Some interesting quotes.
(All from Wikipedia for convenience - generally accurate.)
Openheimer...
Quote:
Oppenheimer later recalled that while witnessing the explosion [of the 'Trinity' test bomb] he thought of a verse from the Hindu holy book, the Bhagavad Gita:
“ If the radiance of a thousand suns were to burst at once into the sky, that would be like the splendor of the mighty one... ”
Years later he would explain that another verse had also entered his head at that time:
“ We knew the world would not be the same. A few people laughed, a few people cried, most people were silent. I remembered the line from the Hindu scripture, the Bhagavad-Gita. Vishnu is trying to persuade the Prince that he should do his duty and to impress him takes on his multi-armed form and says, 'Now, I am become Death, the destroyer of worlds.' I suppose we all thought that one way or another.'[26] ”
According to his brother, at the time Oppenheimer simply exclaimed, "It worked."
Edward Teller:
Quote:
Despite (or perhaps because of) his hawkish reputation, Teller made a public point of noting that he regretted the use of the first atomic bombs on civilian cities during World War II. He further claimed that before the bombing of Hiroshima he had indeed lobbied Oppenheimer to use the weapons first in a "demonstration" which could be witnessed by the Japanese high-command and citizenry before using them to incur thousands of deaths. The "father of the hydrogen bomb" would use this quasi-anti-nuclear stance (he would say that he believed nuclear weapons to be unfortunate, but that the arms race was unavoidable due to the intractable nature of Communism) to promote technologies such as SDI, arguing that they were needed to make sure that nuclear weapons could never be used again (Better a shield than a sword was the title of one of his books on the subject).
However, there is contradictory evidence. In the 1970s, a letter of Teller to Leo Szilard emerged, dated on July 2nd, 1945:
"Our only hope is in getting the facts of our results before the people. This might help convince everybody the next war would be fatal. For this purpose, actual combat-use might even be the best thing."[15]
If a pair of left wing and right wing scientists who both worked on the bombs contradict themselves at the time and later... And let's not get trapped into the 'scientist who can't tie his shoelaces' myth. Both these men were very sharp - that's why they cut themselves as well as others.
Another scientist with a significant input to the Manhattan Project had the most amazing route to Los Alamos, directly from the heart of Occupied Europe. And yes, it's conceivable he could've been coerced into working for Germany; although how effectively, no-one could guess. His name was Niels Bohr, a Dane, and how he escaped in the bomb-bay of a wooden aircraft has to be one of the war's most amazing stories:
Quote:
Bohr and Werner Heisenberg enjoyed a strong mentor/protégé relationship up to the onset of World War II. Heisenberg had made Bohr aware of his talent during a lecture in 1922 in Göttingen. During the mid-1920s Heisenberg worked with Bohr at the institute in Copenhagen. Heisenberg, as most of Bohr's assistants, learned Danish. Heisenberg's uncertainty principle was developed during this period. Bohr's complementarity principle likewise. By the time of WWII, the relationship became strained because, among other reasons Bohr, with his Jewish heritage, remained in occupied Denmark, while Heisenberg remained in Germany and became head of the German nuclear efforts. Heisenberg made a now-famous visit to Bohr in September/October 1941, and during a private moment, it seems that he began to address nuclear energy and morality as well as the war effort. What was said is a matter of scholarly debate as neither Bohr nor Heisenberg spoke about it in any detail to outsiders nor left written records of this part of meeting at the time, and they were alone and outside. Bohr seems to have reacted by terminating that conversation abruptly thereby not giving Heisenberg any hints in any direction. While some suggest that the relationship became strained at this meeting, other evidence shows that the level of contact had been reduced considerably for some time already. One source, Heisenberg himself, suggests that the fracture occurred later. In correspondence to his wife, Heisenberg described the final visit of the trip: "Today I was once more, with Weizsaecker, at Bohr's. In many ways this was especially nice, the conversation revolved for a large part of the evening around purely human concerns, Bohr was reading aloud, I played a Mozart Sonata (A-Major)."[7]
The British intelligence services inquired about Bohr's availability for work or with insights of particular value. Bohr's reply made it clear that he could not help. This reply, just as his reaction to Heisenberg, made sure that, if Gestapo intercepted anything attributed to Bohr it would simply point to no particularly relevant knowledge regarding nuclear energy, as it stood in 1941. This does not exclude the possibility that Bohr privately did make calculations going further than his work in 1939 with Wheeler.
After leaving Denmark in the dramatic day and night (October 1943) when most Jews were able to escape to Sweden due to a series of very exceptional circumstances, Bohr was quickly offered, again, to join British efforts and he was flown to the UK for that purpose. He was evacuated from Stockholm in 1943 in an unarmed De Havilland Mosquito bomber (carried in an improvised cabin in the bomb bay) sent by the RAF. The flight almost ended in tragedy as Bohr did not don his oxygen equipment as instructed, and passed out. He would have died had not the pilot, surmising from Bohr's lack of response to intercom communication that he had lost consciousness, descended to a lower altitude for the remainder of the flight. Bohr's comment was that he had slept like a baby for the entire flight.
As part of the UK team on "Tube Alloys" Bohr was also included at Los Alamos. Oppenheimer credited Bohr warmly for his guiding help during certain discussions among scientists there. Discreetly, he met Roosevelt and later Churchill to warn against the perilous perspectives that would follow from separate development of nuclear weapons by several powers rather than some form of controlled sharing of the basic scientific knowledge, which would spread quickly in any case. Only in the 1950s, after the immense "surprise" that the Soviets could and did in fact develop the weapons independently, was it possible to create the IAEA along the lines of Bohr's old suggestion.
A BOAC Mosquito:

Quote:
BOAC
Between 1943 and the end of the war, Mosquitos were used as transport aircraft on a regular route over the North Sea between Leuchars in Scotland and Stockholm. Lockheed Hudsons and Lodestars were also used but these slower aircraft could only fly this route at night or in bad weather to avoid the risk of being shot down. During the long daylight hours of summer, the Mosquito was the only safe alternative.
Because Sweden was neutral, the aircraft carried civilian markings and were operated by Norwegian officers, who were nominally "civilian employees" of BOAC. They carried small, high value cargos such as precision ball bearings and machine-tool steel. Occasionally, important passengers were carried in an improvised cabin in the bomb bay, one notable passenger being the physicist Niels Bohr, who was evacuated from Stockholm in 1943 in an unarmed Mosquito sent by the RAF.
It's a fascinating world out there...