Bring It Back Alive

In the three days that the cosmic-ray detector hung 130,000 ft. over Sioux City, Iowa, it marked the passage of 75 heavy atomic particles hurtling in from outer space. One of the particles was distinctly different from the others. Its telltale track through a sandwich of three dozen sheets of plastic, nuclear emulsion and photographic film looked unfamiliar to cosmic-ray researchers. Last week, nearly two years after their equipment was brought back to earth, scientists from the universities of California and Houston finally offered an explanation. The unexpected particle, they said, was almost surely a magnetic monopole, the long-sought basic unit of magnetism.

If the new discovery is confirmed by further experiments, the American Institute of Physics and the University of California are both convinced that "it could rank as one of the major scientific events of the century." It would fill in some gaps in current scientific theory, modify present ideas about the basic building blocks of matter, and might eventually have significant practical applications in research, medicine and the generation of energy.

Magnetic Puzzle. At the very least, proof of the existence of the monopole would solve a mystery that has baffled scientists for more than a century. The elegant equations that Scottish Physicist James Clerk Maxwell worked out in 1865 described in detail the symmetrical relationship between electricity and magnetism. They accounted, for example, for the magnetic field formed by every electric current, and they predicted the electric currents that can be generated by moving magnetic fields. But they could not solve one puzzle. Complete symmetry between electricity and magnetism meant that there must be a monopole--a basic magnetic particle of one pole, either north or south. It would, in effect, be the equivalent of the positive proton or negative electron that exists independently in nature. But all magnetized objects, from subatomic particles to giant electromagnets, seemed to have inseparable north and south poles. Broken into the tiniest segments, each piece remained a "dipole." No isolated north or south monopole could be found.

British Physicist Paul A.M. Dirac attacked this dilemma in 1931 with the newly developed tool of quantum mechanics. His calculations showed that there should indeed be a magnetic particle (or family of particles) that carries a basic magnetic charge--either north or south. That charge, said Dirac, would be 68.5 times as strong as the charge on an electron. Or it would be some multiple of 68.5--say, 137. Scientists had good reason to respect Dirac's reasoning. He had earlier predicted the existence of a positron, or positively charged counterpart of the electron. The positron was subsequently discovered during cosmic-ray experiments in 1932, but the monopole proved more elusive. Physicists searched for it without success in everything from ocean-floor minerals to meteorites and moon rocks.

The balloon-borne experiment that finally seems to have found one was directed by Physicists P. Buford Price, 42, and Edward Shirk, 29, of the University of California at Berkeley, and Weymar Zack Osborne, 42, and Lawrence Pinsky, 29, of the University of Houston. But credit for first spotting the monopole's track belongs to two technical assistants: Julie Teague, 31, at Houston and Walter Wagner, 25, at U.C.

Photographic film and a special emulsion layer from the research balloon were processed and the plastic sheets were exposed to a caustic solution that etched away material wherever it had been damaged by the passage of a heavy cosmic particle. The film, emulsion and plastic sheets were examined microscopically. One of the tracks where a particle had penetrated was different from all the others. Its characteristics, said the researchers, "strongly favor identification of the particle as a magnetic monopole with a charge of 137 and a mass greater than 200 times that of a proton, traveling at a velocity half that of the speed of light."

Serious Doubts. A key finding, says Price, was the velocity; the typical cosmic-ray particle travels at close to the speed of light. At half the speed of light, any known particle would have been stopped by the plastic sheets. But the newcomer had surprising heft; it had "slugged right through all 33 sheets of plastic," a clear indication that it was at least 200 times as massive as a proton.

The successful tracking of a monopole raises serious doubts about another great scientific search: the hunt for the theoretical "quark" (TIME, May 19, 1967). The existence of this strange particle was first proposed by Caltech Physicist Murray Gell-Mann. According to his equations, the quark is the basic building block of nature, the unit out of which all members of the catalogue of subatomic particles are constructed. Gell-Mann's figures assigned the quark a smaller electrical charge than the electron's. But if the latest measurements prove correct, they will support Dirac's calculations. And that means no particle like a quark with less than an electron's charge can exist independently in nature. Discovery of the monopole also means that some of the laws of quantum electrodynamics (on which electronics and laser technology are based) will have to be revised to account for the new particle.

Price and his associates speculate that the discovery could some day lead to "new medical therapies in the fight against cancer, new sources of energy, extremely small and efficient motors and generators and new particle accelerators of much higher energy than any yet built." At a Berkeley press conference last week, there was even far-out talk of equipping a great ship with a few monopoles and having the earth's magnetic field tug it across the ocean. But any such achievements require the locating and controlling of at least one monopole, which could be used, says Price, to create others by "banging it against matter" in a particle accelerator. Before that happens, scientists will need more than a photographic trace. "The goal," says Price, "is to capture a monopole and bring it back alive."

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