edgepedia

All articles A–Z

519,064 articles

Double eagle

Double eagle: the United States $20 gold coin, minted 1849-1933 in Liberty Head (Longacre) and Saint-Gaudens designs; largest circulating US gold coin, famous for the 1933 rarity.

Double electron capture

Double electron capture is a nuclear decay process in which a nucleus absorbs two bound atomic electrons, converting two protons into neutrons and lowering the atomic number by two.

Double electron capture of xenon-124

Double electron capture of xenon-124 is a rare radioactive decay in which a xenon-124 nucleus absorbs two atomic electrons and becomes tellurium-124, first observed directly in 2019 with the longest half-life ever measured.

Double electron–electron resonance

Double electron–electron resonance (DEER), also called PELDOR, is a pulsed EPR technique that measures nanometer-scale distances between unpaired electron spins, most often spin labels on biomolecules.

Double entendre

Double entendre: a word or phrase with two meanings, one usually risqué or sexual; a type of pun. From obsolete French, coined in English in the 1670s, attributed to Dryden's 1673 play Marriage a-la-Mode.

Double exchange

Double exchange is a magnetic exchange mechanism in which hopping electrons couple ionic spins ferromagnetically, proposed by Clarence Zener in 1951 for mixed-valence manganese oxides.

Double eyelids

Double eyelids, also called creased upper eyelids, are upper eyelids with a visible supratarsal crease; about 50% of people of Asian descent lack one, and surgery can create it.

Double factorial

The double factorial of a nonnegative integer n, written n!!, is the product of all positive integers up to n with the same parity as n.

Double Falcon

Double Falcon is the conventional name for a putative ruler of Egypt's Dynasty 0, around 3200–3000 BC, attested only by five serekhs surmounted by two facing falcons.

Double Fantasy

Double Fantasy (1980) is the final studio album by John Lennon and Yoko Ono, released by Geffen on November 17, 1980, recorded at the Hit Factory, and winner of the 1982 Grammy for Album of the Year.

Double fertilization

Double fertilization: angiosperm fertilization in which one sperm forms the diploid embryo and a second forms the triploid endosperm; discovered by Nawaschin (1898) and Guignard (1899); also occurs in the gymnosperm genera Ephedra and Gnetum, producing a second embryo.

Double field theory

Double field theory is a T-duality covariant reformulation of the massless sector of closed string theory, introduced by Chris Hull and Barton Zwiebach in 2009.

Double H Pipeline

The Double H Pipeline is a 485-mile crude oil pipeline from Dore, North Dakota, to Guernsey, Wyoming, opened in 2015 and owned by Kinder Morgan.

Double harmonic scale

Double harmonic scale (double harmonic major, Byzantine scale, maqam Hijaz Kar): a seven-note scale, 1 ♭2 3 4 5 ♭6 7, with two augmented seconds, palindrome symmetry, and modes including the Hungarian minor.

Double Helix (双程) (TV series)

Double Helix (双程, Shuang Cheng, A Round Trip to Love) is a 2026 Chinese-Singaporean BL drama series adapted from Lan Lin's novel, starring Ayden Sng and Lu Sitong as reunited lovers Lu Feng and Cheng Yichen, 12 episodes on GagaOOLala, Viki, and Viu from May 8 to June 13, 2026.

Double hull

A double hull is a ship hull made of two watertight steel layers separated by a space, mandated on oil tankers because oil spills require breaching both layers.

Double Impact

Double Impact is a 1991 American action film directed by Sheldon Lettich, in which Jean-Claude Van Damme plays twins Alex and Chad Wagner, separated after their parents' murder in Hong Kong.

Double Indemnity

Double Indemnity: 1944 Billy Wilder film noir, also known by Cain's novella title, in which insurance salesman Walter Neff and Phyllis Dietrichson murder her husband for a double indemnity payout; seven Oscar nominations, no wins.

Double Irish arrangement

The Double Irish arrangement was a corporate tax structure used by US tech firms to shift profits to zero-tax jurisdictions until Ireland closed it in 2015.

Double iSmart

Double iSmart (డబుల్ ఇస్మార్ట్) is a 2024 Telugu sci-fi action film, sequel to iSmart Shankar, directed by Puri Jagannadh, starring Ram Pothineni and Sanjay Dutt; released August 15, 2024, and a box-office failure.

Double jeopardy

Double jeopardy, or ne bis in idem, bars a second prosecution or punishment for the same offense after acquittal or conviction; covers attachment, Blockburger, mistrials, dual sovereignty, and Erlinger (2024).

Double Jeopardy (1999 film)

Double Jeopardy is a 1999 Bruce Beresford thriller starring Ashley Judd and Tommy Lee Jones, a Paramount release about a framed woman who learns the double jeopardy doctrine; it grossed $177.8 million worldwide.

Double Jeopardy Clause

The Double Jeopardy Clause of the Fifth Amendment bars repeat trials or punishments for the same offense; incorporated against states in Benton v. Maryland (1969), limited by the dual sovereignty doctrine and the Blockburger same-elements test.

Double layer (plasma physics)

A double layer is a localized plasma structure of two opposite charge layers producing a strong electric field and a potential jump, seen in auroras and laboratories.

Double layer (surface science)

The electrical double layer, first modeled by Helmholtz in 1879, is the arrangement of charged species and dipoles at a solid-solution interface that stores charge in supercapacitors.

Double layer formation and stability

Double layer formation and stability covers how plasma double layers, localized charge structures that accelerate ions and electrons, form through currents, plasma expansion, or mixed electron populations.

Double layers in space and astrophysical plasmas

Double layers in space and astrophysical plasmas are localized pairs of oppositely charged sheets that accelerate particles without collisions, measured by satellites in Earth's auroral acceleration region and elsewhere.

Double Life (Pharrell Williams song)

"Double Life" is a June 14, 2024 Columbia Records single by Pharrell Williams for the Despicable Me 4 soundtrack. It opens and closes the film's credits, asks "Who will Gru be tonight?", and peaked at UK No. 56 and Billboard Hot 100 No. 89.

Double machine learning

Double machine learning, also known as debiased machine learning, is a statistical method for estimating treatment effects using machine learning, introduced by Victor Chernozhukov and colleagues in 2018.

Double negative

Double negative: two negative words in one clause. In Standard English they cancel (double negation); in many languages and dialects they express one negation (negative concord), with Jespersen's cycle explaining the history.