The big bang theory is an example of the intellectual hole that leading astrophysicists are trapped in.

Part of the basis of the big bang is: (1) the apparent expansion of the universe as demonstrated by the observed red shifts, and (2) the observed cosmic microwave background (CMB) and (3) the observed uniform temperature of 2.7 deg K for microwaves traveling from large distances from the early history of the universe.

However, in addition to the red shift due to the Doppler effect the red shift the red shift includes three other contributions only due to the effect of gravity on the photons. Thus the red shift can not be used to prove an expanding universe.

Also, photons traveling large interstellar distances will have their energy reduced. And will equilibrate with the cold interstellar gas (hydrogen) by means of gravitational drag - similar to the transfer of moon energy to tides on the earth. Collisions are not needed but only gravity drag.

Details are available at:

http://inventing-solutions.com/simplified-universe.htm

No sir it is not so.
no theory can now discard the concept of expanding Universe...we can only add to it.
And what do you mean by a non-expanding Universe ....