Gravity

Gravity is the interaction through which energy and momentum shape spacetime and thereby influence the motion of matter and light. In Newtonian physics, it is described as attraction between masses.

General relativity: Einstein’s theory describes gravity as the curvature of spacetime produced by energy and momentum. It replaces gravitational force with curved spacetime as the central explanation.
Mass: A physical quantity measuring inertia and, in gravity, the source or coupling of gravitational effects. Newtonian gravity treats mass as both the source of attraction and the quantity accelerated.
Aristotelian physics: The natural philosophy of Aristotle, which explained motion through elements, places, and purposes. Its account of natural downward motion preceded mathematical theories of gravity.
Orbital mechanics: The study of the motion of bodies under gravitational influence, especially spacecraft and celestial objects. It uses gravitational models to predict and design trajectories.
Quantum gravity: A proposed framework seeking a quantum description of gravity consistent with general relativity. No experimentally confirmed theory yet unifies gravity with quantum physics.
Newton's law of universal gravitation: A classical law stating that every pair of masses attracts with force proportional to their product and inversely proportional to distance squared. It gives the familiar approximation for gravitational attraction at low speeds and weak fields.
Spacetime: The four-dimensional structure combining three dimensions of space with one dimension of time. General relativity describes gravity through the geometry of this structure.
Galileo Galilei: An Italian scientist whose experiments and mathematical studies reshaped the study of motion and astronomy. His work on falling bodies challenged inherited accounts of terrestrial motion.
Tides: Periodic changes in sea level and solid-body deformation driven chiefly by differences in the Moon’s and Sun’s gravitational pull. Tidal forces reveal how gravity varies across an extended body.
Graviton: A hypothetical quantum particle that would mediate gravitational interactions in a particle description. It is predicted in perturbative quantum approaches but has not been detected.

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