speed of light

plural speeds of light · abbreviation c

1. natural sciencesThe speed of electromagnetic radiation, which in a perfect vacuum is equivalent to 299,792,458 metres per second.

   Early physicists developed insightful methods for measuring the speed of light.

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   As the subjective speed of light is raised within the field, objects outside will appear to red-shift, eventually becoming visible only to radio telescope antennae.

   2008, BioWare, Mass Effect, Redwood City: Electronic Arts, →ISBN, →OCLC, PC, scene: FTL Drive: Appearance Codex entry

   The science world was left in shock when workers at the world's largest physics lab announced they had recorded subatomic particles travelling faster than the speed of light – a feat that Einstein said was impossible.

   2011 September 22, Nick Collins, “Speed of light 'broken' by scientists”, in Daily Telegraph

   Synonyms: lightspeed, light speed, Einstein's constant, Einstein barrier

2. colloquialfigurativelyA very rapid speed.

   When her cat figured out that a trip to the vet was in the offing, he took off towards the closet at the speed of light.

3. cellular automataA rate of travel of a signal equal to one cell per generation, the fastest possible speed in the Moore and von Neumann neighborhoods.

   In a single generation, a cell can only influence its nearest neighbours, and so the speed of light (by analogy with the speed of light in physics) is the maximum rate at which information can propagate.

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   The translated distance divided by the period is the speed of the spaceship. Since the maximum speed of propagation of a signal in Life is one cell per generation, this speed is known as c (the speed of light). This speed is also the fastest possible growth of any finite object for a finite number of generations (think of a long line of ON cells). However, growth (or even just movement) of a finite object for an infinite time cannot occur at this speed.

   1992 August 14, David I. Bell, “Spaceships in Conway's Life (Part 1)”, in comp.theory.cell-automata (Usenet)