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  1. Relativity | Definition, Equations, & Facts | Britannica

    Oct 24, 2025 · Relativity, wide-ranging physical theories formed by the German-born physicist Albert Einstein. Special relativity is limited to objects that are moving with respect to inertial …

  2. Special relativity | Definition & Equation | Britannica

    special relativity, part of the wide-ranging physical theory of relativity formed by the German-born physicist Albert Einstein. It was conceived by Einstein in 1905. Along with quantum …

  3. General relativity | Gravitational Waves, Spacetime & Cosmology ...

    Sep 12, 2025 · general relativity, part of the wide-ranging physical theory of relativity formed by the German-born physicist Albert Einstein. It was conceived by Einstein in 1916. General …

  4. Relativity - Space-Time, Gravity, Physics | Britannica

    Oct 24, 2025 · The answer is that Newton’s theory violates special relativity, for it requires an unspecified “action at a distance” through which any two objects—such as the Sun and …

  5. Relativity - Time, Space, Mass | Britannica

    Oct 24, 2025 · In developing special relativity, Einstein began by accepting what experiment and his own thinking showed to be the true behaviour of light, even when this contradicted …

  6. E = mc² | Equation, Explanation, & Proof | Britannica

    Oct 3, 2025 · His theory of relativity shifted contemporary understanding of space completely. Along with his equation E = mc2, it also foreshadowed the creation of the atomic bomb.

  7. Relativity - Time, Space, Mass | Britannica

    Oct 24, 2025 · Relativity - Time, Space, Mass: To derive further results, Einstein combined his redefinitions of time and space with two powerful physical principles: conservation of energy …

  8. Relativity - Physics, Time, Space | Britannica

    Aug 30, 2025 · The ideas of relativity were widely applied—and misapplied—soon after their advent. Some thinkers interpreted the theory as meaning simply that all things are relative, …

  9. Albert Einstein's theory of relativity describing absolute quantities ...

    The special theory of relativity, first described by Albert Einstein, was merely a statement of the realization that we were wrong-- distances in space and time are actually relative. They …

  10. Relativistic mechanics | Einstein’s Theory of Relativity | Britannica

    Before Einstein’s special theory of relativity was published in 1905, it was usually assumed that the time coordinates measured in all inertial frames were identical and equal to an “absolute …