All articles starting with R
22,461 articles
Relativistic Hamiltonian
The relativistic Hamiltonian generates time evolution consistently with special relativity; for a free particle of mass m it is H = sqrt(p²c² + m²c⁴), the energy as a function of momentum.
Relativistic Heavy Ion Collider
The Relativistic Heavy Ion Collider (RHIC) was a particle collider at Brookhaven National Laboratory in Upton, New York, operating from 2000 to 2026 and recreating the quark-gluon plasma.
Relativistic hydrodynamics in numerical relativity
Relativistic hydrodynamics in numerical relativity is the set of formulations and numerical methods used to evolve relativistic fluids coupled to dynamical spacetime governed by Einstein's equations.
Relativistic jet
A relativistic jet is a collimated outflow of particles moving near light speed, launched from the poles of an accreting black hole or neutron star, seen in quasars and X-ray binaries.
Relativistic jet kinematics
Relativistic jet kinematics is the study of the speeds, directions, and apparent motions of plasma jets launched near black holes and neutron stars at nearly the speed of light.
Relativistic jet shock interactions
Relativistic jet shock interactions are collisions inside and at the boundaries of relativistic jets from active galactic nuclei and gamma-ray bursts, converting kinetic energy into radiation.
Relativistic kinetic energy
Relativistic kinetic energy is the kinetic energy of a moving body in special relativity, K = (γ − 1)mc², which grows without bound as speed approaches light speed.
Relativistic kinetic theory
Relativistic kinetic theory is the extension of kinetic theory to particles whose speeds approach the speed of light, using a relativistic Boltzmann equation to describe gases and plasmas.
Relativistic Lagrangian
Relativistic Lagrangian is a Lagrangian whose action is invariant under Lorentz transformations and whose equations yield the relativistic equations of motion, originating with Henri Poincaré in 1905.
Relativistic Lagrangian mechanics
Relativistic Lagrangian mechanics is the formulation of particle dynamics using an action and Lagrangian consistent with special relativity, built from Lorentz-invariant quantities such as proper time.
Relativistic magnetohydrodynamics
Relativistic magnetohydrodynamics (RMHD) extends magnetohydrodynamics, the fluid description of conducting media coupled to magnetic fields, to flows approaching the speed of light in a Lorentz-invariant form.
Relativistic mechanics
Relativistic mechanics describes the motion of bodies whose speeds are a significant fraction of the speed of light, replacing Newtonian momentum and energy with Lorentz-invariant quantities built from rest mass.
Relativistic momentum
Relativistic momentum is the momentum of a particle in special relativity, p = γmu, which replaces the classical expression so that momentum conservation holds in every inertial frame.
Relativistic polytrope
A relativistic polytrope is a general-relativistic model of a self-gravitating fluid star whose pressure follows a polytropic law, introduced by Robert Tooper in 1964 as a compact-object extension of the Newtonian polytrope.
Relativistic shock waves
Relativistic shock waves are discontinuities in fluid flows moving at nearly the speed of light, pioneered by Abraham Taub in 1948 and applied to gamma-ray bursts and jets.
Relativistic thermodynamics
Relativistic thermodynamics studies how temperature, heat, and entropy behave for bodies moving near light speed; whether a moving body appears cooler, hotter, or unchanged is still debated over 110 years.
Relativistic time scales (TCB, TCG, TT)
Relativistic time scales (TCB, TCG, TT) are coordinate time scales defined by the IAU for general-relativistic modeling of the solar system, because clocks at different gravitational potentials run at different rates.
Relativistic viscous hydrodynamics
Relativistic viscous hydrodynamics is the extension of fluid dynamics to near-light-speed fluids including shear viscosity, bulk viscosity, and diffusion, the standard model of the quark-gluon plasma at RHIC and the LHC.
Relativity (M. C. Escher)
Relativity (1953) is a lithograph by Dutch artist M.C. Escher showing three staircases serving three gravity directions, with nine figures walking up and down; edition of 50, held by MoMA, NGA, and Kunstmuseum Den Haag.
Relativity Media
Relativity Media, the American film company founded by Ryan Kavanaugh (with Lynwood Spinks), began as a Hollywood slate-financing broker, became an independent studio, filed Chapter 11 bankruptcy in 2015, and now operates as an indie film distributor.
Relativity of simultaneity
The relativity of simultaneity is the principle in special relativity that events simultaneous in one inertial frame are not simultaneous in another moving relative to it.
Relativity priority dispute
The relativity priority dispute is the controversy over who discovered relativity: Einstein and Poincaré in 1905 on special relativity, and Einstein and Hilbert in 1915 on general relativity.
Relativity Space
Relativity Space is an American launch-vehicle developer in Long Beach, California, founded by Tim Ellis and Jordan Noone; its 3D-printed Terran 1 reached space in March 2023.
Relatlimab
Relatlimab (BMS-986016) is a human IgG4 anti-LAG-3 monoclonal antibody from Bristol Myers Squibb; combined with nivolumab as Opdualag, it was the first LAG-3 inhibitor FDA-approved (2022) for unresectable or metastatic melanoma.
Relax (song)
Relax (1983) is the debut single by Frankie Goes to Hollywood, written by Johnson, O'Toole, and Gill, produced by Trevor Horn for ZTT. Banned by the BBC in January 1984, it topped the UK chart for five weeks.
RELAX trial
RELAX trial (NCT00763867): NHLBI-sponsored randomized trial of sildenafil versus placebo in 216 HFpEF patients; no improvement in peak VO2, walk distance, or clinical status, published JAMA 2013.
Relaxation (NMR)
Relaxation (NMR relaxation) is the process by which nuclear magnetization perturbed by a radiofrequency pulse returns to thermal equilibrium, characterized by the time constants T1 and T2.
Relaxation kinetics
Relaxation kinetics, or chemical relaxation, is the chemical kinetics technique of suddenly perturbing a system at equilibrium, by temperature, pressure, or electric field, developed by Manfred Eigen in the 1950s.
Relaxation method
A relaxation method measures rates of fast chemical reactions by suddenly perturbing a system at equilibrium, developed by Manfred Eigen, who won the 1967 Nobel Prize in Chemistry.
Relaxation oscillation
A relaxation oscillation is a non-sinusoidal periodic oscillation produced by nonlinear systems alternating slow and fast phases, a term coined by Balthasar van der Pol in 1926.