(Excerpt)

 

The Big Bang & The Expanding Universe 

 

The Hubble Law, also called the Hubble equation describes the relation of the velocity and the distance from the observer of each of many galaxies observed over a wide range by Edwin Hubble,  Vesto Slipher, Milton Humason and their associates and successors, and it is the velocity =H  x  distances or, if v=velocity and s=distances, namely  v=Hs  in which  H is the Hubble Constant is a constant of proportionality.

For each galaxy, the velocity v is calculated from red shift, spectographic observations and from the Doppler effect. The distances from the observer was determined from the absolute brightness, from the period called Cepheid variables, the Cepheid variable stars were the key instrument in Edwin Hubble’s 1923 conclusion that M31 (Andromeda) was an external galaxy as opposed to a smaller nebula within the Milky Way, from the apparent brightness measurements, and from the Inverse Square Law relating those measurements to distances.

As can be seen from this equation, H has the dimension of time with the H^- (with the minus superscript)  and is based on many observations of many galaxes over a wide range of distances and corresponding velocities.

The value of H^- is determined as being between the limits of 15 kilometers per second per million light years, and 30 kilometers per second per million light years, or the equivalent limits of 50 kilometers per second per megaparsec and 10 kilometers per megaparsec.