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Wednesday, August 07, 2002

The J Bomb

According to the Independent, newly discovered documents reveal that the Japanese were "days away" from dropping their own bomb.

I'm a physicist with an interest in the history of the atomic bomb, and I've read quite a bit on the subject. The only place that I've ever heard it suggested that Japan was working on an atom bomb was on Usenet, from the kind of people who construct elaborate theories on how Roosevelt knew details of Pearl Harbor in advance, but let it happen to draw the US into the war so

I can't say I've read every book, nor remembered all of the ones I have read, nor that the truth is presently contained in some published work. But I have never read that the US was concerned about the possibility of a Japanese bomb. They were concerned about a German bomb, and that nightmare fueled the Manhattan Project. Beginning in 1943, a group of scientists under the leadership of Sam Goudsmit, called the Alsos project, investigated Axis laboratories in areas which had been taken by the Allies. Their mission was to discover the status of any German atomic bomb projects. I have never read of a comparable project looking for evidence of a Japanese bomb (of course, that would've been after the war).

However, I don't really go by what I have or haven't read, or remembered of what I've read, but of what I know of atomic science of that period. The men who were the founders of modern physics were overwhelmingly European, and quite a few were Germans. Americans and others had to go to Germany, particularly to Gottingen, to study quantum physics. The people who built the atomic bomb were all students and colleagues of those Europeans
(plus not a few of the Europeans themselves who had escaped/defected). While there were almost certainly Japanese there, they were relatively rare and obscure.

So I don't believe that Japan had the depth and breadth of talent---that is, people working right on the cutting edge---to make a serious start on a bomb project. This is especially true after scientific papers on these subjects were suppressed beginning quite early in the war (or maybe before it). This is how American scientists (individuals I mean) knew something was up---when German papers on these sorts of topics suddenly dried up.

Furthermore, you don't just build an A bomb out of materials you might find lying around the log cabin. When the Manhattan Project started, no one knew which approach was going to work, whether uranium or plutonium was going to be easier to produce and work with, and which uranium enrichment process (U 235 must be separated from U 238) was going to be faster or more efficient. So all of them were tried. This resulted in three huge facilities in three different areas of the country, plus the lab at Los Alamos.

If the Japanese had made a start on acquiring materials necessary for their own bomb, these facilities surely would have been discovered after the war. And their war ended rather suddenly, so there would have been less time---and less incentive---to destroy documents and labs.

The Independent says a "dossier" was uncovered, and later refers to a "document". You don't keep plans for an A-bomb in a "document"; any dossier you have is going to be mighty big, because there are a lot of details. A clue might be in the often-overlooked word "device". A "device" is not a bomb. A bomb has to be delivered somehow, in the present case by plane. A "device" in this context could be a nuclear explosive which was too large and clumsy to be actually put into a plane and dropped on a target. But even this sounds to me to be more than the Japanese could muster at the time.

It's possible that the Japanese could have been given a leg up by information shared by the Germans (although I don't see them being willing to part with secrets of that caliber). However, I believe the Germans had not made much progress on their own bomb. They had the talent, but policy decreed that any weapons whose construction would take longer than a certain amount of time (I think this was two years) would not be pursued. (See the very interesting Hitler's Uranium Club by Jeremy Bernstein, which draws on transcripts of recordings of discussions that captured German scientists held among themselves while in detention in Britain. They were quite surprised that the Americans and British had been able to progress as far as an actual working bomb.)

Now, it's possible that the Japanese were taking steps toward an atomic weapon of their own, and had outlined some broad principles and concepts, and those documents are what were recently uncovered (sort of a straight version of the "How to Make an A-Bomb spoof document supposedly found in an Al Quaeda house in Kabul, and taken seriously by the Beeb). But I'm not buying the idea that they had a fully-fleshed version nearly ready. If nothing else, if they were literally "days away", they would've found a way to use it, or at least demonstrate it, for leverage, or as a bluff.

Disclaimer: I googled up a couple of facts for memory refresher, but most of this was written out of my own memory, which has become very faulty lately. Therefore, don't be surprised if it turns out I'm completely wrong.

OK. I lied. I'll be very surprised if it turns out I was completely wrong.