What if some saboteur disabled the mechanism for engaging the control rods? Or what if he just removed them entirely? How could the fission be turned off in this case? Teller, Dyson, and their colleagues arrived at a clever solution: fold some of the neutron-moderating hydrogen into the fuel elements themselves. Even in the absence of control rods, as the fuel grew hotter the extra hydrogen would speed up the neutrons, making them useless for enabling fission. This whole negative-feedback process, happening in a thousandth of a second, would always be ready to act like a circuit breaker to keep the reactor operation from speeding too far ahead.
* The very process by which thrust comes about in a chemical rocket is limited by the temperature of exhaust gases, and this limits the amount of acceleration. That limitation does not apply to the nuclear propulsion plan just described. For the same mass of fuel a nuclear ship can attain higher speeds, can visit remoter destinations, and carry larger payloads than any chemically powered ship.
With Saturn-style rockets, Dyson argued, the weight of the fuel severely limited the payload. The ship would require multiple stages, which would wastefully have to be discarded along the way. Dyson estimated that for chemical rockets, the ratio of the ship’s takeoff weight to its return weight for low Earth orbit would be 16; for high-earth orbit it would be 64; for a Moon landing mission it would be 1,024. By comparison, Orion’s return trip Moon mission weight ratio would be only 10. (FJD in PT, October 1968.)
* Climate modeling is sort of like writing a vast play about Mother Nature. The principal actors are Ocean, Atmosphere, Soil, Plants, Forest, Fossil Fuels, Wind, and Humanity. The drama unrolls according to the known laws of geology and physics—those that pertain to fluid dynamics and thermodynamics. Compare the measurement of stars with the measurement of greenhouse warming: adaptive optics looks at local weather over periods of a fraction of a second. The study of climate change, by great contrast, looks at local and global weather trends over periods of decades, centuries, and millennia. For doing the latter, many assumptions have to be made and approximations used.
For the sake of computation, you can’t simulate the progress of weather from moment to moment for every tiny volume of air, much less for individual air molecules. No supercomputer would be up to the job. Even if it could, what would you do with all the data? Instead, you have to divide up the sky and ocean and land into imaginary blocks. The smaller these volumes are the better, in order to get a more accurate simulation. But the smaller the sample volumes, the more expensive and time-consuming will be the computer’s task of crunching numbers. There must be a compromise between computer time spent and accuracy obtained. The granularity of the simulation—how much detail you expect—becomes a major issue. This was true in the 1970s and is still true decades later when computers are much more powerful.
Typically simulations seek to show what will happen if, over a stretch of years, we increase the amount of CO2 by 20 percent or 50 percent, and so forth. Will the mean world temperature rise by 1 degree or 3? Or will the extra CO2 be taken up and absorbed into rocks or soil or ocean? Can you be confident enough in your computer models that you could make a cogent policy decision on what to do about CO2? This policy would necessarily have a costly impact on the driving of automobiles and the generation of electricity.
* Oppenheimer won the award but in a roundabout way. The Fermi Award winner was then decided by the AEC General Advisory Committee, the same committee chaired by Oppenheimer that passed negative judgment on the H-bomb back in 1949. The name of the designated winner is then passed along to the president for his approval. Along the way it is routed through the President’s Science Advisory Committee. Richard Garwin, one of the most illustrious physicists of the second half of the twentieth century, a notable expert on defense matters, and a participant in Jason studies, sat on that committee and had this to say about what happened in 1962 when the nomination of Edward Teller was considered:
While there was no dissent that Teller’s accomplishments warranted the award, the preponderance of feeling was that the award should not be made, because of Teller’s role in the Oppenheimer trial. In one of the few political acts of my life, I commented that I abhorred what I judged to be Teller’s attack on Oppenheimer, but that I thought that Oppenheimer certainly himself merited the Fermi Award and that it could only happen if Teller received it first. The argument apparently carried the day, and in successive years it went to Edward Teller (1962) and Robert Oppenheimer (1963). (Richard Garwin, unpublished notes, used with permission.)
Oppenheimer received the award from the hands of President Lyndon Johnson.
* Dyson’s interests and talents reverberated through a kaleidoscope of cultural areas. Here, in a randomly pairwise list, are some of the publications that have carried his writing: Review of Modern Physics and The New Republic; Journal of the American Medical Association and The Physics of Fluids; The Tolstoy Studies Journal and the American Journal of Physics; Nature and The Atlantic; The Journal of Mathematical Physics and The New Yorker; Science and The Christian Science Monitor; Journal of the Optical Society and Foreign Affairs; Astrophysical Journal and Harper’s Magazine; Journal of the Statistical Society and The New York Times; Technology Review and The Baltimore Sun; Popular Science; and The Proceedings of the American Philosophical Society. Who else in modern life has such disparate interests?
* In 1981 the Reverend Robert Moore, a local clergyman, became the executive director of the coalition. His practical goal was formulating the nuclear freeze idea as a referendum to be put on ballots. In fact the initiative was put to a vote in ten states during the election of 1982 and won in nine of the ten. In New Jersey it carried with a margin of two to one. Rev. Moore organized a lobbying meeting in Washington, D.C., bringing 600 freeze supporters to meet with New Jersey’s congressional delegation, most of whom declared they were in favor of the freeze idea.
Dyson believes the public voicing of opinion had a palpable effect. Fourteen of fifteen New Jersey representatives in Congress voted against a proposed multiple warhead missile program. (W&H, p. 235) Nevertheless, the missile program was approved by Congress. The freeze movement began to lose momentum. Rev. Moore felt that many in the coalition did not take a long enough view, and that it was impractical to expect results too soon. He agreed with Dyson’s precepts of moral conviction, persistence, objectivity, and compromise. Thirty years later Moore was still director of the coalition. (PFS interview with Rev. Robert Moore.)
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