Talk:Manhattan Project

Semi-protected edit request on 29 July 2024

add internal link to the name of Vannevar Bush in the final paragraph of == Origins == Nikamavrody (talk) 06:19, 29 July 2024 (UTC)

 Not done: He's already linked on his first appearance. PianoDan (talk) 21:50, 30 July 2024 (UTC)

Manhattan Engineer District

Turns out that the actual name was "Manhattan Engineer District." Many sources have it as having been called the "Manhattan Engineering District", but the more reliable sources all use "Engineer", not "Engineering" (e.g., Rhodes pp. 426-427: "Nichols' previous boss, Colonel Marshall, had worked out of an office in Manhattan (where in August he had disguised the project to build an atomic bomb behind the name Manhattan Engineer District)... On Saturday Groves drafted a letter in the name of Donald Nelson, the civilian head of the War Production Board, assigning a first-priority AAA rating to the Manhattan Engineer District";
or Gosling p. 13, "Part III: The Manhattan Engineer District."

Geoffrey.landis (talk) 20:57, 23 September 2024 (UTC)

"While the legal designation of the new district was Manhattan District, it was often referred to as the Manhattan Engineer District" Jones, Manhattan: The Army and the Atomic Bomb, p. 44 Hawkeye7 (discuss) 21:22, 23 September 2024 (UTC)

Ore production tables

I think the tables here should be included.

The first table is very important as the text does not adequately contrast the gap in African and North American ore production and quality. It could probably be improved by cutting the octoxide column.

The second table is understandably mostly unnecessary as these companies are defunct and mostly irrelevant to the article, but a two-row table with just compound totals is important, as it shows the relative scarcity of metal and hexafluoride which were most relevant to the program, and the more separate production of tetrachloride. Doeze (talk) 00:41, 16 February 2025 (UTC)

What if I create a new article on the Manhattan Project feed materials program? This article could then incorporate the two tables. Hawkeye7 (discuss) 01:10, 16 February 2025 (UTC)

I think at least the first table should be included on this page, even cutting the site and company columns and Czechoslovak row. But the article is also a good idea, as it could incorporate the heavy water P9 project and the underrepresented nuclear graphite production. I would suggest Feed materials of the Manhattan Project in this case. Doeze (talk) 18:45, 16 February 2025 (UTC)

I have started work on the new article in my sandbox. It will be a few weeks before it is completed and I move it to the mainspace. Note that there is already an article on the P-9 Project Hawkeye7 (discuss) 19:04, 16 February 2025 (UTC)

I don't see the need for a detailed table in this overview article. If the relevant details they are meant to convey are just the orders of magnitude and U levels, those can be in the article text (and they are, in fact, although some is relegated to a note). If more specific trends are meant to be conveyed, then a graph would be better. --NuclearSecrets (talk) 22:07, 16 February 2025 (UTC)

@Doeze and NuclearSecrets: I have created the article on the Manhattan Project feed materials program. Hawkeye7 (discuss) 08:03, 7 March 2025 (UTC)

Sentences about Szilard were deleted

The story do not start with the "discovery" of nuclear fission, but with the invention of the idea of nuclear chain reaction in 1934. Szilárd’s 1934 patent outlined the principles of a neutron chain reaction, including moderators, critical mass, and potential military use—concepts far ahead of experimental verification. He proposed initiating reactions with indium, beryllium, bromine, or uranium.--Tubenoon (talk) 21:00, 17 September 2025 (UTC)

Yes, he had no idea of how it could be done. Only with the discovery of nuclear fission and the subsequent calculation of the critical mass of uranium-235 did work commence. Hawkeye7 (discuss) 22:18, 17 September 2025 (UTC)

He invented even the phrase "critical mass", and he made the first nuclear reactor with his close friend, Fermi.

Testimonies and historiography: In the literature on the Manhattan Project, multiple historians (for instance Rhodes in The Making of the Atomic Bomb) credit Szilárd with coining or at least introducing the term “critical mass” into common usage. It fit his role: he was the conceptual thinker who liked neat labels for key physical ideas.

Leo Szilard uniquely conceptualized the potential of a self-sustaining nuclear chain reaction at a time when most leading physicists considered the idea implausible or even absurd. As early as 1933, he recognized that a single neutron-induced nuclear event could trigger additional reactions, leading in principle to a self-amplifying release of energy. While the majority of contemporary scientists, including prominent figures such as Ernest Rutherford, dismissed the notion as speculative, Szilard maintained a steadfast belief in its feasibility.

Throughout the mid-1930s, Szilard undertook experimental work to validate aspects of neutron-induced transformations, exemplified by the Szilard–Chalmers effect (1934), demonstrating that neutron interactions could produce measurable, separable nuclear transmutations. Unlike his contemporaries, Szilard immediately recognized the broader implications of a chain reaction, both for controlled energy production in reactors and for the release of explosive energy in weapons. His 1934 patent (GB630726A) formalized this insight, explicitly describing a chain reaction capable of generating a large energy release.

Szilard’s intellectual foresight was later vindicated by the discovery of nuclear fission by Hahn and Strassmann in 1938, which provided the physical mechanism necessary for a self-sustaining reaction. While the engineering, enrichment, and large-scale plutonium production required the expertise of many scientists such as Fermi and Oppenheimer, the foundational **conceptual insight that a controlled or explosive chain reaction was physically possible originated solely with Szilard**, demonstrating both his originality and prescient understanding of nuclear physics.

Leo Szilard can be credited with originating the conceptual basis for the atomic bomb, while recognizing immediately its potential applications for both power generation and explosive devices (bomb), even though the detailed engineering and large-scale production required the contributions of many-many other scientists. In 1933, Szilard first realized that a single neutron-induced nuclear reaction could trigger further reactions in a self-sustaining chain, a conceptual insight that underlies both nuclear reactors and fission weapons. He immediately understood that such a reaction could be harnessed to release enormous energy, either in a controlled form for a nuclear reactor or in an uncontrolled, explosive form for a weapon. He formalized this idea in his 1934 British patent (GB630726A), which explicitly described a chain reaction capable of producing a large energy release.

Szilard's early experiments, including the Szilard–Chalmers effect (1934), demonstrated the physical reality of neutron-induced nuclear transmutations, providing a tangible ex — Preceding unsigned comment added by Tubenoon (talk • contribs) 17:51, 24 September 2025 (UTC)

Key Scientific Concepts Relevant to Explosive (Prompt-Critical) Chain Reactions

Note: The following are high-level scientific equations and definitions from standard reactor physics. They do not constitute weapon design parameters.

Key formulas, invented by Szilard: — Preceding unsigned comment added by Tubenoon (talk • contribs) 18:29, 24 September 2025 (UTC) Neutron Multiplication Factor (k, k_eff)

$k_{\text{eff}}={\frac {{\text{neutrons in generation }}n+1}{{\text{neutrons in generation }}n}}$

Interpretation: $k_{\text{eff}}>1$ → supercritical (growth); $k_{\text{eff}}=1$ → critical (steady); $k_{\text{eff}}<1$ → subcritical.

Reactivity (ρ) $\rho ={\frac {k_{\text{eff}}-1}{k_{\text{eff}}}}$ Interpretation: Small positive ρ indicates supercritical behavior. The value of ρ relative to the delayed-neutron fraction (β) determines the speed of the reaction. Reference: Nuclear Power

Prompt Criticality Condition

Prompt criticality occurs when $\rho \geq \beta _{\text{eff}}$.

Implication: The chain reaction is sustained by prompt neutrons alone, leading to power growth on a microsecond timescale—the fundamental regime of nuclear explosives.

Reference: Nuclear Power

Point-Kinetics Equations (Time-Dependent Neutron Population) ${\frac {dn(t)}{dt}}={\frac {\rho (t)-\beta }{\Lambda }}n(t)+\sum _{i=1}^{m}\lambda _{i}C_{i}(t)$

${\frac {dC_{i}(t)}{dt}}={\frac {\beta _{i}}{\Lambda }}n(t)-\lambda _{i}C_{i}(t)$

Interpretation: These equations quantify the timescales of reactivity excursions. When $\rho >\beta$, the term $(\rho -\beta )/\Lambda$ drives extremely rapid exponential growth.

Reference: mragheb.com

Subcritical Multiplication

$N={\frac {S_{0}}{1-k}}$ Interpretation: In a subcritical assembly, an external neutron source ($S_{0}$) produces an amplified steady-state neutron population (N). This concept was used experimentally to approach criticality. — Preceding unsigned comment added by Tubenoon (talk • contribs) 16:39, 24 September 2025 (UTC)

"Leo Szilard played a foundational role in the scientific development that ultimately enabled the creation of the atomic bomb. As early as 1933, he conceptualized that a neutron-induced reaction could trigger additional neutrons, potentially leading to a self-sustaining chain reaction. He formalized this concept in 1934 through a British patent (GB630726A), which laid out the possibility of producing large energy releases via nuclear reactions. That same year, Szilard, with T. A. Chalmers, demonstrated that neutron capture can chemically displace the resulting radioactive isotope, experimentally confirming the effects of neutron-induced transmutations.

In 1939, Szilard drafted the Einstein–Szilard letter, alerting President Roosevelt to the military potential of nuclear fission and prompting the U.S. government to support research into uranium and plutonium. From 1939 to 1942, he conducted neutron multiplication experiments with uranium and graphite, demonstrating the feasibility of sustained fission chains and laying the experimental groundwork for plutonium production.

Szilard also participated in the Chicago Pile-1 experiment in December 1942, the first controlled nuclear chain reaction, validating neutron multiplication and enabling the scale-up of plutonium-producing reactors. In 1944, Fermi and Szilard filed a patent for a neutronic reactor, codifying design concepts such as graphite moderation and uranium arrangements. Between 1942 and 1945, Szilard contributed to technical solutions for reactor control, including control rods, moderator purity, and cooling systems, which were directly relevant to producing fissile plutonium-239. Finally, in July 1945, he organized petitions signed by technical staff at the Metallurgical Laboratory, documenting the involvement of the scientific community at the moment the first atomic weapons were completed." — Preceding unsigned comment added by Tubenoon (talk • contribs) 17:02, 24 September 2025 (UTC)

Szilard's contributions after 1938 are already in the article, so we need only discuss his contributions before then. The discovery of the chain reaction is generally attributed to Max Bodenstein in 1913. I checked, and found the term in use in the 1920s. However, Szilard can be credited with the nuclear chain reaction. Have we got anything that says he appropriated the term? Hawkeye7 (discuss) 22:24, 24 September 2025 (UTC) Hawkeye7 (discuss) 22:24, 24 September 2025 (UTC)

Between 1933 and 1938, Leó Szilárd laid the intellectual foundations that make it entirely plausible to regard him as the true inventor of the atomic bomb. While later experimental breakthroughs and engineering efforts turned the weapon into a reality, Szilárd uniquely combined imagination, theoretical foresight, and practical planning during this formative period.

A firm and solitary belief in nuclear divisibility (1933). In 1933, when leading physicists such as Rutherford and Bohr dismissed the possibility of splitting the nucleus as pure fantasy, Szilárd alone insisted that the atom could indeed be divided to release vast energy. Influenced by H.G. Wells’s The World Set Free, he recognized not only that nuclear fission was possible in principle, but also that it could inevitably yield a weapon of unprecedented power. This belief distinguished him sharply from his contemporaries: Szilárd was not merely a theorist, but the first to articulate the bomb as a real and unavoidable prospect.

n September 1933, Szilárd conceived the idea of a neutron-induced chain reaction: a single nuclear event could trigger a cascade of further reactions. By June 1934 he had secured a patent (GB630726A) describing this process, the first legal and scientific document to define the operating principle of both nuclear reactors and nuclear weapons. The fact that the British government immediately placed the patent under secrecy underscores its military significance.

Dual conception: bomb and reactor. Szilárd’s imagination was dual in nature. He understood from the beginning that the chain reaction could serve both destructive and constructive ends. While the weapon was implicit in his 1934 patent, he was also the first to articulate the possibility of controlled, energy-producing reactors—plans he later pursued with Enrico Fermi. The twin legacies of nuclear technology, both the bomb and the reactor, originated conceptually in Szilárd’s mind in his 1934 patents. Intellectual priority. The experimental confirmation of fission came only in late 1938 with Hahn and Strassmann. Yet Szilárd had already anticipated the essential principle five years earlier, formalized it in patent form, and pursued practical pathways for its realization. He thought and acted at a time when most leading physicists dismissed the idea as science fiction. Why Szilárd merits the title of inventor. To invent is not merely to build; it is to recognize a principle and to conceive its practical use. The history of technology shows that most inventions can be traced back to a single conceptual inventor in the strict sense, even though their realization required the work of many-many contributors. In precisely this way, Szilárd occupies the singular role of the atomic bomb’s inventor:

• he first grasped the feasibility of a nuclear chain reaction,

• he articulated both the bomb and the reactor,

• he codified the principle in a patent,

and

• he alone maintained unwavering conviction in nuclear divisibility when nearly all others doubted it.

Thus, while the material construction of the bomb depended on the contributions of countless scientists and engineers, the conceptual leap—the true invention—was Szilárd’s alone. He can therefore justly be called the intellectual originator of the atomic bomb.--Tubenoon (talk) 04:55, 30 September 2025 (UTC)

Do you have a reliable published source that makes these arguments? Without that, it's WP:OR original research and unsuited for Wikipedia. NPguy (talk) 20:03, 1 October 2025 (UTC)

That’s an old beardy trick on Wikipedia, to label automatically every edit as "original research" what you simply don’t like.

The reality is precisely the opposite. My statement reflects a firmly established mainstream — indeed, canonical — view within the scientific community, if you read works by genuine scholars rather than the popular science books written by amateurs.

If one confines oneself to popular science books — especially in America — one might easily come to believe such absurdities as that Henry Ford invented the automobile, Bell the telephone, Edison the light bulb, Tesla c Westinghouse the alternating current, and Oppenheimer the atomic bomb. In serious academic circles, however, these myths provoke little more than amused laughter. — Preceding unsigned comment added by Tubenoon (talk • contribs)

For the record, I don't "dislike" your edits. I was trying to help you make them suitable by finding supporting sources. But it seems you'd rather complain than contribute. NPguy (talk) 20:18, 6 October 2025 (UTC)

First and foremost, one must understand the crucial distinction between an inventor and a contributor. The atomic bomb — as a foundational concept, like so many other great innovations — had a single inventor. Yet its realization as a functioning weapon required the collaborative efforts of countless scientists and a long succession of subsidiary inventions (the so-called contributors).— Preceding unsigned comment added by Tubenoon (talk • contribs)

1. William Lanouette — Genius in the Shadows: A Biography of Leo Szilard, the Man Behind the Bomb — Charles Scribner’s Sons, 1992 (reissued by University of Chicago Press, 1994; Skyhorse Publishing, 2013) The definitive biography portraying Szilard as “the man who conceived the atomic bomb” and “the father of the chain reaction.” It details his 1933 realization of the self-sustaining nuclear chain reaction that made the bomb’s concept possible.

2. Richard Rhodes — The Making of the Atomic Bomb — Simon & Schuster, 1986 Pulitzer Prize–winning history that repeatedly emphasizes Szilard as the first person to conceive the nuclear chain reaction, forming the intellectual foundation of the atomic bomb long before it was built.

3. Arnulf K. Esterer and Louise A. Esterer — Prophet of the Atomic Age: Leo Szilard — Julian Messner, 1972 A narrative biography presenting Szilard as a prophetic scientist who foresaw the potential of atomic energy and is described as “instrumental in developing the atomic bomb.”

4. Jeremy Bernstein — Hitler’s Uranium Club: The Secret Recordings at Farm Hall — Copernicus Books (Springer-Verlag), 2001 This book discusses the wartime German nuclear effort and credits Szilard with being the first to conceive and patent the idea of a self-sustaining chain reaction in 1933–1934, laying the conceptual groundwork for the atomic bomb.

5. Leo Szilard (ed. Bernard T. Feld, Gertrud W. Szilard, and Kathleen R. Winsor) — The Collected Works of Leo Szilard: Scientific Papers — MIT Press, 1972 A primary source collection containing Szilard’s original scientific papers and the 1934 British patent describing a self-sustaining chain reaction—direct evidence that he formulated the atomic bomb’s theoretical basis.

6. Spencer Weart — Nuclear Fear: A History of Images — Harvard University Press, 1985 Examines public and scientific conceptions of atomic energy and consistently identifies Szilard as the first to foresee a chain reaction capable of releasing atomic energy, making him central to the bomb’s conceptual origin.

7. David Holloway — Stalin and the Bomb: The Soviet Union and Atomic Energy, 1939–1956 — Yale University Press, 1994 While focused on the Soviet program, the book situates Szilard’s early theoretical and patent work as the conceptual beginning of the atomic bomb idea worldwide.

8. Herbert S. Parmet and Claire Franco (eds.) — The Making of the Atomic Bomb: The Library of Congress Photographic History — Columbia University Press, 1995 A historical-photographic companion volume whose essays recognize Szilard as “the first to conceive the atomic bomb’s basic principle” through the concept of the nuclear chain reaction.

9. Carroll Quigley — Tragedy and Hope: A History of the World in Our Time — Macmillan, 1966 A sweeping history that acknowledges Szilard among the very few scientists before World War II who recognized the possibility of nuclear chain reactions leading to explosive power.

10. Thomas P. Hughes — Rescuing Prometheus: Four Monumental Projects That Changed the Modern World — Pantheon Books, 1998 Examines major twentieth-century technological projects and credits Szilard’s 1933–1934 chain-reaction patent as a foundational intellectual step toward the atomic bomb.

--Tubenoon (talk) 11:22, 12 October 2025 (UTC)

I do not understand what you are trying to accomplish with this obsessive wall of text. Szilard's contributions are already covered in the existing article. This is not an article about Leo Szilard. It is about the Manhattan Project. Szilard was a part of that story. The fact that Szilard conceived of a chain reaction and patented it is already in the article. NuclearSecrets (talk) 22:55, 13 October 2025 (UTC)

So now all you need is to find specific page citations for specific claims you want to make. That shouldn't be hard. There's still the potential question of how much detail belongs in this article as opposed to a cross-reference to one on Szilard. NPguy (talk) 18:50, 12 October 2025 (UTC)

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