Quantum Physics for Beginners: The Easy Guide to Learn Quantum Physics and the Theory of Relativity by Hanson Cary

Author:Hanson, Cary [Hanson, Cary]
Language: eng
Format: epub
Published: 2020-04-03T16:00:00+00:00

QUANTUM FIELD THEORY AND STANDARD MODEL

D irac not just proposed the relativistic condition for the electron, yet additionally started the relativistic treatment of molecule associations known as quantum field theory. The theory allows for the creation and destruction of particles and requires only the existence of adequate interactions that carry enough energy. Quantum field theory also states that interactions can extend over a distance only if there is a quantum of particles or fields to bring force. The electromagnetic force that can act over vast distances is carried by the photon, the quantum of light. Since theory allows particles to interact with their field quanta, there have been mathematical difficulties in applying the theory.

The theoretical dead-end was broken by a measurement of the American physicist Willis Eugene Lamb Jr. in 1946 and 1947. Using microwave technology developed in World War II, it showed that the hydrogen spectrum is actually about a tenth percent, unlike Dirac's theoretical framework. Later, the German-born American physicist Polykarp Kusch found a similar anomaly in the electron's magnetic moment size. Lamb's results were announced during a famous Shelter Island conference in the United States in 1947. German-born American physicist Hans Bethe and others acknowledged that the so-called Lamb shift was probably caused by electrons and field quanta, which can be generated by emptiness. Previous math difficulties were overcome by Richard Feynman, Julian Schwinger, and Tomonaga Shin’ichirō, who shared the Nobel Prize in Physics in 1965, and Freeman Dyson, who showed that their different approaches were mathematically identical. It has been discovered that the new theory, called quantum electrodynamics, explains all measurements with very high precision. Quantum electrodynamics provides a complete theory on how electrons behave under electromagnetism.

Similarities between weak force and electromagnetism have been found since the 1960s. Sheldon Glashow, Abdus Salam, and Steven Weinberg joined the two forces in the electroweak theory, for which they received the Nobel Prize in Physics in 1979. Notwithstanding the photon, three field quanta ought to have other quality: the W molecule, the Z molecule, and the Higgs boson. The W and Z particles were bearers of the feeble power, and the Higgs boson was the transporter of the Higgs field, with the outcome that the W and Z particles were heavy and the photon had a zero mass. The discoveries of W and Z particles in 1983 with correctly predicted masses confirmed the validity of the electroweak theory. A particle that was probably the Higgs boson was finally discovered in 2012.

A total of hundreds of subatomic particles have been discovered since the first unstable particle, the muon, was identified in cosmic rays in the 1930s. In the 1960s, patterns appeared in the properties and relationships between subatomic particles that led to quark theory. A theoretical framework called a standard model was built from the combination of electroweak theory and quark theory. It contains all known particles and field quanta. In the standard model, there are two major categories of particles, leptons, and quarks. Leptons include electrons, muons, and neutrinos and, in addition to gravity, interact only with electroweak force.

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