Slashdot Mirror
Followup To Bohr-Heisenberg Meeting
December writes "As a follow up to this slashdot article, "The family of Niels Bohr has decided to release all documents deposited at the Niels Bohr Archive, either written or dictated by Niels Bohr, pertaining specifically to the meeting between Bohr and Heisenberg in September 1941. There are in all eleven documents. The decision has been made in order to avoid possible misunderstandings regarding the contents of the documents."
See the Niels Bohr Archive at http://www.nba.nbi.dk/"
Written in the 60's, but never sent and never published. So this is new information.
Second, there has been a lot of speculation on what happened in Copenhagen in 1941. So much, in fact, that a book and play was written that speculated on the meeting.
These letters seem to cast a pretty serious shadow over the speculation that Heisenberg was secretly working against the Nazis and, for the first time, give us a clear answer to what Bohr's opinion had been.
The NY Times (evil reg, blah blah) has a lengthy article on the release of the documents.
-- Don't Tase me, bro!
One very important fact to remember is that the Russians (and Germans) around this time were using an incorrect estimate of the cross section of uranium, which did seem to indicate that sustained fission was not possible. The Americans managed to get a different (and later proven more accurate) measurement, which showed that a chain reaction was possible, this is one of the major reasons the Russians ended up so far behind at first in the atomic race.
The Germans and Russians certainly had a large initial lead in the more theoretical aspects of radiation and atomic physics, however this one incorrect measurement certainly threw the Russians so far off the track that it basically stopped their work in the area for quite a few years.
The Americans for a long time refused to believe how far behind the Russians were, and managed to loose much advantage by following politically 'suitable' beliefs rather than believing their own intelligence information, whcih turned out to be quite accurate with respect to the Russian position.
On the flip side, both of these men were great scientists, I personally feel it is immaterial whos 'side' they were on in a war.
Actually only one of the sites had required the huge demand for electricity. There are two methods discovery in the 1940's for separating Uranium isotopes. One method uses a electric field for separation, the other uses centrifical force. The U.S. decided to do both methods in case one didn't work. Later on, on the Centrifical method was used since it was a lot cheaper and easier to use.
Most likely the Germans would have not done both. Centrifical separation would be very easy for even a small country to achieve. Today Israel, Pakastan, India all have produced Nuclear weapons with relativity small programs.
As a note: Silver was used to produce an electrical conductor for the electric field separation process. The reason the U.S used silver was because copper was in short supply. The silver was on loan from the Federal Reserve and was later returned which at the time was just storage at Fort Knox.
There is a link here of history of the atomic bomb. Oh, and it includes directions on how one is built as well.
On August 2nd 1939, just before the beginning of World War II, Albert Einstein wrote to then President Franklin D. Roosevelt. Einstein and several other scientists told Roosevelt of efforts in Nazi Germany to purify U-235 with which might in turn be used to build an atomic bomb. It was shortly thereafter that the United States Government began the serious undertaking known only then as the Manhattan Project. Simply put, the Manhattan Project was committed to expedient research and production that would produce a viable atomic bomb.
This and this link describe the Japanese atomic bomb program. Germany sent a submarine to Japan carrying uranium oxide, a needed element in building an a-bomb, but it surrendered after Hitler's defeat and was confiscated by the U.S. This uranium could have been used in the atom bombs dropped on Hiroshima and Nagasaki.
Another good link is here.
There was reason to fear that Germany might win the race to produce the bomb. Fission had been discovered in Germany, and German scientists were at least as able as anyone else to assess its significance. Moreover, it seemed ominous that Germany had stopped the sale of uranium ore from the rich mines in Czechoslovakia. Up until mid-1941, concern over a German bomb had been stronger in Britain than in the United States. About that time, however, the sense of urgency began to pervade U.S. nuclear scientists.
--Metrollica
"Heisenberg could have been a hero or a villain, but he ended up being neither. "
Oh, he definitely was and still is (even after all these accusations) my hero. The guy had a big hand in developing QM. Cheers for his efforts.
-Shaunak.
Bohr didn't believe an atomic bomb was possible.
In this draft of a letter to Heisenberg, Bohr said that he had known about the possibility of a bomb for about three years.
Who else thought this was really sad? I makes me sick to see physics caught up in such horrible politics.
What most people don't seem to know is that Heisenberg didn't visit Bohr alone. Carl Friedrich von Weizsäcker was also there, and he is still alive today.
He gave an interview with the Süddeutsche Zeitung one or two days ago. His recollection of the meeting is rather interesting (the interview is in German, sorry).
Firstly, he says that Heisenberg started an A-bomb project in 1939, in which Weizsäcker took part, but by 1941 they came to the conclusion that they would not be able to succeed before the war was over. The problem was the tremendous effort needed to separate the isotopes. So from 1941 on they were only interested in building a reactor. Once that worked (it never did, as the heavy water production was sabotaged) there might have been the possibility to create Plutonium and build a bomb with that. But they didn't expect this to happen before the war was over by conventional means.
The reason Heisenberg went to see Bohr, according to Weizsäcker, was that they didn't want the Americans or the British to build a bomb either. If they stated publically that they're not working on a bomb, then of course nobody would have believed them. But Heisenberg thought that they might believe Bohr. So he hoped that Bohr could convince the Allies not to build the bomb either. This was not motivated by pure pacifism - he didn't want Germany to get nuked.
In 1941 the war looked pretty good for Germany, they were winning on all fronts. So basically Heisenberg believed that a German victory was inevitable, but with conventional weapons. He tried to explain this to Bohr, who was shocked. Bohr may have understood Heisenberg's "inevitable" to mean that he WAS working on a bomb, and planning to use it. But Weizsäcker suggests that Bohr may well have understood correctly, and didn't want the Germans to win (conventionally), and therefor figured that the Allies would have to build a bomb, to avoid a Nazi victory.
What we can accept as quite reliable, is the following: (a) Heisenberg did lead an A-bomb project from 1939 to 1941. (b) He came to the conclusion that he couldn't build a bomb before the war was over. (c) He continued working on a reactor from 1941 onwards (possibly with the option of producing Plutonium for later weapons use).
And what also seem quite plausible: (d) that he tried to convince Bohr that he was only working on a reactor, not a bomb. This is what he claimed afterwards, and is backed up by Weizsäcker. Many people might not believe these two, so here is another interesting piece of the puzzle:
I read some time ago, either in Physics Today or in Scientific American that when Bohr came to Los Alamos, he brought with him a sketch which Heisenberg had made during his 1941 visit. Bohr claimed it depicted a bomb which Heisenberg was building, but the people at Los Alamos recognised it as a heavy water reactor. As far as I remember, the sketch depicted a large bottle, filled with water (presumably heavy water, but only labelled "H2O"), and some stuff inside. Can anybody dig up this sketch on the net? At any rate, this strongly suggests that Bohr had misunderstood Heisenberg, and mistook Heisenberg's reactor for a bomb.
"...Look on my works, ye mighty, and despair!"
Than this.. there is more evidence than just the standard: "Bohr's word against Heisenbergs"
For instance, Gitta Serenys excellent
book "Albert Speer: His battle with truth".
(Albert Speer was the Nazi minister of armaments during the latter part of the war).
In the book Sereny notes that Speer, in a letter to a friend from Spandau prison after the war,
wrote of Heisenbergs engagement in developing an A-bomb, and how he had they had been short of funds.
According to the book, Speer remarked in the letter something to the extent of: "Now, I suppose he'll claim he didn't want the bomb built, and didn't ask for funding".
This is, in fact, what Heisenberg claimed after the war. However, Speer could not have known this, since the prisoners in Spandau were not allowed to read newspapers or have any correspondence with the outside world.
(With the exception of the contraband letters)
To me at least, this seems pretty incriminating,
especially together with the testimony of Bohr.
On the other hand, I would be careful to damn Heisenberg:
Just look at how the USA made a 'hero' out of Werner von Braun, a man who not only built missiles, he administrated the cruel and inhumane concentration camps where the missiles were manufactured.