Theories of the Universe
A Big Bang Alternative
While the big bang was making its way into public consciousness, there were other physicists that still didn't go for it. Fred Hoyle, Thomas Gold, and H. Bondi, three other prominent scientists, put forth a theory that has come to be known as the steady state theory. Like the big bang theory of Lemaître, it was based on philosophical premises, not scientific ones; but unlike the big bang, it proposed an eternal universe, not one that was created in time. This theory was based on the cosmological principle, which contained aspects first put forth by Einstein. Basically the idea was that the universe is homogeneous (smooth) and looks the same from any place in the universe (isotropic). If the big bang occurred, it would look different to observers at different times. The steady state theory proposed a perfect cosmological principle. In other words, the universe looked the same to all observers in all times and at all places.
The cosmological principle is an idea in which the universe, on a very large scale, looks the same to all observers at all times and in any place. Matter is spread evenly throughout, which reflects a smooth, nonclumpy universe. It is a philosophical idea originally proposed by Albert Einstein.
Gold and Bondi suggested a unique solution for their smooth, uniformly dense universe, the spontaneous and continuous creation of matter. In each area of space, about 100 meters square, once a year a new atom comes into existence. Throughout the vast regions of space this small amount of matter would accumulate over time and maintain a constant density in an expanding universe. As old stars and galaxies die, new ones are born and formed by the constant regeneration of matter that is introduced through this spontaneous process.
This theory accounted for the creation of all of the elements in the same way that Gamow's big bang did, so it served as a good argument against the popularity of the big bang. But it never gained the scientific support that the big bang did. It was also very difficult to prove. While it went a long way in providing a sound alternative to the big bang, no one had ever observed the creation of these atoms that were supposed to be occurring spontaneously out in space. But for over fifteen years the two theories were hotly debated in scientific circles, although because of Gamow's push to popularize his, it definitely got a lot more publicity.
Microwaves to the Rescue
When the experiment was first set up to measure the microwave background radiation, the scientists puzzled over the excess noise that their system was picking up. There shouldn't be that much radiation. After adjusting the instruments and the antenna, they still had too much noise. After almost giving up, they found a large amount of bird droppings (who would have thought it could get that deep) inside the microwave antenna that was distorting the information coming in. Any form of excrement gives off heat as it breaks down, and that minuscule amount of heat was affecting the microwave radiation spectrum.
The most important piece of evidence in support of the big bang came in 1965 when two researchers at Bell Labs in New Jersey, Arno Penzias and Robert Wilson, verified the existence of something that was predicted by the big bang. This something is called cosmic microwave background radiation. It's sort of the diluted afterglow of the titanic explosion of the big bang. As you know, all radiation can be described by its spectrum. If you plot that spectrum on a graph it will show you how much power the radiation has at various frequencies. The big bang theory predicts that the cosmic background radiation should be in thermal equilibrium, that is, the spectrum of an object in thermal equilibrium neither absorbs nor gives up heat to its surroundings. If the source of the radiation being measured is an explosion, like the big bang, which involves the entire universe, it must be in equilibrium because there are no surroundings to get energy from or give it to.
With this confirmation of the predicted radiation, scientists became convinced that the big bang was “the answer.” Papers poured in by the hundreds, all developing mathematical theories and reasons in support of its correctness. If there was any doubt, or if some aspect of the theory ran into problems, instead of questioning it, more theories were developed to plug the holes. Scientists received grants and built their reputations on the big bang theory, so no one was about to question its rightness. Besides, it is the best theory around, so why go looking for something new when what you have works pretty well. Is it cosmological laziness or just the fact that too much time, money, and energy have been put into a theory that has been presented as fact? And the assumption that Einstein introduced, that eventually a theory can be proven totally correct, is still a very strong influence, albeit somewhat unconsciously.
However, as more time has gone by, and with more experiments and stronger telescopes to verify big bang cosmology, the very thing that the experiments hoped to show, has ended up causing more problems for it. These are significant questions that the big bang has trouble answering. In the next section we'll take a look at exactly what the problems are and see how science thinks the universe is going to end. You'll also get a chance to learn about some new theories that may offer an alternative to the big bang.
Excerpted from The Complete Idiot's Guide to Theories of the Universe © 2001 by Gary F. Moring. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.