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Dark side of the universe PDF Print E-mail
Written by Daniel Marin   
Friday, 04 July 2008

Until the early 1950s, cosmic rays and spontaneous radioactive decays were our main source of information on the nature of matter in the Universe. Then, particle accelerators made tremendous progress, providing high-energy particle beams to investigate the structure of matter. Today, new techniques allow scientists to study cosmic rays at energies far beyond the limits of accelerators. Astroparticle physics is trying to answer the most exciting questions about the Universe. For instance, we know today that only 4% of the Universe is composed of ordinary matter. Dark matter and a hypothetical repulsive force, dubbed “dark energy”, constitute the rest of the matter and energy content of the Universe. Another enigma is the absence of symmetry between matter and antimatter in the observed Universe.

Iceberg
© ASPERA

Matter as we know it is only the tip of the iceberg and only 4% of the matter in the Universe is ordinary matter. Astroparticle physics seeks to understand the nature of the unknown matter. For instance dark matter should make up 23% of the existing matter and be composed of hypothetical particles known as weakly interacting massive particles (WIMPs) and axions.




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