Hot Pockets

10/10 - 10/16
by C. Zaitz

It was just announced that two Americans, John Mather and George Smoot, won the 2006 Nobel Prize in Physics. They were doing their part to confirm the theory that the universe began in a wild, hot expansion that started from nearly nothing and ended up as the present gigantic universe we see today.

It’s been known since the 1920s is that the universe is expanding. Before that, we had the idea that the universe was a steady state place, where nothing really changed. But Edwin Hubble noticed that galaxies were rushing away from the Milky Way, and the farther away they were, the faster they were going. Either that meant that we were the center of the universe, or that the space between galaxies was growing. Since there was no reason to suppose the Milky Way was at the center of everything, we went with the second idea. We named the great expansion the Big Bang, and scientists got busy trying to find evidence of it. We looked and looked, but we couldn’t see the remnants of the Big Bang. Finally, in the 1960s, some one heard it.

It wasn’t very loud; it was just a bit of noise. Noise heard in a radio receiver meant for earthly communications. The noise couldn’t be accounted for from a terrestrial source, so eventually the sky was blamed. What the radio dish was picking up was the echo of a long ago, tremendous expansion of space and time. It sounded like mere static, but it was the ancient birth-scream of our universe, now spread out, tired and sore after a 13.7 billion year journey.

It was called the Cosmic Microwave Background Radiation, or the CMBR. Its discovery launched a whole cascade of modern cosmology, complete with satellites like COBE, the Cosmic Background Explorer. COBE was sent to map and probe the CMBR. Looking at the background radiation was like looking at the very young universe when it was about 3,000 degrees. In 1992, COBE measured the current temperature of the radiation. Over the past 13.7 billion years, it has cooled down to a mere 2.7 degrees above absolute zero. Even at that lowly temperature, we can read that radiation like a book. And it’s a pretty interesting story.

Interesting because what the scientists working on COBE found was small anisotropies in the CMBR. An anisotropy is a little weirdness. Little pockets of slightly hotter, slightly cooler areas in the CMBR to the tune of a hundredth of a thousandth of a degree. But even this small difference means something. We have long been wondering about galaxy formation. Star and planet birth is pretty well understood, but the formation of giant galaxies has been puzzling. These “hot pockets” may be a key to how they formed. Things get fascinating when we look at the anisotropies of the CMBR. Could they be frozen sound waves or harmonics from the beginning of the universe? Further studies from recent satellites like WMAP have given us a wealth of detail about the CMBR, and it has led us to the idea that the universe is not only expanding, but speeding up its expansion, for reasons known only to the universe as of yet. But we are hard on its heels, and in future years I predict more work on hot pockets in the CMBR and more discoveries about the origins of the universe. It’s an exciting time for all of us who wonder about the cosmos.

Until next week, my friends, enjoy the view!