CeleryKills

I still remember the moment it landed. Intro astrophysics, back row, me already halfway convinced I had chosen the wrong major. Too much spacetime curvature, not enough molecules behaving predictably. The professor was walking us through gravitational collapse, the usual path to a black hole, when Grace, who had the irritating habit of asking the exact question everyone else missed, raised her hand.

“What if you don’t use mass?”

The room stalled. The answer came slowly. You don’t need mass in the usual sense. You need energy. Pack enough energy into a small enough region and spacetime does the same thing. Collapse.

That was my introduction to a a .

The word translates roughly as “ball lightning,” which is misleading in the way physics terms often are. It isn’t lightning. It isn’t really a ball. It’s a black hole formed purely from energy, no star, no collapsing core, just energy density crossing a threshold where gravity wins and geometry folds inward (Misner et al., Gravitation, 1973).

And that was the moment I realized I should probably stick with chemistry and biology. At least molecules wait for you to finish the thought.

Energy Instead of Matter

In general relativity, mass and energy are interchangeable in the only way that matters. Einstein’s equivalence is not philosophical. It’s literal (Einstein, Relativity, 1916). If you put enough energy in a small enough space, spacetime curves as though you had placed a mass there. Push it far enough and you don’t just curve spacetime. You trap it.

That is the kugelblitz. A region where pure energy density creates an event horizon. No atoms required. No protons, no neutrons. Just energy refusing to stay distributed.

The numbers get uncomfortable quickly.

To make a black hole the mass of Mount Everest, you’d need on the order of joules of energy compressed into a region smaller than an atomic nucleus. That’s not a lab problem. That’s not even a planetary problem. That’s engineering on a scale that sounds like a joke until you realize the equations don’t care (Hawking, A Brief History of Time, 1988).

Micro Kugelblitz, or How to Build Trouble in a Small Space

People inevitably ask about micro versions. Could you make a tiny kugelblitz?

In principle, yes. In practice, you have two problems.

First, the energy density requirement scales brutally. Smaller black hole, higher density. The smaller you go, the more ridiculous the compression becomes.

Second, Hawking radiation ruins your day. A small black hole radiates energy rapidly, shrinks, and evaporates almost instantly (Hawking, Particle Creation by Black Holes, 1975). A micro kugelblitz would flicker into existence and then disappear before you finished naming it.

So yes, possible. Also fleeting. Like quantum foam deciding to get dramatic for a moment.

Is It Really a Black Hole?

This is where it gets strange in a more philosophical way.

A black hole formed from collapsing matter has history. A star forms, evolves, collapses. There’s narrative there.

A kugelblitz has no such backstory. It is geometry first, everything else after. Spacetime responding to energy density, not to matter’s story.

Functionally, they are the same. Event horizon. curvature. evaporation. The equations don’t distinguish between matter‑origin and energy‑origin black holes.

But conceptually, they feel different.

One is the end of something.
The other is the direct expression of a rule.

Probability, or Why You Haven’t Seen One

Now the uncomfortable question.

If kugelblitz are allowed, why don’t we see them?

Because probability is not kind.

You need enormous energy concentrated into a vanishingly small volume. Natural processes tend to disperse energy, not compress it. Even extreme astrophysical events, gamma ray bursts, supernovae, tend to spread energy out across space.

Could it happen? Yes.
Is it likely? No.

This is a recurring theme in physics. The laws allow more than the universe tends to produce.

Entropy Doesn’t Care About Your Construction Project

At first glance, a kugelblitz looks like a violation of entropy. You are taking distributed energy and forcing it into a highly ordered state.

But it isn’t.

The second law applies globally, not locally. You can decrease entropy in one region if the total entropy increases elsewhere. Any process capable of creating a kugelblitz would generate vast entropy in the environment in the process (Penrose, Road to Reality, 2004).

Which leads to a stranger thought.

A kugelblitz might resemble, in a very abstract way, something closer to the early universe than to an ordinary black hole. Not because it is simple, but because it represents an extreme concentration of energy before structure has time to differentiate.

That comparison isn’t clean, but it lingers.

Science Fiction Was Already There

Once you see it, you start noticing approximations everywhere.

Arthur C. Clarke danced around similar ideas in The Physics of Immortality adjacency, not explicitly kugelblitz, but energy manipulation at cosmological scales. In Interstellar, the black hole Gargantua is matter-formed, but the idea of engineered spacetime shows up in the background (Nolan, Interstellar, 2014).

More directly, concepts like artificial black holes in sci‑fi revolve around the same core idea. Compress energy or mass into absurd densities and let gravity do the rest. It’s kugelblitz thinking, even when the name isn’t used.

What fiction tends to skip is the fragility. The fact that small ones vanish almost instantly. Stable versions require scale, and scale demands energy budgets that make “civilization” feel like a small word.

Where This Leaves Us

The kugelblitz sits in that category I’ve grown oddly fond of. Concepts that are physically allowed, mathematically clean, and almost completely inaccessible.

It behaves like a black hole. It is a black hole. But it also strips the process down to something more fundamental. Not collapse of matter. Just the consequence of enough energy being in the wrong place.

I think about Grace’s question sometimes. Not because of the answer, but because of how simple it was.

What if you don’t use mass?

That’s the moment where the problem changes shape.

And also the moment where I decided I preferred systems where the answers come back a little slower.

References

• Einstein, Albert. Relativity: The Special and General Theory. 1916.
• Hawking, Stephen. “Particle Creation by Black Holes.” 1975.
• Hawking, Stephen. A Brief History of Time. 1988.
• Misner, Charles W., Thorne, Kip S., Wheeler, John A. Gravitation. 1973.
• Penrose, Roger. The Road to Reality. 2004.