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Take modern cosmology with a billion grains of salt


If you like "The X-Files," you'll love cosmology. Like TV's dogged hero, scientists probing the nature of our universe are driven by faith that the truth is out there. Uncertainties frustrate them. Errors plague them. Key information seems just beyond their grasp. Yet they progress.

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The second millennium has not left humanity's quest to know the cosmos where it found it. Concepts shaped by superstition and dogma have yielded to hypotheses based on natural law and constrained by astronomical observations and laboratory experiments. But mystery and wonder are not outmoded. The concept of our universe suddenly appearing in an explosion of primordial energy some 14 billion years ago seems as "far out" as any medieval miracle.

The last few years, in particular, have brought the awesome insight that our universe may be running away with itself. It isn't just undergoing an expansion from that primordial blast. The expansion appears to be accelerating. If so, it's probably driven by a fudge factor that Einstein originally added to his general relativity equation and then removed. He called it his greatest blunder. It may be essential to his theory after all.

That's the theme of this interesting book. And who better to tell it than an astronomer-turned-science writer who has lived with this unfolding story for decades. Yes, he has the bias of a cosmology buff. But he also knows the limitations of cosmic exploration and where the intellectual pitfalls lie. The large grain of salt with which he advises readers to take our present state of knowledge brings out the true flavor of the tale.

The last century advanced the cosmic story more than all previous intellectual history. Cosmologists can explain how our universe arose out of nowhere in a way that conforms to experiments with subatomic particles and to our present understanding of quantum physics. But they are as ignorant as any medieval mystic as to why this should have happened.

Scientists can weave a coherent tapestry of what developed after that mysterious moment. Our universe expanded to an enormous volume in the twinkling of an eye. This smoothed things out so much that, even today, the cosmos looks much the same in all directions. Some 300,000 years later, some of the primal energy condensed into matter. Over the next billion or so years, matter organized into galaxies and associations of galaxies. Thus began some 12 billion years of evolution that has produced the stars, planets, and organic life we see around us.

Here's that salt grain. The story is subject to change. Our understanding of the underlying physics is bound to grow in this century. New astronomical discoveries will confront our deductions from the present data-

base. One thing is certain: What we think we know today is far from being the final word.

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Consider the accelerating universe. This insight is revealed by measurements on a distant supernova exploding star. The relatively small number of measurements indicates the objects are farther away than they should be, unless our universe's expansion is accelerating. If so, Einstein's fudge factor calls for a new kind of energy. Astronomers can't detect it, but it would counteract gravity that tries to pull the universe together. If the supernova observations aren't distorted by cosmic dust, if these supernovae behave as believed, and if more of them can be found, the researchers will have a solid case. Goldsmith says to stay tuned. The crucial observations are only a decade or two away.

Goldsmith's book is informative and generally well written, but it's easy to get lost in his more technical explanations. It reads like a potboiler rushed into print to get out the news. However, the fire under this pot burns along one of the hottest parts of the scientific frontier.

*Robert C. Cowen writes about science for the Monitor.

(c) Copyright 2000. The Christian Science Publishing Society