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The Universe Shouldn't Exist: Here's Why #science #universe
3/10TL;DR
A tiny early-universe imbalance—about one extra matter particle per billion pairs—left enough matter to form all cosmic structures.
KEY POINTS
The matter–antimatter paradox
Fundamental physics predicts that matter and antimatter are created in equal amounts from energy. When they meet, they annihilate into radiation, implying the universe should have erased itself into pure energy shortly after its birth.
Observed imbalance
The visible universe is overwhelmingly composed of matter, with antimatter exceedingly rare. This asymmetry contradicts the expectation of perfect balance and remains one of cosmology’s central unsolved problems.
A one-in-a-billion surplus
Measurements of the cosmic microwave background indicate roughly a billion photons per matter particle today. Since annihilation of matter–antimatter pairs produces photons, this ratio implies that about one matter particle in a billion survived the early annihilation era.
Annihilation and survival
As the universe cooled, nearly all matter and antimatter pairs annihilated into radiation. The tiny excess of matter—just that one-in-a-billion fraction—remained and ultimately formed stars, galaxies, planets, and life.
Sakharov conditions
In 1967, physicist Andrei Sakharov proposed three requirements for generating this imbalance: processes that change the number of matter particles, slight differences in how matter and antimatter behave (CP violation), and conditions out of thermal equilibrium in the rapidly expanding early universe.
Frozen-in asymmetry
Rapid cosmic expansion and cooling prevented the slight bias from being erased. This “freeze-out” locked in the imbalance before reactions could restore symmetry, preserving the small matter surplus.
CONCLUSION
A minute asymmetry in the early universe—amplified by cosmic expansion—appears to explain why anything exists at all, though the precise mechanism behind this imbalance remains an open question in physics.