Edward Teller, in his memoirs, expresses his great apprehension at what he feared might be the General Advisory Committee’s recommendation and mentions a good meeting he had in November 1949 with Senator McMahon in Washington.{17} It was on a swing to the east in which he also called on Fermi in Chicago and Bethe in Ithaca in an unsuccessful effort to get one or both to drop their academic work and join him in Los Alamos. The day after Teller and Bethe met in Ithaca, the two went on to Princeton to see Oppenheimer, who had invited Bethe and who then enlarged the invitation to include Teller when he learned that the two were together. In his memoirs, Teller recalled that at the Princeton meeting, Oppenheimer, characteristically, kept his personal opinions to himself, although he shared with his visitors a letter from James Conant that contained a strongly worded condemnation of an H-bomb program.{18} Bethe, according to Teller, both in Ithaca and in Princeton, committed himself to joining Teller in Los Alamos, but less than a week later changed his mind.{19}
On this trip, neither Fermi nor Oppenheimer shared with Teller the content of the General Advisory Committee report in which they had participated, although Fermi was more than likely open in discussing his personal views. As for McMahon, he, according to Teller, said “Have you heard about the GAC [General Advisory Committee] report? It just makes me sick.”{20} A few weeks later, back in Los Alamos, Teller was allowed to read the GAC report, which confirmed his worst fears.{21} Then, on January 31, the President’s statement gave Teller a lift. In his memoirs, Teller wonders what brought Truman to the right way of thinking. “Was [Truman’s] decision based simply on his abundant common sense? Probably no one will ever know [what convinced the President],” Teller continues, “but my bet is on the common sense.”{22}
Chapter 5
Nuclear Energy
When Henri Becquerel, in Paris, discovered radioactivity in 1896,{1} my parents were pre-schoolers. I mention this fact only to emphasize that the history of nuclear energy from Becquerel to bombs, from a few relatively harmless alpha, beta, and gamma rays to the destruction of cities and the obliteration of a Pacific island was accomplished in one human lifetime. In 1952, the year in which “Mike” released its ten megatons and Elugelab was no more, my parents turned sixty.
What Becquerel discovered was that a uranium compound emitted some kind of “radiation” that could darken a photographic plate, even if the compound was not “activated” by shining light upon it or stimulated in any other way. The compound, wrapped in paper and kept in a dark drawer, continued, with no apparent diminution of intensity, to emit its radiation. He also found that uranium metal alone had the same property and that seemingly no other element did.
Becquerel had no idea that he was dealing with nuclear energy. He was probably not even sure that atoms existed, much less that atoms—if they did exist—might have tiny nuclear cores at their centers, or that the radiation he discovered might come from such cores. But he did infer that uranium must contain stored energy—energy that could leak out over time, and a lot of it, since it did not weaken over the days and months that he studied it.{2}
Becquerel’s “rays” drew less scientific attention at the time than the recently discovered X rays, with their seemingly magical property of revealing a person’s bone structure. Wilhelm Röntgen had announced his discovery of X rays on New Year’s Day 1896.{3}, [27] Becquerel’s first report on his new penetrating radiation came less than two months later, on February 24, 1896.{4} After that, a year and a half elapsed before a thirty-year-old doctoral candidate at the Sorbonne in Paris, Marie Curie, chose to follow up Becquerel’s work for her dissertation research. She wanted a topic that would give her time to get new results without undue risk that some other researcher would preempt her findings.{5} Uranium, she said, is “radio-actif,” and the name stuck.{6}
As it turned out, Marie Curie opened a floodgate. Within a year, she and her husband Pierre had discovered two new elements, polonium and radium. Soon thereafter Ernest Rutherford, at McGill University in Montreal, discovered radioactive substances with shorter half lives, one of one minute and another of eleven hours, and he verified that their decay followed a simple probabilistic rule. In 1898, Rutherford named the two then-known kinds of radioactive emissions alpha and beta rays, and he later added the coinage gamma rays for a third kind of radiation discovered in 1900 by Paul Villard in Paris.{7}
By 1904, in his 382-page tome Radio-Activity{8} (the hyphen was soon dropped), Rutherford could report the following conclusions, a mind-filling set of ideas unknown and unsuspected less than a decade earlier (these are paraphrases).
• Radioactivity supports the idea that atoms exist, and suggests that they are complex structures.
• Radioactivity is a series of spontaneous explosive changes in atoms; it is not a process of gradual change.
• Radioactivity transmutes one element into another, which no chemical change can do, and has produced hitherto unknown elements.
• In radioactivity, the energy released per atom is enormous, at least a million times greater than in chemical change.
• The intensity of radiation from a given radioactive elements diminishes according to a law of exponential change with a characteristic half life, suggesting that a law of probability operates at the individual atomic scale.
• Helium is emitted in radioactive decay, and alpha particles are probably helium atoms (they were later confirmed to be helium nuclei).
• The beta rays emitted in radioactive decay are electrons, and they shoot out with great energy.
In 1905, the year after this monumental summing up by Rutherford, Albert Einstein offered the world his most famous equation, E = mc2: Energy is mass times the square of the speed of light. Specifically, in the form m = E/c2 the equation tells how much change of mass is required to produce a certain amount of energy. Because of the enormously large value of c2 by normal standards, it takes only very little mass change to produce a great deal of energy. If, for instance, two hydrogen atoms join with an oxygen atom to form a water molecule—a vigorous combustion process that releases energy—the mass of the molecule is less than—but imperceptibly less than—the sum of the masses of the three atoms. Einstein recognized that in ordinary chemical change the changes of mass would be too small to measure. He then asked himself if there was any chance of verifying the correctness of the equation experimentally, and he made this suggestion: “It is not impossible that with bodies whose energy content is variable to a high degree (e.g. with radium salts) the theory may be successfully put to the test.” (Original in German.){9}