Cosmic radiation was discovered by the Austrian physicist Victor Hess in 1912. We now know that it is made up of atomic particles, mainly protons but with a sprinkling of heavier nuclei and electrons. They range up to the most energetic particles known—rather more than 10~(20) electron-volts (eV). Today's largest particle accelerators achieve a mere 10~(12) eV or so-100 million times less energetic.
展开▼
