MEDITATIONS AT SUNSET A Scientist Looks at the Sky By James Trefil Illustrations by Judith Peatross Scribner's. 208 pp. $16.95

James Trefil's "Meditations at Sunset: A Scientist Looks at the Sky" is an exciting attempt to illustrate a simple but profound idea: that only a few laws are needed to explain all the events in nature or, in the author's words, "that there must be many connections between phenomena that, on the surface, appear unrelated."

Unfortunately, that message often gets lost among the long scientific explanations that fill each chapter, so that instead of a unified collection of thought-provoking essays, "Meditations at Sunset" becomes a series of lectures from Physics for Poets. Such a work is not necessarily bad, if your interests lie in understanding the genesis of thunder, lightning, sunsets and clouds, for Trefil's writing is compelling and vivid. But his explanations sometimes get bogged down in detail and scientific jargon that are more confusing than illuminating.

His discussion of how clouds form, for instance, relies too heavily on material not discussed until later, by which time most readers would be lost. At one point, Trefil tries to explain how boiling water and salad dressing resemble the birth of the universe, an idea that certainly had me captivated. He ends this discussion by writing, "That boiling water, heated iron, salad dressing, metal alloys, and the universe itself should all obey the same formula for critical points illustrates better than anything I could say the overwhelming beauty and elegance of our modern scientific view of the world." That is a wonderful thought, but I almost missed it because of the thoroughly confusing physics lecture on critical points, "renormalization groups" and "dimensions of the order parameter" that preceded it.

Where the author writes as an essayist rather than a science lecturer, however, "Meditations at Sunset" is a pleasure to read. In the chapter on sunspots, for example, Trefil shows how even the most level-headed scientists can go astray when their emotions get the best of them. From the 18th century until well into this one, a large number of seemingly level-headed scientists staked their reputations on claims that sunspots controlled a variety of phenomena on earth: "... an entire little industry grew up in the sciences based on these supposed correlations. When closer study and better data started to become available, however, the entire thing collapsed like a house of cards."

Later in the same chapter the author writes, "It has been said in jest -- and by more than one joker -- that anything can be correlated with sunspots if one tries hard enough, even the level of women's skirts. Having nothing better to do one rainy spring morning, I decided to see whether this remark had any validity at all." He then recounts the experiment he conducted, using 54 years of advertisements in The New Yorker, to test the hypothesis. In a lighthearted manner and without lecturing, Trefil illustrates the difficulties of experimental science ("The pantsuit craze of the late 1970s played havoc with data gathering.") and the pitfalls that await those who do not pay heed to the laws of statistics.

Oh yes, women's hemlines did correlate with the appearance of sunspots, and if you believe that, Trefil has a bridge he would like to sell you.

If you can get past the science, "Meditations at Sunset" will entertain and amaze you while showing that seemingly disparate natural phenomena are tied together by only a few scientific principles. My favorite, coming after a long explanation of why the sky is blue and sunsets are red, is Trefil's explanation of why polar bears are white: "The ability of large particles to scatter light of all wavelengths also appears in another, perhaps unexpected phenomenon. Some animals with white fur, such as polar bears, have no pigment in their hair. Instead, the hair shafts contain many tiny air bubbles, which play the same role as water droplets in clouds; they reflect all wavelengths equally. Thus the white of the polar bear and the white of the cloud are caused by the same physical process."

Taken as a whole, "Meditations at Sunset" is a success, for it illustrates how easy it is to see the various laws of nature working in the world around us. It is too bad that lesson is sometimes buried in the science it is supposed to glorify. The reviewer is writing a biography of Ellsworth Bunker.