March 28 – Not With A Wimper

Today’s factismal: The term “Big Bang” for the start of the Universe was used for the first time 67 years ago today.

It is no secret that scientists like to argue with each other. Just look at Newton’s infamous smack down of Hooke (“If I see further than other, it is because I stand on the shoulders of giants” – Hooke was short) or Galileo’s comments on his detractors (he called them Simplicio {“Stupid head”} in his most famous work) for two notorious examples. But perhaps the most famous and least known scientific feud was between Fred Hoyle and  Georges Lemaître and Edwin Hubble.

As is usually the case in scientific arguments, the debate was 1/3 science and 2/3 personalities. Hoyle was a noted devil’s advocate who frequently took an opposing stance just to ensure that no idea was ignored while Lemaître and Hubble were painstaking observers who went where the data took them. And where the data took them was into a new realm of cosmology that still amazes and astounds today. You see, when Hoyle, Lemaître and Hubble had their contretemps in 1947, astronomy was in the middle of a golden age of discovery. Just a few years earlier telescopes had gotten good enough to resolve the “nebulae” in the sky and reveal that most of them were actually galaxies; more importantly, these galaxies were incredibly far away from our Milky Way. Our universe had just gotten vastly larger.

Just a few of the galaxies in the Virgo Supercluster (Image courtesy NASA/ESA/ESO/NAOJ/G. Paglioli;)

Just a few of the galaxies That told us we are not alone in this Universe
(Image courtesy NASA/ESA/ESO/NAOJ/G. Paglioli;)

But the folks who had discovered these new galaxies noticed something very odd. The galaxies that were furthest away from us were also moving the fastest. That would have been weird enough, but they also discovered that it didn’t matter which direction you looked; all of the galaxies at a given distance appeared to be moving at the same velocity! This was important because it told us that it wasn’t the galaxies that were moving – it was the stuff that they were stuck in. Space itself was expanding.

In order to visualize this, think of a lump of raisin bread dough. It starts off small and compact with the raisins all in one bit but as time goes by the dough expands and the raisins move farther and farther apart. Substitute “galaxies” for “raisins” and “space” for “bread dough” and you’ve got what they thought was happening. But the idea of an expanding universe seemed preposterous to a number of astronomers – after all, what could space expand into? Even worse, if space was expanding, then that meant it was smaller in the past. Take it far enough back and you’d run into something that Lemaître called the “hypothèse de l’atome primitif” (hypothesis of the primeval atom); at some point, everything was stuffed into a space smaller than an atom! Such an idea seemed absurd to many.

The Cosmic Microwave Background that proved the existence of the Big Bang (Image courtesy NASA / WMAP Science Team)

The Cosmic Microwave Background that proved the existence of the Big Bang
(Image courtesy NASA / WMAP Science Team)

And so Hoyle and the others came up with a competing hypothesis, known as the Steady State theory (Hoyle and his folks were big on self-promotion, so they called their idea a theory even though it was just a hypothesis). In the steady state theory, the Universe always was and always would be. New stars were formed and old stars died, while all the time new hydrogen was formed via an unknown process in interstellar space. The hypothesis had a lot of problems but it did mean that there would never be a start (or an end) to the Universe.

At the time that these ideas were being debated, there wasn’t much real data to base the arguments on. Radio astronomy would conclusively settle the hash of the Steady State hypothesis with the discovery of quasars in 1959 and the Cosmic Microwave Background in 1960, but in 1947 it was still very much an open question. As is all too common, in the absence of hard data, hard words are frequently used. And that’s exactly what Hoyle did in 1947.

During a radio interview on the BBC, Hoyle described the basic differences between his views and those of Lemaître and Hubble. And in his interview, he came up with a phrase to sum up what Hoyle viewed as the central absurdity of the opposing argument; he called it a “Big Bang”. And the name stuck. It was simple, it was funny, and it actually captured what many astronomers thought was the central problem of the idea. Unfortunately for Hoyle, it turned out that  Lemaître and Hubble were right and he was wrong. Silly name or no, the Universe did start with a Big Bang.

Even though we’ve settled that idea now, there are still plenty of other arguments in science. And scientists still need lots of data to help them decide who is right and who is just calling out silly names. If you’d like to help, why not join Galaxy Zoo? They need folks, just like you, to look at pictures of galaxies and sort them into simple classes to see if the way that galaxies form has changed since the Big Bang. To learn more, head over to:
https://www.galaxyzoo.org/

 

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