elementary particle

String physics - Closed and open strings. Strings can be either open or closed. A closed string is a string that has no end-points, and therefore is topologically equivalent to a circle. An open string, on the otherhand, has two end-points and is topologically equivalent to a line interval. Not all string theories contain both open and closed strings. However, any theory which contains open strings must also contain closed strings as interactions betwee ...

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String physics, String physics - Types of strings, String physics - Closed and open strings, String physics - Orientation

Read more here: » String physics: Encyclopedia II - String physics - Types of strings

Alan H. Guth (born February 27, 1947) is a physicist and cosmologist. Guth has researched elementary particle theory (and how particle theory is applicable to the early universe). As a junior particle physicist, Guth first developed the idea of inflation in 1979 at Stanford University after attending a Big Bang lecture by Robert Dicke. In 1981, Guth formally proposed the idea of cosmic inflation, the idea that the nascent universe passed through a phase of exponential expansion that was driven by a negative v ...

Including:

• Alan Guth - Quote
• Alan Guth - Publications

Read more here: » Alan Guth: Encyclopedia - Alan Guth

A containment hierarchy is a hierarchical collection of strictly nested sets. Each entry in the hierarchy designates a set such that the previous entry is a strict superset, and the next entry is a strict subset. For example, all rectangles are quadrilaterals, but not all quadrilaterals are rectangles, and all squares are rectangles, but not all rectangles are squares. A taxonomy is a classic example of a containment hierarchy: In geometry: shape, polygon, quadrilateral, rectangle, square In biology: anima ...

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A hierarchy (in Greek: Ιεραρχία, it is derived from ιερός-hieros, sacred, and άρχω-arkho, rule) is a system of ranking and organizing things or people, where each element of the system (except for the top element) is subordinate to a single other element. The first usage in the Oxford English Dictionary for hierarchy is from 1380, where it was used in reference to the three orders of three angels as depicted by Pseudo-Dionysius the Areopagite. Areopagite used the word both in reference to t ...

Including:

• Hierarchy - Diverse examples of reasoning with hierarchies
• Hierarchy - Hierarchies in programming
• Hierarchy - Containment hierarchy
• Hierarchy - Social hierarchies
• Hierarchy - Hierarchical nomenclatures in the arts and sciences
• Hierarchy - Alternatives

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There are a number of common objections to the standard interpretation of the experiment; all of the objections demonstrate a lack of understanding of quantum mechanics. Some of these objections, and standard rebuttals, are listed below. Renninger negative-result experiment - Finite radioactive lifetime. It is sometimes noted that the time of the decay of the nucleus cannot be controlled, and that the finite half-life invalidates the result. This objection can be dispelled by sizing the hemispheres appropr ...

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Renninger negative-result experiment, Renninger negative-result experiment - The Mott problem, Renninger negative-result experiment - Renninger's negative-result experiment, Renninger negative-result experiment - Common objections, Renninger negative-result experiment - Finite radioactive lifetime, Renninger negative-result experiment - Classical trajectories, Renninger negative-result experiment - Diffraction, Renninger negative-result experiment - Complex decay products, Renninger negative-result experiment - Non-relativistic language, Renninger negative-result experiment - Imperfect detectors

Read more here: » Renninger negative-result experiment: Encyclopedia II - Renninger negative-result experiment - Common objections

Theoretical physics began at least 2,300 years ago under the pre-Socratic Greek philosophers, and continued by Plato; and Aristotle, whose views held sway for a millennium. During the Renaissance, the modern concept of experimental science, the counterpoint to theory, began with Francis Bacon. The modern era of theory began perhaps with the Copernican paradigm shift in astronomy, soon followed by the actual planetary orbits due to Keple ...

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Theoretical physics, Theoretical physics - Overview, Theoretical physics - Mainstream theories, Theoretical physics - Examples, Theoretical physics - Proposed theories, Theoretical physics - Examples, Theoretical physics - Fringe theories, Theoretical physics - Examples

Read more here: » Theoretical physics: Encyclopedia II - Theoretical physics - Overview

Many aspects of the world are analyzed from a hierarchical perspective. (The concept of hierarchy is thus a good example of interdisciplinary; it sometimes benefits from a sense of connection between otherwise unrelated disciplines.) BIOLOGICAL TAXONOMY: In biology, the study of taxonomy is one of the most conventionally hierarchical kind’s knowledge, placing all living beings in a nested structure of divisions related to their probable evolutionary descent. Most evolutionary biologists assert a hierarchy extending from the le ...

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Hierarchy, Hierarchy - Diverse examples of reasoning with hierarchies, Hierarchy - Hierarchies in programming, Hierarchy - Containment hierarchy, Hierarchy - Social hierarchies, Hierarchy - Hierarchical nomenclatures in the arts and sciences, Hierarchy - Alternatives

Read more here: » Hierarchy: Encyclopedia II - Hierarchy - Diverse examples of reasoning with hierarchies

Neutrinos can interact via the neutral current (involving the exchange of a Z boson) or charged current (involving the exchange of a W boson) weak interactions. In a neutral current interaction, the neutrino leaves the detector after having transfered some of its energy and momentum to a target particle. All three neutrino flavors can participate regardless of the neutrino energy. However, no neutrino flavor information is left behind. In a charged current interaction, the neutrino transforms into its partner lepton (el ...

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Neutrino, Neutrino - Types of neutrinos, Neutrino - Flavor Oscillations, Neutrino - History, Neutrino - Mass, Neutrino - Neutrino sources, Neutrino - Human generated, Neutrino - The Earth, Neutrino - Atmospheric neutrinos, Neutrino - Solar neutrinos, Neutrino - Cosmological phenomena, Neutrino - Cosmic background radiation, Neutrino - Neutrino detection, Neutrino - Motivation for scientific interest in the neutrino

Read more here: » Neutrino: Encyclopedia II - Neutrino - Neutrino detection

Many aspects of the world are analyzed from a hierarchical perspective. (The concept of hierarchy is thus a good example of interdisciplinary; it sometimes benefits from a sense of connection between otherwise unrelated disciplines.) BIOLOGICAL TAXONOMY: In biology, the study of taxonomy is one of the most conventionally hierarchical kinds knowledge, placing all living beings in a nested structure of divisions related to their probable evolutionary descent. Most evolutionary biologists assert a hierachy extending from the level ...

See also:

Hierarchy, Hierarchy - Diverse examples of reasoning with hierarchies, Hierarchy - Hierarchies in programming, Hierarchy - Containment hierarchy, Hierarchy - Social hierarchies, Hierarchy - Hierarchical nomenclatures in the arts and sciences, Hierarchy - Alternatives

Read more here: » Hierarchy: Encyclopedia II - Hierarchy - Diverse examples of reasoning with hierarchies

Founded in 1962, the facility is located on 426 acres of Stanford University-owned land on Sand Hill Road in Menlo Park, California—just down the road from the University's main campus. The main accelerator, a 3.2 kilometer long RF linear accelerator which can accelerate electrons and positrons up to 50 GeV, has been operational since 1966. It is buried 10 metres (30 feet) below ground and passes underneath Interstate 280. As of 2005, SLAC employs over 1,000 people, some 150 of which are physicists with doctorate degrees, and serves over 3 ...

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Stanford Linear Accelerator Center, Stanford Linear Accelerator Center - History, Stanford Linear Accelerator Center - PEP-II and SSRL, Stanford Linear Accelerator Center - Injectors, Stanford Linear Accelerator Center - Other Discoveries

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The tau lepton was detected through a series of experiments between 1974 and 1977 by Martin Lewis Perl with his colleagues at the SLAC-LBL group. Their equipment consisted of SLAC's new e+-e− colliding ring, called SPEAR, and the LBL magnetic detector. They could detect and distinguish between leptons, hadrons and photons. They did not detect the tau lepton directly, rather they discovere ...

See also:

Tau lepton, Tau lepton - Classification, Tau lepton - Decay, Tau lepton - Discovery

Read more here: » Tau lepton: Encyclopedia II - Tau lepton - Discovery

An elementary particle is a particle with no measurable internal structure, that is, it is not a composite of other particles. They are the fundamental objects of Quantum Field Theory. Elementary particles can be classified according to their spin, with fermions having half-integer spin and bosons integer spin. List of particles - Standard Model. The Standard Model of particle physics is our current understanding of the physics of elementary particles. All Standard Model pa ...

See also:

List of particles, List of particles - Elementary particles, List of particles - Standard Model, List of particles - Hypothetical particles, List of particles - Composite particles, List of particles - Hadrons, List of particles - Atomic nuclei, List of particles - Atoms, List of particles - Molecules, List of particles - Condensed matter, List of particles - Other, List of particles - Categorisation by speed, List of particles - Reference

Read more here: » List of particles: Encyclopedia II - List of particles - Elementary particles

Muons were discovered by Carl D. Anderson in 1936 while he studied cosmic radiation. He had noticed particles that curved in a manner distinct from that of electrons and other known particles when passed through a magnetic field. In particular, these new particles curved to a smaller degree than electrons, but more sharply than protons. It was assumed that their electric charge was equal to that of the electron, and so to account for the difference in curvature, it was supposed that these particles were of intermediate mass (lying somewhere between that of an ...

See also:

Muon, Muon - Muonic atoms, Muon - History

Read more here: » Muon: Encyclopedia II - Muon - History

Electron - Classification. The electron is one of a class of subatomic particles called leptons which are believed to be fundamental particles (that is, they cannot be broken down into smaller constituent parts). The word "particle" is somewhat misleading however, because quantum mechanics shows that electrons also behave like a wave, e.g. in the double-slit experimen ...

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Electron, Electron - Overview, Electron - In practice, Electron - Classification, Electron - Properties and behavior, Electron - In the universe, Electron - In industry, Electron - In the laboratory, Electron - Early experiments, Electron - Usage, Electron - In theory, Electron - History

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While the classical theory (i.e. the tree diagrams) and semiclassical corrections (one-loop diagrams) behaved as expected, the Feynman diagrams with two (or more) loops led to ultraviolet divergences - i.e. infinite results that could not be removed because the quantized general relativity was not renormalizable, unlike Quantum electrodynamics. In popular terms, the discreteness of quantum theory is not compatible with the smoothness of Einstein's general relativity. These problems, together with some conceptual puzzles, led many physicists ...

See also:

Graviton, Graviton - Gravitons and models of quantum gravity, Graviton - Gravitons and experiments, Graviton - Problems with the Graviton

Read more here: » Graviton: Encyclopedia II - Graviton - Gravitons and models of quantum gravity

The claims made on behalf of free energy devices have earned them a spot in cultural folklore. In fiction, zero-point energy is often used as technobabble, usually to explain powerful sources of energy or devices that can lift heavy objects. Examples of such uses include the following: In the computer game Half-Life 2, one of the weapons used by the player is the "Zero Point Energy Field Manipulator", better known by its nickname the "Gravity Gun". It allows the user to pick up and launch any medium-sized objects, and was ...

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Zero-point energy, Zero-point energy - Introduction, Zero-point energy - Varieties of zero-point energy, Zero-point energy - Experimental evidence, Zero-point energy - Gravitation and cosmology, Zero-point energy - History, Zero-point energy - Free energy devices, Zero-point energy - Cultural references

Read more here: » Zero-point energy: Encyclopedia II - Zero-point energy - Cultural references

Many human organizations, such as businesses, churches, armies and political movements are hierarchical organizations, at least officially; commonly superiors, called "bosses", have more power than their subordinates. Thus the relationship defining this hierarchy is "commands" or "has power over". (Some analysts question whether power "really" works as the traditional organizational chart indicates, however.) See also chain of command. Some social insect species (bees, ants, termites) depend on ...

See also:

Hierarchy, Hierarchy - Diverse examples of reasoning with hierarchies, Hierarchy - Hierarchies in programming, Hierarchy - Containment hierarchy, Hierarchy - Social hierarchies, Hierarchy - Hierarchical nomenclatures in the arts and sciences, Hierarchy - Alternatives

Read more here: » Hierarchy: Encyclopedia II - Hierarchy - Social hierarchies

Many human organizations, such as businesses, churches, armies and political movements are hierarchical organizations, at least officially; commonly superiors, called "bosses", have more power than their subordinates. Thus the relationship defining this hierarchy is "commands" or "has power over". (Some analysts question whether power "really" works as the traditional organizational chart indicates, however.) See also chain of command. Some social insect species (bees, ants, termites) depen ...

See also:

Hierarchy, Hierarchy - Diverse examples of reasoning with hierarchies, Hierarchy - Hierarchies in programming, Hierarchy - Containment hierarchy, Hierarchy - Social hierarchies, Hierarchy - Hierarchical nomenclatures in the arts and sciences, Hierarchy - Alternatives

Read more here: » Hierarchy: Encyclopedia II - Hierarchy - Social hierarchies

Hierarchies are important for categorization and organization of large numbers of objects. Taxonomies, for example, such as biological taxonomies, are built on hierarchies. Hierarchy is also often used to control complexity in engineering endeavours. For example, large electronic devices such as computers are usually composed of modules, which are themselves created out of smaller components (integrated circuits), which in turn ...

See also:

Hierarchy, Hierarchy - Diverse examples of reasoning with hierarchies, Hierarchy - Hierarchies in programming, Hierarchy - Containment hierarchy, Hierarchy - Social hierarchies, Hierarchy - Hierarchical nomenclatures in the arts and sciences, Hierarchy - Alternatives

Read more here: » Hierarchy: Encyclopedia II - Hierarchy - Hierarchical nomenclatures in the arts and sciences

The Casimir effect has established zero point energy as an uncontroversial and scientifically accepted phenomenon. However, the term zero point energy has also become associated with a highly controversial area of human endevour, the design and invention of so-called free energy devices. These devices purport to tap the zero-point field and somehow extract energy from it, thus providing an inexhaustible, cheap, and non-polluting energy source. By contrast, the scientific community views such devices as a form of perpetual motion ...

See also:

Zero-point energy, Zero-point energy - Introduction, Zero-point energy - Varieties of zero-point energy, Zero-point energy - Experimental evidence, Zero-point energy - Gravitation and cosmology, Zero-point energy - History, Zero-point energy - Free energy devices, Zero-point energy - Cultural references

Read more here: » Zero-point energy: Encyclopedia II - Zero-point energy - Free energy devices