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Plasma Cosmology, Part I: Interpretations of the Visible Universe
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15327 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
8 / 1989 |
3,202 Words |
| Author
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Anthony L. Peratt
Anthony L. Peratt conducts plasma research at the Los Alamos
National Laboratory. He was previously with the Maz Planck
Institute for Plasma Physics in West Germany. |
Cosmology (from the Greek kosmos, meaning "the world," and logos, meaning "discourse") began when man first asked: What is beyond the horizon and what happened before the earliest event I can remember? Pursued to its extreme, these questions led beyond planet Earth to the celestial surroundings.
As attempts to answer cosmological questions coalesced into systematic worldviews, or cosmologies, encompassing the entire universe, they were inevitably based on fragmented observational evidence, oversimplified assumptions, and incomplete physical theories. Yet, today, it is commonly accepted as a matter of faith that the ultimate cosmological theory will turn out to be simple, just as theories in physics have proven to be simple. For example, the laws of mechanics, electricity and magnetism, and quantum mechanics are all remarkably simple in form. Although we do not have any profound understanding as to why the natural laws have such simple descriptions, the fact of their simplicity is largely responsible for progress in physics, where much has been explained.
Since the universe embodies everything, from the tiny electron to the most distant quasar, there is certainly much to be explained in a given cosmology. Included among the cosmological explanations has been an estimate of the age of the universe. As late as 1948, astronomers estimated the age of the universe to be only about 2 billion years. This brought cosmology into direct conflict with geophysics, since geophysicists had calculated that the Earth was more than 3 billion years old. Today, geophysicists estimate the Earth's age to be 4.7 billion years, and the dominant cosmology, the Big Bang model, calculates the age of the universe to be 20 billion years.
Cosmological Controversy
Through much of the twentieth century, two cosmologies--the Steady State model and the Big Bang model--vied for general acceptance. The Steady State cosmology was renowned for the brilliance, if sometimes arrogance, of its advocates. According to the Steady State model, the universe is invariant in time. The appeal of this model derived, in part, from the perfect cosmological principle, which stated that the universe should present a similar aspect when viewed from any point in space and time. The Big Bang model can be traced back to the 1920s, when the Russian mathematician Alexander Friedman (1988-1925) invented cosmological models having an explosive beginning. The Friedman model was adopted by the Belgian mathematician, physicist, and cleric Abbe Georges Lemaitre
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