PRIDE CHEKERAmillion light years away; this means light from Andromeda is
being blue shifted on the electromagnetic spectrum).
Observing the light from these galaxies, it was Doppler shifted
to the red end of the electromagnetic spectrum, Cosmological
redshift. This was an evidence that galaxies were in recession
apart, since as they move away the distance between us and the
galaxies exaggerated, and light takes much time to reach us as
its wavelength increased.
Hubble discovered that much redder shifted galaxies where the
ones far away from us and the ones with greater recession
velocities. This is symbolized in an equation in which velocity
of recession is directly proportional to the radial distance
between us and the galaxy in consideration related by the
changing Hubble’s parameter H, V = Hr. This means that with
time, future cosmic explorers will only have stars of the Milky
Way to study as stars contained in other galaxies will be beyond
the field of our sight.
This milestone discovery by Hubble contradicted Einstein's
stationary universe stabilized by the cosmological constant.
What was causing the galaxies to recess way from us if the net
force of the universe was known to be zero?
In 1922, a Russian cosmologist Alexander Friedman deduced
solution from EFE in which he modeled a cosmos with an
expanding spatial metric, Friedman-Robertson-Walker metric. It