Analog SFF, May 2007 by Dell Magazine Authors

Author:Dell Magazine Authors
Language: eng
Format: mobi, epub
Tags: Science Fiction
Publisher: Dell Magazines
Published: 2010-12-15T07:07:45.407000+00:00

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THE ALTERNATE VIEW: THE UNIVERSE AS WATERMELON

by JOHN G. CRAMER

Nicholas Copernicus, who first proposed the heretical theory of a heliocentric universe with the Sun at its center and the Earth demoted to just one of the planets in orbit around it, was absolutely certain that the orbits of the planets must be perfect circles. They had to be, because they were the creations of a perfect God, and a circle is the most perfect of geometrical objects. When Johannes Kepler, after spending most of his career trying to make sense of the meticulous planetary observations of Tycho Brahe, concluded that the orbits of the planets were not circles but ellipses, the discovery sent shock waves through the community of natural philosophers. The discovery led Newton and others to arrive at the inverse square law of gravitational attraction.

A paradigm shift similar to this one has just occurred in observational cosmology. The “surface” from which the cosmic background radiation was emitted may not be a sphere. This discovery is the subject of this column.

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About 400,000 years after the initial Big Bang, when the era of exponential inflation was over, things settled down to a slower and steadier rate of expansion. As more space became available for the energy in it, the universe was cooling things down. The early universe was a nearly perfect “liquid plasma” saturated with energy, in which quarks behaved as free particles. As the cooling progressed, the only strongly interacting particles around, quarks, organized themselves into composite mesons, protons, and neutrons. By some process that remains obscure, there was a slight excess of protons and electrons over their antimatter equivalents (antiprotons and positrons). During the high-density stages of the early universe, essentially all of the antimatter paired off with its matter counterparts to annihilate, leaving behind the slight excess of matter particles as “the only game in town.” The cooling universe was a “soup” dominated by free electrons and protons. In this environment, a photon of light could travel only a short distance without being absorbed by interacting with one of the free charged particles.

Later, the negative electrons and positive protons tended to pair off, forming neutral hydrogen atoms. In the process, the dominance of free charged particles, which easily absorb photons, was being replaced by light-transparent neutral atoms. The “soup” of the universe was changing from murky black to crystal clear.

The photons that were present in that era had energies that were characteristic of light emitted from an object (the universe) with a temperature of about 2,900 K. (Here, K means “kelvin” and specifies the absolute temperature in Celsius degrees above absolute zero.) As long as the universe was murky black, they were caught in a “ping-pong match” of repeated emission and re-absorption. However, the growing transparency of the universe released them from this trap, and they became free photons. Those photons have been traveling through the universe ever since, and we detect them today as the cosmic microwave background radiation (CMB).

However, as

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