matter-antimatter asymmetry

cosmology

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July 16, 2026

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The universe appears to be composed almost entirely of matter, with very little antimatter. This imbalance is known as matter-antimatter asymmetry and is a significant puzzle in cosmology and particle physics.12

Antimatter consists of antiparticles, which have the same mass as their matter counterparts but opposite electric charges and magnetic moments. For example, the antiparticle of an electron is a positron, which has a positive charge. When matter and antimatter meet, they annihilate each other, releasing a large amount of energy.13

According to conservation laws, the Big Bang should have created equal amounts of matter and antimatter. However, the observed universe is dominated by matter, suggesting that most of the antimatter was annihilated. The process by which this asymmetry arose is called baryogenesis. Theories suggest that phenomena like CP violation in the early universe may explain this imbalance.1342

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cosmology
Matter-antimatter asymmetry
A curious number that appeared in the above discussion was the few parts in 10⁹ asymmetry initially between matter and antimatter (or equivalently, the ratio 10⁻⁹ of protons to photons in the present universe). What is the origin of such a number—so close…
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A curious number that appeared in the above discussion was the few parts in 10⁹ asymmetry initially between matter and antimatter (or equivalently, the ratio 10⁻⁹ of protons to photons in the present universe). What is the origin of such a number—so close…
Read More

antimatter
…universe is referred to as matter-antimatter asymmetry, and its cause remains a major unsolved puzzle for cosmology and particle physics. One possible explanation is that it involves a phenomenon known as CP violation, which gives rise to a small but significant difference in the behavior of particles called K-mesons and…
Read More
…universe is referred to as matter-antimatter asymmetry, and its cause remains a major unsolved puzzle for cosmology and particle physics. One possible explanation is that it involves a phenomenon known as CP violation, which gives rise to a small but significant difference in the behavior of particles called K-mesons and…
Read More

CP violation
…that the observed imbalance or asymmetry in the matter-antimatter ratio may have been produced by the occurrence of CP violation in the first seconds after the big bang—the violent explosion that is thought to have resulted in the formation of the universe.
Read More
…that the observed imbalance or asymmetry in the matter-antimatter ratio may have been produced by the occurrence of CP violation in the first seconds after the big bang—the violent explosion that is thought to have resulted in the formation of the universe.
Read More