207 lines
11 KiB
Markdown
207 lines
11 KiB
Markdown
---
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created_at: '2008-09-03T03:02:16.000Z'
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title: How two students built an A-bomb (2003)
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url: http://www.guardian.co.uk/world/2003/jun/24/usa.science
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author: ken
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points: 60
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story_text: ''
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comment_text:
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num_comments: 15
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story_id:
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story_title:
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story_url:
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parent_id:
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created_at_i: 1220410936
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_tags:
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- story
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- author_ken
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- story_293488
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objectID: '293488'
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year: 2003
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---
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It's one of the burning questions of the moment: how easy would it be
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for a country with no nuclear expertise to build an A-bomb? Forty years
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ago in a top-secret project, the US military set about finding out.
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Oliver Burkeman talks to the men who solved the nuclear puzzle in just
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30 months
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Dave Dobson's past is not a secret. Not technically, anyway - not since
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the relevant US government intelligence documents were declassified and
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placed in the vaults of the National Security Archive, in Washington DC.
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But Dobson, now 65, is a modest man, and once he had discovered his
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vocation - teaching physics at Beloit College, in Wisconsin - he felt no
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need to drop dark hints about his earlier life. You could have taken any
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number of classes at Beloit with Professor Dobson, until his recent
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retirement, without having any reason to know that in his mid-20s,
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working entirely as an amateur and equipped with little more than a
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notebook and a library card, he designed a nuclear bomb.
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Today his experiences in 1964 - the year he was enlisted into a covert
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Pentagon operation known as the Nth Country Project - suddenly seem as
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terrifyingly relevant as ever. The question the project was designed to
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answer was a simple one: could a couple of non-experts, with brains but
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no access to classified research, crack the "nuclear secret"? In the
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aftermath of the Cuban missile crisis, panic had seeped into the arms
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debate. Only Britain, America, France and the Soviet Union had the bomb;
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the US military desperately hoped that if the instructions for building
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it could be kept secret, proliferation - to a fifth country, a sixth
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country, an "Nth country", hence the project's name - could be averted.
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Today, the fear is back: with al-Qaida resurgent, North Korea out of
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control, and nuclear rumours emanating from any number of "rogue
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states", we cling, at least, to the belief that not just anyone could
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figure out how to make an atom bomb. The trouble is that, 40 years ago,
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anyone did.
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The quest to discover whether an amateur was up to the task presented
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the US Army with the profoundly bizarre challenge of trying to find
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people with exactly the right lack of qualifications, recalls Bob
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Selden, who eventually became the other half of the two-man project.
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(Another early participant, David Pipkorn, soon left.) Both men had
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physics PhDs - the hypothetical Nth country would have access to those,
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it was assumed - but they had no nuclear expertise, let alone access to
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secret research.
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"It's a very strange story," says Selden, then a lowly 28-year-old
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soldier drafted into the army and wondering how to put his talents to
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use, when he received a message that Edward Teller, the father of the
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hydrogen bomb and the grumpy commanding figure in the US atomic
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programme, wanted to see him. "I went to DC and we spent an evening
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together. But he began to question me in great detail about the physics
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of making a nuclear weapon, and I didn't know anything. As the evening
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wore on, I knew less and less. I went away very, very discouraged. Two
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days later a call comes through: they want you to come to Livermore."
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Livermore was the Livermore Radiation Laboratory, a fabled army facility
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in California, and the place where Dave Dobson, in a similarly surreal
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fashion, was initiated into the project. The institution's head offered
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him a job. The work would be "interesting", he promised, but he couldn't
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say more until Dobson had the required security clearance. And he
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couldn't get the clearance unless he accepted the job. He only learned
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afterwards what he was expected to do. "My first thought," he says
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today, with characteristic understatement, "was, 'Oh, my. That sounds
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like a bit of a challenge.'"
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They would be working in a murky limbo between the world of military
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secrets and the public domain. They would have an office at Livermore,
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but no access to its warrens of restricted offices and corridors; they
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would be banned from consulting classified research but, on the other
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hand, anything they produced - diagrams in sketchbooks, notes on the
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backs of envelopes - would be automatically top secret. And since the
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bomb that they were designing wouldn't, of course, actually be built and
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detonated, they would have to follow an arcane, precisely choreographed
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ritual for having their work tested as they went along. They were to
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explain at length, on paper, what part of their developing design they
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wanted to test, and they would pass it, through an assigned lab worker,
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into Livermore's restricted world. Days later, the results would come
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back - though whether as the result of real tests or hypothetical
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calculations, they would never know.
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"The goal of the participants should be to design an explosive with a
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militarily significant yield," read the "operating rules", unearthed by
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the nuclear historian Dan Stober in a recent study of the project
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published in the Bulletin of the Atomic Sciences. "A working context for
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the experiment might be that the participants have been asked to design
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a nuclear explosive which, if built in small numbers, would give a small
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nation a significant effect on their foreign relations."
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Dobson's knowledge of nuclear bombs was rudimentary, to say the least.
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"I just had the idea that \[to make a bomb\] you had to quickly put a
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bunch of fissile material together somehow," he recalls. The two men
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were assigned to one of Livermore's less desirable office spaces, in a
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converted army barracks near the facility's perimeter. Bob Selden found
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a book on the Manhattan Project that culminated in America's development
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of the bomb. "It gave us a road map," Dobson says. "But we knew there
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would be important ideas they'd deliberately left out because they were
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secret. This was one of the things that produced a little bit of
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paranoia in us. Were we being led down the garden path?"
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They faced one key decision, Dobson says: whether to design a gun-style
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bomb, like the one dropped on Hiroshima, that used a sawn-off howitzer
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to crash two pieces of fissile material together, or a more complex
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implosion bomb, like that dropped on Nagasaki. By now they were
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beginning to enjoy the challenge, so they went for the harder, more
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impressive option. "The gun device needed a large amount of material,
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and didn't make a very big bang," Dobson says. "The other one was more
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bang, less material."
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Dobson and Selden had decided to assume that their fictional Nth Country
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had already obtained the requisite plutonium - a huge assump tion, since
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it would be, almost certainly, the hardest part - but there was plenty
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more to consider. "Obtaining the fissile material is really the major
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problem - that drives the whole project," says Selden. "But the process
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of designing the weapon - I'm always careful to point out that many
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people overstate how easy it is. You really have to do it right, and
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there are thousands of ways to do it wrong. You can't just guess."
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As Stober's study noted, the two amateurs were ironically aided by
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information published as part of President Dwight Eisenhower's "Atoms
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for Peace" program, which spread word of the benefits of non-military
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nuclear power around the world. And Atoms for Peace was only the most
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prominent example of a fad for everything nuclear that propelled a huge
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amount of technical detail into the public domain.
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Eventually, towards the end of 1966, two and a half years after they
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began, they were finished. "We produced a short document that described
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precisely, in engineering terms, what we proposed to build and what
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materials were involved," says Selden. "The whole works, in great
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detail, so that this thing could have been made by Joe's Machine Shop
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downtown."
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Agonisingly, though, at the moment they believed they had triumphed,
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Dobson and Selden were kept in the dark about whether they had
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succeeded. Instead, for two weeks, the army put them on the lecture
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circuit, touring them around the upper echelons of Washington,
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presenting them for cross-questioning at defence and scientific
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agencies. Their questioners, people with the highest levels of security
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clearance, were instructed not to ask questions that would reveal secret
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information. They fell into two camps, Selden says: "One had been
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holding on to the hope that designing a bomb would be very difficult.
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The other argued that it was essentially trivial - that a high-school
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science student could do it in their garage." If the two physics
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postdocs had pulled it off, their result, it seemed, would fall
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somewhere between the two - "a straightforward technical problem, but
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one that involves some rather sophisticated physics".
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Finally, after a valedictory presentation at Livermore attended by a
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grumpy Edward Teller, they were pulled aside by a senior researcher, Jim
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Frank. "Jim said, 'I bet you guys want to know how it turned out,'"
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Dobson recalls. "We said yes. And he told us that if it had been
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constructed, it would have made a pretty impressive bang." How
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impressive, they wanted to know. "On the same order of magnitude as
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Hiroshima," Frank replied.
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"It's kind of a depressing thing to know, that it could be that easy,"
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Dobson says. "On the other hand, it's far better to know the truth." And
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the truth today, he is certain, is that terrorists - with a bit of luck
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and, crucially, access to the right materials - could easily build a
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nuclear bomb. "Back in the 50s, there were two schools of thought - that
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the ideas could be kept secret, and that the material could be locked
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up. Now? Well, hopefully the materials can still be locked up, but we
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all have our doubts about that." Obtaining sufficiently enriched fissile
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material could be difficult but, when it comes to creating the bomb, "It
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turns out it's not overwhelmingly difficult. There are some subtleties
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that are not trivial ... but an awful lot has been published. If you
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were a grad student today, and you reviewed the literature, a lot of
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pieces would fall into place."
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It was, relatively speaking, easy - so easy that both Selden and Dobson
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seem to have emerged from the Nth Country Experiment deeply troubled by
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their own capacities. Selden stayed in the military, on a career that
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sent him from Livermore to the army's other major research base, at Los
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Alamos, and is still a member of the US Air Force Scientific Advisory
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Board; he has been closely involved in planning how the US might respond
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to a nuclear terrorist incident. Dobson, meanwhile, felt so
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uncomfortable that he left the sector entirely. "It was one thing to
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work on a project which was hopefully going to illuminate the decision
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makers so they could see that weapons were easily designed," he says.
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"It was a rather different thing to go in and say, 'OK, for example,
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let's make a thermonuclear device that's only four inches in diameter.'
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That's an acceleration of the arms race, and I didn't really want to do
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that."
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Einstein was famously said to have commented that if he had only known
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that his theories would lead to the development of the atom bomb, he
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would have been a locksmith. Dave Dobson, having designed one, got a job
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as a teacher.
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