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Erwin Madelung
Erwin Madelung (1881–1972) was a German theoretical physicist, professor at Frankfurt from 1921, known for the Madelung constant of ionic crystals, the Madelung orbital-filling rule, and a hydrodynamical interpretation of quantum mechanics.
Erwin Mayer
Erwin Mayer (1937–2011) was an Austrian inorganic chemist at the University of Innsbruck who first vitrified pure liquid water in 1980 and made cubic ice from liquid water in 1987.
Erwin Reisner
Erwin Reisner (born 1979) is a chemist and Professor of Energy and Sustainability at the University of Cambridge, known for solar fuels and semi-artificial photosynthesis.
Erwin Schrödinger
Erwin Schrödinger (1887–1961) was an Austrian theoretical physicist who formulated wave mechanics, shared the 1933 Nobel Prize in Physics, and coined the term quantum entanglement.
Erwin Wilhelm Müller
Erwin Wilhelm Müller (1911–1977) was a German-born physicist at Penn State who invented the field ion microscope and became the first person to see an atom.
Erythritol
Erythritol is a four-carbon sugar alcohol sweetener, 60–80% as sweet as sucrose, made by fermenting glucose and excreted nearly unchanged in urine with almost no calories.
Erythritol fatty acid esters
Erythritol fatty acid esters, esters of erythritol and fatty acids, are sugar-alcohol-based food emulsifiers and microencapsulants; GRAS Notice GRN 297 (Stepan Company) received an FDA no-questions letter in 2009 for baked goods use.
Erythritol tetranitrate
Erythritol tetranitrate, also known as Cardiloid and Tetranitrol, is a nitrate ester of the sugar alcohol erythritol, first synthesized in 1849, used as an explosive and a vasodilator.
Erythrosine
Erythrosine, also known as FD&C Red No. 3, is a synthetic xanthene dye that colors foods and drugs red; the FDA revoked its food authorization in January 2025.
Escape fraction of ionizing photons
The escape fraction of ionizing photons is the fraction of hydrogen-ionizing photons produced in a star-forming galaxy that escapes its gas and dust into the intergalactic medium.
Escape velocity
Escape velocity, or escape speed, is the minimum initial speed an object needs, without further propulsion, to escape the gravity of a body like Earth, where it is 11.2 km/s.
Escapement
The escapement, also called the escapement mechanism, is the device in a mechanical clock or watch that transfers energy from the weight or mainspring to the pendulum or balance wheel and counts its oscillations.
Escarpment
An escarpment is a long, continuous steep slope facing one direction and separating gentler surfaces, formed by faulting or erosion, including great escarpments about a kilometer high.
Escobal
Escobal is an underground silver-gold-lead-zinc mine in Guatemala, 40 km southeast of Guatemala City, producing about 20 million ounces of silver yearly from 2014 to 2017.
Escondida
Escondida is a copper mine in Chile's Atacama Desert, 170 km southeast of Antofagasta, the world's largest copper producer at about 1 million tonnes a year, operated by BHP since 1990.
ESI-MS/MS
ESI-MS/MS is a tandem mass spectrometry method in which electrospray ionization moves ions from solution into the gas phase, making routine the trace analysis of peptides, metabolites, and drugs in clinical and research laboratories.
Esketamine
Esketamine, marketed as Spravato and Ketanest S, is the S-enantiomer of ketamine, an NMDA receptor antagonist approved in 2019 as a nasal spray for treatment-resistant depression.
ESO/SERC Southern Sky Survey
The ESO/SERC Southern Sky Survey is a two-color photographic atlas of the sky south of declination −20°, the southern counterpart to the Palomar Observatory Sky Survey.
Esper S. Larsen, Jr.
Esper S. Larsen, Jr. (1879–1961) was an American petrologist at Harvard and the U.S. Geological Survey known for optical mineral determination and the lead-alpha method of dating rocks.
Essential amino acid
An essential amino acid, also called an indispensable amino acid, is one the human body cannot synthesize and must obtain from food; nine are essential for adults, including histidine.
Essential Climate Variables
Essential Climate Variables (ECVs) are the physical, chemical, or biological variables the Global Climate Observing System has judged critical for characterizing Earth's climate, currently 55 across atmosphere, ocean, and land.
Essential Science Indicators
Essential Science Indicators (ESI) is a web-based bibliometric tool from Clarivate, introduced in 2001, that ranks researchers, institutions, countries, and journals by output and citation impact.
Essential spectrum
The essential spectrum of a linear operator, denoted σess(T), is the part of its spectrum unchanged by compact perturbations, with key applications to Schrödinger operators in quantum mechanics.
Essentially non-oscillatory scheme
An essentially non-oscillatory (ENO) scheme is a high-order numerical method for hyperbolic partial differential equations that avoids spurious oscillations near shocks via adaptive stencil selection.
Essilor
Essilor, also known as Essilor International, is a French ophthalmic lens maker formed in 1972 from the merger of ESSEL and SILOR, and became the world's leading lens manufacturer.
Estella Leopold
Estella Leopold (1927–2024) was an American paleobotanist and conservationist, the youngest child of Aldo Leopold, who reconstructed ancient vegetation from fossil pollen and won the 2010 International Cosmos Prize.
Ester
An ester is a compound in which an acid's hydroxyl hydrogen is replaced by an organyl group, forming the R-CO-O-R′ linkage, as in ethyl acetate and nitroglycerin.
Ester pyrolysis
Ester pyrolysis is a thermal elimination reaction in which heating an ester bearing a beta-hydrogen gives an alkene and a carboxylic acid by a concerted syn-elimination mechanism.
Esterification
Esterification is the chemical reaction converting a carboxylic acid and an alcohol into an ester and water, first reported by Emil Fischer and Arthur Speier in 1895.
Esther M. Conwell
Esther M. Conwell (1922–2014) was an American condensed matter physicist known for the Conwell–Weisskopf impurity-scattering theory, who in 1997 became the first woman to receive the IEEE Edison Medal.