Changes

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<<c</math>

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>H_o=v/c/r</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=v/c</math>, and <math>r</math> is distance from the observer to the observed galaxy, and its exact value turned out to be  

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