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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...

paleomagnetism

(Encyclopedia)paleomagnetism, study of the intensity and orientation of the earth's magnetic field as preserved in the magnetic orientation of certain minerals found in rocks formed throughout geologic time. Paleom...

magnetism

(Encyclopedia)CE5 Lines of induction around a single bar magnet and between opposite poles of different magnets magnetism, force of attraction or repulsion between various substances, especially those made of i...

aneurysm

(Encyclopedia)aneurysm ănˈyo͝orĭzəm [key], localized dilatation of a blood vessel, particularly an artery, or the heart. Dilatation of an artery, and therefore weakness of that portion of the arterial wall, ma...

Zeeman effect

(Encyclopedia)Zeeman effect, splitting of a single spectral line (see spectrum) into a group of closely spaced lines when the substance producing the single line is subjected to a uniform magnetic field. The effect...

compass

(Encyclopedia)compass. 1 In mathematics, an instrument for making circles and measuring distances. Frequently called a pair of compasses, it consists of two metal legs with one end of each attached to a pivot to fo...

Hall effect

(Encyclopedia)Hall effect, experiment that shows the sign of the charge carriers in a conductor. In 1879 E. H. Hall discovered that when he placed a metal strip carrying a current in a magnetic field, a voltage dif...

mass spectrograph

(Encyclopedia)mass spectrograph, device used to separate electrically charged particles according to their masses; a form of the instrument known as a mass spectrometer is often used to measure the masses of isotop...

dating

(Encyclopedia)dating, the determination of the age of an object, of a natural phenomenon, or of a series of events. There are two basic types of dating methods, relative and absolute. In relative dating, the tempor...

Kastler, Alfred

(Encyclopedia)Kastler, Alfred, 1902–84, German-born French physicist, Ph.D. Univ. of Bordeaux, 1936. Kastler was a lecturer at Clermont-Ferrand Univ. (1936–38), professor at the Univ. of Bordeaux (1938–41), p...