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Could the Universe Be Fundamentally Discrete? - Leejohnston - 01-08-2026
Could the Universe Be Fundamentally Discrete?
We usually think of space and time as smooth and continuous.
You can always zoom in further.
You can always divide distances again.
But some theories suggest this intuition may be wrong.
What if the universe is fundamentally discrete?
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What “discrete” would mean
A discrete universe would have:
• a smallest unit of space
• a smallest unit of time
• no meaning to distances smaller than these limits
Beyond a certain scale, “in-between” would simply not exist.
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Hints from quantum physics
Quantum mechanics already introduces discreteness:
• energy levels in atoms are quantized
• angular momentum comes in fixed units
• photons carry energy in packets
This raises a natural question:
If energy is discrete, why not spacetime itself?
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Planck scales
From known constants, physics defines natural limits:
• Planck length ≈ 1.6 × 10⁻³⁵ m
• Planck time ≈ 5.4 × 10⁻⁴⁴ s
Below these scales:
• quantum gravity effects dominate
• classical spacetime descriptions break down
These are not proven “pixels” — but they mark where current theories fail.
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Discrete spacetime models
Some speculative approaches propose:
• spacetime made of tiny discrete elements
• geometry emerging from networks or graphs
• time advancing in fundamental steps
Examples include:
• loop-based approaches
• causal-set models
• lattice formulations
None are experimentally confirmed.
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What discreteness would change
If spacetime is discrete:
• infinities might disappear from physics
• gravity could become quantizable
• the universe would have a natural resolution limit
But it would also challenge:
• Lorentz invariance
• smooth geometry
• classical notions of motion
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Why this is hard to test
Planck-scale effects are extraordinarily small.
Even the most powerful experiments:
• cannot probe distances remotely close
• cannot access Planck energies
Any signal would be indirect and subtle.
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Continuous vs discrete may be a false choice
It is possible that:
• spacetime is discrete at small scales
• but appears continuous at large scales
Much like matter:
• made of atoms
• but experienced as smooth
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Open question
Is spacetime fundamentally continuous, discrete, or something else entirely?
The answer may require a theory that has not yet been discovered.