| R KIEHN TO R WEST 6 Sep 1999 Subject: Slotin FYI (from one who has constructed numerous critical assemblies) Slotin used a screw driver to prop open two hemispheres of fissionable material. He would reduce the gap to cause the neutron counting rate to increase as the assembly approached criticality. He would increase the gap to lower the neutron counting rate. He was showing off to another colleague when the screw driver slipped. The assembly went critical and self disassembled due to thermal expansion. Slotin received a lethal dose >> 500 R His colleague survived, and died much later of natural causes. ***Although you say that E=mc^2 did not make a difference to the development of the nuclear weapons, IMO you are wrong. Indeed a number of experimental results ultimately led to the result, but if it took 1,000,000 tons of uranium to make a 20 kt device it would not have been built. RMK |
| R WEST TO R KIEHN 6 Sep 1999 Subject: Re: Slotin > FYI ... > Slotin ... screwdriver... lethal dose... ** Yes, I've heard this too. You don't give your source. > Although you say that E=mc^2 did not make a difference to the development > of the nuclear weapons, IMO you are wrong. > Indeed a number of experimental results ultimately led to the result, but if > it took > 1,000,000 tons of uranium to make a 20 kt device it would not have been built. ** This doesn't show that 'E=mc^2' had any effect. The whole thing was empirical. If no energy had been got from the atomic pile, presumably experiments would have stopped, or something else would have been tried. To put it another way, if the equation had never been invented, nevertheless there was widespread awareness (cf slow cooling of the earth, energy from radium etc) that, in principle, a lot of energy was there in atoms; there are plenty of pre-Einstein statements to that effect. I see no evidence that the formula made any difference to the actual work on nuclear weapons. Still less, so to speak, did it help with the work. Regards Rae |
| R KIEHN TO R WEST 6 Sep 1999 Subject: Re: Slotin BUT I WAS THERE |
| R WEST TO R KIEHN 10 Sep 1999 Subject: re Slotin > BUT I WAS THERE You don't make it clear whether you mean with Slotin or just generally involved. As regards Slotin, and no doubt others, the industrial injury side of things isn't very relevant to the main thesis. The idea that e=mc^2 had a contributing part in atomic bombs seems a myth. Except perhaps in the sense of suggesting a lot of energy 'locked' in matter. Regards Rae West |
| R KIEHN TO R WEST 10 Sep 1999 Subject: Re: Slotin I was not with Slotin during his blue glow accident. I have tickled the dragon's tail. I think you are wrong about the effect of e=mc^2 on the thinking of those who designed nuclear devices. It did influence my thinking. Have you had experience designing nuclear devices? RMK |
| R WEST TO R KIEHN Sat, 11 Sep 1999 Subject: Re Slotin [previous email snipped] Have you any experience of theoretical physics? You don't say what you mean by 'influence your thinking'. Have you tried to measure whether there's loss in mass with 'nuclear devices'? Regards Rae West |
| R KIEHN TO R WEST Sat, 11 Sep 1999 Subject: Credentials << Have you any experience of theoretical physics?>> [snip] Yes. A bit: See https://www22.pair.com/csdc/car/carhomep.html PhD Physics MIT. 15 years with the AEC, 35 Years plus as a professor of physics.Many publications, a few patents (including Plutonium Fast Breeder Reactors and dual polarized ring lasers). I have stacked Pu and U235 into critical assemblies of various types, and have conducted experiments that involved nuclear explosions. Also I have been a programmer for more than 45 years, having written multi-group neutron transport programs at LASL for the design of nuclear devices in the early days of computers. I made some of the first measurements of neutron inelastic scattering cross sections, and other neutron cross sections, and must say that the Q values associated with neutron reactions were correlated with mc^2 concepts. Measurements of recoils of charged particles in magnetic spectrometers also justifies the mc^2 idea. The Compton experiment also gives a level of credence to the idea. I have been involved in such experiments. NOW What are your credentials? Do you know anything about Theoretical Physics? Do you know anything about experimental Physics? Have you ever brought an assembly of fissionable material to criticality? Have you ever conducted neutron nuclear reaction experiments. **Although I have never placed Einstein on a pedestal, I think you are wrong about the influence of E=mc^2 on the development of nuclear devices. The development of Oak Ridge and the Hanford Reactors were things that were started well before the Trinity event. Without the Einstein letter to FDR, it is doubtful that anything would have been started at such magnitudes of investment. In this manner, the popularity of the E=mc^2 concept to the nontechnical mind had an enormous impact. ***You can voice your (journalistic) opinion, but I would suggest you talk more to people who were involved, rather than pontificating your point of view. Regards RMK |
| R WEST TO R KIEHN Sat, 11 Sep 1999 Re: credentials [previous email snipped] Yes. I co-wrote this piece with Phil Holland, who spent his working life involved in various ways with physics, including many years at Sellafield, having got as I understand it a double first in physics and chemistry from Cambridge. The question at issue is whether, as is widely believed, e=mc^2 played a crucial part in developing atomic weapons. Not whether Einstein's letter had influence. As I stated in my piece, all the steps leading to nuclear weapons were empirical or, where they weren't, involved empirical discoveries for which no theoretical basis was known at the time or, in most cases, later. You don't give any examples of the part played by e=mc^2 in the development of the sequence of discoveries/ ideas. It may—or may not—be the case that there's empirical evidence for e=mc^2, but such evidence as is produced is highly slender; your own examples use phrases like 'give a level of credence', 'correlated with', 'justifies' which suggest you're not happy about such evidence yourself. I agree the popular use of the equation must have had some influence. On the other hand, if there had been no other evidence, e.g. the heating caused by radium, it seems likely that nobody would have taken it very seriously - as cf. e.g. people like Rutherford's statements that the whole thing was moonshine. So far as I know, everyone agrees that it was the atomic pile experiments, credited to Fermi, that proved that huge energy release was possible, and it was only after this event that the huge expansion of effort took place. According to Phil Holland, not one person at Sellafield took the e=mc^2 idea seriously; they all regarded the energy as produced by rearrangement of the nucleus, and nothing to do with destruction of matter. Possibly we're just verbally shadow boxing here; looking back at your first (6 Sept) email possibly it's just the question of whether it had any effect at all. My guess is that if Einstein had never lived it wouldn't have made a scrap of difference, except perhaps there would have been less speculation and more secrecy about the whole thing. I haven't conducted high-energy physics experiments, but would be interested to know what possible weaknesses there are in the methodology. Regards Rae West |