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Oppenheimer Security Hearing
The Oppenheimer security hearing was a 1954 proceeding by the United States Atomic Energy Commission (AEC) that explored the background, actions, and associations of J. Robert Oppenheimer, the American scientist who had headed the Los Alamos Laboratory during World War II, where he played a key part in the Manhattan Project that developed the atomic bomb. The hearing resulted in Oppenheimer's Q clearance being revoked. This marked the end of his formal relationship with the government of the United States, and generated considerable controversy regarding whether the treatment of Oppenheimer was fair, or whether it was an expression of anti-Communist McCarthyism. Doubts about Oppenheimer's loyalty dated back to the 1930s, when he was a member of numerous Communist front organizations, and was associated with Communist Party USA members, including his wife and his brother. These associations were known to Army Counterintelligence at the time he was made director of the Los Al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Atomic Energy Commission
The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President Harry S. Truman signed the McMahon/Atomic Energy Act on August 1, 1946, transferring the control of atomic energy from military to civilian hands, effective on January 1, 1947. This shift gave the members of the AEC complete control of the plants, laboratories, equipment, and personnel assembled during the war to produce the atomic bomb. An increasing number of critics during the 1960s charged that the AEC's regulations were insufficiently rigorous in several important areas, including radiation protection standards, nuclear reactor safety, plant siting, and environmental protection. By 1974, the AEC's regulatory programs had come under such strong attack that the U.S. Congress decided to abolish the AEC. The AEC was abolished by the En ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Security Clearance
A security clearance is a status granted to individuals allowing them access to classified information (state or organizational secrets) or to restricted areas, after completion of a thorough background check. The term "security clearance" is also sometimes used in private organizations that have a formal process to vet employees for access to sensitive information. A clearance by itself is normally not sufficient to gain access; the organization must also determine that the cleared individual needs to know specific information. No individual is supposed to be granted automatic access to classified information solely because of rank, position, or a security clearance. Canada Background Government classified information is governed by the Treasury Board Standard on Security Screening, the ''Security of Information Act'' and '' Privacy Act''. Only those that are deemed to be loyal and reliable, and have been cleared are allowed to access sensitive information. The policy w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tolman–Oppenheimer–Volkoff Limit
The Tolman–Oppenheimer–Volkoff limit (or TOV limit) is an upper bound to the mass of cold, nonrotating neutron stars, analogous to the Chandrasekhar limit for white dwarf stars. If the mass of the said star reaches the limit it will collapse to a denser form. Theoretical work in 1996 placed the limit at approximately 1.5 to 3.0 solar masses, corresponding to an original stellar mass of 15 to 20 solar masses; additional work in the same year gave a more precise range of 2.2 to 2.9 solar masses. Observations of GW170817, the first gravitational wave event due to merging neutron stars (which are thought to have collapsed into a black hole within a few seconds after merging), placed the limit at close to 2.17 (solar masses). This value was inconsistent with short gamma-ray burst X-ray plateau data however, which suggested a value of ''M''TOV = 2.37 . Reanalysis of the GW170817 event data in 2019 resulted in a higher value of ''M''TOV = 2.3 . If GW ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Volkoff
George Michael Volkoff, (February 23, 1914 – April 24, 2000) was a Russian-Canadian physicist and academic who helped, with J. Robert Oppenheimer, predict the existence of neutron stars before they were discovered. Early life He was born in Moscow. His father was a Russian engineer who emigrated to Vancouver, British Columbia, Canada in 1924. Unable to find work, his father moved the family to Harbin, Manchuria in 1927. His mother died soon after moving to Harbin. In 1936, Volkoff's father returned to Russia but was exiled to the arctic camps as part of the Great Purge where he would die. Education Volkoff returned to Vancouver and entered the University of British Columbia where he received a Bachelor of Arts in physics in 1934 and a Master of Arts degree in 1936. He then studied with J. Robert Oppenheimer at the University of California, Berkeley where he published his paper "On Massive Neutron Cores" and earned his Ph.D. in 1940. Academic In 1940, he joined the physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Dwarf
A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes from the emission of residual thermal energy; no fusion takes place in a white dwarf. The nearest known white dwarf is at 8.6 light years, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910. The name ''white dwarf'' was coined by Willem Luyten in 1922. White dwarfs are thought to be the final evolutionary state of stars whose mass is not high enough to become a neutron star or black hole. This includes over 97% of the other stars in the Milky Way. After the hydrogen- fusing period of a main-sequence star of low or medium mass ends, such a star will expand to a red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 staff, and became known as '' The Los Alamos Primer''. The ''New York Times'' called him “the intellectual midwife at the birth of the atomic bomb.” Early life and education He was born in Philadelphia, the eldest son of Rose (Frankel) and David Serber. His family was Jewish. His mother died in 1922 and his father married her cousin Frances Leof in 1928. Robert Serber earned his BS in engineering physics from Lehigh University in 1930 and earned his PhD in physics from the University of Wisconsin–Madison with John Van Vleck in 1934. He married Charlotte Leof (26 Jul 1911 – 1967), the daughter of his stepmother's uncle, in 1933. Shortly before receiving his doctorate, Serber was selected for a National Research Council postdocto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons. Positrons can be created by positron emission radioactive decay (through weak interactions), or by pair production from a sufficiently energetic photon which is interacting with an atom in a material. History Theory In 1928, Paul Dirac published a paper proposing that electrons can have both a positive and negative charge. This paper introduced the Dirac equation, a unification of quantum mechanics, special relativity, and the then-new concept of electron spin to explain the Zeeman effect. The paper did not explicitly predict a new particle but did allow for electrons having either positive or neg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dirac Equation
In particle physics, the Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928. In its free form, or including electromagnetic interactions, it describes all spin- massive particles, called "Dirac particles", such as electrons and quarks for which parity is a symmetry. It is consistent with both the principles of quantum mechanics and the theory of special relativity, and was the first theory to account fully for special relativity in the context of quantum mechanics. It was validated by accounting for the fine structure of the hydrogen spectrum in a completely rigorous way. The equation also implied the existence of a new form of matter, ''antimatter'', previously unsuspected and unobserved and which was experimentally confirmed several years later. It also provided a ''theoretical'' justification for the introduction of several component wave functions in Pauli's phenomenological theory of spin. The wave functions in the Dirac theo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science. Classical physics, the collection of theories that existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary (macroscopic) scale, but is not sufficient for describing them at small (atomic and subatomic) scales. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale. Quantum mechanics differs from classical physics in that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values ( quantization); objects have characteristics of both particles and waves ( wave–particle duality); and there ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Leiden
Leiden University (abbreviated as ''LEI''; nl, Universiteit Leiden) is a public research university in Leiden, Netherlands. The university was founded as a Protestant university in 1575 by William, Prince of Orange, as a reward to the city of Leiden for its defence against Spanish attacks during the Eighty Years' War. As the oldest institution of higher education in the Netherlands, it enjoys a reputation across Europe and the world. Known for its historic foundations and emphasis on the social sciences, the university came into particular prominence during the Dutch Golden Age, when scholars from around Europe were attracted to the Dutch Republic due to its climate of intellectual tolerance and Leiden's international reputation. During this time, Leiden became the home to individuals such as René Descartes, Rembrandt, Christiaan Huygens, Hugo Grotius, Baruch Spinoza and Baron d'Holbach. The university has seven academic faculties and over fifty subject departments while housin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Max Born
Max Born (; 11 December 1882 – 5 January 1970) was a German physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 1930s. Born won the 1954 Nobel Prize in Physics for his "fundamental research in quantum mechanics, especially in the statistical interpretation of the wave function". Born entered the University of Göttingen in 1904, where he met the three renowned mathematicians Felix Klein, David Hilbert, and Hermann Minkowski. He wrote his PhD thesis on the subject of "Stability of Elastica in a Plane and Space", winning the university's Philosophy Faculty Prize. In 1905, he began researching special relativity with Minkowski, and subsequently wrote his habilitation thesis on the Thomson model of the atom. A chance meeting with Fritz Haber in Berlin in 1918 led to discussion of how an ionic compou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Göttingen
The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded in 1734 by George II, King of Great Britain and Elector of Hanover, and starting classes in 1737, the Georgia Augusta was conceived to promote the ideals of the Enlightenment. It is the oldest university in the state of Lower Saxony and the largest in student enrollment, which stands at around 31,600. Home to many noted figures, it represents one of Germany's historic and traditional institutions. According to an official exhibition held by the University of Göttingen in 2002, 44 Nobel Prize winners had been affiliated with the University of Göttingen as alumni, faculty members or researchers by that year alone. The University of Göttingen was previously supported by the German Universities Excellence Initiative, holds membership ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
