Final answer:
The universe contains significantly more matter than antimatter due to a small asymmetry in the basic forces of particle physics, which is evident from the lack of significant annihilation radiation.
Step-by-step explanation:
Today, the universe is known to contain significantly more matter than antimatter. Observational evidence, such as the absence of large-scale annihilation radiation, particularly of 0.511-MeV gamma rays from electron-positron annihilations, indicates that the universe is predominantly matter. Interactions in the early universe where matter and antimatter annihilated each other left behind a slight surplus of matter.
This matter-antimatter asymmetry was crucial for the formation of stars and galaxies, and by extension, the development of life on Earth. According to the Standard Model of particle physics and experimental observations, such as neutral kaon decays, there appears to be a fundamental but small asymmetry in the basic forces that led to slightly more matter being produced than antimatter.