Difference between revisions of "Hubble constant"
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| − | After astronomers | + | After astronomers realised that the universe is expanding they introduced the '''Hubble constant''' as the measure of speed of this expansion as a ratio of assumed recession velocity of galaxies to their distance. The '''Hubble constant''' equals approximately, for <math>v\ll c</math> |
| − | :<math> | + | :<math>H_0=v/r</math>, |
| − | where <math>v</math> is assumed speed of recession of a galaxy, <math>c</math>, speed of light in vacuum, combined with <math>v</math> producing ''"redshift"'' <math>Z= | + | where <math>v</math> is assumed speed of recession of a galaxy, <math>c</math>, speed of light in vacuum, combined with <math>v</math> producing ''"redshift"'' <math>Z=v/c</math>, and <math>r</math> is distance from the observer to the observed galaxy, and its exact value turned out to be |
:<math>H_o=c/R_E</math>, | :<math>H_o=c/R_E</math>, | ||
| − | where <math>R_E</math> is [[Einstein's radius of universe]]. | + | where <math>R_E</math> is [[Einstein's radius of universe]]. Present observations indicate that the Hubble constant is about 70 km/s/Mpc. |
| − | The recessional velocity turned out not to be proportional to the distance though and so the '''Hubble constant''' is | + | The recessional velocity turned out not to be proportional to the distance though and so the '''Hubble constant''' is referred to the nearest galaxies for which it may be considered to be relatively constant. |
| − | The [[Essay:Problems in Cosmology]] explains the possibility of the '''Hubble constant''' being a feature of universe that is stationary (neither expanding nor contracting) and the recessional velocity of galaxies being an illusion caused by the time | + | The [[Essay:Problems in Cosmology]] explains the possibility of the '''Hubble constant''' being a feature of universe that is stationary (neither expanding nor contracting) and the recessional velocity of galaxies being an illusion caused by the time running slower at the deep space galaxies than in our Galaxy which mimics the accelerating expansion. |
| − | The observations of [[cosmological redshift]]s are consistent with the universe being stationary and [[ | + | The observations of [[cosmological redshift]]s are consistent with the universe being stationary and [[quasar]]s being local rather than remote objects as already suggested by [[Halton Arp]].<ref> |
| + | |||
| + | Halton Arp, ''"Quasars, Redshifts and Controversies"'', 1987. | ||
| + | |||
| + | </ref> | ||
| + | ==See also== | ||
| + | *[[Hubble Law]] | ||
==References== | ==References== | ||
<references/> | <references/> | ||
| − | [[Category: Astronomy]] | + | [[Category:Astronomy]] |
| − | [[ | + | [[Category:Cosmology]] |
| − | [[ | + | [[Category:Physics]] |
Latest revision as of 17:25, July 20, 2016
After astronomers realised that the universe is expanding they introduced the Hubble constant as the measure of speed of this expansion as a ratio of assumed recession velocity of galaxies to their distance. The Hubble constant equals approximately, for 
,
where 
is assumed speed of recession of a galaxy, 
, speed of light in vacuum, combined with producing "redshift" 
, and 
is distance from the observer to the observed galaxy, and its exact value turned out to be
,
where 
is Einstein's radius of universe. Present observations indicate that the Hubble constant is about 70 km/s/Mpc.
The recessional velocity turned out not to be proportional to the distance though and so the Hubble constant is referred to the nearest galaxies for which it may be considered to be relatively constant.
The Essay:Problems in Cosmology explains the possibility of the Hubble constant being a feature of universe that is stationary (neither expanding nor contracting) and the recessional velocity of galaxies being an illusion caused by the time running slower at the deep space galaxies than in our Galaxy which mimics the accelerating expansion.
The observations of cosmological redshifts are consistent with the universe being stationary and quasars being local rather than remote objects as already suggested by Halton Arp.[1]
See also
References
- ↑ Halton Arp, "Quasars, Redshifts and Controversies", 1987.
