Monday, July 25, 2005

The "Field" in Physics

A blog friend of mine, Y, wrote in her recent blog post as follows:
When I have contact with a person to study the problems of either the scene and activity of social welfare or various social phenomena, I, as one of the persons being present at the site, feel many things from that person's talk and behavior, and scientifically consider about the movement that makes the "field."
This sentence has made me think that the study of social problems is similar to that of elementary particles, because both the studies concern interactions and the "field." From this thought I now want to write a simple introduction to the concept of the "field" important in physics.

In everyday life we experience magnetic, electric and gravitational forces; these are respectively caused by the magnetic, electric and gravitational field. You may know that the magnetic field can be visualized by sprinkling iron filings near a bar magnet. The electric and magnetic fields were theoretically found to be unified as the electromagnetic field by James Clerk Maxwell in the 19th century. The things that mediate the fields are elementary particles. The electromagnetic field is mediated by the photon; and the gravitational field, by the graviton. (Gravitons have yet to be discovered experimentally.)

Each kind of elementary particle has a definite mass, including the special cases of zero mass for the photon and the gluon (the gluon is the particle that mediates the "strong nuclear field"; the force of this field binds quarks to make protons and neutrons). Theoretical physicists now consider that the masses arise from the interaction of particles with a kind of field termed "Higgs field" and that the origin of Higgs field is a supposed particle called "Higgs boson." (This consideration is based on the Standard Model and Supersymmetric Standard Models of elementary particle physics.) — Now you may remember the question, "Which came first, the chicken or the egg?" —

One of the main aims of the present high-energy experimental physics is to find Higgs bosons to confirm the above consideration. For this purpose, they use gigantic machines such as Tevatron Collider at Fermi National Accelerator Laboratory in USA. and Large Hadron Collider under construction at CERN, European laboratory for particle physics near Geneva. It is one of grand plans to move the frontiers of human knowledge forward. (You can read more about the mass and the Higgs field in a recent issue of Scientific American [1].)

  1. G. Kane, "The Mysteries of mass," Scientific American, Vol. 293, No. 1, p. 31 (2005).

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