gravitationens

Gravitation, or gravity, is a fundamental interaction that attracts bodies with mass toward one another. It acts over long distances and dominates the motion of planets and stars, the structure of galaxies, and the evolution of the universe. On Earth it gives objects weight, drives tides, and governs orbital motions of satellites. The strength of gravitational attraction depends on the masses involved and their separation, becoming weaker with distance and stronger with mass.

Classical theory describes gravity with Newton’s law of universal gravitation. For two masses m1 and m2 separated by distance r, the force of attraction is F = G m1 m2 / r^2, where G is the gravitational constant. This inverse-square law explains planetary orbits, Kepler’s laws, and the concept of a gravitational potential energy U = -G m1 m2 / r. Measurements of G, including historical Cavendish experiments, quantify the strength of gravity, enabling precise calculations in engineering and astronomy.

Modern theory replaces the Newtonian view in strong fields or high speeds by Einstein’s general relativity. Gravity emerges as the curvature of spacetime caused by mass-energy, guiding the motion of objects along geodesics. Predictions include gravitational time dilation, light deflection by gravity, and gravitational waves, all of which have been confirmed experimentally. In weak-field environments, general relativity reduces to Newtonian gravity, while in extreme regimes it explains phenomena such as black holes and gravitational lensing. Practical applications include satellite navigation, space travel, and tests of fundamental physics.