HyperPhysics. MathPages. Laws of nature. Aharonov–Bohm effect. Werner Ehrenberg and Raymond E. Siday first predicted the effect in 1949,[3] and similar effects were later published by Yakir Aharonov and David Bohm in 1959.[4] After publication of the 1959 paper, Bohm was informed of Ehrenberg and Siday's work, which was acknowledged and credited in Bohm and Aharonov's subsequent 1961 paper.[5][6] Subsequently, the effect was confirmed experimentally by several authors; a general review can be found in Peshkin and Tonomura (1989).[7] Significance[edit] The Aharonov–Bohm effect is important conceptually because it bears on three issues apparent in the recasting of (Maxwell's) classical electromagnetic theory as a gauge theory, which before the advent of quantum mechanics could be argued to be a mathematical reformulation with no physical consequences.
The Aharonov–Bohm thought experiments and their experimental realization imply that the issues were not just philosophical. The three issues are: Potentials vs. fields[edit] Magnetic solenoid effect[edit] . General Relativity For Tellytubbys. General Relativity For Teletubbies Special Relativity, Postulate 1 Sir Kevin Aylward B.Sc., Warden of the Kings Ale Back to the Contents section Overview This section is about clarifying what the 1st postulate of Special Relativity really means, i.e. the uniform motion one. In the literature there is an enormous about of waffle on this, such that many descriptions of this postulate are one big pile of excrement. Despite the fact that this is well treated by thy High Lords of Gravity in the Gravity Bible, i.e.
"Mathematics was not sufficiently refined in 1917 to cleave apart the demands for "no prior geometry" and for a geometric, co-ordinate independent formulation of physics. This statement essentially says that "Relativity" was used as a backbone for General Relativity, but was mistakenly referred to as "covariance". This confusion still persists today, even for those with Ph.D. Postulate 1 of Special Relativity 1 The laws of physics are independent of inertial frames.
Etc… etc… Note: Summary. Franck–Hertz experiment. Photograph of a vacuum tube with a drop of mercury that's used for the Franck–Hertz experiment in instructional laboratories. A - anode disk. G - metal mesh grid. C - cathode assembly; the cathode itself is hot, and glows orange. The Franck–Hertz experiment was the first electrical measurement to clearly show the quantum nature of atoms, and thus "transformed our understanding of the world".[1] It was presented on April 24, 1914 to the German Physical Society in a paper by James Franck and Gustav Hertz.[2][3] Franck and Hertz had designed a vacuum tube for studying energetic electrons that flew through a thin vapor of mercury atoms.
They discovered that, when an electron collided with a mercury atom, it could lose only a specific quantity of its kinetic energy (7.8×10-19 joules or 4.9 electron volts). These experimental results proved to be consistent with the Bohr model for atoms that had been proposed the previous year by Niels Bohr. The experiment[edit] Effect in other gases[edit] Quantum Zeno effect. The name comes from Zeno's arrow paradox which states that, since an arrow in flight is not seen to move during any single instant, it cannot possibly be moving at all. [note 1] The first rigorous and general derivation of this effect was presented in 1974 by Degasperis et al. [4] However it has to be mentioned that Alan Turing described it in 1954:[5] It is easy to show using standard theory that if a system starts in an eigenstate of some observable, and measurements are made of that observable N times a second, then, even if the state is not a stationary one, the probability that the system will be in the same state after, say, one second, tends to one as N tends to infinity; that is, that continual observations will prevent motion …— Alan Turing as quoted by A.
Hodges in Alan Turing: Life and Legacy of a Great Thinker p. 54 resulting in the earlier name Turing paradox. One should also mention another crucial problem related to the effect. Description[edit] In 1989, David J. Notes[edit] Double-slit experiment. The double-slit experiment is a demonstration that light and matter can display characteristics of both classically defined waves and particles; moreover, it displays the fundamentally probabilistic nature of quantum mechanical phenomena.
The experiment belongs to a general class of "double path" experiments, in which a wave is split into two separate waves that later combine back into a single wave. Changes in the path lengths of both waves result in a phase shift, creating an interference pattern. Another version is the Mach–Zehnder interferometer, which splits the beam with a mirror. This experiment is sometimes referred to as Young's experiment and while there is no doubt that Young's demonstration of optical interference, using sunlight, pinholes and cards, played a vital part in the acceptance of the wave theory of light, there is some question as to whether he ever actually performed a double-slit interference experiment.[1] Overview[edit] Variations of the experiment[edit]
Black body. As the temperature of a black body decreases, its intensity also decreases and its peak moves to longer wavelengths. Shown for comparison is the classical Rayleigh–Jeans law and its ultraviolet catastrophe. A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.
A black body in thermal equilibrium (that is, at a constant temperature) emits electromagnetic radiation called black-body radiation. The radiation is emitted according to Planck's law, meaning that it has a spectrum that is determined by the temperature alone (see figure at right), not by the body's shape or composition. A black body in thermal equilibrium has two notable properties:[1] It is an ideal emitter: it emits as much or more energy at every frequency than any other body at the same temperature.It is a diffuse emitter: the energy is radiated isotropically, independent of direction. Definition[edit] Idealizations[edit] Realizations[edit] Casimir effect. Casimir forces on parallel plates A water wave analogue of the Casimir effect. Two parallel plates are submerged into colored water contained in a sonicator.
When the sonicator is turned on, waves are excited imitating vacuum fluctuations; as a result, the plates attract to each other. The typical example is of two uncharged metallic plates in a vacuum, placed a few nanometers apart. In a classical description, the lack of an external field also means that there is no field between the plates, and no force would be measured between them.[1] When this field is instead studied using the QED vacuum of quantum electrodynamics, it is seen that the plates do affect the virtual photons which constitute the field, and generate a net force[2]—either an attraction or a repulsion depending on the specific arrangement of the two plates.
Dutch physicists Hendrik B. Any medium supporting oscillations has an analogue of the Casimir effect. Overview[edit] Possible causes[edit] Vacuum energy[edit] . ). And. Stern–Gerlach experiment. Basic theory and description[edit] Quantum spin versus classical magnet in the Stern–Gerlach experiment Basic elements of the Stern–Gerlach experiment.
The Stern–Gerlach experiment involves sending a beam of particles through an inhomogeneous magnetic field and observing their deflection. The results show that particles possess an intrinsic angular momentum that is closely analogous to the angular momentum of a classically spinning object, but that takes only certain quantized values. Another important result is that only one component of a particle's spin can be measured at one time, meaning that the measurement of the spin along the z-axis destroys information about a particle's spin along the x and y axis. The experiment is normally conducted using electrically neutral particles or atoms. This avoids the large deflection to the orbit of a charged particle moving through a magnetic field and allows spin-dependent effects to dominate.
Spin values for fermions. Sequential experiments[edit] Advanced Search.