All articles starting with M
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Mass segregation (astronomy)
Mass segregation in astronomy is the tendency of the most massive stars in a star cluster to occupy a more centrally concentrated distribution than lower-mass stars.
Mass sexual assault
Mass sexual assault: sexual violence by multiple perpetrators or against multiple victims, notably mass rape as a tactic of war (Bosnia, Tigray, Sudan) and sexual violence at mass gatherings; recognized under IHL and UNSC Resolutions 1820 and 2467.
Mass sexual assault in Egypt
Mob sexual assaults of women around Cairo's Tahrir Square during protests and celebrations from 2011 to 2014, with pre-2011 precedents; documented by Amnesty and HRW, totaling over 500 survivors, prompting OpAntiSH and a 2014 harassment law.
Mass shooting
A mass shooting is a firearm incident in which several people are shot in a single event, with no fixed definition; databases using different thresholds produce counts differing by more than fiftyfold.
Mass shootings in the United States
Mass shootings in the United States: multi-victim firearm attacks counted under competing definitions (FBI active shooter, GVA 4+ shot). Key facts: under 1% of US gun deaths, disputed international share, 2025 record-low mass killings.
Mass spectrometry
Mass spectrometry, also known as mass spectroscopy or MS, is an analytical technique that measures the mass-to-charge ratio of ions to identify and quantify the chemical species in a sample.
Mass spectrometry imaging
Mass spectrometry imaging (MSI) is a label-free analytical technique that maps the spatial distribution of molecules across a sample, with each image pixel holding a full mass spectrum.
Mass suicide
Mass suicide, also called collective suicide, is the simultaneous self-inflicted death of a social group's members, most famously the 1978 Jonestown deaths of more than 900 people.
Mass surveillance
Mass surveillance: suspicionless collection, analysis, or generation of data on indefinite or large numbers of people, via bulk interception, data retention, facial recognition, and camera networks; distinct from targeted, authorized surveillance of specific suspects.
Mass transfer
Mass transfer is the flow of matter from one star in a binary system to its companion, occurring when the donor fills its Roche lobe and gas escapes through the L1 point.
Mass Transit incident (professional wrestling)
Mass Transit incident: November 23, 1996 ECW house show in Revere, Massachusetts, where 17-year-old Erich Kulas, booked after lying about age and training, was cut too deeply by New Jack; the fallout delayed ECW's Barely Legal pay-per-view to April 13, 1997.
Mass trespass of Kinder Scout
Mass trespass of Kinder Scout: 24 April 1932 civil disobedience by about 400 mostly working-class walkers from Manchester, led by Benny Rothman's British Workers' Sports Federation, demanding access to private Peak District moorland; five jailed, fueling the UK right-to-roam movement.
Mass vaccination
Mass vaccination, also called mass immunization, is the delivery of vaccines to a large number of people in a short time, used to raise herd immunity during outbreaks.
Mass versus weight
Mass versus weight is the distinction between mass, the fixed quantity of matter in an object, and weight, the gravitational force on it, which varies with location.
Mass wasting
Mass wasting, also called mass movement, is the downslope movement of rock and soil under gravity alone, ranging from slow creep to debris avalanches reaching 400 km/h.
Mass-impregnated cable
A mass-impregnated (MI) cable is a high-voltage power cable insulated with paper tape impregnated with a viscous oil-like compound, used almost exclusively for HVDC submarine transmission since the 1950s.
Mass-independent fractionation
Mass-independent fractionation is isotope fractionation in which isotope ratios do not follow mass laws, discovered in ozone chemistry in 1983 and used in meteorites, paleoclimatology, and atmospheric science.
Mass-sheet degeneracy
The mass-sheet degeneracy (MSD) is a gravitational lensing invariance found by Falco, Gorenstein, and Shapiro in 1985: adding a uniform mass sheet changes only image time delays.
Mass-to-charge ratio
The mass-to-charge ratio, abbreviated m/z, is a dimensionless quantity used to characterize ions in mass spectrometry, defined by IUPAC as mass number divided by charge number.
Mass-to-light ratio
The mass-to-light ratio (M/L) is the mass of a galaxy or galaxy cluster divided by its light, a diagnostic of unseen dark matter first applied by Fritz Zwicky in 1933.
Mass–energy equivalence
Mass–energy equivalence, also known as E equals mc squared, is the physics principle that mass and energy are the same quantity, stated by Einstein in 1905.
Mass–metallicity relation
The mass–metallicity relation (MZR) is the correlation between a galaxy's stellar mass and its gas metallicity: more massive galaxies are more metal-rich, holding out to redshifts beyond 2.
Massa Makan Diabaté
Massa Makan Diabaté (1938–1988) was a French-language Malian writer and historian from Kita, best known for the Kouta trilogy, who carried the Manding griot oral tradition into the written novel.
Massachusett language
Massachusett language, or Wôpanâak, is an extinct Eastern Algonquian language of Southern New England. It is known for its colonial religious texts and modern reclamation efforts since 1993.
Massachusetts
Massachusetts, the Commonwealth of Massachusetts or Bay State, is a New England state, sixth to ratify (February 6, 1788), capital Boston, 2020 population 7,029,917, area 8,257 sq mi, governed by the General Court and Governor Maura Healey.
Massachusetts Bay
Massachusetts Bay is an Atlantic bay at the southern end of the Gulf of Maine between Cape Ann and Cape Cod, namesake of the 1628 Massachusetts Bay Company and Colony, with semidiurnal tides, Stellwagen Bank, and 12,000 years of Native habitation.
Massachusetts Bay Colony
Massachusetts Bay Colony (1629–1691) was a Puritan-founded English colony in New England, chartered by Charles I, governed from Boston under John Winthrop, absorbing Plymouth in 1691 to become the royal Province of Massachusetts Bay.
Massachusetts Bay Transportation Authority
The Massachusetts Bay Transportation Authority, known locally as the T, is the public transit agency for greater Boston, created in 1964 as the first combined regional transit system in the United States.
Massachusetts Democratic Party
Massachusetts Democratic Party (MassDems), state Democratic Party affiliate chaired by Steve Kerrigan since April 2023; governing Democratic State Committee of 400+ members; holds all statewide offices and congressional seats despite shrinking registration.
Massachusetts Department of Public Health
The Massachusetts Department of Public Health is the state agency responsible for promoting health and preventing illness, working alongside 351 autonomous city and town health departments.