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electrodynamics

(Encyclopedia)electrodynamics, study of phenomena associated with charged bodies in motion and varying electric and magnetic fields (see charge; electricity); since a moving charge produces a magnetic field, electr...

condensate

(Encyclopedia)condensate, matter in the form of a gas of atoms, molecules, or elementary particles that have been so chilled that their motion is virtually halted and as a consequence they lose their separate ident...

decay of organic matter

(Encyclopedia)decay of organic matter or putrefaction, process whereby heterotrophic organisms, including some bacteria, fungi, saprophytic plants, and lower animals, utilize the remains of once-living tissue as a ...

correspondence principle

(Encyclopedia)correspondence principle, physical principle, enunciated by Niels Bohr in 1923, according to which the predictions of the quantum theory must correspond to the predictions of the classical theories of...

atom

(Encyclopedia)CE5 Bohr-Rutherford atom CE5 Probability distribution of the electron in the hydrogen atom: A. Ground state B. Highly excited state atom [Gr.,=uncuttable (indivisible)], basic unit of matte...

dark matter

(Encyclopedia)dark matter, material that is believed to make up nearly 27% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, such as light or ra...

interstellar matter

(Encyclopedia)interstellar matter, matter in a galaxy between the stars, known also as the interstellar medium. The interstellar gas, which constitutes about 99% of the interstellar matter, consists mostly of hyd...

gray matter

(Encyclopedia)gray matter: see nervous system. ...

Einstein, Albert

(Encyclopedia)Einstein, Albert īnˈstīn [key], 1879–1955, American theoretical physicist, known for the formulation of the relativity theory, b. Ulm, Germany. He is recognized as one of the greatest physicists ...

uncertainty principle

(Encyclopedia)uncertainty principle, physical principle, enunciated by Werner Heisenberg in 1927, that places an absolute, theoretical limit on the combined accuracy of certain pairs of simultaneous, related measur...