42,772 articles
Physics World
Physics World is the monthly membership magazine of the Institute of Physics, published by IOP Publishing since October 1988 as the successor to Physics Bulletin.
Physics-informed neural networks
Physics-informed neural networks (PINNs) are neural networks that solve supervised learning tasks while respecting physics laws described by partial differential equations, introduced by Raissi, Perdikaris, and Karniadakis in 2017.
Physics-Uspekhi
Physics-Uspekhi is the English translation of Uspekhi Fizicheskikh Nauk (UFN), a Russian monthly review journal in physics founded in 1918, published since 1958 and titled Physics-Uspekhi from 1993.
Physikalisch-Technische Bundesanstalt
The Physikalisch-Technische Bundesanstalt (PTB) is Germany's national metrology institute, a federal authority seated in Braunschweig and Berlin that realizes the SI units, runs Germany's atomic clocks, and employs about 2100 staff.
Physisorption
Physisorption, also called physical adsorption, is adsorption in which van der Waals forces bind the adsorbate to a surface, in contrast to chemisorption, which forms chemical bonds.
PhysX
PhysX, originally the NovodeX SDK of AGEIA Technologies, is a real-time physics simulation SDK developed by NVIDIA since its 2008 acquisition, used in Unity, Omniverse, robotics, and games, open source under BSD-3 since 2018.
Phytane
Phytane is a branched C20 isoprenoid alkane, 2,6,10,14-tetramethylhexadecane, derived mainly from the phytol side chain of chlorophyll and among the most widespread biomarkers in sediments and crude oils.
Phytoene
Phytoene is a colorless carotenoid hydrocarbon formed from two GGPP molecules by phytoene synthase, the biosynthetic precursor of carotenoids such as lycopene and beta-carotene that give fruits their colors.
Phytosphingosine
Phytosphingosine is a long-chain sphingoid base with formula C18H39NO3, found mainly in fungi and plants and abundant in human skin ceramides, used in cosmetics for antimicrobial and anti-inflammatory effects.
Pi
Pi, also known as Archimedes' constant, is the ratio of a circle's circumference to its diameter, an irrational number equal to about 3.14159 whose digits continue without end.
Pi Aquarii
Pi Aquarii is a bright classical Be star of spectral type B1III-IVe in Aquarius, one half of an 84.1-day binary with a probable white dwarf companion and a source of hard, variable X-ray emission.
Pi backbonding
Pi backbonding, also called back-donation, is the donation of electron density from a filled metal d orbital into an empty antibonding orbital of a ligand such as carbon monoxide.
Pi bond
A pi bond (π bond) is a covalent bond formed by side-by-side overlap of p orbitals on adjacent atoms, forming the second bond of double bonds and triple bonds.
Pi calculus
The pi calculus is a process calculus for concurrent systems in which communication links are names that can be created dynamically and passed as messages, modeling changing structure.
Pi Scorpii
Pi Scorpii, traditionally called Fang (房), is a triple star system about 500 light-years away in Scorpius, visible as a single star of magnitude 2.91.
Pi-stacking
Pi-stacking, also written π–π stacking, is the attractive noncovalent association between aromatic rings. Despite its name, neutral rings favor T-shaped and parallel-displaced geometries over face-to-face stacking.
Pi-system
A pi-system (Π-system) is a collection of subsets of a set closed under finite intersections; a workhorse of measure-theoretic probability, it powers Dynkin's pi-lambda theorem and uniqueness of measures.
Pi1 Ursae Majoris
Pi1 Ursae Majoris (Pi1 UMa) is a near-solar G-type dwarf star in Ursa Major about 47 light years away, a rapidly rotating, flaring BY Draconis variable.
Pi3 Orionis
Pi3 Orionis, also known as Tabit, is an F-type main-sequence star in the constellation Orion about 26.3 light-years away, shining at magnitude 3.19 and visible to the naked eye.
Piacenzian
The Piacenzian is the youngest stage of the Pliocene Series and last age of the Neogene Period, spanning 3.6 to 2.58 million years ago, named after Piacenza, Italy.
Piancatelli rearrangement
The Piancatelli rearrangement is an acid-catalyzed, water-mediated reaction that converts 2-furylcarbinols into 4-hydroxycyclopentenones, discovered by Giovanni Piancatelli's group at the University of Rome in 1976 and used in prostaglandin drug synthesis.
Picard group
The Picard group Pic(X) of a scheme or ringed space X is the group of isomorphism classes of line bundles on X, with tensor product as the group operation.
Picard iteration
Picard iteration, also called Picard–Lindelöf iteration, is a fixed-point method for solving initial value problems for ordinary differential equations, used mainly to prove that a unique solution exists.
Picard theorem
Picard theorem, a pair of results in complex analysis proved by Charles-Émile Picard in 1879: a non-constant entire function takes every complex value with at most one exception.
Picard–Lindelöf theorem
The Picard–Lindelöf theorem, also called the Cauchy–Lipschitz theorem or Picard's existence theorem, guarantees that an initial value problem for an ordinary differential equation whose right-hand side is Lipschitz continuous has a unique local solution.
PICASSO (dark matter experiment)
PICASSO (Project in Canada to Search for Supersymmetric Objects) was a Canadian dark matter experiment using superheated droplet detectors at SNOLAB, Sudbury, Ontario, later merged into PICO.
Piceance Basin
The Piceance Basin is a structural and sedimentary basin in northwestern Colorado, named for Piceance Creek and holding the world's largest known oil shale deposit, about 1.53 trillion barrels.
Piceatannol
Piceatannol is a hydroxylated analog of resveratrol, a natural polyphenol first isolated in 1984 that inhibits tyrosine kinases and is abundant in passion fruit seeds.
Picene
Picene is an ortho-fused polycyclic aromatic hydrocarbon with five benzene rings in an armchair-edge arrangement, C22H14, that superconducts when doped with potassium, reaching 18 K in 2010.
Pickering emulsion
A Pickering emulsion is an emulsion of two immiscible liquids, such as oil and water, stabilized by solid particles that attach nearly irreversibly to the interface, resisting coalescence longer than surfactants.