Definition that contains speed of light
- c the speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second
- inflation (cosmology) a brief exponential expansion of the universe (faster than the speed of light) postulated to have occurred shortly after the big bang
- foucault French physicist who determined the speed of light and showed that it travels slower in water than in air; invented the Foucault pendulum and the gyroscope (1819-1868)
- light speed the speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second
- gravitation wave (physics) a wave that is hypothesized to propagate gravity and to travel at the speed of light
- light time distance measured in terms of the speed of light (or radio waves)
- special relativity theory a physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems
- einstein's special theory of relativity a physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems
- gravity wave (physics) a wave that is hypothesized to propagate gravity and to travel at the speed of light
- rest energy the energy equivalent to the mass of a particle at rest in an inertial frame of reference; equal to the rest mass times the square of the speed of light