Technology and the built world

Leslie A. Geddes

Leslie A. Geddes (1921–2009) was a Scottish-born American biomedical engineer and physiologist at Purdue University whose defibrillation and electrode research earned the 2006 National Medal of Technology.

Leslie A. Momoda

Leslie A. Momoda is an American materials scientist and Executive Vice President of HRL Laboratories in Malibu, California, elected to the National Academy of Engineering in February 2025.

Leslie C. Dirks

Leslie C. Dirks (1936–2001) was an American engineer who served as CIA Deputy Director for Science and Technology and was elected to the National Academy of Engineering in 1980.

Leslie E. Robertson

Leslie E. Robertson (1928–2021) was an American structural engineer best known as lead engineer of the World Trade Center twin towers, completed in 1972 and 1973.

Leslie L. Shoemaker

Leslie L. Shoemaker is an American water resources engineer and Tetra Tech executive elected to the National Academy of Engineering in 2022 for watershed management technology.

Leslie Lamport

Leslie Lamport, born 1941 in New York City, is an American computer scientist who developed LaTeX and won the 2013 ACM Turing Award for work on distributed systems.

Oct 10, 2026

Leslie P. Kaelbling

Leslie Pack Kaelbling is the Panasonic Professor of Computer Science at MIT, known for reinforcement learning and POMDP research and for founding the Journal of Machine Learning Research.

Leslie Valiant

Leslie Valiant, born 1949, is a Harvard computer scientist who founded computational learning theory, defined the counting class #P, and shaped parallel computing, winning the 2010 Turing Award.

Lesotho Highlands Water Project

The Lesotho Highlands Water Project (LHWP) is a bi-national scheme of dams and tunnels supplying Lesotho highlands water to Gauteng, South Africa, under a 1986 treaty.

Less than truckload shipping

Less than truckload (LTL) shipping is a road freight service for shipments too large for parcel but too small to fill a trailer, typically 150 to 10,000 pounds.

Leste do Urucu Oil and Gas Field

Leste do Urucu is an onshore oil and gas field in the Solimões Basin near Coari, Amazonas, Brazil, discovered by Petrobras in 1987 and producing since 1992.

Lester A. Hoel

Lester A. Hoel (1935–2022) was an American transportation engineer, a University of Virginia professor and National Academy of Engineering member who co-authored Traffic and Highway Engineering.

Lester C. Krogh

Lester Christensen Krogh (1925–2013) was an American chemical engineer who spent his 37-year career at 3M, retiring in 1989 as senior vice president of research and development.

Lester F. Eastman

Lester F. Eastman (1928–2013) was an American electrical engineer at Cornell University who built the first US university research program on compound-semiconductor microwave devices such as gallium arsenide.

Lester Hogan

C. Lester Hogan (1920–2008) was an American physicist and semiconductor executive who invented the microwave gyrator at Bell Labs, taught at Harvard, and led Motorola Semiconductor and Fairchild.

Lester Lees

Lester Lees (1920–1986) was an American aeronautical engineer and longtime Caltech professor whose work on supersonic aerodynamics, heat transfer, and high-altitude gas dynamics proved relevant to atmospheric re-entry.

Lester M. Field

Lester M. Field was an American electrical engineer who created modern traveling-wave tube structures, taught at Stanford and Caltech, and directed microwave research at Hughes Research Laboratories.

Lester Pelton

Lester Allan Pelton (1829–1908) was an American inventor and millwright who developed the Pelton wheel, a split-bucket water wheel that roughly doubled water wheel efficiency and became a foundation of hydroelectric generation.

Let L-410 Turbolet

The Let L-410 Turbolet is a Czech 19-seat twin-engine turboprop built for short take-off and landing from unpaved runways. First flown in 1969, more than 1,200 have been built and operate in over 60 countries.

Let's Encrypt

Let's Encrypt is a free, automated certificate authority run by the nonprofit Internet Security Research Group, issuing its first trusted TLS certificate in September 2015 through the ACME protocol it helped create.

Let's roll

"Let's roll" is the phrase passenger Todd Beamer said aboard hijacked United Airlines Flight 93 on September 11, 2001, before passengers moved to retake the plane.

Lethabo power station

Lethabo power station is a 3,708 MW coal-fired power station in South Africa's northern Free State, owned by Eskom and known for burning unusually low-grade coal.

Letter (paper size)

Letter (ANSI A) is the standard paper size for everyday printing in the United States and Canada, measuring 8.5 × 11 inches, slightly wider and shorter than A4.

Letter box

A letter box, also called a mail box or mail slot, is a receptacle for receiving mail: a door slot, wall-mounted box, curbside mailbox, or centralized locked compartments for apartments.

Letterboxd

Letterboxd is a New Zealand social platform for logging, rating, and reviewing films, created in 2011 by Auckland web designers Matthew Buchanan and Karl von Randow, with 13 million members.

Letterboxing (filming)

Letterboxing, or letterbox format, fits a widescreen image onto a narrower screen undistorted, leaving black bars above and below; the classic use was showing widescreen films on 4:3 televisions.

Letterpress printing

Letterpress printing is a relief printing technique in which raised type and images are inked and pressed directly onto paper, introduced by Gutenberg in the mid-15th century.

Leuna Refinery

The Leuna Refinery, TotalEnergies Raffinerie Mitteldeutschland, is an oil refinery in Leuna, Saxony-Anhalt, Germany, that can process up to 12 million tonnes of crude oil a year.

Leuze electronic

Leuze electronic is a German family-owned manufacturer of optical and inductive sensors, identification systems, and safety solutions for industrial automation, founded by the Leuze family in 1963 in Owen, Baden-Württemberg.