Particle physics

Particle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. It is also called high energy physics, because many elementary particles do not occur under normal circumstances in nature, but can be created and detected during energetic collisions of other particles, as is done in particle accelerators.

History of particle physics

The idea that matter is composed of elementary particles dates to at least the 6th century BC. The philosophical doctrine of "atomism" was studied by ancient Greek philosophers such as Leucippus, Democritus, and Epicurus. Although Isaac Newton in the 17th century thought that matter was made up of particles, it was John Dalton who formally stated in 1802 that everything is made from tiny atoms.

Related Topics:
Matter - 6th century BC - Ancient Greek - Philosopher - Leucippus - Democritus - Epicurus - Isaac Newton - 17th century - John Dalton - 1802 - Atoms

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Dmitri Mendeleev's first periodic table in 1869 helped cement the view, prevalent throughout the 19th century, that matter was made of atoms. Work by J.J. Thomson in the late 1890s established that atoms are composed of light electrons and massive protons. Ernest Rutherford established in 1911 that the protons are concentrated in a compact nucleus. The nucleus was initially thought to be composed of protons and confined electrons (in order to explain the difference between nuclear charge and mass number), but was later found to be composed of protons and neutrons.

Related Topics:
Dmitri Mendeleev - Periodic table - 1869 - 19th century - J.J. Thomson - 1890s - Electrons - Protons - Ernest Rutherford - 1911 - Neutron

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The early 20th century explorations of nuclear physics and quantum physics culminated in proofs of nuclear fission in 1939 by Lise Meitner (based on experiments by Otto Hahn), and nuclear fusion by Hans Bethe in the same year. These discoveries gave rise to an active industry of generating one atom from another, even rendering possible (although not profitable) the transmutation of lead into gold. These theories successfully predicted nuclear weapons.

Related Topics:
20th century - Nuclear physics - Quantum physics - Nuclear fission - 1939 - Lise Meitner - Otto Hahn - Nuclear fusion - Hans Bethe - Lead into gold - Nuclear weapons

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Throughout the 1950s and 1960s, a bewildering variety of particles was found in scattering experiments. This was referred to as the "particle zoo". This term was deprecated after the formulation of the Standard Model during the 1970s in which the large number of particles was explained as combinations of a (relatively) small number of fundamental particles.

Related Topics:
1950s - 1960s - Standard Model - 1970s

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