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Howard P. Robertson
Howard Percy "Bob" Robertson (January 27, 1903 – August 26, 1961) was an American mathematician and physicist known for contributions related to physical cosmology and the uncertainty principle. He was Professor of Mathematical Physics at the California Institute of Technology and Princeton University. Robertson made important contributions to the mathematics of quantum mechanics, general relativity and differential geometry. Applying relativity to cosmology, he independently developed the concept of an expanding universe. His name is most often associated with the Poynting–Robertson effect, the process by which solar radiation causes a dust mote orbiting a star to lose angular momentum, which he also described in terms of general relativity. During World War II, Robertson served with the National Defense Research Committee (NDRC) and the Office of Scientific Research and Development (OSRD). He served as technical consultant to the Secretary of War, the OSRD Liaison Officer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoquiam, Washington
Hoquiam ( ) is a city in Grays Harbor County, Washington, Grays Harbor County, Washington (state), Washington, United States. It borders the city of Aberdeen, Washington, Aberdeen at Myrtle Street, with Hoquiam to the west. The two cities share a common economic history in lumbering and exporting, but Hoquiam has maintained its independent identity. It shares a long rivalry with its more populated neighbor, especially in high school sports. Hoquiam was incorporated on May 21, 1890. Its name comes from a Native-American word meaning "hungry for wood", from the great amount of driftwood at the mouth of the Hoquiam River. The population was 8,776 at the 2020 United States census, 2020 census. History One of the first logging operations in Hoquiam was established by Ed Campbell in 1872.Van Syckle, Ed. A Brief Historical Sketch of Grays Harbor Washington. Chambers of Commerce of Hoquiam and Aberdeen, Washington, 1942. About 10 years later, Captain Asa M. Simpson, a Pacific Coast mar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is the foundation of all quantum physics, which includes quantum chemistry, quantum field theory, quantum technology, and quantum information science. Quantum mechanics can describe many systems that classical physics cannot. Classical physics can describe many aspects of nature at an ordinary (macroscopic and Microscopic scale, (optical) microscopic) scale, but is not sufficient for describing them at very small submicroscopic (atomic and subatomic) scales. Classical mechanics can be derived from quantum mechanics as an approximation that is valid at ordinary scales. Quantum systems have Bound state, bound states that are Quantization (physics), quantized to Discrete mathematics, discrete values of energy, momentum, angular momentum, and ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Office Of The Secretary Of Defense
The Office of the Secretary of Defense (OSD) is a headquarters-level staff of the United States Department of Defense. It is the principal civilian staff element of the U.S. Secretary of Defense, and it assists the Secretary in carrying out authority, direction and control of the Department of Defense in the exercise of policy development, planning, resource management, fiscal, and program evaluation responsibilities. OSD (along with the Joint Staff) is the Secretary of Defense's support staff for managing the Department of Defense, and it corresponds to what the Executive Office of the President of the U.S. is to the U.S. president for managing the whole of the Executive branch of the federal government. OSD includes the immediate offices of the Secretary (SECDEF) and the Deputy Secretary of Defense (DEPSECDEF), as well as the Under Secretary of Defense for Research and Engineering; Under Secretary of Defense for Acquisition and Sustainment; Under Secretary of Defense for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weapons Systems Evaluation Group
The Weapons Systems Evaluation Group (abbreviated WSEG) was formed in 1949 to carry out Operational Research work for the Joint Chiefs of Staff of the United States Army and the United States Secretary of Defense. The group oversaw the appraisal of weapons used during the Korean War. The group collaborated with Israel in evaluating the effectiveness of Soviet weapons during the Cold War. History The first Research Director was Philip M. Morse, who served a year and a half before returning to MIT The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ... in the summer of 1950. From 1957 until 1960 John H. Sides was director of WSEG. Lt. Gen. Harvey T. Alness was director from Sept. 1, 1962 until March 1, 1964. Hugh Everett III worked at the WSEG from 1956 until 1964. Much of his works rem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supreme Headquarters Allied Expeditionary Force
Supreme Headquarters Allied Expeditionary Force (SHAEF; ) was the headquarters of the Commander of Allies of World War II, Allied forces in northwest Europe, from late 1943 until the end of World War II. US General Dwight D. Eisenhower was the commander in SHAEF throughout its existence. The position itself shares a common lineage with Supreme Allied Commander Europe and Supreme Allied Commander Atlantic, Atlantic, but they are different titles. History Eisenhower transferred from command of the Mediterranean Theater of Operations, United States Army, Mediterranean Theater of Operations to command SHAEF, which was formed in Camp Griffiss, Bushy Park, Teddington, London, from December 1943; an adjacent street named Shaef Way, and a gate into the park called Shaef Gate, remain to this day. Southwick House was used as an alternative headquarters near Portsmouth. Its staff took the outline plan for Operation Overlord created by Lieutenant General Sir Frederick E. Morgan, Chief of St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secretary Of War
The secretary of war was a member of the U.S. president's Cabinet, beginning with George Washington's administration. A similar position, called either "Secretary at War" or "Secretary of War", had been appointed to serve the Congress of the Confederation under the Articles of Confederation between 1781 and 1789. Benjamin Lincoln and later Henry Knox held the position. When Washington was inaugurated as the first President under the Constitution, he appointed Knox to continue serving as Secretary of War. The secretary of war was the head of the War Department. At first, he was responsible for all military affairs, including naval affairs. In 1798, the secretary of the Navy was created by statute, and the scope of responsibility for this office was reduced to the affairs of the United States Army. From 1886 onward, the secretary of war was in the line of succession to the presidency, after the vice president of the United States, the Speaker of the House of Representative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Office Of Scientific Research And Development
The Office of Scientific Research and Development (OSRD) was an agency of the United States federal government created to coordinate scientific research for military purposes during World War II. Arrangements were made for its creation during May 1941, and it was created formally by Executive Order 8807 on June 28, 1941. It superseded the work of the National Defense Research Committee (NDRC), was given almost unlimited access to funding and resources, and was directed by Vannevar Bush, who reported only to President Franklin Delano Roosevelt. The research was widely varied, and included projects devoted to new and more accurate bombs, reliable detonators, work on the proximity fuze, guided missiles, radar and early-warning systems, lighter and more accurate hand weapons, more effective medical treatments (including work to make penicillin at scale, which was necessary for its use as a drug), more versatile vehicles, and, the most secret of all, the S-1 Section, which later becam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Defense Research Committee
The National Defense Research Committee (NDRC) was an organization created "to coordinate, supervise, and conduct scientific research on the problems underlying the development, production, and use of mechanisms and devices of warfare" in the United States from June 27, 1940, until June 28, 1941. Most of its work was done with the strictest secrecy, and it began research of what would become some of the most important technology during World War II, including radar and the atomic bomb. Its working arm was superseded by the Office of Scientific Research and Development in 1941, but it remained as an influential advisory and consulting agency until it was terminated in 1947. Organization The NDRC was created by an order of President Franklin Delano Roosevelt on June 27, 1940. It was part of the Council of National Defense, which had been created during 1916 to coordinate industry and resources for national security purposes. Vannevar Bush, the director of the Carnegie Institut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks in World War II, Tanks and Air warfare of World War II, aircraft played major roles, enabling the strategic bombing of cities and delivery of the Atomic bombings of Hiroshima and Nagasaki, first and only nuclear weapons ever used in war. World War II is the List of wars by death toll, deadliest conflict in history, causing World War II casualties, the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Allied-occupied Germany, Germany, Allied-occupied Austria, Austria, Occupation of Japan, Japan, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Momentum
Angular momentum (sometimes called moment of momentum or rotational momentum) is the rotational analog of Momentum, linear momentum. It is an important physical quantity because it is a Conservation law, conserved quantity – the total angular momentum of a closed system remains constant. Angular momentum has both a direction (geometry), direction and a magnitude, and both are conserved. Bicycle and motorcycle dynamics, Bicycles and motorcycles, flying discs, Rifling, rifled bullets, and gyroscopes owe their useful properties to conservation of angular momentum. Conservation of angular momentum is also why hurricanes form spirals and neutron stars have high rotational rates. In general, conservation limits the possible motion of a system, but it does not uniquely determine it. The three-dimensional angular momentum for a point particle is classically represented as a pseudovector , the cross product of the particle's position vector (relative to some origin) and its mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Radiation
Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible light perceptible to the human eye as well as invisible infrared (typically perceived by humans as warmth) and ultraviolet (which can have physiological effects such as sunburn) lights. However, according to the American Meteorological Society, there are "conflicting conventions as to whether all three ..are referred to as light, or whether that term should only be applied to the visible portion of the spectrum." Upon reaching the Earth, sunlight is scattered and filtered through the Earth's atmosphere as daylight when the Sun is above the horizon. When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat (atmospheric). When blocked by clouds or reflected off other objects, sunlight is diffused. Sources estimate a global average o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expanding Universe
The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion, so it does not mean that the universe expands "into" anything or that space exists "outside" it. To any observer in the universe, it appears that all but the nearest galaxies (which are bound to each other by gravity) move away at speeds that are proportional to their distance from the observer, on average. While objects cannot move faster than light, this limitation applies only with respect to local reference frames and does not limit the recession rates of cosmologically distant objects. Cosmic expansion is a key feature of Big Bang cosmology. It can be modeled mathematically with the Friedmann–Lemaître–Robertson–Walker metric (FLRW), where it corresponds to an increase in the scale of the spatial part of the universe's spacetime metric tensor (which governs the size and geometry of spacetime). Within ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
