hubble constant

English - English

Definition of hubble constant in English English dictionary

a number the expresses the rate of expansion of the universe; the velocity at which a distant object is receding from the Earth divided by its distance; its reciprocal gives the age of the universe

Related Terms

Hubble's constant

alternative spelling of Hubble constant

Hubble's constant

Constant used to relate the velocities of remote galaxies to their distances from Earth. Denoted H and named in honour of Edwin Hubble, it expresses the rate of expansion of the universe. Its actual value has been debated for decades; improved measurements have narrowed the range in which it falls to about 10.5-14 mi/second (17-23 km/second) per million light-years. The reciprocal of H gives the time, in seconds, since the galaxies began to separate from each other i.e., the approximate age of the universe. Hubble used the redshifts of distant galaxies measured by Vesto Slipher (1875-1969) and his own distance estimates of those galaxies to establish the cosmological velocity-distance law (Hubble law): velocity = H distance, according to which the greater a galaxy's distance, the faster it is receding. Derived from theoretical considerations and confirmed by observations, the Hubble law has made secure the concept of an expanding universe

hubble's constant

(cosmology) the ratio of the speed of recession of a galaxy (due to the expansion of the universe) to its distance from the observer; the reciprocal of the Hubble constant is the age of the universe

Hyphenation

Hub·ble con·stant

Turkish pronunciation

hʌbıl känstınt

Pronunciation

/ˈhəbəl ˈkänstənt/ /ˈhʌbəl ˈkɑːnstənt/

Etymology

() After Edwin Powell Hubble, American astronomer