This is the fourth and last of the book reviews I had published in the SEPA Journal, o' those many years ago. To be honest, I don't think I've read this book since I reviewed it, but after rereading the review, I would like too. Sadly, I have a vague memory of donating it to Ritter Planetarium for a display on planet formation. Sigh.
Worlds Without End—The Exploration of Planets Known and Unknown
By John S. Lewis
Copyright 1998
240 Pages
Helix Books-Perseus Books
ISBN 0-7382-0170-7
Paperback $13.00
Do we live on the best of all possible worlds? John Lewis, Professor of Planetary Sciences at the University of Arizona-Tuscon, puts this age-old question to the test in “Worlds Without End”.
I have to admit that I misread the cover notes of the book. When I first picked it up, I had assumed that it was a book on current ideas of planet formation, and how the new extra-solar planets are putting a slight kink into these ideas. In part, that’s what Worlds Without End is. But it is also much more.
The author does vividly describe the formation of our solar system. He goes into great detail about the chemical and physical properties of the accretion disk, step by step taking the reader through the processes of planet formation right up to the present day.
After explaining the solar system we have, he starts to tinker with reality by asking “what if”. What would the Earth be like if it were 10 times more massive than it is, or 1/10th the mass, and everything else stayed the same? What if instead of a G star, our Sun was an O, F, or K? Lewis plays with the parameters of planets we know, and tries to come up with many, in not most, of the types of environments we can expect to find in the Universe.
Throughout the book, Lewis is searching for places where life might somehow exist. He considers almost every location: Very Earth-like planets, gas giants, satellites, and even brown dwarfs. He even examines star systems with two or more stars and planets ejected into interstellar space.
Not surprisingly, he dismisses many environments. A planet around an O or B star would not have enough time to become biologically interesting before it’s star died. The life zone around the lowest mass stars is so close that any planet there would be tidally locked at best, or ripped apart at worst.
Throughout the book, Lewis straddles the line between being too general and too technical. I found the book to be stimulating rather than challenging. His writing style is very well polished, each thought logically leading to the next. Even the flow between chapters was almost seamless.
In essence, Worlds Without End is a thought experiment, a scientifically grounded flight of fancy. He tries to answer the question of just how Earth-like a planet must be to be considered “Earthlike”. I found his conclusions to be both thought provoking and entertaining.
