An Etymological Dictionary of Astronomy and Astrophysics

The random fluctuation of voltage across a resistor caused by the thermal excitation of electrons within it, and the dissipation of power associated with these fluctuations. More generally, an intrinsic noise generated by thermal agitation of electrons by all bodies whose temperature is above 0 K. Also called → thermal noise, Johnson noise, or Nyquist noise.

See also: Named after John Bertrand Johnson (1887-1970) and Harry Nyquist (1889-1976) Swedish-born American engineers and physicists, who did important work on thermal noise
and information theory. → noise.

The random fluctuation of voltage across a resistor caused by the thermal excitation of electrons within it, and the dissipation of power associated with these fluctuations. More generally, an intrinsic noise generated by thermal agitation of electrons by all bodies whose temperature is above 0 K. Also called → thermal noise, Johnson noise, or Nyquist noise.

See also: Named after John Bertrand Johnson (1887-1970) and Harry Nyquist (1889-1976) Swedish-born American engineers and physicists, who did important work on thermal noise
and information theory. → noise.

A square matrix with a constant value λ (nonzero) along the diagonal, 1’s on the superdiagonal, and all other elements 0.

See also: Named after Marie Ennemond Camille Jordan (1838-1922), French mathematician who pioneered group theory, wrote on the theory of linear differential equations, and on the theory of functions, which he applied to the curve which bears his name. → matrix.

A square matrix with a constant value λ (nonzero) along the diagonal, 1’s on the superdiagonal, and all other elements 0.

See also: Named after Marie Ennemond Camille Jordan (1838-1922), French mathematician who pioneered group theory, wrote on the theory of linear differential equations, and on the theory of functions, which he applied to the curve which bears his name. → matrix.

A relativistic theory of gravitation which involves a → scalar field in addition to the → metric (→ tensor field) used in rarr; general relativity. It obeys the → equivalence principle, but tries at the same time to comply with → Mach’s principle owing to possible spatial and temporal variations of the → gravitational constant, which is inversely proportional to the scalar field. The theory uses a new dimensionless parameter to determine the discrepancy between its predictions and those of general relativity. So far there is no firm indication of its validity. Same as → scalar-tensor theory.

See also: Named after the creators, Carl Brans (1935-) and Robert Dicke (1916-1997), who presented the theory in 1961, based on the initial work of Pascual Jordan (1902-1980); → theory.

A relativistic theory of gravitation which involves a → scalar field in addition to the → metric (→ tensor field) used in rarr; general relativity. It obeys the → equivalence principle, but tries at the same time to comply with → Mach’s principle owing to possible spatial and temporal variations of the → gravitational constant, which is inversely proportional to the scalar field. The theory uses a new dimensionless parameter to determine the discrepancy between its predictions and those of general relativity. So far there is no firm indication of its validity. Same as → scalar-tensor theory.

See also: Named after the creators, Carl Brans (1935-) and Robert Dicke (1916-1997), who presented the theory in 1961, based on the initial work of Pascual Jordan (1902-1980); → theory.

A quantum mechanical → tunnel effect allowing the flow of a continuous current across two weakly coupled → superconductors which are separated by a very thin insulating barrier.

See also: Named after the British physicist Brian David Josephson, who predicted the existence of the effect in 1962; → effect.

A quantum mechanical → tunnel effect allowing the flow of a continuous current across two weakly coupled → superconductors which are separated by a very thin insulating barrier.

See also: Named after the British physicist Brian David Josephson, who predicted the existence of the effect in 1962; → effect.

A type of electronic circuit involving → Josephson effect, capable of switching at very high speeds when operated at temperatures approaching → absolute zero.

See also: → Josephson effect; → junction.

A type of electronic circuit involving → Josephson effect, capable of switching at very high speeds when operated at temperatures approaching → absolute zero.

See also: → Josephson effect; → junction.

A unit of → energy in the → International System of Units equal to the → work performed by one → newton over a distance of 1 → meter.
1 J is equivalent to 10⁷ ergs = 1 Watt second =
2.78 &times 10^-7 kWh = 0.2389 calories =
6.24 × 10¹⁸ eV.

Etymology (EN): In honor of the English physicist James Prescott Joule (1818-1889), who established that the various forms of energy (mechanical, electrical, and heat) are basically the same and can be changed, one into another.

Etymology (PE): Joule is in Pers. pronounced as žul, loaned from the Fr. rendering of the E. name.

A unit of → energy in the → International System of Units equal to the → work performed by one → newton over a distance of 1 → meter.
1 J is equivalent to 10⁷ ergs = 1 Watt second =
2.78 &times 10^-7 kWh = 0.2389 calories =
6.24 × 10¹⁸ eV.

Etymology (EN): In honor of the English physicist James Prescott Joule (1818-1889), who established that the various forms of energy (mechanical, electrical, and heat) are basically the same and can be changed, one into another.

Etymology (PE): Joule is in Pers. pronounced as žul, loaned from the Fr. rendering of the E. name.

A → conductor becomes heated by the passage of an electric current through it due to the → resistance of the conductor. Same as → Ohmic dissipation.

See also: → joule; → effect.

A → conductor becomes heated by the passage of an electric current through it due to the → resistance of the conductor. Same as → Ohmic dissipation.

See also: → joule; → effect.

The change in the temperature of a gas in the → throttling process.

See also: → Joule; → Thomson; → effect.

The change in the temperature of a gas in the → throttling process.

See also: → Joule; → Thomson; → effect.

The proportional relationship of mechanical energy to thermal energy, equal to 4.184 joules per calorie. Also called mechanical equivalent of heat.

See also: → joule; → constant.

The proportional relationship of mechanical energy to thermal energy, equal to 4.184 joules per calorie. Also called mechanical equivalent of heat.

See also: → joule; → constant.

Of or pertaining to the → planet  → Jupiter.

Etymology (EN): From L. Jovius “Jupiter,” Roman god of the sky, cognate with deus “god;” Gk. Zeus “supreme god;” Pers. div “devil, demon” (Mid.Pers. dêw;
O.Pers. daiva- “evil god, demon;” Av. daēva- “evil spirit, false god;” Skt. deva-; PIE base *deiwos “god,” from *dei- “to gleam, to shine”).

Etymology (PE): Hormozi, related to Hormoz, → Jupiter.

Of or pertaining to the → planet  → Jupiter.

Etymology (EN): From L. Jovius “Jupiter,” Roman god of the sky, cognate with deus “god;” Gk. Zeus “supreme god;” Pers. div “devil, demon” (Mid.Pers. dêw;
O.Pers. daiva- “evil god, demon;” Av. daēva- “evil spirit, false god;” Skt. deva-; PIE base *deiwos “god,” from *dei- “to gleam, to shine”).

Etymology (PE): Hormozi, related to Hormoz, → Jupiter.

A planet that does not have a well-defined → solid  → crust, such as any of the four Solar System outer, gaseous planets: → Jupiter, → Saturn, → Uranus, and → Neptune.

See also: → Jovian; → planet.

A planet that does not have a well-defined → solid  → crust, such as any of the four Solar System outer, gaseous planets: → Jupiter, → Saturn, → Uranus, and → Neptune.

See also: → Jovian; → planet.

Sunspot pairs or groups are tilted with the → leader spots closer to the equator than the → follower spots. The tilt of bipolar sunspot pairs increases with latitude.

See also: Alfred Harrison Joy (1882-1973), an American astronomer; → law.

Sunspot pairs or groups are tilted with the → leader spots closer to the equator than the → follower spots. The tilt of bipolar sunspot pairs increases with latitude.

See also: Alfred Harrison Joy (1882-1973), an American astronomer; → law.