The scientist Edward Teller, according to one account, kept a blackboard in his office at Los Alamos during World War II with a list of hypothetical nuclear weapons on it. The last item on his list was the largest one he could imagine. The method of "delivery" — weapon-designer jargon for how you get your bomb from here to there, the target — was listed as "Backyard." As the scientist who related this anecdote explained, "since that particular design would probably kill everyone on Earth, there was no use carting it anywhere."1
Teller was an inventive, creative person when it came to imagining new and previously unheard-of weapons. Not all of his ideas panned out, of course, but he rarely let that stop his enthusiasms for them. He was seemingly always in search of a bigger boom. During the Manhattan Project, he quickly tired of working on the "regular" atomic bomb — it just seemed too easy, a problem of engineering, not physics. From as early as 1942 he became obsessed with the idea of a Super bomb — the hydrogen bomb — a weapon of theoretically endless power.
(One side-effect of this at Los Alamos is that Teller passed much of his assigned work on the atomic bomb off to a subordinate: Klaus Fuchs.)
It took over a decade for the hydrogen bomb to come into existence. The reasons for the delay were technical as well as interpersonal. In short, though, Teller's initial plan — a bomb where you could just ignite an arbitrarily long candle of fusion fuel — wouldn't work, but it was hard to show that it wouldn't work. Shortly after abandoning that idea more or less completely, Teller, with the spur from Stan Ulam, came up with a new design.
The Teller-Ulam design allows you to link bombs to bombs to bomb. John Wheeler apparently dubbed this a "sausage" model, because of all of the links. Ted Taylor recounted that from very early on, it was clear you could have theoretically "an infinite number" of sub-bombs connected to make one giant bomb.
The largest nuclear bomb ever detonated as the so-called "Tsar Bomba" of the Soviet Union. On 1961, it was exploded off the island of Novaya Zemlya, well within the Arctic Circle. It had an explosive equivalent to 50 million tons of TNT (megatons). It was only detonated at half-power -- the full-sized version would have been 100 megatons. It is thought to have been a three-stage bomb. By contrast, the the largest US bomb ever detonated was at the Castle BRAVO test in 1954, with 15 megatons yield. It was apparently "only" a two-stage bomb.
We usually talk about the Tsar Bomba as if it represented the absolute biggest boom ever contemplated, and a product of unique Soviet circumstances. We also talk about as if its giant size was completely impractical. Both of these notions are somewhat misleading:
1. The initial estimate for the explosive force of the Super bomb being contemplated during World War II was one equivalent to 100 million tons of TNT. As James Conant wrote to Vannevar Bush in 1944:
It seems that the possibility of inciting a thermonuclear reaction involving heavy hydrogen is somewhat less now than appeared at first sight two years ago. I had an hour's talk on this subject by the leading theoretical man at [Los Alamos]. The most hopeful procedure is to use tritium (the radioactive isotope of hydrogen made in a pile) as a sort of booster in the reaction, the fission bomb being used as the detonator and the reaction involving the atoms of liquid deuterium being the prime explosive. Such a gadget should produce an explosion equivalent to 100,000,000 tons of TNT.2
Teller was aiming for a Tsar Bomba from the very beginning. Whether they would have supported dropping such a weapon on Hiroshima, were it available, is something worth contemplating.
2. Both the US and the USSR looked into designing 100 megaton warheads that would fit onto ICBMs. The fact that the Tsar Bomba was so large doesn't mean that such a design had to be so large. (Or that being large necessarily would keep it from being put on the tip of a giant missile.) Neither went forward with these.
But remember that the original Tsar Bomba was actually tested at 50 megatons, which was bad enough, right? Both the US and the Soviet Union fielded warheads with maximum yields of 25 megatons. The US Mk-41, of which some 500 were produced, and the Soviet SS-18 Mod 2 missiles were pretty big booms for everyday use. (The qualitative differences between a 50 megaton weapon and a 25 megaton weapon aren't that large, because the effects are volumetric.)
3. Far larger weapons were contemplated. By who else? Our friend Edward Teller.
In the summer of 1954, representatives from Los Alamos and the new Livermore lab met with the General Advisory Committee to the U.S. Atomic Energy Commission. Operation Castle had just been conducted and had proven two things: 1. very large (10-15 megaton or so), deliverable hydrogen bombs could be produced with dry fusion fuel; 2. Livermore still couldn't design successful nuclear weapons.
Norris Bradbury, director of Los Alamos, gave the GAC a little rant on the US's current "philosophy of weapon design." The problem, Bradbury argued, was that the US had an attitude of "we don't know what we want to do but want to be able to do anything." This was, he felt, "no longer relevant or appropriate." The answer would be to get very definite specifications as to exactly what kinds of weapons would be most useful for military purposes and to just mass produce a lot of them. He figured that the strategic end of the nuclear scale had been pretty much fleshed out — if you can routinely make easily deliverable warheads with a 3 megaton yield, what else do you need? All diversification, he argued, should be on the lower end of the spectrum: tactical nuclear weapons.
When Teller met with the GAC, he also pushed for smaller bombs, but he thought there was still plenty of room on the high end of the scale. To be fair, Teller was probably feeling somewhat wounded: Livermore's one H-bomb design at Castle had been a dud, and the AEC had cancelled another one of his designs that was based on the same principle. So he did what only Edward Teller could do: he tried to raise the ante, to be the bold idea man. Cancel my H-bomb? How about this: he proposed a 10,000 megaton design.
Which is to say, a 10 gigaton design. Which is to say, a bomb that would detonate with an explosive power some 670,000 times the bomb that was dropped on Hiroshima.3
If he was trying to shock the GAC, it worked. From the minutes of the meeting:
Dr. Fisk said he felt the Committee could endorse [Livermore's] small weapon program. He was concerned, however, about Dr. Teller's 10,000 MT gadget and wondered what fraction of the Laboratory's effort was being expended on the [deleted]. Mr. Whitman had been shocked by the thought of a 10,000 MT; it would contaminate the earth.4
The "deleted" portion above is probably the names of two of the devices proposed — according to Chuck Hansen, these were GNOMON and SUNDIAL. Things that cast shadows.
The Chairman of the GAC at this time, I.I. Rabi, was no Teller fan (he is reported to have said that "it would have been a better world without Teller"), and no fan of big bombs just for the sake of them. His reaction to Teller's 10 gigaton proposal?
Dr. Rabi's reaction was that the talk about this device was an advertising stunt, and not to be taken too seriously.
Don't listen to Teller, he's just trying to rile you. Edward Teller: trolling the GAC. A 10,000 megaton weapon, by my estimation, would be powerful enough to set all of New England on fire. Or most of California. Or all of the UK and Ireland. Or all of France. Or all of Germany. Or both North and South Korea. And so on.
In 1949, Rabi had, along with Enrico Fermi, written up a Minority Annex to the GAC's report recommending against the creation of the hydrogen bomb. The crux of their argument was thus:
Let it be clearly realized that this is a super weapon; it is in a totally different category from an atomic bomb. The reason for developing such super bombs would be to have the capacity to devastate a vast area with a single bomb. Its use would involve a decision to slaughter a vast number of civilians. We are alarmed as to the possible global effects of the radioactivity generated by the explosion of a few super bombs of conceivable magnitude. If super bombs will work at all, there is no inherent limit in the destructive power that may be attained with them. Therefore, a super bomb might become a weapon of genocide.
If that doesn't apply to a 10,000 megaton bomb, what does it apply to?
Was Teller serious about the 10 gigaton design? I asked a scientist who worked with Teller back in the day and knew him well. His take: "I don't doubt that Teller was serious about the 10,000 MT bomb. Until the next enthusiasm took over." In this sense, perhaps Rabi was right: if we don't encourage him, he'll move on to something else. Like hydrogen bombs small enough to fit onto submarine-launched missiles, for example.
It's hard not to wonder what motivates a man to make bigger and bigger and bigger bombs. Was it a genuine feeling that it would increase American or world security? Or was it just ambition? I'm inclined to see it as the latter, personally: a desire to push the envelope, to push for the bigger impact, the biggest boom — even into the territory of the dangerously absurd, the realm of self-parody.
- Robert Serber, The Los Alamos primer: The first lectures on how to build an atomic bomb (Berkeley: University of California Press, 1992), page 4, fn. 2. [↩]
- Letter dated October 20, 1944 from James B. Conant to Vannevar Bush, Subject: Possibilities of a Super Bomb. Vannevar Bush-James B. Conant Files, Records of the Office of Scientific Research & Development, S-1, NARA, Record Group 227, folder 3. Quoted from Chuck Hansen, The swords of Armageddon: U.S. nuclear weapons development since 1945 (Sunnyvale, Calif.: Chukelea Publications, 1995), III-17. [↩]
- Actually, if you take the Hiroshima yield to be 15 kilotons, it comes out to a nice round 666,666 times the strength of the Hiroshima bomb. But the precision there seemed arbitrary and the symbolism seemed distracting, so I'm relegating this to just a footnote. [↩]
- Minutes of the Forty-First Meeting of the General Advisory Committee to the U.S. Atomic Energy Commission, July 12-15, 1954, on p. 55. [↩]