“Hubble constant”的概念、定义、翻译、参考文献-科学参考

Hubble constant

Physics

The rate at which the velocity of recession of the galaxies increases with distance as determined by the redshift. The value is not agreed upon but current measurements indicate that it lies between 49 and 95 km s⁻¹ per megaparsec. The reciprocal of the Hubble constant, the Hubble time, is a measure of the age of the universe, assuming that the expansion rate has remained constant. In fact, it is necessary to take into account the observation that the expansion of the universe is accelerating to get an accurate determination of the true age of the universe. The constant is named after Edwin Hubble.

Astronomy

The figure that relates the speed of an object’s recession in the expanding Universe to its distance in the Hubble law. It represents the current rate of expansion of the Universe. This important cosmological parameter is usually measured in units of kilometres per second per megaparsec (km/s/Mpc). In the Big Bang theory, H₀ varies with time and is therefore more properly known as the Hubble parameter. The first published value (by E. P. Hubble himself, in 1929) was 500 km/s/Mpc from observations of relatively nearby galaxies. By the late twentieth century two rival camps of astronomers were favouring values of about 100 and 50 km/s/Mpc respectively. In 2001 the Hubble Space Telescope Key Project team reported a figure for H₀ of 72 ± 8 km/s/Mpc, followed in 2010 by 71 ± 2.5 km/s/Mpc from the Wilkinson Microwave Anisotropy Probe (WMAP). More recent observations from the Planck mission report a value of 67.2 ± 1.2 km/s/Mpc, whereas measurements involving Cepheids and Type Ia supernovae give a result of 73.2 ± 1.7 km/s/Mpc. These differences might point to limitations in one (or both) of the measurement techniques, or could be revealing some missing physics in our cosmological models.

Space Exploration

A measure of the rate at which the universe is expanding, named after US astronomer Edwin Hubble. Observations suggest that galaxies are moving apart at a rate of 50–100 kps for every million parsecs of distance. This means that the universe, which began at one point according to the Big Bang theory, is between 10 billion and 20 billion years old. Observations by the Hubble Space Telescope in 1996 produced a figure for the constant of 73 kps.

Geology and Earth Sciences

See hubble parameter.

单词	Hubble constant
释义	Hubble constant Physics The rate at which the velocity of recession of the galaxies increases with distance as determined by the redshift. The value is not agreed upon but current measurements indicate that it lies between 49 and 95 km s⁻¹ per megaparsec. The reciprocal of the Hubble constant, the Hubble time, is a measure of the age of the universe, assuming that the expansion rate has remained constant. In fact, it is necessary to take into account the observation that the expansion of the universe is accelerating to get an accurate determination of the true age of the universe. The constant is named after Edwin Hubble. Astronomy The figure that relates the speed of an object’s recession in the expanding Universe to its distance in the Hubble law. It represents the current rate of expansion of the Universe. This important cosmological parameter is usually measured in units of kilometres per second per megaparsec (km/s/Mpc). In the Big Bang theory, H₀ varies with time and is therefore more properly known as the Hubble parameter. The first published value (by E. P. Hubble himself, in 1929) was 500 km/s/Mpc from observations of relatively nearby galaxies. By the late twentieth century two rival camps of astronomers were favouring values of about 100 and 50 km/s/Mpc respectively. In 2001 the Hubble Space Telescope Key Project team reported a figure for H₀ of 72 ± 8 km/s/Mpc, followed in 2010 by 71 ± 2.5 km/s/Mpc from the Wilkinson Microwave Anisotropy Probe (WMAP). More recent observations from the Planck mission report a value of 67.2 ± 1.2 km/s/Mpc, whereas measurements involving Cepheids and Type Ia supernovae give a result of 73.2 ± 1.7 km/s/Mpc. These differences might point to limitations in one (or both) of the measurement techniques, or could be revealing some missing physics in our cosmological models. Space Exploration A measure of the rate at which the universe is expanding, named after US astronomer Edwin Hubble. Observations suggest that galaxies are moving apart at a rate of 50–100 kps for every million parsecs of distance. This means that the universe, which began at one point according to the Big Bang theory, is between 10 billion and 20 billion years old. Observations by the Hubble Space Telescope in 1996 produced a figure for the constant of 73 kps. Geology and Earth Sciences See hubble parameter.
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