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Period: to
Discoveries
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Radioactivity Discovered
In 1896 Henri Becquerel was using naturally fluorescent minerals to study the properties of x-rays, which had been discovered in 1895 by Wilhelm Roentgen. -
Discovery Of The Electron
J.J. Thomson's discovery of the electron in 1897 showed us that the atom can be split into even smaller parts. His discovery was the first step towards a detailed model of the atom. -
Discovery Of Radium
Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite sample. -
First Quantum Theory Of Atom
The first model of the atom was developed by J.J. Thomson and Lord Kelvin in 1904. They called it the 'plum pudding' model because the negative electrons (the plums) were embedded in a sphere of uniform positive charge (the pudding). -
Einstein's Theory Of Special Relativity
Einstein explained that when two objects are moving at a constant speed as the relative motion between the two objects, instead of appealing to the ether as an absolute frame of reference that defined what was going on. If you and some astronaut, Amber, are moving in different spaceships and want to compare your observations, all that matters is how fast you and Amber are moving with respect to each other. -
Discovery Of The Nucleus
In March 1911 Rutherford announced that each atom contains a positively charged nucleus -
Cloud Chamber Invented
Charles Thomson Rees Wilson perfected the first cloud chamber in 1911. -
General Relativity
Einstein's Theory Of General Relativity Published. -
Link Between Symmetry And Conservation
Noether's (first) theorem states that every differentiable symmetry of the action of a physical system has a corresponding conservation law. The theorem was proven by German mathematician Emmy Noether in 1915 and published in 1918. The action of a physical system is the integral over time of a Lagrangian function (which may or may not be an integral over space of a Lagrangian density function), from which the system's behavior can be determined by the principle of least action -
Discovery Of Photons
Arthur Compton discovers the quantum (particle) nature of x rays, thus confirming photons as particles. -
Relation Between Wavelength And Momentum
De Broglie, in his 1924 PhD thesis, proposed that just as light has both wave-like and particle-like properties, electrons also have wave-like properties. By rearranging the momentum equation stated in the above section, we find a relationship between the wavelength, λ associated with an electron and its momentum, p, through the Planck constant, h. -
First Theory Of QED
Quantum electrodynamics, commonly referred to as QED, is a quantum field theory of the electromagnetic force. Taking the example of the force between two electrons, the classical theory of electromagnetism would describe it as arising from the electric field produced by each electron at the position of the other. -
Positron Discovered
Carl D. Anderson found that cosmic-ray collisions produced these particles in a cloud chamber— a particle detector in which moving electrons (or positrons) leave behind trails as they move through the gas. -
Discovery Of The Neutron
It is remarkable that the neutron was not discovered until 1932 when James Chadwick used scattering data to calculate the mass of this neutral particle -
Idea Of Nuclear Chain Reaction
The concept of a nuclear chain reaction was first hypothesised by Hungarian scientist Leó Szilárd on Tuesday, September 12, 1933 -
Cyclotron Patented
In 1929 Ernest Lawrence – then associate professor of physics at the University of California, Berkeley, in the US – invented the cyclotron, a device for accelerating nuclear particles to high velocities without the use of high voltages. Lawrence was granted US patent 1948384 for the cyclotron on 2 February 1934. The machine was used in the following years to bombard atoms of various elements with swiftly moving particles. Such high-energy particles could disintegrate atoms, in some cases formin -
Discovery of Nuclear Fission
In December 1938, over Christmas vacation, physicists Lise Meitner and Otto Frisch made a startling discovery that would immediately revolutionise nuclear physics and lead to the atomic bomb. -
First Fission Reactor
Chicago Pile-1 (CP-1) was the world's first artificial nuclear reactor. The first man-made self-sustaining nuclear chain reaction was initiated in CP-1 on 2 December 1942, under the supervision of Enrico Fermi. -
First Fission Bomb
The first atomic device tested successfully at Alamagordo in New Mexico on 16 July 1945. -
Pions Discovered
The pions, which turned out to be examples of Yukawa's proposed mesons, were discovered later: the charged pions in 1947, and the neutral pion in 1950. -
CERN's First Director
1952–1954: Edoardo Amaldi (General secretary before September's 1954 official foundation). -
Bubble Chamber Invented
A bubble chamber is a vessel filled with a superheated transparent liquid (most often liquid hydrogen) used to detect electrically charged particles moving through it. It was invented in 1952 by Donald A. Glaser -
First Fusion Bomb
Ivy Mike was the codename given to the first test of a full-scale thermonuclear device, in which part of the explosive yield comes from nuclear fusion. It was detonated on November 1, 1952 by the United States on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy. -
Anitproton Discovered
A paper titled "Observation of antiprotons," by Owen Chamberlain, Emilio Segrè, Clyde Wiegand, and Thomas Ypsilantis, members of what was then the Radiation Laboratory of the University of California at Berkeley in the US, appeared in the 1 November 1955 issue of Physical Review Letters. It announced the discovery of a new subatomic particle, identical in every way to the proton – except its electrical charge was negative instead of positive. -
Antineutron Discovered
Team working at the Bevatron – Bruce Cork, Glen Lambertson, Oreste Piccione and William Wenzel discovered the antineutron -
Beginning Of Tokamak Creation
A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus. Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape. -
Discovery Of The Neutrino
In 1959, Clyde Cowan and Fred Reines finally found a particle that fit the description of the proposed neutrino by studying the particles created by a nuclear power plant. By doing this they actually discovered the electron neutrino. -
Higgs Particle Theory
The existence of the Higgs boson - sometimes nicknamed the God Particle - was first predicted by Professor Peter Higgs, a theoretical physicist at the University of Edinburgh, and five other physicists in 1964. -
Multiwire Counter
A multi-wire proportional chamber is a type of proportional counter that detects charged particles and photons and can give positional information on their trajectory, by tracking the trails of gaseous ionization. In 1968, Georges Charpak, while at the European Organization for Nuclear Research in CERN, invented and developed the multi-wire proportional chamber (MWPC). -
Quarks Discovered
In 1968, deep inelastic scattering experiments at the Stanford Linear Accelerator Center (SLAC) showed that the proton contained much smaller, point-like objects and was therefore not an elementary particle. -
Gluon Discovered
Gluons are elementary particles that act as the exchange particles (or gauge bosons) for the strong force between quarks. The gluon was discovered at DESY in 1979 by TASSO and the other experiments at the PETRA collider. -
Discovery Of W And Z Particles
W and Z particles found at CERN.