Physical world and mathematics

Hongtao Yuan

Hongtao Yuan (袁洪涛) is a Chinese condensed matter physicist and professor at Nanjing University since 2017, after posts at Stanford and SLAC, known for electric-double-layer transistors inducing superconductivity and ferromagnetism.

Hongyu Chen

Hongyu Chen (陈虹宇) is a Chinese chemist known for nanosynthesis, controlling the growth, shape, and assembly of nanoparticles; he has been a professor at Westlake University since 2021.

Hongyu Zhao

Hongyu Zhao (赵宏宇) is a biostatistician at Yale University, holding the Ira V. Hiscock Professorship of Biostatistics, known for statistical and computational methods in genomics.

Honokiol

Honokiol is a natural bisphenol neolignan with formula C18H18O2, found mainly in magnolia bark, studied for anticancer and anti-inflammatory effects but limited by poor solubility and low bioavailability.

Hoodoo (geology)

A hoodoo, also called an earth pillar or fairy chimney, is a tall, thin rock spire left by erosion. The most famous ones stand in Bryce Canyon, Utah.

Hook echo

A hook echo is a hook-shaped region of radar reflectivity in supercell thunderstorms, formed when precipitation wraps around the rotating mesocyclone, and a key indicator in tornado warning decisions.

Hook length formula

The hook length formula is a 1954 theorem of combinatorics giving the number of standard Young tableaux of a shape, and the dimensions of symmetric group representations.

Hooke's law

Hooke's law, or the spring equation, is the physical law that an elastic object's deformation is directly proportional to the deforming force, stated by Robert Hooke in 1660.

Hooman Davoudiasl

Hooman Davoudiasl is a theoretical physicist at Brookhaven National Laboratory in Upton, New York, known for work on warped extra dimensions and dark matter cosmology, and a 2007 PECASE awardee.

Hopane

Hopane is a stable pentacyclic hydrocarbon with formula C₃₀H₅₂, the geologic degradation product of bacterial hopanoid lipids and a key biomarker used in oil correlation, maturity assessment, and oil spill fingerprinting.

Hopcroft–Karp algorithm

The Hopcroft–Karp algorithm, published by John E. Hopcroft and Richard M. Karp in 1973, finds a maximum matching in a bipartite graph in O(m√n) time.

Hope Bay

Hope Bay is a gold mining and exploration property in the Kitikmeot region of mainland Nunavut, Canada, owned by Agnico Eagle, which approved a construction decision in May 2026.

Hope Diamond

The Hope Diamond, or Le Bijou du Roi, is a 45.52-carat deep grayish-blue diamond cut from the stolen French Blue and displayed at the Smithsonian since 1958.

Hopf algebra

A Hopf algebra is an algebraic structure that is both an algebra and a coalgebra with a compatible antipode map, generalizing groups and Lie algebras and underlying the theory of quantum groups.

Hopf bifurcation

The Hopf bifurcation, or Andronov-Hopf bifurcation, is a local bifurcation of dynamical systems in which an equilibrium changes stability and a small limit cycle emerges.

Hopf fibration

The Hopf fibration is the map from the 3-sphere to the 2-sphere whose fibers are pairwise linked circles, defined by Heinz Hopf in 1931 as the first nontrivial fiber bundle.

Hopf invariant

The Hopf invariant is an integer assigned to the homotopy class of a map between spheres, introduced by Heinz Hopf in 1931 and central to homotopy theory.

Oct 22, 2026

Hopfion

A hopfion is a three-dimensional topological soliton, a localized particle-like field configuration classified by a nonzero Hopf charge, studied experimentally in magnetic materials, liquid crystals, and optical fields.

Oct 22, 2026

Hopfions in chiral liquid crystals

Hopfions in chiral liquid crystals are stable, particle-like three-dimensional topological solitons of molecular alignment, micrometer-scale knots first realized experimentally in chiral nematics in 2017 and controllable with electric fields.

Horace Bolingbroke Woodward

Horace Bolingbroke Woodward (1848–1914) was a British geologist who spent 41 years on the Geological Survey of Great Britain and wrote The History of the Geological Society of London (1907).

Horace Lamb

Horace Lamb (1849–1934) was an English applied mathematician who held chairs at Adelaide and Manchester, wrote the standard Hydrodynamics, and gave his name to Lamb waves.

Horace R. Byers

Horace R. Byers was an American meteorologist who directed the Thunderstorm Project, the first large-scale US thunderstorm study, and built the University of Chicago's meteorology department.

Horace Richard Crane

Horace Richard Crane was an American experimental physicist at the University of Michigan, the first to measure the magnetic moment of free electrons, receiving the National Medal of Science in 1986.

Horace Tabberer Brown

Horace Tabberer Brown (1848–1925) was a British chemist who spent 1866 to 1895 in the Burton-on-Trent brewing industry, published on fermentation chemistry, and won the Royal and Copley Medals.

Horace W. Babcock

Horace W. Babcock was an American astronomer at Mount Wilson and Palomar who made the first detection of a magnetic field on a star other than the sun.

Horacio Casini

Horacio Casini is an Argentine theoretical physicist at CONICET and Centro Atómico Bariloche known for rigorous results on entanglement entropy in quantum field theory, including the c-theorem and F-theorem.

Hořava–Lifshitz gravity

Hořava–Lifshitz gravity, also known as HL gravity, is a candidate quantum theory of gravity proposed by Petr Hořava in 2009, in which spacetime scales anisotropically at short distances.

Horia Metiu

Horia Metiu (Horia Mețiu) is a Romanian-born theoretical physical chemist, a UC Santa Barbara professor since 1976, known for surface-enhanced Raman theory and the 2017 molten-metal methane conversion work.

Horizon

The horizon is the apparent line where the sky seems to meet the ground or sea, a circle centered on the observer whose distance grows with eye height.