* Ancient Greeks: Philosophers like Empedocles and Aristotle theorized that light traveled at a finite speed. However, their ideas were based on speculation, not scientific measurement.
* 17th Century: Galileo Galilei attempted the first scientific measurement of the speed of light. His experiment involved two lanterns on distant hills, but the distance was too short to detect a difference.
* 1676: Ole Rømer, a Danish astronomer, observed that the time it took for the moons of Jupiter to eclipse varied depending on the Earth's position in its orbit. He deduced that light must take a finite time to travel, and calculated an approximate speed.
* 1849: Hippolyte Fizeau used a rotating toothed wheel to measure the speed of light with greater accuracy.
* 1862: Léon Foucault used a rotating mirror to obtain an even more accurate measurement.
* 20th Century: The speed of light in a vacuum became a fundamental constant in physics, used in Einstein's theory of relativity.
Therefore, the "discovery" of the speed of light is a long, ongoing process of scientific exploration and refinement. We continue to measure it with increasing accuracy to this day.
