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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).
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...
Jun 18, 2024 · Learn about the speed of light, a fundamental constant of nature that limits the speed of signals and material particles. Find out how the speed of light varies in different media and how it relates to mass and energy.
- The Editors of Encyclopaedia Britannica
Jul 16, 2020 · We all know and love the speed of light — 299,792,458 meters per second — but why does it have the value that it does? Why isn't it some other number? And why do we care so much about some...
Jan 23, 2024 · Learn how the speed of light was first measured, why it is a constant and what it means for relativity. Explore the experiments, theories and discoveries that reveal the cosmic speed limit of the universe.
Apr 11, 2021 · Learn what the speed of light is, how it is measured, and why it is a constant. Find out how the speed of light affects space, time, and matter, and what are the challenges and possibilities of going faster than light.
May 30, 2023 · So, what is the speed of light? Light moves at an incredible 186,000 miles per second (300,000 kilometers per second), equivalent to almost 700 million mph (more than 1 billion km/h).
