The Term ‘Big Bang’ Came from Its Biggest Doubter

Fred Hoyle is astronomy's classic contrarian. The brains behind the theory of nucleosynthesis—the process by which elements are created within stars via nuclear fusion—and author of science-fiction-by-scientists classics such as the Black Cloud, Hoyle was brutally stubborn and profoundly wrong on a whole catalog of otherwise settled topics. He was also a precursor to modern pop science, delivering a series of popular BBC talks on astronomy through the '40s and '50s, including one on March 28, 1949 in which he infamously rejected the notion of a "big bang" origin of the universe, while also coining the very term.

The specific line offered by Hoyle was this: "These theories were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past." By now the Big Bang is very much so settled science, but in 1949 it looked to Hoyle to be a distinctly unscientific notion. If everything that is everything came into being in one momentous cosmic belch, that meant there was something "before science." An unpleasant thought.

Hoyle advocated a "steady state" theory of the universe. This idea was a fudge, mostly, though at the time it was taken very seriously. It explained that the universe of today always was and always would be, while accounting for the fact of universal expansion by saying that, in an expanding universe, matter is continually being created out there in the gaps between stars.

It's a bit like saying that instead of a single Big Bang event, the Big Bang is a perpetual process that's been occurring for all of time—with no beginning—and will continue for all of time. With no end. However unpopular, the steady state idea hadn't been quite disproven and wouldn't be until the maturation of radio astronomy several years later.

"The big bang and steady state models made distinctly different predictions about the distant universe," the astrophysicist Mario Livio wrote in his bestselling Brilliant Blunders. "When we observe galaxies that are billions of light-years away, we get a picture of those galaxies as they were billions of years ago. In a continuously evolving universe (the big bang model), this means that we observe that particular part of the universe when it was younger and therefore different."

"In the steady state model," Livio continued, "on the other hand, the universe has always existed in the same state. Consequently, the remote parts of the universe are expected to have precisely the same appearance as the local cosmic environment."

So, the steady state model was clearly disprovable and that would come in the form of radio astronomy and the Cambridge physicist Martin Ryle. Ryle began cataloging radio sources (then still ambiguously referred to as dark stars or radio galaxies) beyond our solar system, noting their varying intensities. He made a simple, intuitive assumption: the weaker the signal, the farther away the source (and, thus, the older the source). This led to the observation that there are many more weaker signals out there than strong signals. This meant (or was proposed to mean) that the density of the universe used to be much greater than it is today.

This didn't fit with a steady state universe, a theory implying uniformity through time, but it did align well with the Big Bang concept. In 1961, in a classic sketchy move, Ryle invited Hoyle to attend a press conference about his new findings—a further tally of astronomical radio sources—which turned into an extended pillorying of the steady state theory and Hoyle by association. Though he'd done basically the same thing to Ryle a decade before in his steady state-based attacks on the emerging Big Bang cosmology, Hoyle was basically shamed into hiding for several weeks.

Two years later, the steady state theory's fate was really, truly sealed. Astronomers had discovered quasars—first 3C 273, and then many more. A quasar, a hyperactive galaxy built around a supermassive black hole nucleus, is both a powerful radio source and also extremely luminous. Astronomers can observe such objects both optically and within the radio spectrum. This allowed for very clear observations/inferences of distance and age, and, thanks to Hubble's Law, it could be determined that these new objects were very, very far away and very, very bright. What looked like nearby stars were really distant superluminous galaxies.

This was really the end of Hoyle's steady state theory, though he never really let go, even until his death in 2001. As noted in a New York Times obit, many of the intervening years were spent worrying about "diseases from space." He was a firm believer that life must have originated from outer space, and that its Earth-based genesis should be impossible, which led him to the conclusion that the onset of various UK epidemics could be attributed to "lifeclouds" and "cosmic life forces" and so forth. (These are all names of books he published between 1958 and 1988, among others.)

Despite all of the friction and ugliness, Hoyle didn't mean his "big bang" nomenclature to be derisive in itself. The astronomer just wanted a good illustration for a radio audience. And by now we can probably say that it was the best.