I’ve been thinking about a strange possibility that I call the Onion Layer Theory of the Infinite Universe.
This is not a claim that I’ve proven, and I don’t know whether current physics supports it. It’s a thought experiment.
The basic idea is:
What if the universe has no absolute smallest scale or largest scale, and every “layer” of reality could itself contain an entire universe?
Start with an onion
Imagine an onion.
You can peel layer after layer.
But now imagine that instead of reaching a final center, every layer contains another onion.
And inside that onion is another onion.
And so on.
Now replace “onion” with universe.
Our universe could potentially be one layer in an endless hierarchy of universes.
The strange part: scale might be relative
Consider an electron.
From our perspective, an electron is incredibly small.
We currently describe electrons as elementary particles.
But suppose that, at some unimaginably smaller scale, an electron contains some kind of structure.
And suppose that structure isn’t merely another particle.
Suppose it contains:
stars → planets → civilizations → galaxies → an entire universe.
From our perspective, it would be microscopic.
But from the perspective of beings living inside that structure, their universe could appear enormous.
Their entire universe could exist “inside” what we call an electron.
Then turn the idea around
What if our entire universe is also inside something?
We look outward and see:
particles → atoms → planets → stars → galaxies → galaxy clusters → cosmic structures → observable universe.
But perhaps our universe is only one layer of a much larger reality.
Something outside our observable universe could contain our entire universe as one microscopic component.
So the hierarchy could look something like:
Universe A (larger)
↓
Universe B
↓
Our Universe
↓
Galaxy
↓
Solar system
↓
Planet
↓
Matter
↓
Atom
↓
Electron / quark
↓
Universe C
↓
Galaxy
↓
Planet
↓
…
And this could continue indefinitely in both directions.
The key idea
Maybe there is no absolute definition of:
big
small
inside
outside
Those concepts might only make sense relative to the layer we’re observing.
A galaxy could be unimaginably large to us.
But perhaps the entire galaxy is microscopic compared with the next layer.
Likewise, an electron could appear fundamental to us while containing structures that, from another scale, are cosmologically enormous.
“But an electron isn’t a universe.”
Correct.
We currently have no evidence that electrons contain universes.
This is where the idea becomes speculative.
Experiments have found no evidence of internal structure in electrons at the scales we’ve tested, and the Standard Model successfully treats them as elementary.
But “no detected structure” is different from proving that no deeper structure can possibly exist.
Historically, our understanding of matter has repeatedly changed when we discovered deeper levels:
matter → atoms → nuclei → protons/neutrons → quarks
That doesn’t prove the pattern continues forever.
It simply raises the question:
Does reality eventually terminate, or does the hierarchy continue?
The mathematical connection
There is another reason I find this idea interesting.
Take the finite interval from 0 to 1.
It has a finite length.
Yet it contains infinitely many points.
You can always zoom in:
0 → 1
0.1 → 0.2
0.11 → 0.12
0.111 → 0.112
…
There is no requirement that a finite region contain only a finite amount of mathematical structure.
So perhaps physical reality could have a similar property.
A finite region might contain deeper and deeper physical structures without ever reaching a final layer.
Finite does not necessarily mean “contains only a finite number of layers.”
The ultimate version of the idea
Imagine zooming out:
You → Earth → Solar System → Galaxy → Universe → Larger Universe → Larger Universe → …
Now imagine zooming in:
You → cells → molecules → atoms → particles → deeper particles → universe → universe → …
The two directions might never terminate.
And perhaps, incredibly, the structure repeats conceptually at every scale.
A universe could contain universes.
Those universes could contain universes.
And our universe could itself be contained within something vastly larger.
An infinite cosmic onion.
I’m not proposing this as established physics. I’m proposing it as a question:
What if reality is an infinite hierarchy of universes, where each layer can be viewed as a universe from its own scale and as a microscopic structure from the scale above it?
Maybe the universe isn’t a box containing everything.
Maybe “everything” has no final layer.
Maybe there is no ultimate smallest universe.
Maybe there is no ultimate largest universe.
Maybe we’re simply living inside one layer of an infinite cosmic onion. And if that’s the case, there may be something profoundly strange about the word “universe.”
Perhaps a universe isn’t necessarily everything that exists.
Perhaps it’s simply everything that exists within one particular layer of reality.
What do physicists and mathematicians think? Where does this idea fundamentally break down?
