The Big Bang is the defining narrative of modern cosmology: a bold declaration that our universe had a beginning and has a finite age, just like the humans who live within it. That finite age, in turn, is defined by the evidence that universe is expanding (again, and unfortunately, many of us are familiar with that feeling as well). Those two ideas — a singular cosmic beginning, followed by billions of years of cosmic growth — are so strange that some people have never made peace with them. As a result, skeptics have been questioning the validity of the Big Bang model for as long as there has been a Big Bang model.
Among mainstream cosmologists, doubts about the Big Bang largely melted away in the 1960s with the discovery of the cosmic microwave background–an omnidirectional buzz of radiation that makes sense only as a relic from the hot, early era of the universe. But around the fringe, the doubts have persisted. Lately they have intensified, inspired by a puzzling discrepancy in different measurements of how the universe is expanding. Even scientific centrists acknowledge that our understanding of the early universe is glaringly incomplete. So now is a prime time, it seems to me, to dig into the big question: Could the Big Bang be wrong?
