42,772 articles
Hadronic vacuum polarization
Hadronic vacuum polarization is the modification of the photon propagator in quantum electrodynamics caused by virtual hadrons, the dominant uncertainty in the muon's anomalous magnetic moment prediction.
Hadronization
Hadronization, also called hadronize, is the non-perturbative quantum chromodynamics process by which quarks and gluons produced in high-energy collisions combine into the color-neutral hadrons seen in detectors.
Hadwiger conjecture (graph theory)
Hadwiger's conjecture, proposed by Hugo Hadwiger in 1943, states that every graph with no complete graph Kt as a minor can be colored with t − 1 colors.
Hadwiger–Nelson problem
The Hadwiger–Nelson problem, or chromatic number of the plane, asks the fewest colors needed so points a unit distance apart differ, known to be 5, 6, or 7.
Hae Jung Son
Hae Jung Son (손해정) is a South Korean chemist and organic photovoltaics researcher who is a principal researcher at the Korea Institute of Science and Technology.
Haematococcus pluvialis
Haematococcus pluvialis is a freshwater unicellular green microalga that accumulates astaxanthin in thick-walled resting cells under stress, making it the primary natural source for supplements.
Haeshin Lee
Haeshin Lee is a South Korean chemist and professor at KAIST known for inventing polydopamine, a mussel-inspired surface coating, and for bio-inspired adhesives and hemostatic medical devices.
Hafele–Keating experiment
The Hafele–Keating experiment was a 1971 test of relativity in which four cesium atomic clocks were flown around the world on commercial jets, confirming predicted time dilation against ground clocks.
Hafnium
Hafnium is a corrosion-resistant transition metal, atomic number 72, discovered in Copenhagen in 1923, known for neutron absorption in nuclear reactor control rods and its oxide in microchips.
Hafnium disulfide
Hafnium disulfide (HfS2) is an inorganic layered compound of hafnium and sulfur, a transition metal dichalcogenide first reported in 1958 and studied for transistors, photodetectors, and energy storage.
Hafnium oxide ferroelectricity
Hafnium oxide ferroelectricity is the switchable spontaneous polarization in hafnium dioxide thin films, unexpectedly discovered in silicon-doped HfO2 in 2011 and compatible with standard CMOS chipmaking.
Hafnium pentatelluride
Hafnium pentatelluride (HfTe5) is a layered compound of hafnium and tellurium, studied first as a thermoelectric material and since 2014 as a topological quantum material.
Hafnium(IV) oxide
Hafnium(IV) oxide, also known as hafnia (HfO₂), is a white, chemically stable oxide of hafnium. It replaced silicon dioxide as the gate insulator in Intel's 45 nm chips in 2007 and underlies ferroelectric memory.
Hagen–Poiseuille equation
The Hagen–Poiseuille equation, also called Poiseuille's law, gives the pressure drop for laminar flow of a Newtonian fluid through a pipe, with flow rate proportional to the pipe radius to the fourth power.
Hahn–Banach theorem
The Hahn–Banach theorem, a result of functional analysis, states that a bounded linear functional on a subspace of a Banach space extends to the whole space with the same norm.
Hail
Hail is precipitation in the form of ice pellets more than 5 mm across that falls from thunderstorms, causing about $10 billion a year in US damage.
Hailiang Dong
Hailiang Dong (董海良) is a Chinese geomicrobiologist and professor at China University of Geosciences, Beijing, who showed iron-reducing bacteria catalyze clay transformation and won the 2025 Arthur L. Day Medal.
Hailiang Wang
Hailiang Wang is an energy chemist and Yale professor of chemistry since 2014 who studies electrocatalysis and batteries, known for the 2019 molecular catalyst that converts carbon dioxide to methanol.
Hailstorm
A hailstorm is a thunderstorm that produces hail, ice pellets that damage roofs, vehicles, and crops, causing about $10 billion a year in the United States.
Haïm Brezis
Haïm Brezis (1944–2024) was a French mathematician who worked in functional analysis and nonlinear partial differential equations, as professor at the Université Pierre et Marie Curie and Rutgers University.
Haim Hanani
Haim Hanani (1912–1991) was an Israeli mathematician born in Poland, known for the Hanani–Tutte theorem and combinatorial design theory, who served as the first rector of the University of the Negev.
Haimin Wang
Haimin Wang is a solar physicist, Distinguished Professor of Physics at NJIT, and director of its space weather research centers, known for showing that solar flares visibly rotate the Sun's surface magnetic fields.
Hairy ball theorem
The hairy ball theorem, also called the hedgehog theorem, is an algebraic topology result: a hairy ball cannot be combed flat without creating a cowlick.
Hajime Ito
Hajime Ito (伊藤 肇, born 1968 in Osaka) is a Japanese materials chemist and Distinguished Professor at Hokkaido University, known for solvent-free mechanochemistry and asymmetric catalysis.
Hajime Tanaka
Hajime Tanaka (田中 肇) is a Japanese soft matter and liquid physicist known for viscoelastic phase separation, water's anomalies, and the glass transition, and a University of Tokyo professor.
Hajos–Parrish–Eder–Sauer–Wiechert reaction
The Hajos–Parrish–Eder–Sauer–Wiechert reaction, also called the Hajos-Parrish reaction, is a proline-catalyzed enantioselective aldol reaction reported independently in 1971 at Hoffmann-La Roche and Schering, credited with founding modern organocatalysis.
Hakuhō earthquake
The Hakuhō earthquake (白鳳地震, also called the Tenmu earthquake) was a magnitude 8.3 earthquake that struck Japan on 29 November 684, the oldest recorded great earthquake along the Nankai Trough.
Hal Tasaki
Hal Tasaki (田﨑 晴明), born 1959, is a Japanese mathematical condensed-matter physicist at Gakushuin University in Tokyo, co-inventor of the AKLT chain that rigorously established the Haldane gap.
Hal Thirlaway
Hal Thirlaway, born Henry Ivison Shipley Thirlaway (1917–2009), was a British seismologist who led the UK's forensic seismology program at Blacknest, Berkshire, developing methods to distinguish underground nuclear explosions from earthquakes.
Halbach array
A Halbach array is an arrangement of permanent magnets whose rotating magnetization concentrates the magnetic field on one side and largely cancels it on the other.