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Einstein–Szilard letter

March 10, 2023

The Einstein–Szilard letter was a letter written by Leo Szilard and signed by Albert Einstein on August 2, 1939, that was sent to President of the United States Franklin D. Roosevelt. Written by Szilard in consultation with fellow Hungarian physicists Edward Teller and Eugene Wigner, the letter warned that Germany might develop atomic bombs and suggested that the United States should start its own nuclear program. It prompted action by Roosevelt, which eventually resulted in the Manhattan Project, the development of the first atomic bombs, and the use of these bombs on the cities of Hiroshima and Nagasaki.

Facsimile of the Einstein–Szilard letter

Origin

 
Leo Szilard
 
Albert Einstein
The letter was conceived and written by Szilard, and signed by Einstein

Otto Hahn and Fritz Strassmann reported the discovery of nuclear fission in uranium in the January 6, 1939, issue of Die Naturwissenschaften, and Lise Meitner identified it as nuclear fission in the February 11, 1939, issue of Nature. This generated intense interest among physicists. Danish physicist Niels Bohr brought the news to the United States, and the U.S. opened the Fifth Washington Conference on Theoretical Physics with Enrico Fermi on January 26, 1939. The results were quickly corroborated by experimental physicists, most notably Fermi and John R. Dunning at Columbia University.[1]

Hungarian physicist Leo Szilard realized that the neutron-driven fission of heavy atoms could be used to create a nuclear chain reaction which could yield vast amounts of energy for electric power generation or atomic bombs. He had first formulated and patented such an idea while he lived in London in 1933 after reading Ernest Rutherford's disparaging remarks about generating power from his team's 1932 experiment using protons to split lithium. However, Szilard had not been able to achieve a neutron-driven chain reaction with neutron-rich light atoms. In theory, if the number of secondary neutrons produced in a neutron-driven chain reaction was greater than one, then each such reaction could trigger multiple additional reactions, producing an exponentially increasing number of reactions.[2][3]

Szilard teamed up with Fermi to build a nuclear reactor from natural uranium at Columbia University, where George B. Pegram headed the physics department. There was disagreement about whether fission was produced by uranium-235, which made up less than one percent of natural uranium, or the more abundant uranium-238 isotope, as Fermi maintained. Fermi and Szilard conducted a series of experiments and concluded that a chain reaction in natural uranium could be possible if they could find a suitable neutron moderator. They found that the hydrogen atoms in water slowed neutrons but tended to capture them. Szilard then suggested using carbon as a moderator. They then needed large quantities of carbon and uranium to create a reactor. Szilard was convinced that they would succeed if they could get the materials.[4]

Szilard was concerned that German scientists might also attempt this experiment. German nuclear physicist Siegfried Flügge published two influential articles on the exploitation of nuclear energy in 1939.[5][6] After discussing this prospect with fellow Hungarian physicist Eugene Wigner, they decided that they should warn the Belgians, as the Belgian Congo was the best source of uranium ore. Wigner suggested that Albert Einstein might be a suitable person to do this, as he knew the Belgian Royal Family.[7] Szilard knew Einstein well; between 1926 and 1930, he had worked with Einstein to develop the Einstein refrigerator.[8][9]

The letter

 
Wikisource has original text related to this article:
Albert Einstein to Franklin D. Roosevelt - August 2, 1939

On July 12, 1939, Szilard and Wigner drove in Wigner's car to Cutchogue on New York's Long Island, where Einstein was staying.[10] When they explained about the possibility of atomic bombs, Einstein replied: "Daran habe ich gar nicht gedacht" ("I did not even think about that").[11] Szilard dictated a letter in German to the Belgian Ambassador to the United States. Wigner wrote it down, and Einstein signed it. At Wigner's suggestion, they also prepared a letter for the State Department explaining what they were doing and why, giving it two weeks to respond if it had any objections.[10]

This still left the problem of getting government support for uranium research. Another friend of Szilard's, the Austrian economist Gustav Stolper, suggested approaching Alexander Sachs, who had access to President Franklin D. Roosevelt. Sachs told Szilard that he had already spoken to the President about uranium, but that Fermi and Pegram had reported that the prospects for building an atomic bomb were remote. He told Szilard that he would deliver the letter, but suggested that it come from someone more prestigious. For Szilard, Einstein was again the obvious choice.[7] Sachs and Szilard drafted a letter riddled with spelling errors and mailed it to Einstein.[12]

Szilard also set out himself for Long Island again on August 2. Wigner was unavailable, so this time Szilard co-opted another Hungarian physicist, Edward Teller, to do the driving. After receiving the draft, Einstein dictated the letter first in German. On returning to Columbia University, Szilard dictated the letter in English to a young departmental stenographer, Janet Coatesworth. She later recalled that when Szilard mentioned extremely powerful bombs, she "was sure she was working for a nut".[13] Ending the letter with "Yours truly, Albert Einstein" did nothing to alter this impression. Both the English letter and a longer explanatory letter were then posted to Einstein for him to sign.[13]

The letter dated August 2 and addressed to President Roosevelt warned that:

"In the course of the last four months it has been made probable – through the work of Joliot in France as well as Fermi and Szilard in America – that it may become possible to set up a nuclear chain reaction in a large mass of uranium, by which vast amounts of power and large quantities of new radium-like elements would be generated. Now it appears almost certain that this could be achieved in the immediate future.

This new phenomenon would also lead to the construction of bombs, and it is conceivable – though much less certain – that extremely powerful bombs of a new type may thus be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory. However, such bombs might very well prove to be too heavy for transportation by air."[14]

It also specifically warned about Germany:

"I understand that Germany has actually stopped the sale of uranium from the Czechoslovakian mines which she has taken over. That she should have taken such early action might perhaps be understood on the ground that the son of the German Under-Secretary of State, von Weizsäcker, is attached to the Kaiser-Wilhelm-Institut in Berlin where some of the American work on uranium is now being repeated."[14]

At the time of the letter, the estimated material necessary for a fission chain reaction was several tons. Seven months later a breakthrough in Britain would estimate the necessary critical mass to be less than 10 kilograms, making delivery of a bomb by air a possibility.[15]

Delivery

 
Roosevelt's reply

The Einstein–Szilard letter was signed by Einstein and posted back to Szilard, who received it on August 9.[13] Szilard gave both the short and long letters, along with a letter of his own, to Sachs on August 15. Sachs asked the White House staff for an appointment to see President Roosevelt, but before one could be set up, the administration became embroiled in a crisis due to Germany's invasion of Poland, which started World War II.[16] Sachs delayed his appointment until October so that the President would give the letter due attention, securing an appointment on October 11. On that date he met with the President, the President's secretary, Brigadier General Edwin "Pa" Watson, and two ordnance experts, Army Lieutenant Colonel Keith F. Adamson and Navy Commander Gilbert C. Hoover. Roosevelt summed up the conversation as: "Alex, what you are after is to see that the Nazis don't blow us up."[17]

Roosevelt sent a reply thanking Einstein, and informing him that:

"I found this data of such import that I have convened a Board consisting of the head of the Bureau of Standards and a chosen representative of the Army and Navy to thoroughly investigate the possibilities of your suggestion regarding the element of uranium."[18]

Einstein sent two more letters to Roosevelt, on March 7, 1940, and April 25, 1940, calling for action on nuclear research. Szilard drafted a fourth letter for Einstein's signature that urged the President to meet with Szilard to discuss policy on nuclear energy. Dated March 25, 1945, it did not reach Roosevelt before his death on April 12, 1945.[14]

Results

Roosevelt decided that the letter required action, and authorized the creation of the Advisory Committee on Uranium. The committee was chaired by Lyman James Briggs, the Director of the Bureau of Standards (currently the National Institute of Standards and Technology), with Adamson and Hoover as its other members. It convened for the first time on October 21. The meeting was also attended by Fred L. Mohler from the Bureau of Standards, Richard B. Roberts of the Carnegie Institution of Washington, and Szilard, Teller and Wigner. Adamson was skeptical about the prospect of building an atomic bomb, but was willing to authorize $6,000 ($100,000 in current USD) for the purchase of uranium and graphite for Szilard and Fermi's experiment.[19]

The Advisory Committee on Uranium was the beginning of the US government's effort to develop an atomic bomb, but it did not vigorously pursue the development of a weapon. It was superseded by the National Defense Research Committee in 1940,[20] and then the Office of Scientific Research and Development in 1941.[21] The Frisch–Peierls memorandum and the British Maud Reports eventually prompted Roosevelt to authorize a full-scale development effort in January 1942.[22] The work of fission research was taken over by the United States Army Corps of Engineers's Manhattan District in June 1942, which directed an all-out bomb development program known as the Manhattan Project.[23]

Einstein did not work on the Manhattan Project. The Army and Vannevar Bush denied him the work clearance needed in July 1940, saying his pacifist leanings and celebrity status made him a security risk.[24] At least one source states that Einstein did clandestinely contribute some equations to the Manhattan Project.[25] Einstein was allowed to work as a consultant to the United States Navy's Bureau of Ordnance.[26][27] He had no knowledge of the atomic bomb's development, and no influence on the decision of any being used.[14][24] According to Linus Pauling, Einstein later regretted signing the letter because it led to the development and use of the atomic bomb in combat, adding that Einstein had justified his decision because of the greater danger that Nazi Germany would develop the bomb first.[28] In 1947 Einstein told Newsweek magazine that "had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing."[24][29]

See also

Notes

  1. ^ Hewlett & Anderson 1962, pp. 10–13.
  2. ^ GB patent 630726, Leo Szilard, "Improvements in or relating to the transmutation of chemical elements", published 1949-09-28, issued 1936-03-30 
  3. ^ Lanouette & Silard 1992, pp. 132–136.
  4. ^ Hewlett & Anderson 1962, pp. 13–14.
  5. ^ Flügge, Siegfried (August 15, 1939). "Die Ausnutzung der Atomenergie. Vom Laboratoriumsversuch zur Uranmaschine – Forschungsergebnisse in Dahlem". Deutsche Allgemeine Zeitung (in German). No. 387, Supplement.
  6. ^ Flügge, Siegfried (1939). "Kann der Energieinhalt der Atomkerne technisch nutzbar gemacht werden?". Die Naturwissenschaften (in German). 27 (23/24): 402–410. Bibcode:1939NW.....27..402F. doi:10.1007/BF01489507. S2CID 40646390.
  7. ^ a b Hewlett & Anderson 1962, pp. 15–16.
  8. ^ U.S. Patent 1,781,541
  9. ^ Dannen, Gene (February 9, 1998). "Leo Szilard the Inventor: A Slideshow". from the original on August 20, 2020. Retrieved May 24, 2015.
  10. ^ a b Lanouette & Silard 1992, pp. 198–200.
  11. ^ Lanouette & Silard 1992, p. 199.
  12. ^ Lanouette & Silard 1992, pp. 200–201.
  13. ^ a b c Lanouette & Silard 1992, p. 202.
  14. ^ a b c d "Albert Einstein's Letters to President Franklin Delano Roosevelt". E-World. 1997. from the original on April 17, 2012. Retrieved October 9, 2013.
  15. ^ Gowing 1964, pp. 40–45.
  16. ^ Lanouette & Silard 1992, p. 207.
  17. ^ Hewlett & Anderson 1962, p. 17.
  18. ^ "President Roosevelt's response to Dr. Einstein Letter, Atomic Archive". Atomic Archive. from the original on October 22, 2013. Retrieved October 9, 2013.
  19. ^ Hewlett & Anderson 1962, pp. 20–21.
  20. ^ Hewlett & Anderson 1962, pp. 24–26.
  21. ^ Hewlett & Anderson 1962, p. 41.
  22. ^ Hewlett & Anderson 1962, p. 49.
  23. ^ Hewlett & Anderson 1962, p. 75.
  24. ^ a b c "The Manhattan Project". American Museum of Natural History. from the original on September 22, 2013. Retrieved October 9, 2013.
  25. ^ Genius, Albert Einstein, National Geographic 2017
  26. ^ "Einstein Exhibit – Nuclear Age". American Institute of Physics. from the original on March 30, 2014. Retrieved October 9, 2013.
  27. ^ "Prof. Einstein Working on Explosives for U.S. Navy Department". Jewish Telegraphic Agency. June 16, 1943. from the original on December 12, 2013. Retrieved October 9, 2013.
  28. ^ (PDF). The Philadelphia Bulletin. May 13, 1955. Archived from the original (PDF) on November 8, 2006.
  29. ^ "Einstein, the Man Who Started It All". Newsweek. March 10, 1947.

References

  • Gowing, Margaret (1964). Britain and Atomic Energy, 1935–1945. London: Macmillan Publishing. OCLC 3195209.
  • Hewlett, Richard G.; Anderson, Oscar E. (1962). The New World, 1939–1946 (PDF). Physics Today. Vol. 15. University Park: Pennsylvania State University Press. p. 62. Bibcode:1962PhT....15l..62H. doi:10.1063/1.3057919. ISBN 978-0-520-07186-5. OCLC 637004643.
  • Lanouette, William; Silard, Bela (1992). Genius in the Shadows: A Biography of Leo Szilárd: The Man Behind The Bomb. New York: Charles Scribner's Sons. ISBN 978-0-684-19011-2.

Further reading

  • Hargittai, István (2006). The Martians of Science: Five Physicists Who Changed the Twentieth Century. Oxford: Oxford University Press. ISBN 978-0-19-517845-6. OCLC 62084304.

External links

 
Wikimedia Commons has media related to Einstein-Szilárd letter.
 
Wikisource has original text related to this article:
Einstein–Szilard letter
  • Reproduction of 1939 Einstein–Szilárd letter
  • Roosevelt correspondence with Einstein and Szilárd, FDR library, Marist University
  • for the film Atomic Power (1946)

March 10, 2023
einstein, szilard, letter, letter, written, szilard, signed, albert, einstein, august, 1939, that, sent, president, united, states, franklin, roosevelt, written, szilard, consultation, with, fellow, hungarian, physicists, edward, teller, eugene, wigner, letter. The Einstein Szilard letter was a letter written by Leo Szilard and signed by Albert Einstein on August 2 1939 that was sent to President of the United States Franklin D Roosevelt Written by Szilard in consultation with fellow Hungarian physicists Edward Teller and Eugene Wigner the letter warned that Germany might develop atomic bombs and suggested that the United States should start its own nuclear program It prompted action by Roosevelt which eventually resulted in the Manhattan Project the development of the first atomic bombs and the use of these bombs on the cities of Hiroshima and Nagasaki Facsimile of the Einstein Szilard letter Contents 1 Origin 2 The letter 3 Delivery 4 Results 5 See also 6 Notes 7 References 8 Further reading 9 External linksOrigin Edit Leo Szilard Albert EinsteinThe letter was conceived and written by Szilard and signed by Einstein Otto Hahn and Fritz Strassmann reported the discovery of nuclear fission in uranium in the January 6 1939 issue of Die Naturwissenschaften and Lise Meitner identified it as nuclear fission in the February 11 1939 issue of Nature This generated intense interest among physicists Danish physicist Niels Bohr brought the news to the United States and the U S opened the Fifth Washington Conference on Theoretical Physics with Enrico Fermi on January 26 1939 The results were quickly corroborated by experimental physicists most notably Fermi and John R Dunning at Columbia University 1 Hungarian physicist Leo Szilard realized that the neutron driven fission of heavy atoms could be used to create a nuclear chain reaction which could yield vast amounts of energy for electric power generation or atomic bombs He had first formulated and patented such an idea while he lived in London in 1933 after reading Ernest Rutherford s disparaging remarks about generating power from his team s 1932 experiment using protons to split lithium However Szilard had not been able to achieve a neutron driven chain reaction with neutron rich light atoms In theory if the number of secondary neutrons produced in a neutron driven chain reaction was greater than one then each such reaction could trigger multiple additional reactions producing an exponentially increasing number of reactions 2 3 Szilard teamed up with Fermi to build a nuclear reactor from natural uranium at Columbia University where George B Pegram headed the physics department There was disagreement about whether fission was produced by uranium 235 which made up less than one percent of natural uranium or the more abundant uranium 238 isotope as Fermi maintained Fermi and Szilard conducted a series of experiments and concluded that a chain reaction in natural uranium could be possible if they could find a suitable neutron moderator They found that the hydrogen atoms in water slowed neutrons but tended to capture them Szilard then suggested using carbon as a moderator They then needed large quantities of carbon and uranium to create a reactor Szilard was convinced that they would succeed if they could get the materials 4 Szilard was concerned that German scientists might also attempt this experiment German nuclear physicist Siegfried Flugge published two influential articles on the exploitation of nuclear energy in 1939 5 6 After discussing this prospect with fellow Hungarian physicist Eugene Wigner they decided that they should warn the Belgians as the Belgian Congo was the best source of uranium ore Wigner suggested that Albert Einstein might be a suitable person to do this as he knew the Belgian Royal Family 7 Szilard knew Einstein well between 1926 and 1930 he had worked with Einstein to develop the Einstein refrigerator 8 9 The letter Edit Wikisource has original text related to this article Albert Einstein to Franklin D Roosevelt August 2 1939 On July 12 1939 Szilard and Wigner drove in Wigner s car to Cutchogue on New York s Long Island where Einstein was staying 10 When they explained about the possibility of atomic bombs Einstein replied Daran habe ich gar nicht gedacht I did not even think about that 11 Szilard dictated a letter in German to the Belgian Ambassador to the United States Wigner wrote it down and Einstein signed it At Wigner s suggestion they also prepared a letter for the State Department explaining what they were doing and why giving it two weeks to respond if it had any objections 10 This still left the problem of getting government support for uranium research Another friend of Szilard s the Austrian economist Gustav Stolper suggested approaching Alexander Sachs who had access to President Franklin D Roosevelt Sachs told Szilard that he had already spoken to the President about uranium but that Fermi and Pegram had reported that the prospects for building an atomic bomb were remote He told Szilard that he would deliver the letter but suggested that it come from someone more prestigious For Szilard Einstein was again the obvious choice 7 Sachs and Szilard drafted a letter riddled with spelling errors and mailed it to Einstein 12 Szilard also set out himself for Long Island again on August 2 Wigner was unavailable so this time Szilard co opted another Hungarian physicist Edward Teller to do the driving After receiving the draft Einstein dictated the letter first in German On returning to Columbia University Szilard dictated the letter in English to a young departmental stenographer Janet Coatesworth She later recalled that when Szilard mentioned extremely powerful bombs she was sure she was working for a nut 13 Ending the letter with Yours truly Albert Einstein did nothing to alter this impression Both the English letter and a longer explanatory letter were then posted to Einstein for him to sign 13 The letter dated August 2 and addressed to President Roosevelt warned that In the course of the last four months it has been made probable through the work of Joliot in France as well as Fermi and Szilard in America that it may become possible to set up a nuclear chain reaction in a large mass of uranium by which vast amounts of power and large quantities of new radium like elements would be generated Now it appears almost certain that this could be achieved in the immediate future This new phenomenon would also lead to the construction of bombs and it is conceivable though much less certain that extremely powerful bombs of a new type may thus be constructed A single bomb of this type carried by boat and exploded in a port might very well destroy the whole port together with some of the surrounding territory However such bombs might very well prove to be too heavy for transportation by air 14 It also specifically warned about Germany I understand that Germany has actually stopped the sale of uranium from the Czechoslovakian mines which she has taken over That she should have taken such early action might perhaps be understood on the ground that the son of the German Under Secretary of State von Weizsacker is attached to the Kaiser Wilhelm Institut in Berlin where some of the American work on uranium is now being repeated 14 At the time of the letter the estimated material necessary for a fission chain reaction was several tons Seven months later a breakthrough in Britain would estimate the necessary critical mass to be less than 10 kilograms making delivery of a bomb by air a possibility 15 Delivery Edit Roosevelt s reply The Einstein Szilard letter was signed by Einstein and posted back to Szilard who received it on August 9 13 Szilard gave both the short and long letters along with a letter of his own to Sachs on August 15 Sachs asked the White House staff for an appointment to see President Roosevelt but before one could be set up the administration became embroiled in a crisis due to Germany s invasion of Poland which started World War II 16 Sachs delayed his appointment until October so that the President would give the letter due attention securing an appointment on October 11 On that date he met with the President the President s secretary Brigadier General Edwin Pa Watson and two ordnance experts Army Lieutenant Colonel Keith F Adamson and Navy Commander Gilbert C Hoover Roosevelt summed up the conversation as Alex what you are after is to see that the Nazis don t blow us up 17 Roosevelt sent a reply thanking Einstein and informing him that I found this data of such import that I have convened a Board consisting of the head of the Bureau of Standards and a chosen representative of the Army and Navy to thoroughly investigate the possibilities of your suggestion regarding the element of uranium 18 Einstein sent two more letters to Roosevelt on March 7 1940 and April 25 1940 calling for action on nuclear research Szilard drafted a fourth letter for Einstein s signature that urged the President to meet with Szilard to discuss policy on nuclear energy Dated March 25 1945 it did not reach Roosevelt before his death on April 12 1945 14 Results EditRoosevelt decided that the letter required action and authorized the creation of the Advisory Committee on Uranium The committee was chaired by Lyman James Briggs the Director of the Bureau of Standards currently the National Institute of Standards and Technology with Adamson and Hoover as its other members It convened for the first time on October 21 The meeting was also attended by Fred L Mohler from the Bureau of Standards Richard B Roberts of the Carnegie Institution of Washington and Szilard Teller and Wigner Adamson was skeptical about the prospect of building an atomic bomb but was willing to authorize 6 000 100 000 in current USD for the purchase of uranium and graphite for Szilard and Fermi s experiment 19 The Advisory Committee on Uranium was the beginning of the US government s effort to develop an atomic bomb but it did not vigorously pursue the development of a weapon It was superseded by the National Defense Research Committee in 1940 20 and then the Office of Scientific Research and Development in 1941 21 The Frisch Peierls memorandum and the British Maud Reports eventually prompted Roosevelt to authorize a full scale development effort in January 1942 22 The work of fission research was taken over by the United States Army Corps of Engineers s Manhattan District in June 1942 which directed an all out bomb development program known as the Manhattan Project 23 Einstein did not work on the Manhattan Project The Army and Vannevar Bush denied him the work clearance needed in July 1940 saying his pacifist leanings and celebrity status made him a security risk 24 At least one source states that Einstein did clandestinely contribute some equations to the Manhattan Project 25 Einstein was allowed to work as a consultant to the United States Navy s Bureau of Ordnance 26 27 He had no knowledge of the atomic bomb s development and no influence on the decision of any being used 14 24 According to Linus Pauling Einstein later regretted signing the letter because it led to the development and use of the atomic bomb in combat adding that Einstein had justified his decision because of the greater danger that Nazi Germany would develop the bomb first 28 In 1947 Einstein told Newsweek magazine that had I known that the Germans would not succeed in developing an atomic bomb I would have done nothing 24 29 See also EditAlexander Sachs role in bringing President Roosevelt s attention to the possibility of an atomic bomb Frisch Peierls memorandum List of most expensive books and manuscripts Nuclear weapons and the United States Szilard petitionNotes Edit Hewlett amp Anderson 1962 pp 10 13 GB patent 630726 Leo Szilard Improvements in or relating to the transmutation of chemical elements published 1949 09 28 issued 1936 03 30 Lanouette amp Silard 1992 pp 132 136 Hewlett amp Anderson 1962 pp 13 14 Flugge Siegfried August 15 1939 Die Ausnutzung der Atomenergie Vom Laboratoriumsversuch zur Uranmaschine Forschungsergebnisse in Dahlem Deutsche Allgemeine Zeitung in German No 387 Supplement Flugge Siegfried 1939 Kann der Energieinhalt der Atomkerne technisch nutzbar gemacht werden Die Naturwissenschaften in German 27 23 24 402 410 Bibcode 1939NW 27 402F doi 10 1007 BF01489507 S2CID 40646390 a b Hewlett amp Anderson 1962 pp 15 16 U S Patent 1 781 541 Dannen Gene February 9 1998 Leo Szilard the Inventor A Slideshow Archived from the original on August 20 2020 Retrieved May 24 2015 a b Lanouette amp Silard 1992 pp 198 200 Lanouette amp Silard 1992 p 199 Lanouette amp Silard 1992 pp 200 201 a b c Lanouette amp Silard 1992 p 202 a b c d Albert Einstein s Letters to President Franklin Delano Roosevelt E World 1997 Archived from the original on April 17 2012 Retrieved October 9 2013 Gowing 1964 pp 40 45 Lanouette amp Silard 1992 p 207 Hewlett amp Anderson 1962 p 17 President Roosevelt s response to Dr Einstein Letter Atomic Archive Atomic Archive Archived from the original on October 22 2013 Retrieved October 9 2013 Hewlett amp Anderson 1962 pp 20 21 Hewlett amp Anderson 1962 pp 24 26 Hewlett amp Anderson 1962 p 41 Hewlett amp Anderson 1962 p 49 Hewlett amp Anderson 1962 p 75 a b c The Manhattan Project American Museum of Natural History Archived from the original on September 22 2013 Retrieved October 9 2013 Genius Albert Einstein National Geographic 2017 Einstein Exhibit Nuclear Age American Institute of Physics Archived from the original on March 30 2014 Retrieved October 9 2013 Prof Einstein Working on Explosives for U S Navy Department Jewish Telegraphic Agency June 16 1943 Archived from the original on December 12 2013 Retrieved October 9 2013 Scientist Tells of Einstein s A bomb Regrets PDF The Philadelphia Bulletin May 13 1955 Archived from the original PDF on November 8 2006 Einstein the Man Who Started It All Newsweek March 10 1947 References EditGowing Margaret 1964 Britain and Atomic Energy 1935 1945 London Macmillan Publishing OCLC 3195209 Hewlett Richard G Anderson Oscar E 1962 The New World 1939 1946 PDF Physics Today Vol 15 University Park Pennsylvania State University Press p 62 Bibcode 1962PhT 15l 62H doi 10 1063 1 3057919 ISBN 978 0 520 07186 5 OCLC 637004643 Lanouette William Silard Bela 1992 Genius in the Shadows A Biography of Leo Szilard The Man Behind The Bomb New York Charles Scribner s Sons ISBN 978 0 684 19011 2 Further reading EditHargittai Istvan 2006 The Martians of Science Five Physicists Who Changed the Twentieth Century Oxford Oxford University Press ISBN 978 0 19 517845 6 OCLC 62084304 External links Edit Wikimedia Commons has media related to Einstein Szilard letter Wikisource has original text related to this article Einstein Szilard letter Reproduction of 1939 Einstein Szilard letter Roosevelt correspondence with Einstein and Szilard FDR library Marist University Einstein and Szilard re enact their meeting for the film Atomic Power 1946 Portals World War II Nuclear technology History of science Retrieved from https en wikipedia org w index php title Einstein Szilard letter amp oldid 1129612549, wikipedia, wiki, book, 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