For an explanation, see the main splats page
SPLATS about particle physics
The principles of particle physics
- Particles exert attractive and repulsive forces on each other, mostly from their electrical charges, in part from other forces which control atomic behaviour.
- There is a limited number of fundamental particles over and above the standard electron, neutron and proton, which set is all that most people know.
- Most of chemistry can be explained with no more than the proton, neutron and electron. When it comes to physics, the behaviour of atoms needs more structure.
- When particles collide at high speed, we can learn a great deal from the careful study of the fragments that are thrown off, and their energies.
- Mesons are of medium mass, between the size of an electron and a proton, and they are very unstable, medium-mass elementary particles with short life spans.
- Matter exists also in the form of antimatter, and when it comes in contact with ordinary matter, the two will annihilate each other, becoming energy.
- In 1873, Johannes van der Waals wrote about intermolecular forces in fluids, and introduced the idea of weak attractive forces between molecules.
- In 1930, Fritz London explained van der Waals forces in terms of their being caused by the interacting fluctuating dipole moments between molecules.
- In 1911, Victor Hess discovered high altitude radiation from space after ascending in a balloon. At this time, cosmic rays were referred to as 'Hess rays'.
- In 1912, Victor Hess used more ascents to show that the ionization of air increases with altitude indicating the existence of some form of cosmic radiation.
- In 1927, Eugene Wigner concluded that parity is conserved in a nuclear reaction, that the laws of physics should not distinguish between right and left.
- In 1958, Yang and Lee showed that, contrary to Wigner, certain types of reaction involving the weak nuclear force, such as beta decay, do not conserve parity.
- The Standard Model says that there are hundreds of particles, but that these are all made up of various combinations of six quarks and six leptons.
- In 1924, Edward Appleton demonstrated the presence of the ionosphere when he used radio ranging to measure the distance to the Heaviside layer.
- The F-layer or Appleton layer (after Sir Edward Appleton) is a layer of ions about 200 km above the Earth by day, and 300 km above the Earth at night.
- The Appleton layer reflects radio waves at frequencies up to about 50 MHz, and so allows radio signals below that frequency to travel around the world.
- Ernst Rutherford predicted that there must be a neutron as early as 1920, but finding it was harder. Chadwick did not detect one experimentally until 1932.
- In 1931, Wolfgang Pauli suggested that the neutrino could explain both the missing energy and spin in weak nuclear decay, starting the search for neutrinos.
- In 1932, Werner Heisenberg suggested that nuclei are made of protons and neutrons, which would explain why there are isotopes, when the neutron number varies.
- In 1923, Arthur Compton discovered the Compton effect which confirmed photons as particles. Compton and Debye provided the theory of Compton effect.
- A lepton is a light-weight charged or uncharged particle: each with an anti-particle. They are the electron, the muon, the tau, and their associated neutrinos.
- Within the nucleus, two main forces operate: the repulsion of the positively charged protons, and the strong nuclear force which pulls them together.
- In 1934, Pavel Cherenkov discovered that what is now Cherenkov radiation was caused when very fast particles entered an optically dense medium.
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