<P> 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 . Early Islamic philosophers initially agreed with the Aristotelian view that light had no speed of travel . In 1021 , Alhazen ( Ibn al - Haytham ) published the Book of Optics , in which he presented a series of arguments dismissing the emission theory of vision in favour of the now accepted intromission theory , in which light moves from an object into the eye . This led Alhazen to propose that light must have a finite speed , and that the speed of light is variable , decreasing in denser bodies . He argued that light is substantial matter , the propagation of which requires time , even if this is hidden from our senses . Also in the 11th century , Abū Rayhān al - Bīrūnī agreed that light has a finite speed , and observed that the speed of light is much faster than the speed of sound . </P>
<P> 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 . Early Islamic philosophers initially agreed with the Aristotelian view that light had no speed of travel . In 1021 , Alhazen ( Ibn al - Haytham ) published the Book of Optics , in which he presented a series of arguments dismissing the emission theory of vision in favour of the now accepted intromission theory , in which light moves from an object into the eye . This led Alhazen to propose that light must have a finite speed , and that the speed of light is variable , decreasing in denser bodies . He argued that light is substantial matter , the propagation of which requires time , even if this is hidden from our senses . Also in the 11th century , Abū Rayhān al - Bīrūnī agreed that light has a finite speed , and observed that the speed of light is much faster than the speed of sound . </P>
who discovered that light is faster than sound
who discovered that light is faster than sound
Abū Rayhān al - Bīrūnī
Abū Rayhān al - Bīrūnī