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Physical Realm
Physical Laws (Constants) Relativity
Matter Molecule, Atom (Periodic Table), Particle
Force Gravity, Electromagnetism (Light, Color)


These are organized by a classification scheme developed exclusively for Cosma. More…



relativity : a theory which is based on the two postulates (1) that the speed of light in a vacuum is constant and independent of the source or observer and (2) that the mathematical forms of the laws of physics are invariant in all inertial systems and which leads to the assertion of the equivalence of mass and energy and of change in mass, dimension, and time with increased velocity — called also special relativity, special theory of relativity — Webster

OneLook, Free Dictionary, Wiktionary, Urban Dictionary


Roget’s II (, Merriam-Webster Thesaurus, Visuwords


Relativity, generally refers to the theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity.

Special relativity applies to elementary particles and their interactions, describing all their physical phenomena except gravity.

General relativity explains the law of gravitation and its relation to other forces of nature. It applies to the cosmological and astrophysical realm, including astronomy.

The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction.

In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in the nuclear age. — Wikipedia

Encyclopædia Britannica

Relativity Theory (Eric Weisstein’s World of Physics, Wolfram Research)


What is relativity? Einstein’s mind-bending theory explained (Dan Falk, Mach, NBC News)
The Theory of Relativity (Ask an Astronomer, Cornell University)






The Collected Papers of Albert Einstein (California Institute of Technology)


WorldCat, Library of Congress, UPenn Online Books, Open Library




Special Relativity Course (Minute Physics)

Crash Course Physics (YouTube)

Einstein, Oppenheimer, Feynman: Physics in the 20th Century (MIT OCW Physics)
Introduction to Nuclear and Particle Physics (MIT OCW Physics)
Relativity (MIT OCW Physics)
OER Commons: Open Educational Resources


Science Daily,, NPR Archives









Albert Einstein News -- ScienceDaily Albert Einstein in the News. Research institutes have been testing Albert Einstein's theory of special relativity and general relativity. Was Albert Einstein right?

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