A team of Princeton scientists this year took a giant stride toward what will be mankind’s greatest technological achievement—the creation of unlimited energy by nuclear fusion, the force that powers the sun. On July 24 the Princeton plasma physics lab generated heat of 60,000,000° C in a special magnetic chamber. Even higher temperatures will be necessary before significant fusion can occur, but of this dramatic advance, the lab’s 61-year-old director, Melvin Gottlieb, spoke for his 980 colleagues when he enthused: “People here were walking on air. Their feet weren’t touching the ground.”
For the Princeton physicists—and their counterparts in the U.S.S.R., Western Europe and Japan—fusion is simple in essence and excruciatingly difficult in execution. The nuclei of two heavy hydrogen atoms are fused together to form another nucleus and release energy. But these positively charged nuclei, whose natural tendency is to repel each other, must be confined in adequate numbers or density and at a temperature of 100,000,000° C. (The surface of the sun, by comparison, is only 6,000° C.) This incredible heat must be maintained for a full second to achieve a self-sustaining fusion of hydrogen into helium, with a loss of mass that is converted to energy. In 1905 Einstein described such a conversion with his celebrated formula E = mc2. Because of the technical difficulties, scientists do not expect fusion to produce power commercially until 2025.
Before July 24 the highest temperature Gottlieb’s team had achieved was 26,000,000° C. That day the 60,000,000° was held for a 20th of a second. “It was amazing,” Gottlieb says. “It took us seven years to go from 5 million to 25 million and only six months to go 35 million more.” They subsequently hit 74.1 million for a 50th of a second. At those heats the hydrogen nuclei separated from their electrons, creating what physicists call a plasma—a fourth state of matter, different from gas, solid or liquid.
The plasma physicists are now at work on a giant doughnut-shaped reactor that will cost $239 million and be operational in 1981. It will, the director hopes, achieve the temperature, density and confinement time necessary to produce at least as much energy as is fed into it.
Gottlieb, a graduate of the University of Chicago, joined the Princeton lab in 1954 and has run it since 1961. He shares a home nearby with Golda, his wife of 30 years; their two daughters are grown. Work leaves him little time for relaxation. He sold his 27-foot yawl, and his summertime zucchini, cantaloupe and tomatoes don’t get the attention they once did. “This is an all-consuming task,” Gottlieb sighs. “I have very few distractions.”