History of Physics and Astronomy

1925 AD to 1949 AD

This section shows the important events in Physics and Astronomy from 1925 AD until 1949 AD. The names of people are highlighted in blue, important people are in bold blue.

1925 Cosmic rays – term introduced
1925 Electron spin – Uhlenbeck and Goudsmit
1925 Franck and Hertz – Nobel prize for Physics
1925 Ionosphere detected by reflected radio waves - Appleton
1925 Pauli exclusion principle
1926 Fermi-Dirac statistics
1926 Helium solidified – Keesom
1926 Perrin – Nobel prize for Physics
1926 Rocket – liquid propellant – Goddard
1926 Wave mechanics – particle-wave equation – Schrφdinger
1927 Big Bang Theory - Lemaitre
1927 Electron diffraction – Davisson, Germer and Thomson
1927 Milky Way rotation detected - Oort
1927 Uncertainty principle – Heisenberg
1927 Wilson and Compton – Nobel prize for Physics
1928 Complementarity
1928 De Broglie – Nobel prize for Physics
1928 Electron – negative energy states – Dirac
1928 Electron – relativistic quantum mechanical description - Dirac
1928 Kerr cell
1928 Wave mechanical alpha emission – Gamov
1928 Wave mechanical barrier penetration
1928 Zero point energy
1929 Anti- matter predicted - Dirac
1929 Coincidence counters
1929 Electrostatic accelerator – Cockcroft and Walton
1929 Expansion of Universe demonstrated - Hubble
1929 Fusion suggested as the energy of the stars
1929 Hubble's Law
1929 Isotopes of oxygen discovered in nature
1929 Pentode
1929 Quartz crystal clock invented
1929 Radio astronomy - Jansky – merry go round aerial
1929 Rocket motors – Soviets begin development
1929 Television – first experimental TV service - BBC
1929 Television tube – Zworykin

1930 Pluto discovered
1930 Quantum mechanics – Dirac
1930 Raman – Nobel prize for Physics
1930 Schmidt telescope
1930 Superfluid helium produced
1930 Tape recorder
1931 Diffraction of molecules – Strong
1931 Electron- microscope
1931 Neutrino - Pauli
1931 Van de Graaff generator
1932 Cyclotron – Lawrence
1932 Deuterium – Urey and Washburn
1932 Heisenberg – Nobel prize for Physics
1932 High voltage generator – Cockcroft and Walton
1932 Methane and ammonia discovered in the giant planets
1932 Neutron – Chadwick
1932 Polaroid invented – Land
1932 Positron discovered – Anderson
1933 Adiabatic demagnetisation perfected
1933 Dirac – Nobel prize for Physics
1933 Guided weapons – Germans experiment with these
1933 Magnetron
1933 Meissner effect detected in superconductors
1934 Accelerator – smoke ring accelerator proposed
1934 Cerenkov radiation
1934 Fission proposed by Fermi
1934 Neutrino theory of beta decay
1934 Phase contrast microscope – Zernike
1934 Radioactivity – artificial radioactivity - Curie and Joliot
1934 Tritium discovered – Oliphant

1935 Mesons predicted - Yukawa
1935 Nuclear force theory – Yukawa
1935 Weber introduced as a unit of magnetic flux
1936 Anderson – Nobel prize for Physics
1936 Liquid drop model of the nucleus – Bohr
1936 Neutron diffraction
1936 Radar – Watson-Watt
1936 TV station opened at Alexandra Palace in north London
1937 Electron microscope – Ruzcka
1937 Rocket tests at Peenmόnde
1937 Technetium discovered - Segre
1937 Thermodynamics - Third law of thermodynamics
1937 Thomson and Davisson – Nobel prize for Physics
1937 TV – first regular 405 line TV broadcasting - BBC
1938 Cloud chamber – continuously sensitive – Langsdorf
1938 Fermi – Nobel prize for Physics
1938 Fission - Uranium fission – Hahn and Strassman
1938 Magnetic resonance principle
1938 Superfluidity – Kapitza
1939 Klystron – Varian
1939 Lawrence – Nobel prize for Physics
1939 Photometric source – standard – melting platinum
1939-1945 War – Second World War

1940 Carbon 14 discovered and used in carbon dating
1940 Isotope separation - Urey
1940 Neptunium discovered
1941 Betatron - Kerst
1941 Jet aircraft – first British jet aircraft flew
1942 Chain reaction – first nuclear chain reaction – Chicago – Fermi
1942 Plutonium discovered
1942 Rocket - V2 rocket – first successful one flew
1942 Solar radio emission detected
1943 Electronic computer developed – Turing
1943 Enigma decoded – Bletchley park
1943 Mars – a little water vapour detected
1944 Curium discovered – element 96
1944 Rabi – Nobel prize for Physics
1945 Meteors – observation by radar – Hey and Stewart
1945 Nuclear explosion – first nuclear explosion – Alamogordo desert in the USA
1945 Hiroshima – nuclear bomb
1945 Nagasaki – nuclear bomb
1945 Pauli – Nobel prize for Physics
1945 Radar signals reflected off the Moon
1945 Synchrocyclotron
1946 Atomic bomb – first British A bomb – Bikini Atoll
1946 Computer - electronic
1946 Electronic computer – ENIAC – general purpose
1946 Linear accelerator
1946 Reactor – fast reactor – Los Alamos
1946'Strange' particles detected in cosmic ray experiments – named later
1946 Synchrotron – electron synchrotron
1946 Two fluid theory – superfluids – Landau
1947 Atomic pile – British version at Harwell
1947 Lamb shift
1947 Mars – small amount of carbon dioxide detected – Kuiper
1947 Microwave ovens first go on sale
1947 Neutron diffraction – Zinn
1947 Photomultiplier tube
1947 Pi meson discovered
1947 V particle discovered
1948 Cygnus A radio source discovered
1948 Decay of the neutron - Snell and Miller
1948 Mesons first produced in the laboratory
1948 Palomar 200" reflector completed and goes into operation
1949 Berlelium (element 97) – Ghiorso, Seaborg and Thompson
1949 Holography – Gabor
1949 Lambda 0 discovered
1949 Plutonium bomb – USSR
1949 Polarisation of starlight by interstellar dust observed
1949 Steady state theory – Hoyle
1949 TV – colour
1949 Yukawa – Nobel prize for Physics