Scientists under Surveillance consists of the Federal Bureau of Investigation (FBI) files of sixteen twentieth-century scientists, ranging from Neil Armstrong, the first man to step on the moon, to Alfred Kinsey, author of Sexual Behavior in the Human Male, which created a sensation in the United States when it appeared in 1948. The compilers of this collection seem to have lacked criteria to determine who should be included. The only characteristic common to all of the subjects is that they had something to do with science. Among those included are some who were not U.S. citizens.

But during the late 1940s, when the nuclear bomb became part of the U.S. arsenal, the FBI's mission became more pointed. Under FBI Director J. Edgar Hoover, the agency was charged with learning what it could about the mathematicians, physicists, and engineers who had invented the bomb and finding out whether any of them, because of Communist leanings, might be tempted to pass “the secret” to the Soviet Union. This volume shows how zealously—but at times ineptly—the FBI carried out its mission.

The bureau's treatment of the great theoretical physicist Hans Bethe is a case in point. Told to watch Bethe, FBI agents on 16 September 1951, met a flight from Europe on which he was due to arrive. After the plane landed, they searched and photographed all of his clothing and the contents of four manila envelopes he was carrying. They followed him to his mother's house on suburban Long Island, then tracked him to La Guardia Airport, where he boarded a flight to Chicago. At the physics conference in Chicago at which he was scheduled to speak, FBI agents continued to keep watch on Bethe, reporting that he received no mail at his hotel and that a search of the wastebasket in his room turned up nothing.

To be sure, the FBI had reason for its interest in Bethe. He had led the theoretical physics group at Los Alamos during the war and had worked closely with Klaus Fuchs, who, the year before, had confessed in a British court to spying for the Soviet Union. But surveillance, too, carried risks. FBI agents in the late 1940s and early 1950s knew little or nothing about the nuclear weapons program or the people they were spying on. They did not know that the man they were surveilling, Bethe, was indispensable to the bomb program. Nor did they realize that their intense surveillance of him had to be kept secret.

An outspoken colleague of Bethe's, Richard Feynman, became aware that he was being watched and took the opportunity to protest. He warned the FBI that excessive secrecy could cause the United States to lose its lead in nuclear weapons. He became so angry at the agency's snooping among his family and friends that FBI Director Hoover finally wrote a memorandum to his senior staff indicating that no one was to bother Feynman without his explicit permission.

The most important decision taken after the end of the Second World War—and, some would say, the decision that launched the Cold War—was President Harry Truman's 1950 order to scientists to develop the hydrogen bomb, a weapon with more than a thousand times the explosive force of the fission bomb. Announcing the decision, which was made after a highly secret debate inside the government, Truman ordered that those privy to that debate were now to maintain silence. The public was to be excluded.

The veil of secrecy that had built up around the nuclear bomb now gave way to a much tighter curtain around the hydrogen bomb. But after the United States tested two powerful hydrogen devices in the Pacific in the early 1950s, and after the Soviet Union lofted the Sputnik satellite into space in 1957, many in the United States suddenly realized that a full-blown arms race was under way, enabling each side to destroy the other.

That realization gave rise to the anti-nuclear movement in the United States and Great Britain and also inspired the U.S. Congress to pass the Freedom of Information Act (FOIA) in 1965. That piece of legislation was hedged with limits and provisos, and an applicant sometimes had to wait years for a reply, let alone for a requested document to be released. MuckRock, an organization founded in 2010, used the FOIA to secure release of the FBI documents reproduced in this book. MuckRock's purpose was to show us the world as the FBI, led by Hoover, saw it.

The demise of the Soviet Union in 1991 gave rise to hopes of a less armed and more open world, and for several years things seemed to be moving that way. But as the 21st century has progressed, the nuclear arms control treaties the United States and the Soviet Union concluded in the late 1980s and early 1990s have been abrogated or weakened, and secrecy has regained its importance on both sides. Even though Donald Trump is no longer president, the climate of secrecy and fear that predated his administration and intensified during his four years may never be fully dissipated.