background preloader


Nomenclature[edit] In 1900, Max Planck was working on black-body radiation and suggested that the energy in electromagnetic waves could only be released in "packets" of energy. In his 1901 article [4] in Annalen der Physik he called these packets "energy elements". The word quanta (singular quantum) was used even before 1900 to mean particles or amounts of different quantities, including electricity. Physical properties[edit] The cone shows possible values of wave 4-vector of a photon. A photon is massless,[Note 2] has no electric charge,[13] and is stable. Photons are emitted in many natural processes. The energy and momentum of a photon depend only on its frequency (ν) or inversely, its wavelength (λ): where k is the wave vector (where the wave number k = |k| = 2π/λ), ω = 2πν is the angular frequency, and ħ = h/2π is the reduced Planck constant.[17] Since p points in the direction of the photon's propagation, the magnitude of the momentum is Experimental checks on photon mass[edit]

W and Z bosons The W bosons are named after the weak force. The physicist Steven Weinberg named the additional particle the "Z particle",[3] and later gave the explanation that it was the last additional particle needed by the model. The W bosons had already been named, and the Z bosons have zero electric charge.[4] The two W bosons are verified mediators of neutrino absorption and emission. The Z boson mediates the transfer of momentum, spin and energy when neutrinos scatter elastically from matter (a process which conserves charge). Basic properties[edit] These bosons are among the heavyweights of the elementary particles. Weak nuclear force[edit] The W and Z bosons are carrier particles that mediate the weak nuclear force, much as the photon is the carrier particle for the electromagnetic force. W bosons[edit] The W bosons are best known for their role in nuclear decay. 60 27Co → 60 28Ni+ + e− + ν e This reaction does not involve the whole cobalt-60 nucleus, but affects only one of its 33 neutrons.

Photoelectric effect Emission of electrons when light hits a material The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physics, solid state, and quantum chemistry to draw inferences about the properties of atoms, molecules and solids. The effect has found use in electronic devices specialized for light detection and precisely timed electron emission. Emission of conduction electrons from typical metals requires a few electron-volt (eV) light quanta, corresponding to short-wavelength visible or ultraviolet light. Emission mechanism[edit] The photons of a light beam have a characteristic energy, called photon energy, which is proportional to the frequency of the light. Experimental observation of photoelectric emission[edit] Even though photoemission can occur from any material, it is most readily observed from metals and other conductors.

This stunning animal looks like a glitch in reality's programming Isn't there a butterfly with similar properties? SExpand Morpho butterfly? There was a clothing company called Biomimetic Design that claimed to have been able to duplicate the effect, but I think they're defunct or something now. Quantum Minimum amount of a physical entity involved in an interaction Etymology and discovery[edit] The word quantum is the neuter singular of the Latin interrogative adjective quantus, meaning "how much". "Quanta", the neuter plural, short for "quanta of electricity" (electrons), was used in a 1902 article on the photoelectric effect by Philipp Lenard, who credited Hermann von Helmholtz for using the word in the area of electricity. However, the word quantum in general was well known before 1900,[2] e.g. quantum was used in E. A. In 1901, Max Planck used quanta to mean "quanta of matter and electricity",[5] gas, and heat.[6] In 1905, in response to Planck's work and the experimental work of Lenard (who explained his results by using the term quanta of electricity), Albert Einstein suggested that radiation existed in spatially localized packets which he called "quanta of light" ("Lichtquanta").[7] Quantization[edit] See also[edit] References[edit] Further reading[edit]

Photonic topological insulator Photonic topological insulators are artificial electromagnetic materials that support topologically non-trivial, unidirectional states of light.[1] Photonic topological phases are classical electromagnetic wave analogues of electronic topological phases studied in condensed matter physics. Similar to their electronic counterparts, they, can provide robust unidirectional channels for light propagation.[2] The field that studies these phases of light is referred to as topological photonics, even though the working frequency of these electromagnetic topological insulators may fall in other parts of the electromagnetic spectrum such as the microwave range.[3] History[edit] Topological order in solid state systems has been studied in condensed matter physics since the discovery of integer quantum Hall effect. Platforms[edit] Chern number[edit] See also[edit] References[edit]

Higgs boson The Higgs boson is named after Peter Higgs, one of six physicists who, in 1964, proposed the mechanism that suggested the existence of such a particle. Although Higgs's name has come to be associated with this theory, several researchers between about 1960 and 1972 each independently developed different parts of it. In mainstream media the Higgs boson has often been called the "God particle", from a 1993 book on the topic; the nickname is strongly disliked by many physicists, including Higgs, who regard it as inappropriate sensationalism.[17][18] In 2013 two of the original researchers, Peter Higgs and François Englert, were awarded the Nobel Prize in Physics for their work and prediction[19] (Englert's co-researcher Robert Brout had died in 2011). A non-technical summary[edit] "Higgs" terminology[edit] Overview[edit] If this field did exist, this would be a monumental discovery for science and human knowledge, and is expected to open doorways to new knowledge in many fields. History[edit]

Leibniz's Philosophy of Physics 1. The Historical Development of Leibniz’s Physics In his earliest days, Leibniz read a wide range of works drawn from his father’s considerable library. Later he was formally educated at the University of Leipzig (1661–1666), briefly at the University of Jena (1663), and finally at the University of Altdorf (1666–1667). From these sources, Leibniz gained an early acquaintance with the Aristotelian-Scholastic tradition, as well as a taste of neo-platonic themes common in Renaissance humanism. According to his own recollection, it appears that Leibniz threw himself into the mechanical philosophy sometime around the year 1661.[1] In a well-known letter to Nicolas Remond, Leibniz – then in the twilight of his years – recounted his early conversion: After having finished the trivial schools[2], I fell upon the moderns, and I recall walking in a grove on the outskirts of Leipzig called the Rosental, at the age of fifteen, and deliberating whether to preserve substantial forms or not. 2. 3.

Hierochloe odorata Characteristics[edit] Hierochloe odorata is a very hardy perennial. Its leaves do not have rigid stems, so only grow to about 20 cm (7.9 in) in height, and then the leaves grow outward horizontally to 100 cm (39 in) long or more, by late summer. The bases of the leaves, just below the soil surface are broad and white, without hairs; the underside of the leaves are shiny, without hairs. In the wild, the bases of the leaves are frequently purple-red colored, this indicates a phosphorus-deficient soil. There are several strains of sweetgrass—a regular strain that can be harvested once or twice a year, and a naturally occurring polyploid strain, which is much faster growing and can be harvested three to five times a year. [3] Taxonomy[edit] The name Hierochloe odorata is from the Greek, literally "holy fragrant grass". Propagation[edit] Easiest by cutting out plugs from established plants. Distribution[edit] Uses[edit] European traditions[edit] Native American traditions[edit] References[edit]

Laser Device which emits light via optical amplification Red (660 & 635 nm), green (532 & 520 nm) and blue-violet (445 & 405 nm) lasers A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation".[1][2] The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. Lasers are used in optical disk drives, laser printers, barcode scanners, DNA sequencing instruments, fiber-optic and free-space optical communication, laser surgery and skin treatments, cutting and welding materials, military and law enforcement devices for marking targets and measuring range and speed, and in laser lighting displays for entertainment. Fundamentals Lasers are characterized according to their wavelength in a vacuum. Terminology Maser

Pinch (plasma physics) Compression of an electrically conducting filament by magnetic forces A current-driven toroidal Z-pinch in a krypton plasma This is a basic explanation of how a pinch works.(1) Pinches apply a high voltage and current across a tube. This tube is filled with a gas, typically a fusion fuel such as deuterium. The MagLIF concept, a combination of a Z-pinch and a laser beam Model of the kink modes that form inside a pinch Pinched aluminium can, produced via a pulsed magnetic field created by rapidly discharging 2 kilojoules from a high voltage capacitor bank into a 3-turn coil of heavy gauge wire. Electromagnetic pinch "can crusher": schematic diagram In plasma physics three pinch geometries are commonly studied: the θ-pinch, the Z-pinch, and the screw pinch. A sketch of the θ-pinch equilibrium. The θ-pinch has a magnetic field directed in the z direction and a large diamagnetic current directed in the θ direction. Since B is only a function of r we can simplify this to ) for the θ-pinch reads:

Gluon Gluons /ˈɡluːɒnz/ are elementary particles that act as the exchange particles (or gauge bosons) for the strong force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles.[6] In technical terms, gluons are vector gauge bosons that mediate strong interactions of quarks in quantum chromodynamics (QCD). Gluons themselves carry the color charge of the strong interaction. This is unlike the photon, which mediates the electromagnetic interaction but lacks an electric charge. Properties[edit] Diagram 1: e+e− -> Y(9.46) -> 3g Numerology of gluons[edit] Unlike the single photon of QED or the three W and Z bosons of the weak interaction, there are eight independent types of gluon in QCD. This may be difficult to understand intuitively. Color charge and superposition[edit] This is read as "red–antiblue plus blue–antired". Color singlet states[edit] The color singlet state is:[7] Eight gluon colors[edit] Group theory details[edit] Confinement[edit]