The Last Three Minutes: Conjectures about the Fate of the Universe.

Basic Books, $20, 162 pp.

Cosmos's Missing Mass: Wispy Particle Weighs In." "Hubble Space Telescope Photographs a Black Hole." "Astronomers Debate Conflicting Answers for the Age of the Universe." The newspapers recently have reminded us with striking regularity that science is not as gridlocked as politics. First there was the Cosmic Background Explorer (COBE) satellite and its discovery of the long-sought variations in the cosmic background radiation. Then results from the optically improved Hubble telescope began filtering in and, most recently, a report that part of the "missing mass" that has puzzled astronomers may be accounted,for by particles known as neutrinos.

Among cosmological questions, at least one really big one still remains. How and when will it all end? Will the universe expand forever, heading into an infinity of cold darkness, or will it regather itself into a fiery last crunch, a time reversal of its explosive start? Will the Democrats and Republicans agree on the budget before it happens?

Budget issues aside, two recent books survey the science of the universe, cradle to grave. The Origin of the Universe, by University of Sussex professor John Barrow, and The Last Three Minutes, by scientist and Templeton Prize winner Paul Davies, are the second and third volumes in The Science Masters Series, a new and growing collection of short, entertaining, and accessible-without-being-simplistic treatises by internationally known scientists. Barrow and Davies were preceded by Richard Leaky (The Origins of Humankind) and will be followed by such notables as Stephen Jay Gould, Marvin Minsky, and Mary Catherine Bateson. In these books, one encounters the most intriguing scientific ideas and questions, speculations that all too rarely appeared in the science courses we took in school. The best science often comes from asking the most basic questions. One learns in chemistry and physics that the charge on the electron is 1.6 x [10.sup.19] coulombs. The world's leading scientists ask "Why?" There are planets and stars and galaxies. How did they come to be? Students study the Big Bang and learn that the universe is expanding. Cosmologists ask if the expansion will go on forever. In these cases, the questions of the experts really do translate easily into the vernacular.

Barrow describes his own book as "the Beginning for beginners." The birth of the universe can be divided into three stages: 0 to 1 second, a period in which temperatures exceeded anything known on earth and not even hydrogen atoms were stable; 1 to 1,000 seconds, when light elements formed; and the time from 1,000 seconds on. After 1,000 seconds (less than the time required to read this review), "it's all over." That doesn't mean that the formation of stars and galaxies isn't interesting, just that terrestrial physics seems to explain most of what we know about how it happened. This isn't true, however, of the earliest times. Barrow refers to the first second as the "cosmic watershed" and much of the book is focused on that very short, but infinitely interesting period after the Big Bang.

It's a fascinating story, told with a wealth of analogy and a minimum of equations (other than the famous E=[mc.sup.2], I counted only one, and that one, as fate would have it, has a typographical error!). Little or no science background required. What will help is some familiarity with, or at least a willingness to pause and think about numbers, large and small.

Consider, for example, a time when the universe is [10.sup.-43] seconds old. (Remember, [10.sup.-43] is 0.000..... 1, with 42 zeros before the one. Since no Commonweal editor would tolerate that many zeros, we write [10.sup.-43].) [10.sup.-43] s is called the Planck time, a time at which the entire universe was so small that it was subject to quantum uncertainty. To describe this incredibly early time in the universe, we need new physical models and new theories, like Stephen Hawking's idea that "time becomes another dimension of space." It gets hard for science writers, too, as analogies fail. And yet, as Barrow says, that might be good, a sign that we are touching upon some brute fact of reality rather than just redeploying our old familiar concepts."

Origin and destiny are often connected. in life as well as cosmology. So it is a short hop from Barrow's book to Davies's "doomsday" reflections. Davies begins by considering a comet impact on the earth, similar to Jupiter's experience last summer. Will this happen? Probably. It has happened before. Anytime soon? Not likely. The vast emptiness of space means that cosmic collisions are relatively rare. But the possibility reminds us that, even given our best effort to preserve the environment and ourselves, the universe ultimately has other things in mind. Whether by slow decay or violent collapse, the expanding universe portends change.

The question of the ultimate fate of the universe has occupied scientists long before Einstein revolutionized our ways of thinking about time and space. Helmholtz in 1856 wrote of the "heat death of the universe," extending the second law of thermodynamics to questions of cosmology. This idea has affected the thinking of many philosophers since. What is the point, if it's all headed for maximum disorder and decay anyway? But Davies paints a variety of other pictures, in which humans, or perhaps more accurately some other form of conscious beings, play a less passive role as their universe moves inexorably on its path to the future.

Of one thing there is no doubt: the earth will be a victim of the death of the sun. Based on its size, the sun should become a red giant, expanding to approximately 500 times its current size and engulfing the earth in flames. Before this fiery end, the atmospheres and oceans will be gone and presumably life as well. This won't occur for more than a billion years. But whatever the ultimate fate of the universe as a whole. our descendants will have to be elsewhere if they hope to watch.

This is where Davies takes the reader on flights of dizzying imagination and speculation, and the unsuspecting reader must beware as he crosses back and forth between fact and fantasy. Societies, writes Davies, may get their energy from black holes, send fertilized ova out to colonize other worlds, and manipulate galaxies as well as the human species in an attempt to survive in an increasingly inhospitable universe. There is, Davies writes, "no reason why these colonists should be human in appearance or even in mentality. If beings can be engineered to meet various needs, then each expedition could involve purpose-designed entities with the necessary anatomy and psychology for the job." Science fiction now, but a billion years is a long time.

When we think hard enough about the beginning and the end of the universe, the how and the why questions start to overlap. It is in these realms that science and theology most readily intersect. Whichever way one's reading taste normally tends, these books are a worthy addition to the list.