Who needs to know?

In my earlier years I had some dealings with classified material, enough that I was able to see how arbitrary, foolish and transitory security classification can be. That there may be information on somebody’s computer that was classified at some point in the past doesn’t necessarily have any relevance for national security.

In summer 1958, I was briefly a consultant for the Rand Corporation in Santa Monica. I had a Q clearance, the most rigorous that the Atomic Energy Commission had. This enabled me to receive classified information on nuclear weapons on a ‘need to know’ basis. During most of my short stay I didn’t need to know anything, but one day the theory division leader descended on me with stacks of numbers he wanted me to add up on a Marchant calculator.

The physicist Nicholas Christofilos had suggested that if several hydrogen bombs were exploded in the magnetosphere above the atmosphere, the electrons generated would get trapped in the magnetic lines of force and destroy incoming missiles. But the astronomer James Van Allen had meanwhile discovered that there were already natural belts of trapped electrons, and putting more in would ruin them. He made a great public fuss and the people at Rand who were in favour of Christofilos’s idea set about to prove Van Allen wrong. Somehow the numbers I was adding up played a part in this effort. The Starfish Prime test on 9 July 1962 – after the Rand report was written – showed that the effects were even worse than Van Allen had feared. The Treaty Banning Nuclear Weapon Tests in the Atmosphere was signed in August 1963.

I left Rand before the report was written so I never saw it. In 1960 I was working at the Brookhaven National Laboratory on Long Island. My Q clearance was no longer active. But I received a phone call from the lab security people saying a package had arrived from the Rand Corporation and they wanted my permission to open it. I said that I could not give my permission without seeing the contents and they said that I couldn’t see them because they were classified. I told them to send the package back to Rand. By now all the details of this business are available in the open literature and the whole classification seems absurd.

After a few weeks at Rand I got an offer from Freeman Dyson to join him at General Atomics. He couldn’t tell me the details but I knew what it was about: the Orion Project. A couple of physicists at Los Alamos had had the idea that small nuclear devices could be used as propellants for space travel. They would be dropped from the bottom of the ship sequentially and the detritus from the explosions would act as an efficient propellant. Dyson had gone to La Jolla to work on the design of the ship. There was to be a large flat metallic plate, known as the ‘pusher’, attached to the body of the ship by springs that would absorb the shocks of the explosions.

The question was whether the pusher would ‘ablate’ away under the influence of the successive bombs. This depended in large measure on the opacity – the capacity to absorb radiation – of the materials involved. They were to be relatively light elements. At the time I didn’t appreciate the importance of this limitation. Any information, theoretical or experimental, on the opacity of any element heavier than lutetium was and is classified. This includes gold, platinum and lead. To compute an opacity is a problem in quantum mechanics and atomic physics. Anyone can try to do it, but if you do it for lead, the result is classified. Is anything more absurd? Dyson had an idea for a ‘super Orion’ with a pusher made of uranium, which might have been used as fuel for, say, a return trip to Mars. But the opacity of uranium was classified, though it might be an interesting project for a graduate student.

In autumn 1945, Enrico Fermi gave a lecture at Los Alamos on Edward Teller’s hydrogen bomb, the Classical Super. Fermi concluded that he did not see how it could be made to work. The audience was all Q-cleared and the lecture was classified. One of the people in the audience was Klaus Fuchs, who turned the lecture over to the Russians. I am not sure they learned anything they did not already know. But the lecture remained classified by the US government even after the Russians had put it on the web. You can download it at your leisure.