I read once that the base commander found a note in his personal safe that said, “Guess who.”
If true, that may have been Richard Feynman’s handiwork. In “Surely You’re Joking, Mr. Feynman!”, he talks at length about taking up safecracking and lockpicking as hobbies while at Los Alamos on the Manhattan Project. He marveled at how superficial many of the security measures were (desks with huge locks on the front but removable back panels), and took great pleasure in freaking people out by re-arranging their papers or leaving nose-tweaking messages like this.
The story is true (although I’m not sure that’s what the note said, and I don’t feel like looking it up now), and it was Feynman. Here’s how he did it.
The standard government-issue safes at Los Alamos had a dial with 100 numbers and used a three-digit combination: 100x100x100=1 million possible combinations. It would seem impossible to figure out which of a million combinations it might be or to try all the possibilities. But Feynman thought there had to be a way to reduce the possibilities.
Playing around with a safe to which he had access, he found that the mechanism wasn’t very precise: if the combination number was five, and you turned the dial to four or six, it would open anyway. This reduces the possibilities substantially. Now instead of 1 million different combinations, it’s down to about 36,000 (33x33x33). Still too many to try in a reasonable amount of time, though.
But he had another brainwave. He realized that in choosing three numbers, most people would use a date. This may not seem so brilliant these days, when we’re constantly being told by security experts not to use birthdays for our passwords. But this was sixty years ago.
So with a dial precision of ±1, your possibilities are now 4x10x33 (i.e. months, days, and years all divided by 3) = 1,320. A substantially smaller number than 1 million. And you could probably go through half of them in an hour or two if you had to. But if you can find out your subject’s birthday, and those of his immediate family, you can probably get in in a minute or two. That’s how Feynman did it.
I know, it’s kind of like hearing how a magic trick is done: Of course! It’s so obvious! But Feynman figured it out himself. He was a genius.
Actually, if my not-looking-it-up memory is any better than commasense’s, the dials had a slop of ±2, so it was effectively only 20x20x20, or 8000. And Feynman also had a method of checking multiple combos rapidly: He figured out how one could set the first and second numbers and, without unsetting those, go through all the possibilities for the third, and then change the second number without unsetting the first. If I recall correctly, he figured that he could brute-force any safe in the facility in 8 hours this way, 4 on average.
He had other tricks, too. As noted, he tried dates and fundamental constants first (apparently, lots of physicists use things like pi and e), which often sped things up. He also developed a method for reading off two of the three digits, while a lock was opened: I think all he needed to do was to feel the inside of the dial. So he had almost the entire combination written down for many folks on the project.
The base commander, though, IIRC, was one he hadn’t spied out in advance, so when the situation came up where it was necessary to get into his safe when he wasn’t available, he called a locksmith, rather than face the prospect of having to spend hours and ruining his reputation. The locksmith was in and out in minutes, to Feynman’s amazement. It turns out that the locksmith’s secret was to just try the combo 50-100-50, that being the default put on the safes at the factory, before they’re reset by the end user.
I also did a certain amount of systematic study. For instance, a typical combination was 69-32-21. How far off could a number be when you’re opening the safe? If the number was 69, would 68 work? Would 67 work? On the particular locks we had, the answer was yes for both, but 66 wouldn’t work. You could be off by two in either direction. That meant you only had to try one out of five numbers, so you could try zero, five, ten, fifteen, and so on. With twenty such numbers on a wheel of 100, that was 8000 possibilities instead of the 1,000,000 you would get if you had to try every single number
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I practiced all the time on my own safe so I could do this process as fast as I could and not get lost in my mind as to which number I was pushing and mess up the first number. Like a guy who practices sleight of hand, I got it down to an absolute rhythm so I could try the 400 possible back numbers in less than half an hour. That meant I could open a safe in a maximum of eight hours – with an average time of four hours.
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We had no entertainment there at Los Alamos, and we had to amuse ourselves somehow, so fiddling with the Mosler lock on my filing cabinet was one of my entertainments. One day I made an interesting observation: When the lock is opened and the drawer has been pulled out and the wheel is left on ten (which is what people do when they’ve opened their filing cabinet and are taking papers out of it), the bolt is still down. Now what does that mean, the bolt is still down? It means the bolt is in the slot made by the three discs, which are still properly lined up. Ahhhh!
Now, if I turn the wheel away from ten a little bit, the bolt comes up; if I immediately go back to ten, the bolt goes back down again, because I haven’t yet disturbed the slot. If I keep going away from ten in steps of five, at some point the bolt won’t go back down when I go back to ten: the slot has just been disturbed. The number just before, which still let the bolt go down, is the last number of the combination!
I realized that I could do the same thing to find the second number: As soon as I know the last number, I can turn the wheel around the other way and again, in lumps of five, push the second disc bit by bit until the bolt doesn’t go down. The number just before would be the second number.
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I practiced and I practiced until I could get the last two numbers off an open filing cabinet, hardly looking at the dial. Then, when I’d be in some guy’s office discussing some physics problem, I’d lean against his opened filing cabinet, and just like a guy who’s jiggling keys absent-mindedly while he’s talking, I’d just wobble the dial back and forth, back and forth. Sometimes I’d put my finger on the bolt so I wouldn’t have to look to see if it’s coming up. In this way I picked off the last two numbers of various filing cabinets. When I got back to my office I would write the two numbers down on a piece of paper that I kept inside the lock of my filing cabinet. I took the lock apart each time to get the paper – I thought that was a very safe place for them.
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I’d be in there alone and I’d open the safe in a few minutes. All I had to do was try the first number at most twenty times, then sit around, reading a magazine or something, for fifteen or twenty minutes. There was no use trying to make it look too easy; somebody would figure out there was a trick to it! After a while I’d open the door and say, “It’s open.”[right]Richard Feynman, Surely You’re Joking, Mr. Feynman[/right]
Feynman goes on to describe how he went to Oak Ridge and opened up a safe via the same method (having previously recovered the combination on an earlier trip and committed the numbers to memory), and then demonstrated to a colonel how he could open the colonel’s fancy ginormous safe (which used the exact same locking mechanism), to which the colonel’s response was to issue a memo telling people to change their locks if Dick Feynman had been in their office and secure the safe when he was around in the future. It’s an excellent read, even if (or perhaps espically if) you’re not technically inclined; they’re all anecdotes that Feynman relayed to Ralph Leighton and later transcribed to be edited by Feynman. It does show a kind of happy-go-lucky persona which is somewhat at odds with reality (Feynman could be quite cranky, especially when dealing with people he felt were intentionally ignorant or crackpots) but it’s an easy read that you can pick up for a few minutes and enjoy.
Anyway, people like this give security people fits, because they expose security flaws that are otherwise secure. Even though Feynman was simply expressing his intellectual curiosity about how things work and was forthright about the security problem, it now exposes another way that some less than scrupulous person could obtain a vast amount of secure information, and just telling people to “keep your safe closed” is an inadequate solution, but installing new locking mechanisms would be a large cost and disruption. So instead of fixing the problem, they try to obscure it.
Stranger
Which sort of sums up the vast majority of most post-9/11 security “enhancements.” “Security theater” as someone has dubbed them. Imagine the field day that Feynman would have with the TSA!
Heisenberg concluded or was he merely uncertain that it could be done?
I believe that the team deduced that you could not get a sufficiently energetic reaction quickly enough to get significant yield before the device blew itself a part (what is referred to as a fizzle). The basic assumption is true for a gun-type bomb using plutonium, and IIRC they decided it was prohibitively complex (to a point of impossibility, certainly for the meager resources available to them) of separating enough [sup]235[/sup]U to a sufficent level of purity to make a weapon. The more complex plutonium implosion device used in Fat Man was beyond their theoretical and computational capabilities to design (and indeed, it stretched the limits of what the British and Americans could do with an essentially unmetered bank account.) In any case, no significant efforts toward a viable weapon were made by the Heisenberg team, and in fact they never produced a critical, self-sustaining reaction necessary to produce weaponizable material. There was a second team under strictly military control which may or may not have gotten further (there are allegations, mostly unsubstantiated, that they did in fact build and text crude fission devices) but most historians believe that they were far from producing a viable weapon, and relatively little funding was provided to either project, certainly in comparison to the jet interceptor and V-2 programs.
Stranger
Offhand, I don’t think there’s any evidence that Heisenberg even considered a gun-type assembly - or indeed any assembly method at all - while in Germany. He certainly sketches out the idea as part of the lecture he gave at Farm Hall on August 14th 1945. However, there’s no obvious indication from what he says that this is something he’s discussed before and no indication from the questions asked by the other detainees that they’d heard of the idea before.
The traditional debate about Heisenberg’s understanding has been about whether he understood the concept of critical mass for a bomb well enough during the war, not whether he had doubts about the assembly method. For all the various permutations that people have produced, there is agreement that he never got close to weaponising anything, so he never had to worry about such details. (Though those who argue that he understood the concepts clearly enough, but voluntarily hid them from the Nazi leadership, would no doubt take the Farm Hall lecture as evidence that he’d understood the gun-assembly device all along. But they don’t see any perceived technical problems as necessary to explain his “failure”.)
Stranger, for the Heisenberg “fizzle” I suspect you’re misremembering the suggestion that he was conceiving a bomb as a runaway reactor. But, on this view, he was thinking of the weapon having to consist of many tonnes of uranium. Not something that could be assembled during detonation, but equally not something that would be set off in that fashion.
There is the diagram found by Karlsch and Walker, but it almost certainly has nothing to do with Heisenberg. (Indeed, I suspect it was knocked together based on the Smyth Report.)
Uh, guys, I think you just got whooshed. CaveMike was making the obligatory Heisenberg Uncertainty joke. Although it does seem plausible that Heisenberg might have been deliberately sabotaging the Nazi project, a hypothesis to which bonzer referred. We’ll probably never know the truth on that point.
Marginal is an exaggeration. I grant you that the USSR scientists did not learn very much that they did not already know or could learn by themselves, but they got confirmation. That helped them close the gap to US research very quickly; much more quickly than anyone in the US had expected. At LANL, the scientists had to stumble about in the dark, while in the USSR, the scientists could look at our data and confirm whether or not they were on the right track.
It’s all a goofy story. Some US people thought Oppenheimer was a Soviet spy; Winston Churchill suspected Niels Bohr of being a spy! In fact, Oppenheimer told falsehoods to cover his friends, and Bohr pushed for an openness that the politicians of the time could not accept. None of the scientists could make it clear to the politicians or generals that the atomic bomb was not that much of a secret.
Yes, it was really like that. Rhodes book Dark Sun quotes the participants at length.
Fuchs and the others helped the USSR develop atomic bombs much more quickly than we expected. Rhodes points out that we were also freely handing over stuff to the USSR all during the war; it might not have been highly classified but it was certainly sensitive and gave the USSR what it otherwise might have taken many years to get on its own.
End result? Massive confusion. Many American scientists, Oppenheimer among them, lobbied against the hydrogen bomb on the grounds that it was expensive overkill. We had a huge head start in A-bomb technology; why build something even more powerful? General Groves predicted that the USSR would not have an A-bomb before 1960. Better to have international organizations that would make bombs unnecessary.
Then comes 1949 and the first USSR bomb. Suddenly Oppenheimer looks like a traitor for delaying H-bomb work, and we suddenly feel we need to have a better bomb than they do. The spies helped the USSR get the bomb quickly, and at a time when the world was still in upheaval. Not, IMHO, a good thing.
The real reason I intensely dislike what the spies did is not that they endangered the US per se, but that they naively gave such powerful information to a thoroughly evil dictatorship. These men and women were blindly stupid and so out of touch with reality that they thought the USSR system was better than the US system. I guess I can never accept that.
I’m not stating that this is the case, but one could argue that it was not necessarily naive.
After WWI there was a pretty big outbreak of anti-communism in the USA, it would not be difficult to predict a repeat performance after WWII.
If the USSR had felt itself the underdog, then it might have pushed to boundaries until the USA used atomic weopons.
After the Pakistanis achieved ‘parity’ with India, things calmed down a lot, sure an earthquake and cricket helped - but I reckon that ‘parity’ was a significant factor.
Personally I dislike nuclear proliferation, but uneven power balances might have been more dangerous with respect to the USSR and China.
It’s distinctly more complicated than that.
For a start, on at least one occasion Fuchs provided the Soviets with key information that came as a complete surprise to them: in February 1945 he tells them that spontaneous fission is a significant problem with plutonium and that Los Alamos is developing the implosion design as a solution. All this was news to Kurchatov. Again this was stuff they would probably have overcome themselves anyway, but it did mean they avoided the equivalent of the 1944 summer crisis at Los Alamos.
That he also provided details of the implosion design helped the Soviets, but copies of his diagrams and reports survive in Moscow and make it obvious that Beria was exagerating when he claimed that they were good enough to produce blueprints directly from. In practice all the engineering details - and it’s exactly these that make the implosion design difficult - had to be worked through as if from scratch.
How much Fuchs saved them has always been a matter of controversy. But that some in the US were immensely surprised at the time by the speed of the Soviet programme tells us far more about their prejudices than anything else. There were obvious tendencies in the immediate postwar years to both vastly overestimate the uniqueness of what had been done by the US and underestimate the capabilities of Soviet scientists. (Leslie Groves is an obvious example of someone who was prey to both, partly prompted by a large degree of self-flattery.) That they caught up in 4 years rather than a decade or two was not primarily because of espionage.
David Holloway (Stalin and the Bomb, 1994, Yale, p222) has summarised the more recent estimates as that intelligence saved them one to two years, which he regards as plausible, but speculative. As he points out, regardless of the espionage issue, they exploded a gun-design uranium weapon in 1951 anyway.
However, as Holloway also recognised, there’s a broader issue here. It’s the usual bias that restricts peoples’ attention to just designing the final bomb. It’s the same bias that reduces the Manhattan project to just Oppie and the guys up on the mesa, ignoring that the vast majority of the resourses involved had to be devoted elsewhere, with technical challenges no less daunting. While the Soviets knew about the likes of Hanford and Oak Ridge during the war, they had relatively little access to the details. As a result, they had to develop these aspects by themselves. Their strategy was not unlike the US’s: throw lots of resources at developing multiple alternative methods and see what works and what doesn’t. There was thus essentially no reduction of effort whatsoever in these areas.
The critical path on the Soviet project would possibly never have been the bomb design. What determined the timescale in practice for them was their initial shortage of uranium ore. They’d managed to seize some of the Belgian ore that had been taken to Germany and they could reopen Joachimsthal, but it took them time to establish a reliable supply by finding other deposits and that held the whole programme up. That it took them until 1949 wasn’t because they were waiting for Kurchatov’s team to iron out the design. Correspondingly, it’s not obvious that had they not had the espionage help in that area that they’d have taken much longer.