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Longitudinal mode
A longitudinal mode is one of the discrete optical frequencies at which an optical resonator, such as a laser cavity, sustains a standing wave along its axis.
Longitudinal study
A longitudinal study, also called a panel study, is an observational research design that measures the same participants repeatedly over time to observe change and development.
Longitudinal wave
A longitudinal wave, also known as a compression or pressure wave, is a mechanical wave in which particles oscillate parallel to the direction of travel, as in sound.
Longshore drift
Longshore drift is the transport of sand and gravel along a coastline by waves approaching the shore at an angle, moving material in a zigzag path.
Longwave radiation
Longwave radiation is infrared radiation emitted by Earth's surface and atmosphere at wavelengths of roughly 3 to 100 micrometers, also called terrestrial or thermal radiation.
Lonnie G. Thompson
Lonnie G. Thompson is an American paleoclimatologist at The Ohio State University who founded tropical alpine paleoclimatology, recovering ice cores from Kilimanjaro, the Andes, and the Himalayas, and won the National Medal of Science in 2007.
Lonsdaleite
Lonsdaleite, also called hexagonal diamond, is a hexagonal form of carbon first identified in 1967 in the Canyon Diablo meteorite and named for crystallographer Kathleen Lonsdale.
Loo (लू) (wind)
The Loo (लू) is a strong, hot, dry, dusty westerly summer wind across the northern plains of India and Pakistan, blowing in May and June before the monsoon.
Look-and-say sequence
The look-and-say sequence, also called the Conway sequence or audioactive decay, is an integer sequence where each term describes the previous one, giving 1, 11, 21, 1211, 111221.
Look-elsewhere effect
The look-elsewhere effect is the inflation of apparent statistical significance when a signal's location is found by searching a range rather than fixed in advance.
Loop algebra
A loop algebra is an infinite-dimensional Lie algebra formed from a Lie algebra by extending its scalars to Laurent polynomials, and it underlies affine Kac-Moody algebras.
Loop current order
Loop current order is a proposed electronic state in underdoped cuprate superconductors, in which microscopic currents circulate within each unit cell and break time-reversal symmetry.
Loop quantum cosmology
Loop quantum cosmology (LQC) applies loop quantum gravity to the early universe, replacing the big bang singularity with a quantum bounce; its predicted effects may leave imprints in the cosmic microwave background.
Loop quantum gravity
Loop quantum gravity (LQG) is a candidate theory of quantum gravity that quantizes general relativity without a background spacetime, describing space as discrete quanta of geometry.
Loop representation
The loop representation is a formulation of quantum general relativity in which quantum states are functionals of loops in space, introduced by Rovelli and Smolin in 1988.
Loop space
The loop space ΩY of a pointed topological space Y is the space of loops in Y that start and end at the base point.
Lopinavir
Lopinavir is an antiretroviral HIV-1 protease inhibitor, used almost exclusively in the fixed-dose combination with ritonavir marketed as Kaletra, which Abbott Laboratories developed and the FDA approved in 2000 for HIV-1 infection.
Lopingian
The Lopingian is the youngest epoch of the Permian, from about 259.5 to 251.9 million years ago, ending at the Permian-Triassic boundary and divided into the Wuchiapingian and Changhsingian stages.
Loránd Eötvös
Loránd Eötvös (Eötvös Loránd, 1848–1919) was a Hungarian physicist who measured the equality of inertial and gravitational mass and invented the Eötvös torsion balance used in oil prospecting.
Lord Kelvin
Lord Kelvin, born William Thomson, was a Belfast-born physicist who founded the absolute temperature scale named the kelvin and taught at Glasgow for 53 years.
Lord Rayleigh
Lord Rayleigh, born John William Strutt, was a British physicist who worked on acoustics, optics, and gases, discovered argon, and won the 1904 Nobel Prize in Physics.
Loren David Walensky
Loren David Walensky is a chemical biologist and pediatric oncologist, Professor of Pediatrics at Harvard Medical School and Dana-Farber researcher, known for hydrocarbon-stapled peptides and BAX activation studies.
Loren N. Pfeiffer
Loren N. Pfeiffer is an American experimental condensed-matter physicist at Princeton University, elected to the National Academy of Sciences in 2011, known for growing the world's purest gallium arsenide crystals.
Lorena Bociu
Lorena Bociu is an applied mathematician, Professor and Associate Department Head at North Carolina State University, known for optimal control of partial differential equations and a 2019 PECASE award.
Lorentz covariance
Lorentz covariance, also called relativistic covariance, is the property that a physical law keeps the same form under Lorentz transformations, expressing Einstein's principle that the laws of nature are the same in all inertial frames.
Lorentz ether theory
Lorentz ether theory, also called Lorentzian relativity, is Hendrik Lorentz's theory in which light propagates through a stationary ether while moving matter contracts, making ether motion undetectable.
Lorentz factor
The Lorentz factor, or gamma factor, is a quantity in special relativity that gives time dilation, length contraction, and the energy of a moving particle.
Lorentz force
The Lorentz force, or Lorentz force law, is the combined force that electric and magnetic fields exert on a moving charge, formulated by Hendrik Lorentz in 1892.
Lorentz group
The Lorentz group, or homogeneous Lorentz group, is the six-parameter Lie group of spacetime transformations preserving the Minkowski interval, the symmetry group of special relativity.
Lorentz oscillator model
The Lorentz oscillator model, named after Hendrik Lorentz, treats bound electrons as driven, damped harmonic oscillators, yielding a dielectric function that describes refraction, absorption, and dispersion.