Definition:Speed of Light
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Physical Law
The speed of light (in a vacuum) is a physical constant.
Information cannot travel faster.
It is usually denoted $c$, and its value is given as:
- $c = 299 \, 792 \, 458 \text { m s}^{-1}$
exactly.
The metre is in fact defined in terms of the speed of light and the definition of the second.
As the speed of light is at base a velocity, it has dimension $\mathsf {L T}^{-1}$.
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $2^{86243} - 1$
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): speed of light
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): constant (in physical laws)
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): speed of light