Physics energy are no longer valid. The two chief theories of modern physics present a different picture of the concepts of space, time, and matter from that presented by classical physics. Classical mechanics approximates nature as continuous, while quantum theory is concerned with the discrete nature of many phenomena at the atomic and subatomic level and with the complementary aspects of particles and waves in the description of such phenomena. The theory of relativity is concerned with the description of phenomena that take place in a frame of reference that is in motion with respect to an observer; the special theory
Ionizing radiation cancer, and death. Ionizing radiation is categorized by the nature of the particles or electromagnetic waves that create the ionizing effect. These have different ionization mechanisms, and may be grouped as directly or indirectly ionizing. Any charged massive particle can ionize atoms directly by fundamental interaction through the Coulomb force if it carries sufficient kinetic energy. This includes atomic nuclei, electrons, muons, charged pions, protons, and energetic charged nuclei stripped of their electrons. When moving at relativistic speeds these particles have enough kinetic energy to be ionizing, but relativistic speeds are not required. For example, a typical alpha particle is