HOME

TheInfoList



OR:

Seth Henry Neddermeyer (September 16, 1907 – January 29, 1988) was an American physicist who co-discovered the
muon A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of  ''ħ'', but with a much greater mass. It is classified as a ...
, and later championed the
implosion-type nuclear weapon Nuclear weapons design are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types: # Pure fission weapons are the simplest, least technically de ...
while working on the
Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...
at the
Los Alamos Laboratory The Los Alamos Laboratory, also known as Project Y, was a secret scientific laboratory established by the Manhattan Project and overseen by the University of California during World War II. It was operated in partnership with the United State ...
during
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
.


Early life

Seth Henry Neddermeyer was born in Richmond, Michigan, on September 16, 1907. He attended Olivet College, a small college that his mother, older sister, and uncle had also attended, for two years before his family moved to California. He transferred to
Stanford University Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth ...
, from which received his
Bachelor of Arts A Bachelor of Arts (abbreviated B.A., BA, A.B. or AB; from the Latin ', ', or ') is the holder of a bachelor's degree awarded for an undergraduate program in the liberal arts, or, in some cases, other disciplines. A Bachelor of Arts deg ...
(AB) degree in 1929. His interest in physics was inspired by the work of Robert A. Millikan, and he enrolled in graduate school at
California Institute of Technology The California Institute of Technology (branded as Caltech) is a private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of institutes ...
(Caltech), where he wrote his 1935
PhD A Doctor of Philosophy (PhD, DPhil; or ) is a terminal degree that usually denotes the highest level of academic achievement in a given discipline and is awarded following a course of graduate study and original research. The name of the deg ...
thesis on "The absorption of high energy electrons", under the supervision of Carl D. Anderson. He confirmed the theory espoused by
Niels Bohr Niels Henrik David Bohr (, ; ; 7 October 1885 – 18 November 1962) was a Danish theoretical physicist who made foundational contributions to understanding atomic structure and old quantum theory, quantum theory, for which he received the No ...
for this process. He also noted large radiative energy losses of electrons in
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
, in agreement with the theory propounded by
Hans Bethe Hans Albrecht Eduard Bethe (; ; July 2, 1906 – March 6, 2005) was a German-American physicist who made major contributions to nuclear physics, astrophysics, quantum electrodynamics and solid-state physics, and received the Nobel Prize in Physi ...
and
Walter Heitler Walter Heinrich Heitler (; 2 January 1904 – 15 November 1981) was a German physicist who made contributions to quantum electrodynamics and quantum field theory. He brought chemistry under quantum mechanics through his theory of valence bondi ...
. Neddermeyer contributed to the research which led to the 1932 discovery of the
positron The positron or antielectron is the particle with an electric charge of +1''elementary charge, e'', a Spin (physics), spin of 1/2 (the same as the electron), and the same Electron rest mass, mass as an electron. It is the antiparticle (antimatt ...
, for which Anderson was awarded the
Nobel Prize in Physics The Nobel Prize in Physics () is an annual award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions to mankind in the field of physics. It is one of the five Nobel Prizes established by the ...
in 1936. That year, Neddermeyer and Anderson discovered the
muon A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of  ''ħ'', but with a much greater mass. It is classified as a ...
, using
cloud chamber A cloud chamber, also known as a Wilson chamber, is a particle detector used for visualizing the passage of ionizing radiation. A cloud chamber consists of a sealed environment containing a supersaturated vapor of water or alcohol. An energetic ...
measurements of
cosmic rays Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar ...
. Their discovery predated
Hideki Yukawa Hideki Yukawa (; ; 23 January 1907 – 8 September 1981) was a Japanese theoretical physicist who received the Nobel Prize in Physics in 1949 "for his prediction of the existence of mesons on the basis of theoretical work on nuclear forces". B ...
's 1935 theory of
meson In particle physics, a meson () is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles, the ...
s that postulated the particle as mediating the nuclear force. Anderson and Neddermeyer collaborated with Millikan in high altitude studies of cosmic rays, which confirmed
Robert Oppenheimer J. Robert Oppenheimer (born Julius Robert Oppenheimer ; April 22, 1904 – February 18, 1967) was an American theoretical physicist who served as the director of the Manhattan Project's Los Alamos Laboratory during World War II. He is often ...
's theory that the air showers produced in the atmosphere by cosmic rays contained electrons. They also obtained the first evidence that
gamma rays A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...
can generate positrons.


Manhattan Project work

In early 1941, with
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
raging in Europe but the United States not yet a belligerent, Neddermeyer joined a team led by Charles C. Lauritsen and William A. Fowler at the Department of Terrestrial Magnetism at the
Carnegie Institution of Washington The Carnegie Institution for Science, also known as Carnegie Science and the Carnegie Institution of Washington, is an organization established to fund and perform scientific research in the United States. This institution is headquartered in W ...
, and then at the
National Bureau of Standards The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sc ...
in Washington, D.C., that worked on the photoelectric
proximity fuze A Proximity Fuse (also VT fuse or "variable time fuze") is a fuse that detonates an explosive device automatically when it approaches within a certain distance of its target. Proximity fuses are designed for elusive military targets such as air ...
. After this work was completed, Neddermeyer was recruited by Oppenheimer to work at the
Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...
's
Los Alamos Laboratory The Los Alamos Laboratory, also known as Project Y, was a secret scientific laboratory established by the Manhattan Project and overseen by the University of California during World War II. It was operated in partnership with the United State ...
. Neddermeyer was an early advocate for the development of an implosion technique for assembling a
critical mass In nuclear engineering, critical mass is the minimum mass of the fissile material needed for a sustained nuclear chain reaction in a particular setup. The critical mass of a fissionable material depends upon its nuclear properties (specific ...
in an atomic bomb. Although implosion was suggested by
Richard Tolman Richard Chace Tolman (March 4, 1881 – September 5, 1948) was an American mathematical physicist and physical chemist who made many contributions to statistical mechanics and theoretical cosmology. He was a professor at the California In ...
as early as 1942 and discussed in the introductory lectures given to Los Alamos scientists by
Robert Serber Robert Serber (March 14, 1909 – June 1, 1997) was an American physicist who participated in the Manhattan Project. Serber's lectures explaining the basic principles and goals of the project were printed and supplied to all incoming scientific st ...
, Neddermeyer was one of the first to urge its full development. Unable to find much initial enthusiasm for the concept among his fellow Los Alamos scientists, Neddermeyer presented the first substantial technical analysis of implosion in late April 1943. Oppenheimer considered this to be the beginning of implosion research at Los Alamos. Though many remained unimpressed, Oppenheimer appointed Neddermeyer the head of a new group to test implosion. His group became the E-5 (Implosion) Group, which was part of
Captain Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader or highest rank officer of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police depa ...
William S. Parsons' E Division. A gun-type nuclear weapon was the preferred method, but implosion research constituted a backup. Neddermeyer embarked on an intensive series of experiments testing cylindrical implosions. The result was a series of distorted shapes. Progress was made; Neddermeyer and a member of his team,
Hugh Bradner Hugh Bradner (November 5, 1915 – May 5, 2008) was an American physicist at the University of California, Berkeley, University of California who is credited with inventing the neoprene wetsuit, which helped to revolutionize scuba diving and sur ...
, along with James L. Tuck from the British Mission, conceived the idea of
explosive lens An explosive lens—as used, for example, in nuclear weapons—is a highly specialized shaped charge. In general, it is a device composed of several explosive charges. These charges are arranged and formed with the intent to control the sha ...
es, in which shaped charges are used to focus the force of an explosion. Nevertheless, seemingly unsolvable problems with
shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...
uniformity brought progress on implosion to a crawl. By September 1943, Neddermeyer's team had grown from five people to fifty. That month,
John von Neumann John von Neumann ( ; ; December 28, 1903 – February 8, 1957) was a Hungarian and American mathematician, physicist, computer scientist and engineer. Von Neumann had perhaps the widest coverage of any mathematician of his time, in ...
came to Los Alamos at Oppenheimer's request. Von Neumann was impressed by the implosion concept and, working with
Edward Teller Edward Teller (; January 15, 1908 – September 9, 2003) was a Hungarian and American Theoretical physics, theoretical physicist and chemical engineer who is known colloquially as "the father of the hydrogen bomb" and one of the creators of ...
, an old friend, made a series of suggestions. Von Neumann was able to create a sound mathematical model of implosion, enabling Neddermeyer to present a proposal for a greatly expanded research program. Edwin McMillan and
Isidor Isaac Rabi Israel Isidor Isaac Rabi (; ; July 29, 1898 – January 11, 1988) was an American nuclear physicist who received the Nobel Prize in Physics in 1944 for his discovery of nuclear magnetic resonance, which is used in magnetic resonance imaging. H ...
recommended that George Kistiakowsky, who had a specialized knowledge in the precision use of explosives, be brought in to help the program. In February 1944, Kistiakowsky became Parsons' deputy for implosion. In April 1944, tests on the first sample of
plutonium Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...
that had been produced with neutrons in a nuclear reactor revealed that reactor-bred plutonium contained five times more
plutonium-240 Plutonium-240 ( or Pu-240) is an isotope of plutonium formed when plutonium-239 captures a neutron. The detection of its spontaneous fission led to its discovery in 1944 at Los Alamos and had important consequences for the Manhattan Project. ...
than that hitherto produced in
cyclotron A cyclotron is a type of particle accelerator invented by Ernest Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Januar ...
s. This unwanted isotope that spontaneously decayed and produced neutrons promised to cause a predetonation without sufficiently quick critical mass assembly. It now became apparent that only implosion would work for practical plutonium bombs; a powerful enough gun could not be constructed small enough to be carried in an aircraft, and plutonium-240 was even more difficult to separate from plutonium-239 than the isotopes of uranium that were giving the rest of the Manhattan Project such difficulties. Plutonium was unusable unless implosion worked, but only plutonium could be produced in quantities that would allow regular production of atomic bombs. Thus, the implosion technique now suddenly stood as the key to production of nuclear weapons. In mid-June 1944, a report from Kistiakowsky to Oppenheimer detailing dysfunctionality within the implosion team led to the ousting of Neddermeyer. He was replaced as the head of the E-5 Group by Kistiakowsky on June 15, 1944, but remained a technical adviser to the implosion program, with group leader status. Neddermeyer was said to have been much embittered by this episode. In Oppenheimer's August 1944 reorganization of the Los Alamos Laboratory, Neddermeyer's group was renamed X-1, with Norris Bradbury as group leader. The implosion method championed by Neddermeyer was used in the first atom bomb exploded (in the
Trinity test Trinity was the first detonation of a nuclear weapon, conducted by the United States Army at 5:29 a.m. MWT (11:29:21 GMT) on July 16, 1945, as part of the Manhattan Project. The test was of an implosion-design plutonium bomb, or "gadg ...
), the
Fat Man "Fat Man" (also known as Mark III) was the design of the nuclear weapon the United States used for seven of the first eight nuclear weapons ever detonated in history. It is also the most powerful design to ever be used in warfare. A Fat Man ...
bomb dropped on
Nagasaki , officially , is the capital and the largest Cities of Japan, city of Nagasaki Prefecture on the island of Kyushu in Japan. Founded by the Portuguese, the port of Portuguese_Nagasaki, Nagasaki became the sole Nanban trade, port used for tr ...
, and almost all modern nuclear weapons. Kistiakowsky later insisted that "the real invention should be given full credit to ethNeddermeyer" (sic).


Later years

In 1946, after World War II ended, Neddermeyer left Los Alamos to become an
associate professor Associate professor is an academic title with two principal meanings: in the North American system and that of the ''Commonwealth system''. In the ''North American system'', used in the United States and many other countries, it is a position ...
at the
University of Washington The University of Washington (UW and informally U-Dub or U Dub) is a public research university in Seattle, Washington, United States. Founded in 1861, the University of Washington is one of the oldest universities on the West Coast of the Uni ...
, where he would spend the rest of his career. In due course he became a full professor. He resumed his studies of cosmic rays using a cloud chamber and a new device that he invented to measure the speed of charged particles known as a "chronotron". He was particularly interested in the properties of the muon, and conducted experiments with muons at SLAC. He participated in the DUMAND Project, for which he helped design large-scale underwater
neutrino A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...
detectors. Neddermeyer became interested in
parapsychology Parapsychology is the study of alleged psychic phenomena (extrasensory perception, telepathy, teleportation, precognition, clairvoyance, psychokinesis (also called telekinesis), and psychometry (paranormal), psychometry) and other paranormal cla ...
, insisting, in spite of the skepticism of many colleagues, that it warranted proper scientific investigation. He retired in 1973, becoming a
professor emeritus ''Emeritus/Emerita'' () is an honorary title granted to someone who retirement, retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". ...
, but he continued his research activities for as long as his health permitted. He was afflicted with
Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor system, motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become ...
. In 1982, he was presented with the Department of Energy's
Enrico Fermi award The Enrico Fermi Award is a scientific award conferred by the President of the United States. It is awarded to honor scientists of international stature for their lifetime achievement in the development, use or production of energy. It was establ ...
. His citation read: In later life, Neddermeyer was sometimes troubled by the nuclear weapons he had helped to invent. He told an interviewer in 1983: Neddermeyer died in
Seattle Seattle ( ) is the most populous city in the U.S. state of Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the 18th-most populous city in the United States. The city is the cou ...
on January 29, 1988, from complications of Parkinson's disease.


In popular culture

Neddermeyer is portrayed by Colin Bennett in the 1980 BBC series '' Oppenheimer'', by Joe D'Angerio in '' Fat Man and Little Boy'', and by Devon Bostick in the
Christopher Nolan Sir Christopher Edward Nolan (born 30 July 1970) is a British and American filmmaker. Known for his Cinema of the United States, Hollywood Blockbuster (entertainment), blockbusters with complex storytelling, he is considered a leading filmma ...
-directed film '' Oppenheimer'' (2023).


Notes


References

* * * {{DEFAULTSORT:Neddermeyer, Seth 1907 births 1988 deaths 20th-century American physicists Manhattan Project people Stanford University alumni California Institute of Technology alumni University of Washington faculty Enrico Fermi Award recipients Neurological disease deaths in Washington (state) Deaths from Parkinson's disease in the United States People from Richmond, Michigan Fellows of the American Physical Society Nuclear weapons scientists and engineers