History
| 1675 | Rømer and Huygens, moons of Jupiter | 220,000 |
| 1729 | James Bradley, aberration of light | 301,000 |
| 1849 | Hippolyte Fizeau, toothed wheel | 315,000 |
| 1862 | Léon Foucault, rotating mirror | 298,000±500 |
| 1907 | Rosa and Dorsey, EM constants | 299,710±30 |
| 1926 | Albert Michelson, rotating mirror | 299,796±4 |
| 1950 | Essen and Gordon-Smith, cavity resonator | 299,792.5±3.0 |
| 1958 | K.D. Froome, radio interferometry | 299,792.50±0.10 |
| 1972 | Evenson et al., laser interferometry | 299,792.4562±0.0011 |
| 1983 | 17th CGPM, definition of the metre | 299,792.458 (exact) |
Until the early modern period, it was not known whether light travelled instantaneously or at a very fast finite speed. The first extant recorded examination of this subject was in ancient Greece. The ancient Greeks, Muslim scholars and classical European scientists long debated this until Rømer provided the first calculation of the speed of light. Einstein's Theory of Special Relativity concluded that the speed of light is constant regardless of one's frame of reference. Since then, scientists have provided increasingly accurate measurements.
Read more about this topic: Speed Of Light
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