Monday, August 27, 2007

The Passing of Ralph Alpher

Image Credit: American Institute of Physics

Two weeks ago, physicist Ralph Alpher passed away at the age of 86. "WHO?" I hear echoing from across the blogosphere. Only one of the relatively unknown yet important contributors to astronomy of the 1900s, that's all.

In the late 1940s, Alpher was a PhD student working with physicist George Gamow. They were working on calculations surrounding a new idea about the creation of the Universe. It had been known for some time that all the galaxies in the Universe appeared to be moving away form one another, as if they had exploded out of a single point eons ago. Alpher and Gamow worked on a mathematical treatment of what the Universe would have been like during such an explosion. They determined it would have been hot enough to cause nuclear reactions to occur (and they calculated the relative amounts of elements these reactions would have created), and that the fireball should still be visible as a faint echo only a few degrees above absolute zero today.

Their paper was published in the prestigious journal Nature on April 1, 1948. Because it was appearing on April Fool's Day, George Gamow added the name of famed physicist Hans Bethe to the paper, making the authors "Alpher, Bethe and Gamow," a pun on the first three letters of the Greek alphabet: alpha, beta, and gamma. Bethe had done no work for the paper, but was amused at the joke. The idea that the Universe began in a huge explosion was scoffed at, the explosion being derided as just a "big bang."

Yet the paper did something that no other work on the subject had done -- it not only explained why galaxies were flying apart, but it offered concrete predictions on other observables -- how much of the Universe was made of hydrogen and helium, and that faint echo. This is a crucial lesson in science for everybody -- it is not just enough for a theory to explain why things appear to be the way they are. The theory has to make specific predictions on things that have not yet been seen. If those predictions hold true, the theory is strengthened; if they aren't right, the theory is incorrect.

In 1965, two engineers, Arno Penzias and Robert Wilson, were tracking down sources of noise in a radio receiver they were building, but one noise just wouldn't go away. It was noise that seemed to have a temperature of a few degrees above absolute zero. Alpher's prediction (which, in the meantime, he had fleshed out further with Robert Hernan) had been proven correct, and the Big Bang theory instantly became far and away the strongest scientific theory on the creation of the Universe.

George Gamow became famous for his work; Hans Bethe won the Nobel Prize for Physics (not for this work, but for many other vital contributions). Two Nobel Prizes have been awarded for the Big Bang Theory -- to Penzias and Wilson for discovering Alpher's predicted echo, and this year to John Mather and George Smoot for further work on understanding this background. All four deserved this recognition. Unfortunately, Alpher's work went unrecognized by the Nobel committee. But, in 2005, Alpher was awarded the National Medal of Science, nearly 50 years after his crucial work on the Big Bang Theory.

1 comment:

  1. Having been around for many of my Dad's post-Big Bang years, I don't think "who"? really applies. I've been asked if he is my father in many, many places....on the other hand, he was present at the launching of the COBE on which Mather and Smoot based their Nobel research, and Penzias and Wilson's "discovery" was fortuitous (although they cited Alpher in their published Nobel acceptance addresses. So, there are 4 Nobels on the Cosmic Background Radiation...and since his 2005 National Medal of Science was awarded in July, 2007 (while he was alive), why not a 2007 Nobel? Stranger things have happened.