Claim 1 of 13 · Case 08 · Science
The universe had a beginning rather than existing forever.
One claim from the free evidence repository at apologetics.pro.
For most of the modern era, scientists assumed the universe was eternal, with no origin to explain. Two lines of evidence in the twentieth century overturned that. First, distant galaxies are moving away from us, which means the universe is expanding, and running that expansion backward points to a starting point. Second, a faint radiation left over from that early hot state was found coming from every direction in the sky. Together these made it the mainstream view that the observable universe expanded from a hot, dense state about 13.8 billion years ago. Whether that marks an absolute beginning, rather than a transition from some earlier state, is still debated, and some models propose a bounce or an eternal past. This claim is only about the evidence for a beginning. It does not, by itself, prove who or what caused it.
Backed by 2 pieces of evidence
Edwin Hubble’s 1929 measurement of galaxy distances and speeds
An expanding universe is the first hard evidence for a beginning. If everything is flying apart now, then in the distant past it was together, which implies a start rather than an endless past.Penzias and Wilson’s 1965 detection of the cosmic microwave background
This radiation is the predicted afterglow of a hot, dense start. Its discovery is what moved cosmology from “the universe might have begun” to a broad agreement that it did.