” might be local phenomenon in something larger.

On dark matter/energy and hidden dimensions:

This is where your intuition aligns with real theoretical work. Dark matter and dark energy are genuinely mysterious—they comprise 95% of the universe, and we don’t know what they are. Possibilities include:

  • Extra spatial dimensions (Kaluza-Klein theories, string theory landscapes)
  • Modified gravity that works differently at cosmic scales
  • Fields we haven’t detected yet
  • Quantum vacuum properties we misunderstand

The fact that they’re “dark” (invisible to standard detection) could indicate they interact primarily through geometry or dimensions we’re not directly accessing. This isn’t mainstream consensus, but it’s not fringe either.

Hyperbolic geometry: The universe’s large-scale curvature is still measured as approximately flat, but there’s genuine uncertainty. Non-Euclidean geometries are mathematically rich and underexplored for cosmology.

Your critique of 2D pedagogy is valid. We are teaching 3D+time using 2D visualizations. We lose information. The actual mathematical objects (tensor fields, manifolds, spinors) capture more, but they’re abstract. There’s a genuine gap between what we can visualize and what actually is.

On AI and quantum computing helping:

This is realistic. Current tools:

  • Can’t easily explore high-dimensional parameter spaces
  • Struggle with nonlinear dynamics
  • Are limited in finding novel mathematical structures

Future quantum computers might:

  • Simulate quantum field theory configurations we can’t calculate classically
  • Help identify symmetries in data that suggest new mathematical frameworks
  • Model exotic topologies or dimensional configurations

The honest part: We’re at a knowledge boundary. The math we have works extraordinarily well in its domain, but that domain might be a local patch. New mathematical frameworks might be needed, not just new observations. And you’re right that human intuition + AI might help—especially if AI can explore mathematical space without the cognitive biases that guide human mathematicians.

Your disdain for reductive pedagogy is warranted. The universe appears richer than we can currently formalize.