According to the ancient Greeks, before the universe was formed there was an utter, infinite nothing--a timeless void they called Chaos. From this chaos sprang an unimaginably dense and energetic seed of order--the Cosmos. The search for the origin and operation of the universe is called cosmology (the study of order). The clues to the birth and life of the universe are all around us, sometimes in the strangest of places.
According to the most accepted theory of the cosmos, the universe began as an incredibly hot, dense, tiny spark of energy that flashed into existence from the nothingness. All of the mass the universe ever had, or ever will have, was contained in a speck of pure energy smaller than the smallest speck of dust. Within this tiny cauldron, the temperatures and energy were so high that the familiar physical laws that govern the universe of today simply did not apply. Instead, time, space, energy and mass were all the same; governed by a single law and force that would later break up into all the present forces and laws. This is the event scientists call The Big Bang. Such an event can hardly go unnoticed. As a matter of fact, the universe should still be reverberating or ringing from the bang and the fires of creation should have etched their marks in everything around us.
This is why we look for clues at the two ends of the universe. On the very fringe of the observable heavens we should be able to see the universe still vibrating from the initial bang. On the smallest of scales, we also try to recreate the conditions under which the early universe existed (extremely high temperatures and energies in a compact place) using particle accelerators. Hopefully, we can catch a glimpse of how and why the universe has turned out the way it has. These two places should hold the fossils that can provide the most promising information about the history of the universe.
The searing, initial flash of the universe would by now have had time to cool to a mere 2.74 degrees kelvin. This corresponds to light in the microwave region of the electromagnetic spectrum. In 1964, Arno A. Penzias and Robert W. Wilson, while working at Bell Telephone Laboratories, discovered this microwave background radiation. Everywhere they looked they could see it, always the same, always uniform.
The Big Bang theory had been wonderfully successful in describing many of the observed characteristics of the universe. It can explain the expansion of the universe, as well as predict the correct abundances of hydrogen and helium. But for all its success, the standard Big Bang model simply could not stand the test of direct observation. The model predicts that the fireball that started the universe was completely the same in all directions. Therefore, the universe should be very smooth, with no "lumpiness" or clustering. But the cosmos is resplendent with lumpiness. Not only do subatomic particles clump together to form atoms that in turn clump together to make objects, but careful observations of the heavens show that stars cluster, galaxies cluster, and even clusters of galaxies cluster (to form "superclusters"). So where did all this lumpiness come from?
In 1980, a brilliant MIT physicist, Alan Guth, proposed a modified version of the big bang called Inflation. In this theory, the uniformity and the lumpiness of the universe can be explained if, shortly after the Big Bang, the early cosmos underwent a period of incredibly rapid expansion or inflation. Before this period, the universe was small enough that much of it was in equilibrium. After the enormous expansion, much of the equilibrium still persisted. Careful consideration of Inflationary theory showed that the microwave background should have minute ripples or temperature differences to explain how the universe could be so clumpy.
On November 18, 1989 a special satellite, the COsmic Background Explorer (COBE), was launched into Earth orbit. Its sole purpose was to tell us once and for all if the background was entirely smooth or if ripples did exist. On April 23, 1992, George F. Smoot, a chief COBE investigator at Lawrence Berkeley Laboratories, announced the discovery of detectable "lumpy" structures in the cosmic background radiation. These structures are relics from the end of the inflationary period (about 300,000 years after the Big Bang), when the universe had cooled sufficiently to allow protons and electrons to form hydrogen - the first observable clumping. It seems at first glance that Inflationary Big Bang theory is alive and well.
This initial COBE finding suggests that the universe is much more massive than previously observed. Much of the mass of the universe must probably be in the form of illusive "cold, dark matter" which doesn't interact much with light, making it very difficult to see. If this is true, it could mean that the universe will someday stop its expansion and begin to fall back in on itself, leading to what some scientists call the Big Crunch. Perhaps from Big Bang to Big Crunch is how the universe was meant to be. The only way for us to tell is to keep looking very closely at the clues the universe offers and to make careful use of remarkable instrument like COBE to see the universe in new and wonderful ways.
Astronomy Magazine, October 1989, April and August 1992.
Scientific American, July 1992.
PBS Home Video, "The Creation of the Universe", by Dr. Timothy Ferris.
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