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Backward Causation Retrocausality Retrocausality is a concept of cause and effect where the effect temporally precedes its cause.[1] Retrocausality Retrocausality is primarily a thought experiment in philosophy of science based on elements of physics, addressing whether the future can affect the present and whether the present can affect the past.[2] Philosophical considerations of time travel often address the same issues as retrocausality, as do treatments of the subject in fiction, although the two terms are not universally synonymous.[1] While some discussion of retrocausality is confined to fringe science or pseudoscience, a few physical theories with mainstream legitimacy have sometimes been interpreted as leading to retrocausality [...More...]  "Backward Causation" on: Wikipedia Yahoo Parouse 

Cause And Effect Causality Causality (also referred to as causation,[1] or cause and effect) is the natural or worldly agency or efficacy that connects one process (the cause) with another process or state (the effect),[citation needed] where the first is partly responsible for the second, and the second is partly dependent on the first. In general, a process has many causes,[2] which are said to be causal factors for it, and all lie in its past. An effect can in turn be a cause of, or causal factor for, many other effects, which all lie in its future. Causality Causality is metaphysically prior to notions of time and space.[3][4] Causality Causality is an abstraction that indicates how the world progresses, so basic a concept that it is more apt as an explanation of other concepts of progression than as something to be explained by others more basic. The concept is like those of agency and efficacy [...More...]  "Cause And Effect" on: Wikipedia Yahoo Parouse 

Yoichiro Nambu Yoichiro Nambu Yoichiro Nambu (南部 陽一郎, Nambu Yōichirō, 18 January 1921 – 5 July 2015) was a JapaneseAmerican physicist and professor at the University of Chicago.[1] Known for his contributions to the field of theoretical physics, he was awarded half of the Nobel Prize in Physics [...More...]  "Yoichiro Nambu" on: Wikipedia Yahoo Parouse 

Richard Feynman Richard Phillips Feynman (/ˈfaɪnmən/; May 11, 1918 – February 15, 1988) was an American theoretical physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics for which he proposed the parton model. For his contributions to the development of quantum electrodynamics, Feynman, jointly with Julian Schwinger Julian Schwinger and Shin'ichirō Tomonaga, received the Nobel Prize in Physics Nobel Prize in Physics in 1965. Feynman developed a widely used pictorial representation scheme for the mathematical expressions governing the behavior of subatomic particles, which later became known as Feynman diagrams. During his lifetime, Feynman became one of the bestknown scientists in the world [...More...]  "Richard Feynman" on: Wikipedia Yahoo Parouse 

Destructive Interference In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude. Interference usually refers to the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same frequency [...More...]  "Destructive Interference" on: Wikipedia Yahoo Parouse 

Wave In physics, a wave is a disturbance that transfers energy through matter or space, with little or no associated mass transport. Waves consist, instead, of oscillations or vibrations of a physical medium or a field, around relatively fixed locations. There are two main types of waves: mechanical and electromagnetic. Mechanical waves propagate through a physical matter, whose substance is being deformed. Restoring forces then reverse the deformation. For example, sound waves propagate via air molecules colliding with their neighbors. When the molecules collide, they also bounce away from each other (a restoring force). This keeps the molecules from continuing to travel in the direction of the wave. Electromagnetic waves Electromagnetic waves do not require a medium. Instead, they consist of periodic oscillations of electrical and magnetic fields originally generated by charged particles, and can therefore travel through a vacuum [...More...]  "Wave" on: Wikipedia Yahoo Parouse 

Maxwell's Equations Maxwell's equations Maxwell's equations are a set of partial differential equations that, together with the Lorentz force Lorentz force law, form the foundation of classical electromagnetism, classical optics, and electric circuits. The equations provide a conceptual underpinning for all electric, optical and radio technologies, including power generation, electric motors, wireless communication, cameras, televisions, computers etc. Maxwell's equations describe how electric and magnetic fields are generated by charges, currents, and changes of each other. One important consequence of the equations is that they demonstrate how fluctuating electric and magnetic fields propagate at the speed of light. Known as electromagnetic radiation, these waves may occur at various wavelengths to produce a spectrum from radio waves to γrays [...More...]  "Maxwell's Equations" on: Wikipedia Yahoo Parouse 

Ernst Stueckelberg Ernst Carl Gerlach Stueckelberg (full name after 1911: Baron Ernst Carl Gerlach Stueckelberg von Breidenbach zu Breidenstein und Melsbach;[1] February 1, 1905 – September 4, 1984) was a Swiss mathematician and physicist, regarded as one of the most eminent physicists of the 20th century.[2][3] Despite making key advances in theoretical physics, including the exchange particle model of fundamental forces, causal Smatrix theory, and the renormalization group, his idiosyncratic style and publication in minor journals led to his work being unrecognized until the mid1990s.Contents1 Early life 2 Career 3 See also 4 Notes 5 References 6 External linksEarly life[edit] Born into a semiaristocratic family in Basel Basel in 1905,[4] Stueckelberg's father was a lawyer, and his paternal grandfather a distinguished Swiss artist [...More...]  "Ernst Stueckelberg" on: Wikipedia Yahoo Parouse 

Positron me 6969910938355999999♠9.10938356(11)×10−31 kg[1] 6996548579909000000♠5.485799090(16)×10−4 u[1] 6999510998946099999♠0.5109989461(13) MeV/c2[1]Electric charge +1 e +6981160217656499999♠1.602176565(35)×10−19 C[1]Spin 1/2 (same as electron)The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1 e, a spin of 1/2 (same as electron), and has the same mass as an electron. When a positron collides with an electron, annihilation occurs [...More...]  "Positron" on: Wikipedia Yahoo Parouse 

Dirac Equation In particle physics, the Dirac equation Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac Paul Dirac in 1928. In its free form, or including electromagnetic interactions, it describes all spin1/2 massive 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,[1] 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 details 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 [...More...]  "Dirac Equation" on: Wikipedia Yahoo Parouse 

Electric Charge Electric charge Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charges; positive and negative (commonly carried by protons and electrons respectively). Like charges repel and unlike attract. An object with an absence of net charge is referred to as neutral. The SI derived unit of electric charge is the coulomb (C). In electrical engineering, it is also common to use the amperehour (Ah), and, in chemistry, it is common to use the elementary charge (e as a unit). The symbol Q often denotes charge [...More...]  "Electric Charge" on: Wikipedia Yahoo Parouse 

Oneelectron Universe The oneelectron universe postulate, proposed by John Wheeler in a telephone call to Richard Feynman Richard Feynman in the spring of 1940, hypothesises that all electrons and positrons are actually manifestations of a single entity moving backwards and forwards in time. According to Feynman:“ I received a telephone call one day at the graduate college at Princeton from Professor Wheeler, in which he said, "Feynman, I know why all electrons have the same charge and the same mass" "Why?" "Because, they are all the same electron!"[1] ”Overview The idea is based on the world lines traced out across spacetime by every electron. Rather than have myriad such lines, Wheeler suggested that they could all be parts of one single line like a huge tangled knot, traced out by the one electron. Any given moment in time is represented by a slice across spacetime, and would meet the knotted line a great many times [...More...]  "Oneelectron Universe" on: Wikipedia Yahoo Parouse 

World Line The world line (or worldline) of an object is the path that object traces in 4dimensional spacetime. It is an important concept in modern physics, and particularly theoretical physics. The concept of a "world line" is distinguished from concepts such as an "orbit" or a "trajectory" (e.g., a planet's orbit in space or the trajectory of a car on a road) by the time dimension, and typically encompasses a large area of spacetime wherein perceptually straight paths are recalculated to show their (relatively) more absolute position states—to reveal the nature of special relativity or gravitational interactions. The idea of world lines originates in physics and was pioneered by Hermann Minkowski [...More...]  "World Line" on: Wikipedia Yahoo Parouse 

Annihilation In particle physics, annihilation is the process that occurs when a subatomic particle collides with its respective antiparticle to produce other particles, such as an electron colliding with a positron to produce two photons.[1] The total energy and momentum of the initial pair are conserved in the process and distributed among a set of other particles in the final state. Antiparticles have exactly opposite additive quantum numbers from particles, so the sums of all quantum numbers of such an original pair are zero. Hence, any set of particles may be produced whose total quantum numbers are also zero as long as conservation of energy and conservation of momentum are obeyed.[2] During a lowenergy annihilation, photon production is favored, since these particles have no mass [...More...]  "Annihilation" on: Wikipedia Yahoo Parouse 

Wheeler–Feynman Absorber Theory The Wheeler–Feynman absorber theory (also called the Wheeler–Feynman timesymmetric theory), named after its originators, the physicists Richard Feynman Richard Feynman and John Archibald Wheeler, is an interpretation of electrodynamics derived from the assumption that the solutions of the electromagnetic field equations must be invariant under timereversal transformation, as are the field equations themselves. Indeed, there is no apparent reason for the timereversal symmetry breaking, which singles out a preferential time direction and thus makes a distinction between past and future. A timereversal invariant theory is more logical and elegant [...More...]  "Wheeler–Feynman Absorber Theory" on: Wikipedia Yahoo Parouse 

Closed Timelike Curve In mathematical physics, a closed timelike curve (CTC) is a world line in a Lorentzian manifold, of a material particle in spacetime that is "closed", returning to its starting point. This possibility was first discovered by Willem Jacob van Stockum Willem Jacob van Stockum in 1937[1] and later confirmed by Kurt Gödel Kurt Gödel in 1949,[2] who discovered a solution to the equations of general relativity (GR) allowing CTCs known as the Gödel metric; and since then other GR solutions containing CTCs have been found, such as the Tipler cylinder and traversable wormholes. If CTCs exist, their existence would seem to imply at least the theoretical possibility of time travel backwards in time, raising the spectre of the grandfather paradox, although the Novikov selfconsistency principle seems to show that such paradoxes could be avoided [...More...]  "Closed Timelike Curve" on: Wikipedia Yahoo Parouse 