For discussion .. this has not been settled, and may never be settled, despite some people insisting that "science says the Universe had a beginning" -- whoever "science" is.
The big bang theory postulates that the entire universe originated in a cosmic explosion about 15 billion years ago. Such an idea had no serious constituency until Edwin Hubble discovered the redshift of galaxy light in the 1920s, which seemed to imply an expanding universe. However, our ability to test cosmological theories has vastly improved with modern telescopes covering all wavelengths, some of them in orbit. Despite the widespread acceptance of the big bang theory as a working model for interpreting new findings, not a single important prediction of the theory has yet been confirmed, and substantial evidence has accumulated against it. Here, we examine the evidence for the most fundamental postulate of the big bang, the expansion of the universe. We conclude that the evidence does not support the theory; and that it is time to stop patching up the theory to keep it viable, and to consider fundamentally new working models for the origin and nature of the universe in better agreement with the observations.