In a universe expanding as per the Big Bang or Steady State theory the cosmic redshifts should increase exponentially with time, which is not actually observed. So the universe is NOT expanding. In Unified Theory’s non-expanding universe the total energy-mass content is eternally conserved with NO?initial creation of matter from nothing’ in a single big explosive event of the Big Bang theory or continuously as in the Steady State theory. The cosmic redshift is caused not by Doppler effects of receding velocities of stellar light sources but by depletion of photon energy during long passage through the sharmon medium due to non-Doppler effects of gravitational, electromagnetic & viscous losses. Cosmic microwave background follows naturally and plausible explanation given to the observation on Ia type supernovae, which has amazed & horrified the astronomers. Halton Arp’s observations of high-redshift quasars in the vicinity of low-redshift parent star systems, negative redshift, and the ejection of two huge mass bodies in opposite directions are also explained. But his?quantization of redshifts’ is not a natural phenomenon. There is no antigravity force permeating space and no likelihood for the universe to become empty ever in future. Age of the non-expanding universe is about 45 billion years. Dark energy and dark matter are related to the Sharmon medium. Realistic theory of Non-expanding universe replaces Big Bang & Steady State theories of expanding universe.
Keywords: Big Bang, Steady State, Expanding Universe, Non-expanding Universe, Unified Theory