But in the visible universe, we see mostly matter, and no one has been able to account for the "missing" antimatter.
This imbalance is what allows us to exist—had there been precisely equal amounts of matter and antimatter in the early universe, they would have quickly destroyed each other.
Physicists therefore think there must have been some tiny breaking of symmetry that made matter win out over antimatter.
This symmetry breaking is all around us in nature, noted Close of Oxford.
"If you freeze water, you get the beautiful six-fold symmetry of a snowflake," he said (see snowflake photos).
But liquid water is symmetric in all directions, and its molecules have to rearrange to form snowflakes.
"So when you freeze water, that symmetry [in all directions] disappears," Close said.
Kobayashi and Maskawa's work was also recognized by the Nobel committee for predicting at least three families of quarks—particles that combine to form protons and neutrons, which make up the nuclei of atoms.
Particle colliders, which smash atoms together at high speeds to break them into their components, were able to create these short-lived quarks in the 1970s and 1990s.
The theorists' work later motivated the construction of two huge particle colliders in Japan and California that have since confirmed the researchers' precise predictions of how often exotic particles known as B-mesons would show symmetry breaking.
Oxford's Close noted that Nambu's work directly relates to understanding the Higgs boson, a theoretical particle that might give all other particles their mass.
Researchers hope the Higgs boson will appear for the first time in experiments soon to start at the recently launched Large Hadron Collider near Geneva, Switzerland.
Last year's physics Nobel went to two European researchers, who had discovered the electromagnetic phenomenon that made possible the massive hard drives used in modern computers, cell phones, and music players.
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