Lemaître’s Big Bang: 1931–

“We could conceive the beginning of the universe in the form of a unique atom, the atomic weight of which is the total mass of the universe,” said Georges Lemaître. The Big Bang is one of the scientific concepts that has taken hold in the popular imagination. It originated when Lemaître, a Jesuit and physicist, proposed that the universe had originated in a primeval atom. Ironically, the theory was not named by its supporters, but by Fred Hoyle, an opponent who favored the alternative theory that the universe is in a steady state that has existed for ever. The models make different predictions, because a Big Bang leaves relics of the original explosion that can be detected in the form of cosmic radiation and gravitational waves. While some of these predictions have been confirmed, there are many discrepancies. The universe is expanding too fast. There are gravitational effects that cannot be explained by the existence of matter as we know it. In fact, matter can account for only 5% of the universe. And the likelihood that the universe would develop conditions propitious to support life is infinitely small. Efforts to reconcile these results with what we can infer of the Big Bang seem to come closer to science fiction than describable reality.