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The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).
Jul 16, 2024 · Learn about the speed of light, a fundamental constant of nature that limits the speed of signals and material particles. Find out its value in a vacuum and how it relates to mass and energy.
- The Editors of Encyclopaedia Britannica
Sep 29, 2020 · Learn about the speed of light in different units, how it compares to sound, space, and wormholes, and what happens if you travel faster than light. Find out if there is anything faster than light, such as dark matter, black holes, or space expansion.
May 17, 2023 · The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) per second. That's about 186,282 miles per second — a universal constant known in...
Jan 23, 2024 · Learn how the speed of light was first measured, why it is a constant and what it means for relativity. The speed of light is 299,792,458 meters per second, but it slows down in media.
Apr 11, 2021 · The speed of light is a constant value of exactly 299,792,458 meters per second. Learn how it is measured, how it changed over time, and why nothing can go faster than it.
The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour ).
