when?
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who discovered that light travels faster than sound Abū Rayhān al-Bīrūnī define the 'speed of light' UNANSWERABLE the person who made the discovery, what is his profession? UNANSWERABLE what role does the speed of light play in physics? Invariance of the speed of light: In 1905 Einstein postulated that the speed at which light waves propagate in vacuum is independent both of the motion of the wave source and of the inertial frame of reference of the observer. what is its numerical value? UNANSWERABLE which unit is used to measure it? Since 1983, the metre has been defined in the International System of Units (SI) as the distance light travels in vacuum in of a second. who made the first attempt to measure it? Empedocles
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Speed of light [SEP] Early history
Empedocles (c. 490–430 BC) was the first to propose a theory of light and claimed that light has a finite speed. He maintained that light was something in motion, and therefore must take some time to travel. Aristotle argued, to the contrary, that "light is due to the presence of something, but it is not a movement". Euclid and Ptolemy advanced Empedocles' emission theory of vision, where light is emitted from the eye, thus enabling sight. Based on that theory, Heron of Alexandria argued that the speed of light must be infinite because distant objects such as stars appear immediately upon opening the eyes.