The speed of light is fast, really fast. How can you measure something that travels at almost 300,000 km/s (186,000 miles/second)? Galileo, a pretty smart guy, first tried in 1638 and concluded that light traveled “fast” (I told you he was smart). It wasn’t until almost 40 years later that someone found a reasonable value for the speed of light. This article is a history of the measurement of the speed of light.
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