Heisenberg and the German Bomb

Operation Epsilon: Heisenberg and the German Bomb. Farm Hall transcripts. German Uranium Project

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Videos mentioned:
Critical Mass: when the atomic bomb got real https://youtu.be/LduH7613QXw
Physics of a Nuclear Explosion https://youtu.be/6VSrGDOrWXc
Series on Nuclear Weapons Physics https://www.youtube.com/playlist?list=PL_UV-wQj1lvUhNttvv4_KsYrQxHygj3Ey

Papers:
The History of ‘Hitler’s Atomic Bomb’ needs to be corrected, M. Popp (2015) https://onlinelibrary.wiley.com/doi/10.1002/bewi.201601794
Why Hitler Did Not Have Atomic Bombs, M. Popp (2021) https://www.mdpi.com/2673-4362/2/1/2
The Peculiarities of the German Uranium Project, M. Popp & de Klerk (2023) https://www.mdpi.com/2673-4362/4/3/40

Special thanks to:
– The Hoover Institution Archives for kindly allowing the use of the Alsos Mission Films, part of the Boris T. Pash papers
– the American Institute of Physics for permission to access and use the secret documents captured during the Alsos Mission, now part of the Samuel A. Goudsmit papers; and
– Professor Manfred Popp for internal communication and documents.

Affiliate links (may earn a commission)
The Night of the Physicists: Operation Epsilon https://amzn.to/483wpfZ
The Secret Recordings at Farm Hall https://amzn.to/41tJ4Gx
Operation Epsilon, The Farm Hall Transcripts https://amzn.to/472uBCA
Operation Epsilon https://amzn.to/476PWuD
Brighter Than a Thousand Suns: A Personal History of the Atomic Scientists https://amzn.to/48qrDsz
Heisenberg’s War: The Secret History of the German Bomb https://amzn.to/3tq8BUq
Alsos https://amzn.to/3RMXz4Z

Credits:
Alsos Mission Films, Boris T. Pash papers, Film reel 1, Hoover Institution Archives https://www.youtube.com/watch?v=K7K1l1Px6fY
Alsos Mission Films, Boris T. Pash papers, Film reel 2, Hoover Institution Archives https://www.youtube.com/watch?v=BrPH6nQ2qtY
Alsos Mission Films, Boris T. Pash papers, Film reel 3, Hoover Institution Archives https://www.youtube.com/watch?v=ucqlEqiO6Bg
Alsos Mission Films, Boris T. Pash papers, Film reel 4, Hoover Institution Archives https://www.youtube.com/watch?v=Xw3Huup5v-I
Operation Epsilon, National Archives and Records Administration https://discovery.nationalarchives.gov.uk/details/r/C4414534
A portrait of LTG Leslie R. Groves by U.S. Army, public domain
Alsos team at cache of uranium by AIP Emilio Segrè Visual Archives
Germany map by Freepik https://www.freepik.com/free-vector/germany-silhouette_761383.htm
Stern-Gerlach experiment by Theresa Knott under CC BY-SA 3.0 Deed https://creativecommons.org/licenses/by-sa/3.0/deed.en
Alsos members by U.S. Army, public domain
US map by Freepik https://www.freepik.com/free-vector/flat-design-usa-outline-map_24746646.htm
Quantum projection of S by Theresa Knott under CC BY-SA 3.0
Alsos aircraft by Mickey Thurgood, Samuel A. Goudsmit papers, 1921-1979. Niels Bohr Library & Archives, American Institute of Physics (AIP).
Semi-empirical mass formula diagram adapted from Daniel FR under CC BY-SA 3.0 Deed https://creativecommons.org/licenses/by-sa/3.0/deed.en
Farm-Hall by sps1955 under CC BY 2.0 Deed https://creativecommons.org/licenses/by/2.0/
Tape recorder by Cottonbro Studio on Pexels https://www.pexels.com/video/a-vintage-reel-tape-recorder-spinning-8382683/
Typewriter by KoolShooters on Pexels https://www.pexels.com/video/hands-typing-on-typewriter-6980271/
BBC radio microphone by Leif Jørgensen under CC BY-SA 4.0 Deed https://creativecommons.org/licenses/by-sa/4.0/deed.en
Critical mass by Fastfission, public domain
Heidelberg cyclotron, Samuel A. Goudsmit papers, 1921-1979. Niels Bohr Library & Archives, American Institute of Physics (AIP).
French cyclotron, Musée des Arts et Métiers, Paris by Edal under CC BY-SA 3.0 Deed https://creativecommons.org/licenses/by-sa/3.0/deed.en
Cyclotron diagram, Samuel A. Goudsmit papers, 1921-1979. Niels Bohr Library & Archives, American Institute of Physics (AIP).
Heidelberg cyclotron courtesy of Archives of the Max Planck Society, Berlin
Graphitkugel fuer Hochtemperaturreaktor by Stefan Kühn, public domain
Walther Bothe portrait courtesy of Archives of the Max Planck Society, Berlin
Haigerloch reactor replica by ArtMechanic under CC BY-SA 3.0 Deed https://creativecommons.org/licenses/by-sa/3.0/deed.en
Baseball card of Morris “Moe” Berg by Goudey, public domain
The Catcher Was a Spy poster by Animus Films/PalmStar Media/Serena Films/Windy Hill Productions
Heisenberg papers by Springer Berlin
Kosmische Strahlung cover by Springer Berlin
Particle cascade by Theturnipmaster under CC BY-SA 3.0 Deed https://creativecommons.org/licenses/by-sa/3.0/deed.en
Albert Speer by the German Federal Archive (Deutsches Bundesarchiv) under CC BY-SA 3.0 DE Deed https://creativecommons.org/licenses/by-sa/3.0/de/deed.en

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During World War II a secret British American effort known as the alus mission gather intelligence on the enemies weapons development at the end of the war the alus mission was ordered to execute operation Epsilon capture the most important nuclear scientists in Germany including otan valter gerlock Carl fedich from visaka and their most

Valuable Target verer Heisenberg the alsa mission was created by General Leslie Groves the director of the Manhattan Project with the assignment of investigating the enemy’s scientific developments mostly nuclear weapons research operation Epsilon had two objectives find out the truth about the German nuclear program and capture the

Scientist to keep them away from the French and the Soviets in addition to the scientist they also members found many loads of uranium that were quickly shipped to England as well as the last experimental nuclear reactor in the village of haalo in the south of Germany that would soon become part of the

French occupation Zone after taking their heavy water and uranium the reactor was dismantled and blown apart after nuclear fishion was discovered by otan and Fritz trustman and explained by Le Miner and OT frish scientists all over the world realize the consequences in April 1939 the physical chemist Paul hartek wrote a

Memorandum alerting the German war Ministry about the possibility of nuclear explosives this was just a couple of months before pyes and frish in England calculated the critical mass for a bomb that led to their historical memorandum which I have discussed in detail in previous videos coming from hartek his memorandum was taken

Seriously he was already the advisor for for the army weapons office or hwa and the director of the physical chemistry Department in Hamburg a position that he got after OT Stern one of the most influential experimentalists of his time and mentor of OT frish decided to leave Germany after heart’s report the hwa

Created a special research group to explore the military use of nuclear fishion called the uranium Club contrary to the Manhattan Project instead of collecting all the scientists in dedicated Laboratories for collaboration and sharing of resources three main groups spread over more than 20 institutions had to allocate this cars

Materials and funding in Hamburg led by PA hartek another in Berlin initially led by a less known physicist called Kurt dner and the third one in liik led by ver Heisenberg after being captured the scientists were taken to the American base establish in heidleberg to be interrogated by the physicist Samuel

Gmid for those familiar with quantum mechanics gmid is one of the theorist who proposed the existence of the electrons of spin in 1925 to explain the result of the famous experiment by OT Stern and wter gerlock in 1922 gerlock nominated 30 times to the Nobel Prize in physics was now a prisoner sitting

Across interrogation table from GMI one by one the scientists were questioned it was found that the Germans mostly work on Rea physics rather than a bomb and that their 21 experimental reactors failed to reach criticality mostly due to the lack of enough uranium and heavy water still their knowledge was too

Valuable to let them be captured by the Soviets from heidleberg they were moved to France and Belgium and along the way the group grew two weeks before the Trinity test on July 3rd 1945 the final group of 10 physicists and chemists was taken to a small Airfield to boore a

Shiny airplane you might know some of the names but I want to give you an idea of the incredible intellectual level of this group Verna heis Noel laurat in 1932 known by the general public for his uncertainty principle he was one of the architects of quantum physics and the

Most notable and respected theoretical physicist in Germany otan radiochemist who discovered nuclear fishion in 1938 and would be awarded a Nobel Prize in chemistry a few months later valter gerlak world famous for his remarkable experiment demonstrating the quantum nature of the electron spin during the war he served as a powerful

Administrator of the nuclear program and managed to get funding and relevant materials for Heisenberg’s and hands experiment Max Fon La novel laurate in 1914 for discovering x-ray defraction in crystals he was one of the seniors in the group and was not involved in the uranium Club Car fredrich V visaka

Heisenberg’s prot and one of the most brilliant young theorists before the war he discovered in parallel to H beta the CNO cycle a collection of nuclear fusion reactions that powers the Sun and more notably he developed the semiempirical mass formula The crucial mathematical description of protons and neutrons in atomic

Nuclei Paul herk physical chemist leading reactor design in Hamburg he has spent years in rather for’s Lab in Cambridge where in 1834 together with rather for and Mark olifant produced the first artificial nuclear fusion reaction and discovered traum he was also the world expert on heavy water and the

First to alert the hwa about the possibility of military applications of a nuclear Chain Reaction Carl vers physicist in charge of reactor construction at the Kaiser willham Institute in Berlin Kurt dipner one of the organizers of the uranium Club but not a famous Professor he developed the reactor design with uranium cubes in

Heavy water used in their most successful experiments the group was completed by Eric B and hortz King Junior scientist working on Reactor design and isotope separation in the book The Night of the physicists there is a passage about the scientist at the Belgian Airfield hesitant to board a small airplane with

With a known destination otan wondered if they would be dropped in the ocean to which Paul hartek humorously replied if the British really wanted to get rid of us in a crash they would not use such a brand new aircraft the flight took them to an

English Airfield and then a bus to an old Countryside house called Farm Hall the scientists were never charged and always treated as guests accommodation was great food was abandoned and they were no longer interrogated more importantly all the rooms were backed hidden microphones captur every conversation which would be quickly

Transcribed and translated into English the transcripts of these conversations were kept secret until 1992 today they can be found online and also as published books with extra commentary the now called farmhold transcripts reveal important information many conversations were between no more than two or three trusted men members

Which can be used to infer what the scientists knew but also what they didn’t know the guests spent over a month leaving peacefully in farm Hall mostly talking about physics politics worrying about their families and speculating about their future they even organized an informal physics seminar

They had access to newspaper a radio and even recent scientific Publications the evening of August 6th the British officer in charge of farm Hall took otan aside and inform him that a 20 kiloton atomic bomb was dropped over Hiroshima the report from that day indicates that Han was completely

Shattered by the news he felt personally responsible for the deaths of hundreds of thousands of people after being called down Han then joined the rest of the group and shared the news they could not believe that it was possible to separate large amounts of uranium 235 and they even rejected

The news as propaganda Heisenberg claimed that this was probably just a new type of high explosive equivalent to 20,000 tons of TNT to Which F Biser commented it correspond exactly to the factor CH to the four in the video physics of a nuclear explosion I show you how to determine the energy released

By The fici of 1 kilogram of uranium 235 which is equivalent to around 10 to the four tons of TNT this is a calculation that Heisenberg and the others of course also did and this is probably what Fon viser refers to at 900 p.m. they listened to the BBC Radio report about

The bomb which included more technical details they finally accepted that the bomb was real and began to speculate how it was done the amount of necessary resources and about possible isotop separation methods but quickly moved to justifications for why this could not be done in Wartime Germany and even blaming

One another it is important to emphasize that up to this moment the German scientists in particular Heisenberg were convinced that they were ahead of the world on nuclear research and they plan to use what they had learned as a bargaining chip During the Reconstruction of postwar German science

They had written reports outlining the use of their uranium machine as they called their nuclear reactor for power generation and even submarine propulsion they believed that they had invaluable and Noble insights and were proud of what they would share with the world world after the war the night of August

6th they realized not only that they were not ahead but they had lost the nuclear race if the Allies had built a bomb they must also have working nuclear reactors now they had nothing to offer historians of Science and some physicists keep debating some fundamental questions why did the

Germans fail to make an atomic bomb did the nuclear scientists really try to make a bomb for Hitler how much did Heisenberg understand about Bond physics personally I grew up with The Narrative of Heisenberg and his team sabotaged the bomb program for moral reasons it is the story that fisa pushed

Already at Farm Hall and that he repeated over and over again after the war it is also the thesis of the controversial and highly criticized book brighter than a thousand Sons along similar lines the book Heisenberg’s War the secret history of the German bomb was written by a Heber fan being a

Member of the same Club I loved this book when I read it many years ago however being interested in the facts I also read some opposing views one of the strongest is by Samuel gmid he was the scientist leading the alsos mission in Hager and heidleberg interrogating the

Scientists in his book alsos he describes the absence of a Nazi bomb due to incompetence Heisenberg and the others failed to build a bomb because they didn’t understand the necessary physics and Heisenberg could not tell the difference between a bomb and a runaway reactor however I find gmi’s

View Blur by personal emotions during the war he asked Heisenberg for help when his parents were sent to a concentration camp understandably gaus smid’s descriptions are filled with condescending comments and anger but some of his conclusions like Heisenberg never thought about plutonium have been proven wrong one of the most basic questions

About bomb design is the estimate of the critical mass during the war a range of values between 10 and 100 kilg of pure u235 circulated in German reports but there is no reference to the origin of this range or who calculated it the correct value is close to 100 kg so it

Is tempting to believe that the Germans were on the right track however Heisenberg usually named a critical mass close to 10 tons a range of values several orders of magnitude wide is meaningless to conclude anything back to August 6th at Farm Hall there is one conversation that is particularly interesting during a very

Private conversation between Han and Heisenberg away from the group Heisenberg estimates that thousands of mass spectrometers could produce 30 kg of pure u35 per year to which hand asked do you think they would need as much as that which is another way to ask what is critical mass Heisenberg reply is a

Startling quite honestly I have never worked it out as I never believed that one could get pure u235 this statement is disclosing if there is ever a film about operation Epsilon this would be one of those Revelations that would shock the viewers the critical mass is a step number one

In the development of a bomb it is what led pyal and fish to alert the British government that a nuclear bomb was possible the fact that Heisenberg never calculated the critical mass confirms again that they did not work on a bomb moreover this confession to hand must be

Taken seriously it makes him look like a traitor during wartime putting his life in danger it is definitely something that Heisenberg would not lie about after explaining to Han that slow neutrons cannot produce a nuclear explosion and that fast neutrons in pure u35 are needed which is all correct and

That I explained in detail in the video nuclear bomb versus nuclear reactor Han asked an important question how does the bomb explode here Heisenberg gives a long and incorrect description of the physics of a nuclear explosion let me show you what Heisenberg did and why he got it

Wrong as explained in the physics of a nuclear explosion 1 kilogram of uranium 235 contains around 10 to the 24 nuclei in a nuclear Chain Reaction if each fast Neutron fishion in nucleus producing two secondary neutrons the number of fishion grows exponentially as due to the K doubling after each generation

Heisenberg realized that the ficient of 1 kilogram of uranium 235 requires 81 Generations because 2 to the 81 is approximately 10 to the 24 then he correctly reasoned that the distance between fishion is given by the fishion mean-free path close to 6 cm with the values at the time with this he

Calculated the critical radius in a wrong way he considered the process to be a random walk where a neutron bounces in random directions within the uranium fishing nuclei with each Collision the average distance traveled by a random worker giv n steps of size Lambda is

Lambda time the sare RO TK of n so Heisenberg multiplied the mean free path by the square root of the number of generations to get a critical radius of 54 cm much higher than the correct value close to 11 cm and the overly optimistic 2 cm of PES on frish with this radius

Heisenberg got a critical mass of 13 metric tons this is where Heisenberg got the 10 ton value for the critical mass although he got the critical radius wrong only by a factor five the critical mass is proportional to the critical radius to the third power so he got the

Critical mass about 120 times larger than the correct one it took a full week for Heisenberg to realized how wrong his calculation was and the reason for his mistake on August 14 he gave a lecture to the rest of the group in which he finally uses diffusion Theory just like

Pyal and frish Heisenberg solved the neutron diffusion equation and found a critical radius of 13.5 CM very close to the correct value he finally and evidently for the first time calculated the correct critical mass solving the diffusion equation is an exercise that every physics student has done several times thus solving this

Equation was a trivial task for Heisenberg and for his audience to follow but applying the fusion Theory to the neutrons in a nuclear chain reaction was clearly a conceptual jump new for everyone this whole episode confirms again that the Germans did not work on a bomb Heisenberg’s lecture also showed that

Once he got intensely interested in the problem he was able to solve it in just a few days as a side note in the video about critical mass I asked if you would like me to show you how to solve the neutron diffusion equation and the response has been an overwhelming yes

Despite the high level of math involved this deserves its own video and is coming soon so what did the members of the uranium Club do during the war as indicated earlier most reactor research in February 1942 the Iranian Club presented a complete report to the hwa reviewing their progress in the past few

Years nuclear physicist Manfred pop has carefully studied the hwa report and argues that many parts have been misrepresented in a natural pop presents evidence that the German scientists had little interest in answering basic scientific questions like cross-sections and other crucial figures that they could have easily measured they had

Valter B cyclotron in heidleberg and access to cyclotrons in Paris and Copenhagen so they could have easily separated a few milligrams of u235 to measure its Key Properties fundamental calculations like Heisenberg’s critical mass were never revised nobody questioned them valter B is usually blamed for ruling out graphite as a

Moderator for the reactors but nobody repeated his measurements the issue with this material was that industry grade graphite contains Boron a great neutral absorber that completely ruins the graphite but according to pop letters between Heisenberg and the seens company show that highly pure graphite could have being manufactured in Germany

At the time this is exactly what Leo tillard and enrio fery did in the US for their Chicago pile discarding graphite and choosing heavy water to moderate the reactor led to years of delays there is also the fact that the different groups never joined forces and resources to

Achieve the goal they could have reached criticality by combining their reserves of uranium and heavy water regarding a bomb there is only one report about uranium explosives cited in the hwa report written by Paul Mueller the only Nazi physicist in the uranium Club he was a former student of shinger that had

Just graduated Heisenberg gave him the task to the cherine the uranium enrichment needed for an explosion Mueller found it to be at least 70% leading to the conclusion that a bomb Was Out Of Reach Additionally the hwa report makes no mention of fishion of u235 by fast

Neutrons all the focus is on as low neutrons relevant for a reactor useless for a bomb in an article published in 20123 physicists manred pop and pep the clerk provide a list of what they called peculiarities of the German uranium project it is a fascinating read that agrees with my current personal

Interpretation of Heisenberg’s lack of interest in the bom project there is a story about Heisenberg visiting Switzerland to give a seminar in late 1942 the alsos mission considered kidnapping Heisenberg but this could lead to a diplomatic crisis so instead they sent to the seminar a physics trained baseball player spy

Named MO ber to evaluate whether Heisenberg was working on a bomb there’s a film about this called the catcher was a spy in this seminar Heisenberg presented his most recent work the S Matrix after the seminar Berg even went for a walk with Heisenberg to talk more

About physics with a gun on his pocket pointing at Heisenberg at all times bur concluded that there was no bomb and the alsos mission LED Heisenberg return to Germany I bring this story because of the topic of the seminar vs Matrix is an advanced methodology to describe collisions of fundamental particles and

I always founded baffling that Heisenberg developed this remarkable work and published a series of revolutionary papers while working on the uranium project I cannot imagine any of the Manhattan Project scientists taking time off the bomb project at Los Alamos to think develop and published research on fundamental physics

Heisenberg even took time to organize a small conference on mic Ray physics and then edited a book with the contributions published in 1943 which included four of the guests at Farm Hall during my doctorate I studied s matric Theory and cosmic ray physics and they are very Advanced topics so I got

Convinced that Heisenberg’s priority during the war was not the uranium project but fundamental physics or as Pop and the clerk put it Heisenberg Publications during World War II revealed his real scientific interests pop and the clerk include several other peculiarities and their explanation in a phenomenal manner their papers are open

Source so if you’re interested in this topic I highly recommend them the last opportunity for a German bomb came in June 1942 when the minister of armament Albert spur offered extra funding expecting a request for millions of reichmarks fun visaka only asked for 40,000 spare left the meeting convinced that

The uranium Club was just an academic research program the hwa gave up on the project and pass it to the research Council a sign that it was seen as Irrelevant for the war effort the hwa decided to focus on Rockets because contrary to the uranium project they offer short-term

Results the great irony is that the Allies were convinced that the Germans were working on nuclear weapons and they began them man hatam project officially started in August of 1942 2 months after the German military had completely given up on a nuclear bomb this video was sponsored by

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