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Subatomic Particles

Current And Future Research

Subatomic particles are important in all electronic, optical, and nuclear technologies. Cathode-ray tubes, for example, use beams of electrons to create the pictures. A television antenna first picks up the television signal—a series of radio-frequency photons—which is then processed electronically and used to control an electron gun. An electron gun shoots a beam of electrons which is steered by magnets and hits the coated inner surface of the picture tube. When electrons hit this surface, it lights up, creating the picture as the electron beam is steered rapidly across it. A common type of smoke detector that uses subatomic particles is an ionization smoke detector; in an ionization smoke detector, alpha particles ionize (strip electrons from) air molecules. These ionized air molecules cause electric current to flow in the detector. If there is a fire, other particles enter the detector and interfere with the flow of the electric current, and this makes the alarm go off. Proton beams are used to treat cancer; all technologies involving optics or radio manipulate photons; all electronic devices manipulate electrons; nuclear weapons and nuclear power depend on controlling neutrons so as to produce either an explosive or a controlled nuclear chain reaction, respectively; positron-emitting isotopes are used to image metabolic activity in the human brain in real time; and so on.

In recent years, particle physics has been particularly exciting, with several important experimental developments. Besides the discovery of the W and Z bosons and the top quark, scientists working in Japan in 1998 found evidence that at least some of the three types of neutrinos have a small but nonzero mass. Their experiment did not allow them to determine the exact value for the mass, but subsequent work has shown that the mass of the neutrino is too small to account for the "dark matter" which astronomers have shown must account for a significant fraction of the mass of the Universe. Previously, it seemed that the unknown mass of the neutrino might explain the "dark matter" mystery; today, suspicion centers on "dark energy" rather than on "dark matter" as an explanation of the Universe's nonvisible mass.



Barnett, Michael R., Henry Möhry, and Helen R. Quinn. The Charm of Strange Quarks: Mysteries and Revolutions of Particle Physics. New York: Springer-Verlag, 2000.

Gribbin, John. Q is for Quantum: An Encyclopedia of Particle Physics. New York: The Free Press, 1998.

Kane, Gordon. The Particle Garden: Our Universe as Understood by Particle Physicists. Reading, MA: Helix Books, 1995.

Weinberg, S. The First Three Minutes. New York: Basic Books, 1977.

Weinberg, Steven. Dreams of a Final Theory. New York: Patheon Books, 1992.


Barnett, R. "The Charm of Strange Quarks: Mysteries and Revolutions of Particle Physics." Physics Today 54 (2001)50–51.

Gibbs, W. Wayt. "A Massive Discovery." Scientific American (August 1998).

Kalmus, P. I. P. "Particle physics at the Turn of the Century." Contemporary Physics. 41 (2000):129–142.

Pokrovsky, V. "Particle Physics: Russian Turmoil Rattles CERN." Science 292 (2001):2414B–22415.

Lesley L. Smith
Larry Gilman
K. Lee Lerner


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—The standard unit of electric charge, defined as the amount of charge flowing past a point in a wire in one second, when the current in the wire is one ampere.

Fundamental force

—A basic force, which has its own elementary mediator particle(s). There are four fundamental forces: the strong force, the electromagnetic force, the weak force, and gravity.

Mega electron volt (MeV)

—A unit of energy. One MeV is one million Electron Volts. An Electron Volt is the amount of energy an electron gains as it passes through one Volt of potential difference.


—Believed to be the most fundamental units of protons and neutrons.

Additional topics

Science EncyclopediaScience & Philosophy: Stomium to SwiftsSubatomic Particles - Neutrons, Quark Model, Elementary Mediator Particles, Baryons, Mesons, Current And Future Research - Discovery of particles, Subatomic particle classifications