The Manhattan Project was a top secret U.S. project begun in 1941 and ended in 1946 to develop the first atomic bombs. It was led by physicist Robert Oppenheimer and General Leslie Groves and employed over 600,000 people at its peak. The project culminated in the bombing of Hiroshima and Nagasaki in August 1945, which helped end World War II.

1. Presented By:
Pranamesh Chakraborty
Department of Civil Engineering
1st Year M.Tech (Transportation Engineering)
Indian Institute of Technology, Kanpur

2. The Manhattan Project
A top secret U.S. project
 Program to develop atom bombs
Began December 1941 & ended in 1946
(Source: The Manhattan Project by Diana Galer)

3. How it started
In 1933 the charismatic Hitler rose to power causing a
great fear and hatred for him among the Jewish people
including Albert Einstein
In 1938 Germany was able to split an uranium atom
and was getting more aggressive.
Physicists Leo Szilard and Eugene Winger became
concerned with the recent aggression by Germany
Leo and Eugene consulted with Einstein and they
wrote a letter to Roosevelt with his signature
Roosevelt received the Letter from Einstein on
October 11, 1939 from Alexander Sachs.
After Roosevelt read the Letter he assigned a
committee of people to study uranium chain reactions.

4. Albert Einstein Eugene Wigner
Leó Szilárd Franklin D. Roosevelt
(Source: The Manhattan Project by Diana Galer)

5. Source : http://www.fdrlibrary.marist.edu/index.html

6. American Involvement in World War II
Before 1941, U.S was acting as a supporting role for
Britain in World War II.
But on 7th Dec 1941, Imperial Japan’s First Air Fleet
launched a surprise attack against the United States
Navy (USN) based at Pearl Harbor in Hawaii.
361 Japanese warplanes attack American airfields and
shipyards, disabling 19 ships, destroying 200 planes, and
killing over 2300 men. Southeast Asia, Hong Kong, Malaya,
Philippines soon fell to Japan
On Dec 8, Congress approves entry into war. Germany
and Italy declare war on U.S.

7. Source: athenaphrodite.wordpress.com

8. Nuclear Programs: Germany
 Germany started experimenting with
Nuclear Fission in 1938.
 German scientist Otto Hahn, Fritz
Strassman, Max Born, Max Planck,
Heisenberg were involved in the
project.

9. Otto Hahn
German Chemist
Regarded as “the father of the
Nuclear Chemistry
Awarded Nobel Prize in 1944 in
Chemistry "for his discovery of
the fission of heavy atomic
nuclei."

10. Werner Heisenberg
German physicist
Awarded the Nobel Prize for Physics
in 1932 "for the creation of quantum
mechanics“.
"He lies here, somewhere."
This is a joke about the famous
Heisenberg Uncertainty Principle,
which implies that one may not know
the position and momentum of a
particle simultaneously.

11. Failure of the German Nuclear Program
 June 1942 – German atomic program slows down
because Germany felt victory in WWII was
imminent.
 When Adolf Hitler was in power, Hitler
encouraged many top scientists to leave Europe.

12. The Discovery of Fission
Henri Becquerel
• Discovered Radioactivity in
1896.
• Observed that Uranium
salts would expose
photographic film even when
covered with opaque paper.
(Source: The Manhattan Project by Diana Galer)

13. James Chadwick
• Discovered the neutron
in 1932.
• The neutron is a
particle that has the
same mass as a proton
with zero charge.
(Source: The Manhattan Project by Diana Galer)

14. Frederic and Irene
Joliot-Curie
• Discovered Artificial
Radioactivity in 1934
27
Al +
13
4
2α → 30
P
15 + 1
n
0
(Source: The Manhattan Project by Diana Galer)

15. Enrico Fermi
• Bombarded almost every
element in the Periodic
Table with neutrons.
• He came to the conclusion
that a new element
(transuranic element)
have been discovered by
bombarding Uranium with
neutrons.
(Source: The Manhattan Project by Diana Galer)

16. Walter and Ida Noddack
They suggested the possibility that
"it is conceivable that the nucleus
breaks up into several large fragments,
which would of course be isotopes of
known elements but would not be
neighbours of the irradiated element."
Ida Noddack
But, there were no theoretical basis
in support of it and hence the theory
was rejected by scientists like Otto
Hahn, Ernest Rutherford and others.
Source: Biswasghatak by Narayan Sanyal

17. Otto Hahn and Fritz Strassman
Fritz Strassman
Otto Hahn
In 1939, Otto Hahn and Fritz Strassman confirmed
through their experiments that the element was
not a trans-uranic element, but it was Barium only.
So, it confirmed that the fission of the nucleus of
an atom can be done by Neutron.
Source: Biswasghatak by Narayan Sanyal

18. Ping-pong Ball destroying a Fort
In 1919, Rutherford tried for nuclear fission with alpha- particles
having 3-7 MeV kinetic energy
Later on, Sir J. Cockcroft used proton (kinetic energy of the order
of MeV) for nuclear fission.
On the other hand, Neutrons have kinetic energy of the order
of eV only. Still it is able to produce nuclear fission .
The Reason is:
Source: physbot.co.uk

19. The Manhattan Project
Who Was In Charge?
 US physicist Robert Oppenheimer and
General Leslie R. Groves served as
directors of this project

20. •Robert Oppenheimer
•General Leslie R. Groves
•(Photo from U.S. National Archives, RG 77-BT)

21. The Manhattan Project (Contd.)
 Secret program from 1942-1946 in the U.S.
focusing on building the first atomic bomb
 Even Harry S. Truman did not know about the
project until Roosevelt’s death in 1945.
 Cost $ 2.2 Billion
 Employed more than 600,000 people
Approved by FDR with out direct
knowledge of Congress
Funds came from secret Presidential
accounts

22. Cost of Manhattan Project
In a meeting, the scientists told the production chief of
Manhattan Project, Daniel Bell that they require Silver
instead of Copper for their work as electrical conductivity
of silver is higher than that of copper.
Mr. Bell asked them how much silver they want?
The answer was: “For now, 15 thousand tons.”
Mr. Bell was astonished and told that silver is
measured in ounce, not in tons.
Their reply was: “5.4*108 ounce”
Source: Biswasghatak by Narayan Sanyal

23. Nuclear Reactions as an Energy
Source
•Uranium-235, a source
of nuclear power.

24. A typical fission reaction of U-235.
Source: Nuclear Chemistry by Cary R. Wilard

25. Schematic diagram of the cascading effect of a typical chain reaction initiated by a
single neutron.
Source: Nuclear Chemistry by Cary R. Wilard

26. The operation of fission bombs.
Source: Nuclear Chemistry by Cary R. Wilard

27. •The plutonium bomb use chemical
explosives arranged around a subcritical mass of
plutonium-239. When imploded by the explosives,
the increased density makes this mass supercritical.
Source: Nuclear Chemistry by Cary R. Wilard

28. •A subcritical-size cylinder of uranium-235 is fired
into the hole in a subcritical sphere of uranium-235
to make a supercritical mass of uranium-235.
Source: Nuclear Chemistry by Cary R. Wilard

29. Scientists Involved in Manhattan Project
Neils Bohr
Danish Physicist
Won Nobel Prize in Physics in
1922
During World War II, he fled
to Copenhagen to escape Nazis
prosecution under Hitler. He
travelled to Los Alamos, New
Mexico to work as a consultant for
the Manhattan Project.
He worked under the pseudonym
of Nicholas Baker in the
Manhattan Project.
Source: Biswasghatak by Narayan Sanyal

30. Scientists Involved in Manhattan Project (Contd.)
J. Robert Oppenheimer
Scientific Director of the
Manhattan Project.
A physicist at UC Berkeley
A strong communist in earlier
life.
Source: Biswasghatak by Narayan Sanyal

31. Scientists Involved in Manhattan Project (Contd.)
Richard Feynman
American theoretical physicist
Received Nobel Prize in Physics in
1965
Calculated the yield of the Fission
Bomb
Source: Biswasghatak by Narayan Sanyal

32. Scientists Involved in Manhattan Project (Contd.)
E.O.Lawrence
American Physicist
Received Nobel Prize in 1939
in Physics for invention of
Cyclotron.
Supervised magnetic
separation of 235U from 238U in
Manhattan Project.
Source: Biswasghatak by Narayan Sanyal

33. Klaus Fuchs
 Born in Germany and
came to Los Alamos as
part of the British
Mission
 Worked on the
explosive lens
Source: Biswasghatak by Narayan Sanyal

34. Los
Alamos
 Secret City in the Sangre de Christo Mountains in
New Mexico.
 The purpose was to design and build the bombs.
•(Photo from U.S. National Archives, RG 77-BT)

35. The TrinityTest
 “The Gadget” (code-name for the bomb) was
tested on July 16, 1945 in the desert of New
Mexico at 5:30 in the morning.
 After the blast Oppenheimer is remembered to
have quoted a portion of the Bhagavad Gita. “I
am become Death,” he said, “the destroyer of the
worlds.”

36. •(Photo from U.S. National Archives, RG 77-BT)

37. After explosion
•(Photo from U.S. National Archives, RG 77-AEC)

38. July, 1945
 With the war in Europe over, the Nazis and
Hitler defeated, President Truman gives
the Japanese an ultimatum.
 Potsdam Declaration in July 26, 1945

39. Japanese View of Unconditional
Surrender
 Emperor Hirohito was
totally against
unconditional
surrender.
 Americans viewed
Hirohito as a symbol of
military aggression
Source: Biswasghatak by Narayan Sanyal

40. Little Boy
Little boy was the codename used for the
atomic bomb dropped over Hiroshima on August
6th, 1945.
The uranium bomb, 3m (10 ft) long and 0.7 m (2.3 ft) in diameter, was called
“Little Boy.”
•(Photo from U.S. National Archives, RG 77-AEC)

41. The Enola Gay
 On August 6, 1945, the
B-29 Enola Gay, under
colonel Paul Tibbits left
Tinian airbase in the
West Pacific.
 The six hour flight went
exactly as expected.
 The bomb was armed
midway and clear
weather permitted for
accuracy.
•(Photo from U.S. National Archives, RG 77-AEC)

42.  Wind force- 980 miles per hour
 Temperature- 7,000 degrees F
 Killed immediately- 70,000 people
 Blast equivalent to 13 kilotons of TNT
 Buildings destroyed- 62,000 buildings
 Total deaths -150,000 people

43. A Shot of the Aftermath of Hiroshima.
•(Photo from U.S. National Archives, RG 77-AEC)

44. Bockscar
 Sometimes called Bock’s car.
 B-29 bomber Superfortress,
flown by Major Charles W.
Sweeney dropped
the “Fat Man” on August 9, 1945.
 The Bockscar didn't have enough
fuel to return to Tinian or Iwo
Jima, so Major Sweeney flew the
aircraft to Okinawa for an
emergency landing with
practically
dry fuel tanks.
•(Photo from U.S. National Archives, RG 77-AEC)

45. Fat Man
•(Photo from U.S. National Archives, RG 77-AEC)

46. What did bomb do?
 Initial blast killed about 50,000
people almost instantly.
 By the end of the year the total
killed passed 80,000 people.
 1 sq. mile of total destruction
 2-3 sq. miles of fires

47. A Shot of the Before & After Effects on Nagasaki.
•(Photo from U.S. National Archives, RG 77-AEC)

48. Truman’s Motivations
 Many historians believe that a main reason
for the use of the bomb was retaliation for
the surprise and brutal attack on Pearl
Harbor.
 After the bomb was dropped on Hiroshima,
Truman said “This is the greatest thing in
history.” and “Nobody is more disturbed over
the use of atomic bombs than I am but I was
greatly disturbed over the unwarranted
attack by the Japanese on Pearl Harbor.

49. VJ-Day
 Japan surrenders
unconditionally on
Aug. 14, 1945.
 Surrender signed in
Tokyo Harbor on
Sept. 2.
•(Photo from U.S. National Archives, RG 77-AEC)

50. The Treachery
On 14th Sept 1945, Truman received a letter from William
Lyon Mackenzie King, the President of Canada, informing
that the secrets of Manhattan Project and Atom Bomb has
been transferred to Soviet Union.
All necessary information were briefed in microfilm
(foolscap 8 pages only) and transferred within a CIGARETTE
PACKET.
It was transferred by Dexter(pseudonym) to Raymond
(pseudonym) on 11th August,1945.
Truman after receiving the letter told Henry L. Stimson,
the then Secretary of War, “This also requires action”
The investigation committee was headed by Col. Pash.
Source: Biswasghatak by Narayan Sanyal

51. The Atomic Spies
David Greenglass
Confessed that he gave crude schematics of lab
experiments to the Russians.
He was sentenced to 15 years inprisonment.
Julius and Ethel Rosenberg
Alleged to have been communist sympathizers
They were executed in the electric chair at Sing
Sing Prison

52. Who was Dexter ?

53. Klaus Fuchs
German-born British scientist and an integral part of the
Manhattan Project
Sentenced to 14 years imprisonment, but was released after
9 years.

54. Why?
The Manhattan Project made U.S.A. the sole owner of
the most disastrous weapon in world history, the ATOM
BOMB.
But the scientists who contributed in its discovery
were mostly foreigners, not Americans (except few like
Lawrence, Compton,etc).
But, the entire capital was invested by U.S.A
government.
Russia after getting information from Fuchs made
successful atom bomb test on 23rd Sept, 1949.
They were followed by Britain (1957), France (1960),
China (1964), India (1974).
This reduced the dominancy of U.S.A. to a great
extent.

55. Why?
After Fuchs was released, his father
told:
“Neither he nor I have ever blamed the
British people for his sentence. He
endured his fate bravely, with
determination and a clear conscience.
He said to himself ’If I don’t take this
step, the imminent danger to humanity
will never cease.’ I can only have
greatest respect for the decision he
took.”
Source: Biswasghatak by Narayan Sanyal

56. The monetary value of this treachery
The monetary value of this treachery can be found out
by solving a simple mathematical equation for the unknown
X (in $)
X*(X-10 )=0 9
Then X=?

57. Bibliography
•Sanyal Narayan, 1974, 'Viswasghatak (Traitor)', Dey's Publishing, Calcutta
•"Archival Milestones". National Archives and Records Administration. Retrieved
2011-03-31
•Galer,D. The Manhattan Project.
•Cary R. Wilard. Nuclear Chemistry
•American Nation in the Modern Era. New York: Holt, Rinehart and Winston, 2005.
•"The Manhattan Project: An Interactive History." Department of Energy - CFO
Home. 20 Apr. 2009. <http://www.cfo.doe.gov/me70/manhattan/index.htm>.
•"Key Issues: Nuclear Weapons: History: Pre Cold War: Manhattan Project."
Nuclear Files - From nuclear proliferation to nuclear testing, from Hiroshima to
North Korea, Nuclear Files offers the A to Z on nuclear issues. 26 Apr. 2009.
<http://www.nuclearfiles.org/menu/key-issues/nuclear-weapons/history/pre-cold-
war/manhattan-project/>.
•"The Manhattan Project." Travel and History. 26 Apr. 2009. <http://www.u-s-
history.com/pages/h1644.html>.
•http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB162/index.htm
•America: Pathways to the Present, Prentice Hall
•http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB162/index.htm
•http://www.loc.gov/index.html?gclid=CIrKuOifg4kCFQ2uSAod7irfAA