Unified field theory, a unified theory of matter, intended to reduce the variety of the properties of elementary particles and of the laws of their mutual transformation (interaction) to a few universal principles. No such theory has yet been constructed, and it is regarded rather as a strategy for the development of the physics of the microworld.
Maxwell's equations are taken to be the first example of the unification of different physical phenomena (electric, magnetic, optical). The next stage consisted of attempts to unify electromagnetic and gravitational phenomena on the basis of Einstein's general relativity, which relates the gravitational interaction of matter to the geometrical properties of space-time. It did not, however, prove possible to advance substantially along this path of the “geometrisation” of the interactions.
More fruitful was the path of extending the global symmetry of the equations of motion to a local gauge symmetry, holding at every point of space-time. Along this path the American physicists S. Glashow and S. Weinberg and the Pakistani physicist A. Salam constructed (in the 1960s) a unified theory of the weak and the electromagnetic interactions of leptons and quarks, which so far has no contradictions with experiment (see Weak interaction). The most important prediction of this theory is the existence of three heavy (about 80—90 proton masses) weakly interacting vector particles, the intermediate vector bosons (detected experimentally in 1983), which play the part of carriers of the weak interaction. Attempts are being made to include the strong interaction in this scheme as well — the so-called “grand unification” (Grand Unification), which unites quarks and leptons in a single family. One of the predictions of the various models of “grand unification” that admits experimental test is the violation of the laws of conservation of baryon and lepton charge (in particular, the instability of the proton, with a lifetime of 1030—1032 years).
Another direction of unification, which also includes the gravitational interaction, is the extension of the gauge symmetry to the so-called supergravity (see Supersymmetry), which unites particles with different spins (and therefore with different statistical properties). These attempts, too, have so far proved unsatisfactory.
Unified field theory thus remains a dream for the present. Yet the inseparable connection between all particles, their mutual transformability and the ever more clearly apparent features of the unity of matter compel an unrelenting search for ways of approaching a unified field theory, one that will explain the whole variety of the forms of matter.
Maxwell's equations are taken to be the first example of the unification of different physical phenomena (electric, magnetic, optical). The next stage consisted of attempts to unify electromagnetic and gravitational phenomena on the basis of Einstein's general relativity, which relates the gravitational interaction of matter to the geometrical properties of space-time. It did not, however, prove possible to advance substantially along this path of the “geometrisation” of the interactions.
More fruitful was the path of extending the global symmetry of the equations of motion to a local gauge symmetry, holding at every point of space-time. Along this path the American physicists S. Glashow and S. Weinberg and the Pakistani physicist A. Salam constructed (in the 1960s) a unified theory of the weak and the electromagnetic interactions of leptons and quarks, which so far has no contradictions with experiment (see Weak interaction). The most important prediction of this theory is the existence of three heavy (about 80—90 proton masses) weakly interacting vector particles, the intermediate vector bosons (detected experimentally in 1983), which play the part of carriers of the weak interaction. Attempts are being made to include the strong interaction in this scheme as well — the so-called “grand unification” (Grand Unification), which unites quarks and leptons in a single family. One of the predictions of the various models of “grand unification” that admits experimental test is the violation of the laws of conservation of baryon and lepton charge (in particular, the instability of the proton, with a lifetime of 1030—1032 years).
Another direction of unification, which also includes the gravitational interaction, is the extension of the gauge symmetry to the so-called supergravity (see Supersymmetry), which unites particles with different spins (and therefore with different statistical properties). These attempts, too, have so far proved unsatisfactory.
Unified field theory thus remains a dream for the present. Yet the inseparable connection between all particles, their mutual transformability and the ever more clearly apparent features of the unity of matter compel an unrelenting search for ways of approaching a unified field theory, one that will explain the whole variety of the forms of matter.