Answer to Question #89713 in Astronomy | Astrophysics for DEEPAK

Question

Explain why at one time, the steady state theory appeared necessary. What is its status now?

Answer 1

According to steady-state theory, the Universe is always expanding but maintaining a constant average density. A steady-state universe has no beginning or end in time, and from any point within it the view on the grand scale, the average density and arrangement of galaxies are the same. The theory was first put forward in 1948 by British scientists Sir Hermann Bondi, Thomas Gold, and Sir Fred Hoyle. It was further developed by Hoyle to deal with problems that had arisen in connection with the alternative big-bang hypothesis. Observations since the 1950s have produced much evidence contradictory to the steady-state picture and have led scientists to overwhelmingly support the big-bang model. Like all scientific theories, the Big Bang theory has its pros and cons. For example, the cosmic background radiation, which is the main proof of the Big Bang Theory, comes from widely separated parts of the sky. These regions are too far from each other to be able to interact with each other, even with signals travelling at the speed of light. But according to the smooth background radiation whose sources have similar properties, they must have interacted with each other. This problem is referred to as the “horizon problem”. Another problem with the Big Bang theory is the “flatness” problem. The experimental evidence is that the present universe has very low geometrical curvature in its space-time. In other words, it is flat. According to the Big Bang theory, the universe expands but unless this expansion is confined to an incredibly narrow range of possibilities, it would not have stayed “flat”.