Physicists and astronomers
Early work on Relativity. Astrophysics. The internal composition of stars. Led
an expedition to Africa in 1919 to measure the deflection of starlight by the gravitational field
of the Sun. Edison, Thomas Alva
Born in the U.S.A.
Invented the evacuated light bulb (1879) and the gramophone. Street lighting in New York in
German-Swiss Physicist. Later a
naturalised American. Developed the theories of Special and General relativity. Proposed his
photoelectric equation based on the quantum theory in 1905 and was awarded the Nobel
Prize for Physics for this in 1921. Proposed the idea of stimulated emission that led to the
development of the laser some forty years later.
Greek philosopher. Optical tentacles theory of vision (444 BC).
Proposed that all matter was composed of four elements – earth, air, fire and
First measurement of the size of the
Earth - 24000 miles. This was found in 240 BC. He found that the Sun's rays went vertically
down a well at Syene (now Shahhat, Lybia) at noon in mid summer, while they made an
angle of 7½o
with a vertical stick at Alexandria, 800 km to the north. Eudoxus
(Greek) 400-355 BC
Explained the motion of the planets by a set of
twenty seven transparent concentric spheres centred on the Earth.