Let us now praise rotting logs, black holes and babies' brains. Whether you're gazing at stars, at trees or at a toddler, these science books can bring the picture into focus.

THE FIVE AGES OF THE UNIVERSE

By Fred Adams and Greg Laughlin

Free Press.

251 pp. $25

You want the BIG picture? Look no further. Consider this snapshot of New Year's Day, 7,000,000,000 A.D.: "Earth's surface is a torrid unrecognizable wasteland. The Sun has swelled to enormous size, so large that its seething red disk nearly fills the daytime sky. The planet Mercury and then Venus have already been obliterated. . . . Earth's life-producing oceans have long since evaporated, first into a crushing, sterilizing blanket of water vapor, and then into space entirely. . . . By noon, the temperature reaches nearly 3000 degrees Fahrenheit, and the rocky surface begins to melt."

Astrophysicists Fred Adams and Greg Laughlin guide the reader on a space/time tour of the universe that can only be called mind-boggling. They start at the beginning, with a remarkably lucid discussion of the Big Bang, and carry on all the way to the unimaginably remote Dark Era, when all the stars will have burned out, all the protons will have decayed, and even the black holes will have "evaporated," leaving a lightless universe that contains only electrons, positrons and neutrinos. By then, of course, we humans -- along with our planet and our Sun -- will be long gone. Already, the sun's 12-billion-year lifespan is almost half over.

Yet our very presence was a long shot. It took more than 3 billion of the Earth's 4.6 billion years of existence merely to evolve the molecular machinery that made possible complex cells like those in our bodies. Judging from this precedent, in order for a star to last long enough for life to develop, it can't have a mass bigger than 1.15 times that of the sun. That, plus a host of other factors, puts most places out of the running. Using various data, Adams and Laughlin estimate that only about one in 10 thousand habitable planets is likely to develop life and that there may be "roughly one thousand" civilizations in our galaxy. Unfortunately, the nearest one to us is probably three thousand light-years away, and "the chances that we will soon make contact remain extremely remote."

The physics in this book is unavoidably sophisticated, and the time scales and distances involved will make your stomach turn over. But the road is smoothed by marvelous descriptive writing and mind-expanding explanations of how stars, black holes and other celestial bodies behave. What makes it even better than good science fiction is that it's true.

-- Susan Okie

WHAT'S GOING ON IN THERE?

How the Brain and Mind Develop

In the First Five Years of Life

By Lise Eliot

Bantam. 533 pp. $26.95

(Available September 1)

They are momentous occasions in most families: an infant's first smile, a baby's first word, a toddler's first step. As parents celebrate these milestones, they marvel at the rapid and mysterious development of their youngster.

The flourishing of a young child's brain is a phenomenon that humbles even the smartest adults. Lise Eliot, a neuroscientist with three children of her own, attempts to explain this growth for a lay audience. She asserts that half of a child's intellectual development comes from genes and half from parenting and experience. And she makes clear that infants are not "blank slates at birth." Instead, she argues, while they appear helpless and clueless, infants have strong mental skills and abilities that allow them to survive, including the sense of touch that began developing in the womb and will help a child's physical growth and emotional well-being; the sense of movement that is important for future development of motor skills; and the sense of smell that helps infants bond to their mothers.

These first five years of a child's life are a joy to watch and often a challenge to manage. But Eliot fails to capture the glory of these changes or the fun. Although she makes reference to a variety of children, including her own, there are few examples that captivate the reader. Even when she talks about a handful of children who have been badly abused and neglected, she fails to bring those children and their horrors to life.

Instead this is a workmanlike guide to a child's brain development, carefully laid out in an easy-to-follow continuum and clearly written. Although her subject is often technical, Eliot works hard to keep the writing simple and literate. But since Eliot begins the book by following the developing brain from its first prenatal cells, much of the most intriguing material is left for the end of this long book, and overburdened parents may never get that far. The chapters on social-emotional growth, language and intelligence are by far the most complex and helpful.

Still, in our age of parental angst this is a book that has a reassuring message about providing the best for children. Eliot points out that Grandmother was right and that simple efforts such as talking to your child, providing good nutrition and a safe home will provide a fertile environment for her growth. There is no magic formula for raising a bright child, she asserts, but love, natural reactions and common sense will go a long way.

-- Lexie Verdon

THE HIDDEN FOREST

The Biography of an Ecosystem

By Jon R. Luoma

Henry Holt. 228 pp. $25

This book, which could be subtitled "Let Us Now Praise Rotting Logs," begins with its author's wish to "help readers, well, be able to see the forest for the trees."

The trees in question are in the Andrews Experimental Forest of central Oregon, the most studied primal forest ecosystem in North America. The Andrews, as it's known, is a 16,000-acre parcel set aside by the U.S. Forest Service in 1948 as a living laboratory. The oldest trees there began growing around the time Columbus landed in North America.

Old-growth forests are much championed in this era of environmental activism, but science writer Jon R. Luoma reminds us that before most people had heard of the spotted owl, "old growth" was largely a forester's dero-gatory term. Dwindling old-growth forests were dismissed as "cellulose cemeteries."

Indeed, such forests are full of decay and disorderly rot. But they're also home to "an explosive diversity of life-forms," from fungi to lichen, budworms to bark beetles, termites to truffles. And unappreciated rotten logs. Far from being timber trash, fallen logs turn out to be as vital to the ecosystem in death as they were in life. Teeming with life, they enable old-growth forests to recover from catastrophic fires, blowdowns or volcanic eruptions.

Biologists are sometimes criticized for studying small, easily quantifiable matters -- a trend some attribute to "physics envy." A recent review of 97 ecological field experiments found that nearly half covered an area of less than one square meter, about the size of a coffee table. By contrast, researchers at the Andrews revel in complexity and big questions such as: How does a forest survive? Not content with trying to make trees produce wood faster, they are true pioneers of ecology, which Luoma calls "the great integrative biological science of not just molecules, not just cells, not just whole organisms, but of the complex dance of nature across space and time."

Luoma uses the Andrews research to illuminate the contemporary debate between "sawlog foresters" and "ologists," the Old Forestry and the New. He is an adept and careful explainer, but there are lapses of overwriting: "The forest clonks and bangs and sings with the hissing and the booming and the knocking and the thwacking of bits of litter. . . ." (Nor is it good form for a timber industry critic to misspell Weyerhaeuser repeatedly.)

And despite Luoma's efforts to turn ecological research into a suspense story, the tale lacks narrative drive. It has its moments of discovery, fascination, irony and controversy, told through many -- perhaps too many -- voices. Their collective punch line remains a huge unanswered question: Can the Andrews-based research help the nation protect wild forests and have its lumber too? -- Don Colburn

ALMOST EVERYONE'S GUIDE TO SCIENCE

By John Gribbin with Mary Gribbin

Yale. 232 pp. $24

In Almost Everyone's Guide to Science, the prolific British writer John Gribbin attempts to achieve a grand thing -- an overview of modern science pleasing to both the novice and the expert -- in a narrow space (scarcely more than 200 pages). To call the result less than entirely successful seems less a criticism of the book itself than an affirmation of the unlikelihood of reaching such a goal.

The attempt by Gribbin, an astrophysicist who says he turned to writing to avoid the fate of scientists who focus so narrowly "that they end up knowing everything about nothing," is certainly engaging enough. He works outward from the atom to explain how 20th-century scientists have pieced together our current understanding of the universe and everything in it. And there are certainly places throughout Gribbin's "guide for the perplexed" where for the novice the formerly inscrutable becomes a bit clearer.

At the same time, the book's combination of reach and brevity assures an approach that at certain points feels a bit cursory. In compensation, Gribbin recommends a number of books for further reading, including three of his own.

-- Gregory Mott

THE CONSUMER'S GUIDE TO EFFECTIVE

ENVIRONMENTAL CHOICES

By Michael Brower

and Warren Leon

Three Rivers. 292 pp.

$15 Paperback

Paper or plastic? Cloth diapers or disposables? Compact car or sports utility vehicle? Modern American life is full of such choices. Many of us agonize over the trivial ones and make the big ones -- like buying a new car or house -- without giving enough thought to the environmental impact.

If you worry about how individual behavior affects your community's air, water and soil and wonder what you can do to make a difference, this book offers plenty of information and context for making intelligent choices. Perhaps its biggest contribution is distinguishing between decisions that matter a lot and those that don't. Brower and Leon explain that the diaper issue, for example, is almost a wash; it shouldn't keep already sleep-deprived parents awake. Similarly, trash, despite the attention it receives in the media, is not one of the nation's most pressing environmental problems. The authors praise recycling programs for raising everyone's awareness of environmental issues but emphasize that other actions may help more in the long run.

What actions? Brower and Leon urge readers to do all they can to limit driving and gasoline consumption: Choose to live near public transportation, walk or bike, don't buy a gas-guzzling car. In the interests of efficient land use and reduction of pesticide levels, they favor eating less meat and buying organic produce. And they offer detailed advice about how to choose heating and lighting methods, appliances and gardening products that will minimize environmental damage.

This book is a helpful, science-based tool for consumers interested in preserving the quality of the environment for our children and grandchildren.

-- Susan Okie

The reviewers are science writers for The Washington Post.