Physicists and Astronomers

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Airy, Sir George 1801-1892
Determined the mean density of the Earth by the measurement of the acceleration due to gravity at the top and bottom of a coal mine (1854). Measured the period of rotation of Jupiter. Astronomer Royal

Alhazan 965-1038
Optical Thesaurus (c.1038) first scientific treatment of optics. Born in Basra, Iraq. Primitive camera obscura using a pinhole. Worked out that it is the curvature of a lens that makes it focus light.

Ampere, Andre Marie 1775-1836
Gave his name to the unit for electric current. Worked on the magnetic effect of an electric current and the theory of refraction of light. A French scientist who was born at Polémieux, near Lyon. Professor of mathematics in Paris. Proposed the law of force between two electric currents known as Ampere's Law. He was the first person to develop ways of measuring an electric current using a sensitive galvanometer.

Anaxagoras 500-428 BC
A Greek astronomer and philosopher born at Clazomenae in what is now part of Turkey. He gave the correct explanation of lunar eclipses. He was the first to suggest that the Moon shines by reflected light from "a hot stone", the Sun.

Anderson, Carl David 1905-1991
American physicist. Discovered the positron (1932) and anti matter in general. He was awarded the Nobel prize for this in 1936. Discovered the muon in 1935.

Andrews, Thomas 1813-1885
An Irish physical chemist. Behaviour of real gases. Liquefaction of gases, carbon dioxide in 1869. Identified the critical temperature for gases

Angström, Anders Jonas 1814-1874
Swedish professor of Physics at Uppsala. The father of modern spectroscopy. Unit of wavelength (now superseded by the nanometre). Spectral analysis of the aurorae. Devised a method of measuring thermal conductivity, showed it to be related to electrical conductivity.

Appleton, Sir Edward Victor 1892-1965
British physicist. Proved the existence of a layer of charged particles some 100 km above the Earth's surface – the Kennelly-Heaviside layer. This layer in the ionosphere reflects radio waves.

Arago, Dominique Francois 1786-1853
French physicist. Although he used polarisation to prove that light was a transverse wave he also made some early discoveries about the corpuscular theory of light. He predicted that the speed of light would be slower in a more dense material. Helped in the development of electromagnetism.

Archimedes 287-212 BC
Greek scientist and mathematician. Best known for his studies of statics and hydrodynamics. Proposed Archimedes principle (240 BC) – upthrust. Archimedian screw for raising water. Killed at the siege of Syracuse.

Aristarchus (Greek) 310-230 BC
Not quite the modern heliocentric theory! He believed that the Earth, planets and the Sun all moved round an invisible central fire. This idea eventually lead to the Galilean theory of the Sun centred solar system. Geometrical method of measuring the distance of the Moon from the Earth.

Aristotle (Greek) 384-322 BC
Logician and scientist and a disciple of Plato. Four element theory – earth, air, fire and water. He even added a fifth – the ether. Earth centred idea of the solar system. Projectile paths – a body could only move in one direction at a time – things went up in a straight line at an angle, reached the top of their path and then fell straight down to the ground. He believed that a continual force was needed to keep an object moving.

Aston, Francis William 1877-1945
Developed the mass spectrograph to measure the masses of ions. He was awarded the Nobel Prize for Chemistry for this is 1922. Discovered many naturally occurring nuclides.