In mathematical physics, the concept of quantum spacetime is a generalization of the usual concept of spacetime in which some variables that ordinarily commute are assumed not to commute and form a different Lie algebra. The choice of that algebra still varies from theory to theory. As a result of this change some variables that are usually continuous may become discrete. Physical reasons have been given to believe that physical spacetime is a quantum spacetime. are already noncommutative, obey the Heisenberg uncertainty principle, and are continuous. Again, physical spacetime is expected to be quantum because physical coordinates are already slightly noncommutative. Both arguments are based on pure gravity and quantum theory, and they limit the measurement of time by the only time constant in pure quantum gravity, the Planck time. Quantum spacetimes are often described mathematically using the noncommutative geometry of Connes, quantum geometry, or quantum groups. and the time variable
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Planck constantPlaque at the Humboldt University of Berlin: "Max Planck, discoverer of the elementary quantum of action h, taught in this building from 1889 to 1928." In 1905 the value (E), the energy of a charged atomic oscillator, was theoretically associated with the energy of the electromagnetic wave itself, representing the minimum amount of energy required to form an electromagnetic field (a "quantum"). Further investigation of quanta revealed behaviour associated with an independent unit ("particle") as opposed to an electromagnetic wave and was eventually given the term photon. The Planck relation now describes the energy of each photon in terms of the photon's frequency. This energy is extremely small in terms of ordinary experience. Since the frequency , wavelength λ, and speed of light c are related by λν = c, the Planck relation for a photon can also be expressed as The above equation leads to another relationship involving the Planck constant. Value Significance of the value
Quantum entanglementQuantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently – instead, a quantum state may be given for the system as a whole. Such phenomena were the subject of a 1935 paper by Albert Einstein, Boris Podolsky and Nathan Rosen, describing what came to be known as the EPR paradox, and several papers by Erwin Schrödinger shortly thereafter. Einstein and others considered such behavior to be impossible, as it violated the local realist view of causality (Einstein referred to it as "spooky action at a distance"), and argued that the accepted formulation of quantum mechanics must therefore be incomplete. History However, they did not coin the word entanglement, nor did they generalize the special properties of the state they considered. Concept Meaning of entanglement Apparent paradox The hidden variables theory
Uncertainty reigns over Heisenberg's measurement analogyA row has broken out among physicists over an analogy used by Werner Heisenberg in 1927 to make sense of his famous uncertainty principle. The analogy was largely forgotten as quantum theory became more sophisticated but has enjoyed a revival over the past decade. While several recent experiments suggest that the analogy is flawed, a team of physicists in the UK, Finland and Germany is now arguing that these experiments are not faithful to Heisenberg's original formulation. Heisenberg's uncertainty principle states that we cannot measure certain pairs of variables for a quantum object – position and momentum, say – both with arbitrary accuracy. When Heisenberg proposed the principle in 1927, he offered a simple physical picture to help it make intuitive sense. Not necessarily wrong Then in 1988 Masanao Ozawa at Nagoya University in Japan argued that Heisenberg's original relationship between error and disturbance does not represent a fundamental limit of uncertainty. Truer to Heisenberg?
Efimov stateThe Efimov effect is an effect in the quantum mechanics of Few-body systems predicted by the Russian theoretical physicist V. N. Efimov in 1970. The unusual Efimov state has an infinite number of similar states. In 2005, for the first time the research group of Rudolf Grimm and Hanns-Christoph Nägerl from the Institute for Experimental Physics (University of Innsbruck, Austria) experimentally confirmed such a state in an ultracold gas of caesium atoms. The interest in the "universal phenomena" of cold atomic gases is still growing, especially because of the long awaited experimental results. The discipline of universality in cold atomic gases nearby the Efimov states are sometimes commonly referred to as "Efimov physics". The Efimov states are independent of the underlying physical interaction, and can in principle be observed in all quantum mechanical systems (molecular, atomic, and nuclear). References Jump up ^ В.И. External links
Artificial Intelligence Versus Collective Intelligence (18)We want scientifically-grounded two-way traffic between philosophy and the Web. Technologies are ideas given flesh, the exteriorization of the conceptual structures and utopian impulses of humanity, and so are alien only insofar as their history and materiality are unknown. Artifactualization does not happen for and of itself, but reflects the ontological assumptions of their historical period. What is most interesting about the Web is it is clear that older philosophical categories like "mind" and "language" have to be fundamentally rethought. Thesis The Web is the rise of increasingly "intertwingled" techno-social assemblage that increasingly displaces the previous stable ontological assumption of the individual. A disciple of Norbert Wiener, the psychologist J.C.R. "Man-Machine Symbiosis" by J.C.R. "The fig tree is pollinated only by the insect Blastophaga grossorun. AI attempted to define an individual on a level of abstraction and then implement this computationally.
AmplituhedronAn amplituhedron is a geometric structure that enables simplified calculation of particle interactions in some quantum field theories. In planar N = 4 supersymmetric Yang–Mills theory, an amplituhedron is defined as a mathematical space known as the positive Grassmannian. The connection between the amplituhedron and scattering amplitudes is at present a conjecture that has passed many non-trivial checks, including an understanding of how locality and unitarity arise as consequences of positivity. Research has been led by Nima Arkani-Hamed. Edward Witten described the work as “very unexpected" and said that "it is difficult to guess what will happen or what the lessons will turn out to be. Description Using twistor theory, BCFW recursion relations involved in the scattering process may be represented as a small number of twistor diagrams. Implications See also References Notes Bibliography External links
Personal and Historical Perspectives of Hans Bethe