In astroparticle physics, an ultra-high-energy cosmic ray (UHECR) or extreme-energy cosmic ray (EECR) is a cosmic ray particle with an extreme kinetic energy, far beyond both its rest mass and energies typical of other cosmic ray particles.
These particles are significant for astrophysics and fundamental physics theory, because they have energies comparable to the Greisen–Zatsepin–Kuzmin limit, which occurs at about 5×1019 electron volts (8 J). This limit should be the maximum energy of cosmic ray particles that have traveled long distances (about 160 million light years), due to the theoretical energy losses of higher-energy ray particles and to scattering from photons in the cosmic microwave background.
Read more about Ultra-high-energy Cosmic Ray: Observational History, Active Galactic Cores As One Possible Source of The Particles, Other Possible Sources of The Particles, Pierre Auger Observatory, Ultra-high-energy Cosmic Ray Observatories
Famous quotes containing the words cosmic and/or ray:
“Unless they are immediate victims, the majority of mankind behaves as if war was an act of God which could not be prevented; or they behave as if war elsewhere was none of their business. It would be a bitter cosmic joke if we destroy ourselves due to atrophy of the imagination.”
—Martha Gellhorn (b. 1908)
“These facts have always suggested to man the sublime creed that the world is not the product of manifold power, but of one will, of one mind; and that one mind is everywhere active, in each ray of the star, in each wavelet of the pool; and whatever opposes that will is everywhere balked and baffled, because things are made so, and not otherwise.”
—Ralph Waldo Emerson (18031882)