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Measuring the Speed of Light Throughout History

Not only am I a lover of science, but I’m also very interested in the history of science and so I wanted to do an occasional series on some of our most important scientific breakthroughs and discoveries. For the first in this series I want to look at the speed of light, how we first measured it, and how we measure it today. Let's find out more. Before we start let us look at what the speed of light actually is. It is 299 million, 792 thousand 458 metres per second. That is 186 thousand 282 point 4 miles per second. That value has now been set and won’t change, it was actually set in 1983. The speed of light isn’t just the speed of light though, it’s the speed of causality. It is the universes ultimate speed limit. Objects and particles with mass are slowed down by that mass and so must travel slower than the speed of light. Massless things such as electromagnetic waves of which visible light is just one type are not slowed down by any mass and so are able to travel at this ultimate speed. Chapters 0:00 Introduction 2:00 Ancient Times 3:07 Beeckman and Galileo 4:45 Ole Roemer 6:52 James Bradley 8:15 Hippolyte Fizeau 9:50 Leon Foucault 10:50 Weber & Kohlrausch 11:50 James Clerk Maxwell 12:50 Albert Michelson 14:50 Cavity Resonance 16:15 Home Experiment 17:00 Interferometry Ole Roemer Image Jacob Coning, Public domain, via Wikimedia Commons Hasan Ibn al Haytham image artwork drawn by Adolph Boÿ, engraved by Jeremias Falck, Public domain, via Wikimedia Commons Christiaan Huygens Image Caspar Netscher, Public domain, via Wikimedia Commons Albert Michelson Image The original uploader was Bunzil at English Wikipedia., Public domain, via Wikimedia Commons