The big bang theory is incompatible with an infinte universe. It is widely accepted nowdays that the universe is not infinite, it was discredited a long time ago by a logical thought experiment.

It was assumed some time ago that the universe was infinite, this was because if it wasn't infinite, then it would collapse in on itself due to gravity. So it was postulated that the universe was infinite (and also almost uniform in distribution to prevent to much variance in mass at different regions, which would also cause many smaller collapses).

However, IF the universe was infinte in size AND unifrom, then the sky as we look at it would be INFINITELY bright. The explanation for this is that if you consider imaginary spherical shells of all different sizes with earth at the centre of them, and the surface area of each of these shells is determined by 4*pi*radius(squared) (radius being the unifrom distance of the shell fromthe earth) : Then, since the universe must be uniform, then the amount of stars on each shell must be proportional to
the distance from earth (i.e. the shells radius) squared.

Following on from this, when you take into account the physical relationship that the intensity of radiation decreases inversely proportional to the distance from the source squared(i.e. once again the radius of the shell squared), then it must be concluded that the amount of radiation coming from each shell must be equal, no matter how far away the shell is. Since the amount of radiation coming from each shell is finite, and that there are an infinite number of shells, then the radiation wacking the earth every second would be infinte.


The big bang theory originally came about to counter this by trying to explain the fact the universe is expanding, and not collapsing in on itself as it would if it were finite.

However, since then, even crazier shit have been hypothesized (but not proved) such as anti-gravity to take into account the expanding universe.