Britannica Sources used in this answer

How did Einstein's theories of relativity challenge Newtonian physics?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Marble bust of Aristotle with a beard and draped robe, showing detailed facial features and wavy hair, set against a dark background. — Philosophy of science Aristotle, marble portrait bust, Roman copy (2nd century bce) of a Greek original (c. 325 bce); in the Museo Nazionale Romano, Rome.

Albert Einstein’s theories of relativity fundamentally challenged Newtonian physics by replacing the classical concepts of absolute space and time with a unified, dynamic framework.12

Special Relativity and the Rejection of Absolute Space

Newtonian physics relied on the assumption that space and time were independent, absolute, and universal. Einstein’s special theory of relativity (1905) overturned this by asserting that the speed of light is constant for all inertial observers, regardless of their motion. This postulate necessitated the abandonment of Galilean transformations in favor of Lorentz transformations, leading to the discovery that:12345
* Relativity of Simultaneity: Events that appear simultaneous to one observer may occur sequentially for another.15
* Time Dilation and Length Contraction: Time intervals and spatial distances are not absolute; they depend on the observer's state of motion.5
* Space-time: Space and time are inextricably linked into a four-dimensional space-time continuum.12

General Relativity and the Nature of Gravity

Einstein’s general theory of relativity (1916) further challenged Newton by reinterpreting gravitation. While Newton viewed gravity as a force acting across space, Einstein proposed that gravity is the result of the curvature of space-time caused by mass and energy. This shift moved physics from a model of "force acting on mass" to one where "mass-energy tells space-time how to curve, and curved space-time tells mass-energy how to move".32