Scientists of the Manhattan Project
Albert Einstein (left) and Leo Szilard after the war 
In early August 1939, Szilard drafted a letter in consultation with Einstein that was sent to President F.D. Roosevelt warning him of the possibility of nuclear weapons. Ten days after the President received the letter, the “Briggs Uranium Committee” held its first meeting in Washington, DC on President Roosevelt’s orders. MORE
The opening paragraph of the “Memorandum on the properties of a radioactive “super-bomb” 
In 1940, Otto Frisch and Rudolph Peierls, living in England, authored what would become known as the “Frisch-Peierls Memorandum,” which explained to the British government how a uranium fission bomb could become a weapon with the potential to win World War II. Greatly interested, the British government formed the “MAUD Committee” to coordinate further research into Frisch’s and Peierls’ extraordinary claims. MORE
concept of implosion in an atomic bomb 
By mid-May 1944, six months after the start of accelerated implosion
research, little progress towards successful implosion of the atomic bomb had
been made. Two British scientists joined Los Alamos who had important impacts on
the implosion program. Geoffrey Taylor pointed out implosion instability
problems (especially the Rayleigh-Taylor instability), which ultimately lead to
a very conservative design to minimize possible instability, and James Tuck
brought the critical idea of explosive lenses for detonation wave shaping.
Tuck’s method for producing a super-critical mass of plutonium for a
nuclear explosion was to fashion a sub-critical mass of Pu-239 in a spherical
shape and then set off high explosives to drive it inward.
He proposed a spherical shell of high-explosive material made up of
fitting pieces called “lenses” to focus the explosion inward.
The lenses were wired with detonators in order to set them off
simultaneously. Using the spherical
arrangement with lenses produces enough force to increase the density of the
sphere of plutonium to the point where it is supercritical .
The term supercritical means that more neutrons are produced than lost
(the neutron population increases) in a nuclear reaction.
This condition occurs when
k > 1,
where k is
the multiplication factor (net number of neutrons per initial neutron).
The multiplication factor, k, is determined from the four factor
formula which is the product of the reproduction factor, h,
the thermal utilization factor, ¦,
the fast fission factor, e,
the resonance escape probability,Ã,
and the non-leakage probabilities, L.
did the Germans fail at building a nuclear bomb? 
German’s discovered uranium fission in 1939, Nazi Germany had a three-year
head start in the research of an atomic bomb.
In the spring of 1940, a large part of the Kaiser Wilhelm Institute in
Berlin had been set aside for uranium research.
By 1941, Nazi Germany was leading the race for the atomic bomb.
They had a heavy-water plant, high-grade uranium compounds, a nearly
complete cyclotron, capable scientists and engineers, and the greatest chemical
engineering industry in the world. With
all these factors in the German’s favor, how did the German’s nuclear
program fail? There are many theories to this question.
Factors include internal struggles, a major scientific error (or maybe
not an error), and the devastation of total war compromised any successful
research. Unlike the American
program, the Germans never had a clear mission under continuously unified
 Reinhardt, Joachim. Pictures of Famous Physicists. http://www.th.physik.uni-frankfurt.de/~jr/portraits.html. April 4, 2002.
 Atomic Weapons Establishment (AWE). Frisch-Peierls Memorandum. http://www.awe.co.uk/main_site/about_awe/keeping_the_peace/1940.htm. April 28, 2002.
 Lawrence Livermore National Laboratory. Figures and Tables. http://www.llnl.gov/science_on_lasers/01Figure_list2.html. April 4, 2002.
 Nuclear Weapons. Hyperphysics. http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/bomb3.html. April 4, 2002.
 Holbert, Dr. Keith. Nuclear Concepts of the 21st Century. Arizona State University. Lecture, April 15, 2002.
 Australian National Botanic Gardens. http://www.anbg.gov.au/images/flags/nation/germany.gif. April 28, 2002.