Why did the Germans fall behind the Americans in the development of the atomic bomb after an initial lead?

Question

I actually know certain facts about this matter, but am seeking guidance in interpreting these facts into "theories."

1) Theory 1, Economic: The Americans spent something like $2 billion (in money of the time) to build the atomic bomb. Germany simply did not have that level of resources, meaning that her initial lead in atomic understanding was moot. Like other areas (e.g. tank production), American economic power "swamped" Germany even though Germany had superior quality.

2) Theory 2, Scientific: The balance of (scientific) power was held by Jewish scientists like Einstein, Fermi (his wife was Jewish, not Fermi himself), and Bohr, meaning that Germany could have built the bomb if it had stayed on good terms with these people. Fermi and America's Robert Oppenheimer were referred to as the "fathers" of the atomic bomb. Einstein was the "grandfather" insofar his atomic theories paved the way for the others' work. Bohr was notable for what he DIDN'T do (correct the mistakes of his former student, Germany's Werner Heisenberg).

Do either theory alone or both theories together explain why America took the lead in atomic development? Are there other reasonable theories that I may have missed?

I am trying to check the validity of the comments I made in answering this other question. At the end of WWII, were nazis working on any other super weapon besides V-2?

Answer 1

Germany had its own version of the Manhattan project know as Uranprojekt; here is a comparison between them.

In a project like an atomic bomb, the intellectual requirements are far greater than economic needs. No doubt, there is a minimum economic limit to carry out such a project, but Nazi Germany, when it started Uranprojekt in April 1939, still possessed the economic capability to make the atom bomb a success.

One of the main reasons for Germany to fall back on the atom bomb was the emigration of its nuclear scientists to America, when Adolf Hitler passed the Law for the Restoration of the Professional Civil Service; and when the induction of Nazi ideology into the education system was complete, the catalyst already started acting, and whole waves of intellectuals -- mainly from the physical sciences -- emigrated to the United States and to some extent the UK.

I quote the quantitative data on the emigration of German nuclear scientists to the United States from Wikipedia:

Out of 26 German nuclear physicists cited in the literature before 1933, 50% emigrated. Qualitatively, 10 physicists and four chemists who had won or would win the Nobel Prize emigrated from Germany shortly after Hitler came to power, most of them in 1933. These 14 scientists were: Hans Bethe, Felix Bloch, Max Born, Albert Einstein, James Franck, Peter Debye, Dennis Gabor, Fritz Haber, Gerhard Herzberg, Victor Hess, George de Hevesy, Erwin Schrödinger, Otto Stern, and Eugene Wigner.

Apart from this major downfall, there were a number of scientific reason for Germany not meeting the nuclear deadline:

• German scientists chose heavy water as the neutron regulator, which was not abundantly available in high quantities, whereas the Americans made it work with pure refined graphite.

• The Germans used plutonium for developing the A-bomb, but plutonium can only be obtained by fission in a reactor. Till 1945, the reactors produced plutonium in small quantities, which were not suitable for testing.

• To obtain the 98% pure Uranium-235 suitable for fission from the uranium ore required an elaborate array of cyclotron installations to enrich the uranium; by 1943 the tide of the war changed, and such resources stopped being available.

Other notable causes were the heavy water sabotage by the Norwegians, and a theory that Werner Heisenberg had deliberately bought the program to its knees by choosing heavy water, which is a poor and rare neutron regulator.

Answer 2

This was also a direct question in an interview with J. Robert Oppenheimer's biographer Ray Monk, which he chose to answer thus (approx. 16' into the program):

One of the aspects of the Manhattan project that is often not emphasized as much as it should is the sheer scale of the industrial operation. Two whole towns were created for doing nothing but producing fissile material, in Hanford in Washington and Oak Ridge in Tennessee. And the Germans did not have that, and that I think was the main reason why their project got nowhere.

The interview also contains several other interesting references e.g. to Werner Heisenberg's role as well as this quote by Winston Churchill :)

The reason we won the war is that our Germans were better than their Germans.

Answer 3

First, a correction on Deuterium; it is a hydrogen atom with a neutron as well as a proton in its nucleus, giving it an atomic mass of ~2 instead of ~1. Heavy water is a molecule with one hydrogen and one deuterium atom bonding to the oxygen, instead of two regular hydrogen bonding to the oxygen. It's chemical formula is DHO, (or sometimes colloquially but incorrectly D2O) compared to the H2O of regular water.

Now to the main point: Another reason for the inability of the Germans in WWII to develop the atomic bomb (as well as their inability to perfect numerous other possible weapon systems) is their determination to expend resources on everything. The economic resources of Germany were likely more than sufficient to build an atomic bomb faster; or to perfect a jet fighter sooner; or to complete the V1 and V2 programs a year earlier; but not to attempt all of the above and numerous others simultaneously while resource-starved.

Answer 4

I would say there were two main reason...

First off, they miscalculated badly on how much uranium it would take to make a bomb. Thus their calculations for how long time it would take to stockpile and enrich enough uranium was much too long. (German scientists captured by the USA and secretly under surveillance, were surprised by how little uranium was needed when they heard about the American bombs.)

Second, the Germans knew they needed a quick victory. They knew they couldn't stand against all the resources available to the USA for long, once the USA went on a war-footing and put all resources into making weapons. Partly due to the assumption about the amount of uranium needed, the Germans thus concluded that it would take too long to make an atomic-bomb. They wouldn't be able to create such a bomb for several years; and by then they would either 1)have had to already have won the war or 2)being overwhelmed by a fully militarized USA - in either case, a German atomic bomb wouldn't impact the result. Thus money, resources and scientists were allocated to other projects, while the atom-bomb was put on a back-burner.

IMHO there is no doubt the Germans could've succeeded and probably should have tried. They after all made some rather stunning invention; like V1, V2, jet-engines and rocket-planes... Imagine combining an a-bomb with a rocket. But by the time it was obvious the war would drag on, they'd lost too much time in the research of an a-bomb.

Answer 5

There is a relevant new publication on the topic:

Popp (2016) "Misinterpreted Documents and Ignored Physical Facts: The History of ‘Hitler's Atomic Bomb’ needs to be corrected"

"It is shown that until the end of the war the German physicists did not know that an atomic bomb can only be made with fast neutrons, except Heisenberg, who, however, discovered it rather late, did not communicate it clearly and did not study any bomb physics. The physically correct interpretation of the documents reveals that the German physicists worked unsuccessfully on a reactor, which would have been a prerequisite for a plutonium bomb. But they did not know how to build a bomb because they never worked on a realistic bomb theory."