Despite the title, this is a book more about physics than about the physicist. There is nothing really wrong with that -- fate, a word Stephen W. Hawking would question and probably abhor, has the two more tightly intertwined than usual. To understand even a little bit of Hawking, you have to understand some of the ground he has explored.

And Kitty Ferguson is a good guide for that. The mark of a good science writer is the ability to take extremely technical and complex subjects that are usually discussed and debated among lifetime specialists, and convert them to prose understandable by the almost-casual reader.

Hawking himself has no small abilities along those lines, as evidenced by his own best seller "A Brief History of Time," and other books for the general audience. But Ferguson, author of an earlier work on Hawking as well as other well-received science books, is a perfectly positioned biographer.

Not only has she had access to the world-renowned Cambridge theorist (who turned 70 last Sunday), she was a consultant for his book "The Universe in a Nutshell" and immersed enough in his world to offer the short review and critique that appears in this book of his later "The Grand Design."

What this book is not, is a tell-all.

Hawking, of course, has a compelling personal story. An active young man (he was coxswain on a college rowing team), he was diagnosed with ALS -- Lou Gehrig's disease -- while still a graduate student, and was told he had two years to live.

ALS has taken its toll, and Ferguson weaves the progression of the disease into the story of his scientific progress.

As ALS continues to rob Hawking of control over his voluntary muscles, he simply refuses to yield -- or to make much of what to almost everybody would be a devastating and all-consuming loss.

His ability to walk eventually deserts him, confining him to a wheelchair. His speech slurs. Eventually, technology comes to his aid.

Today, he controls a computer and voice synthesizer by twitching a cheek muscle. The next step, he believes, may be direct-wiring into the brain.

Hawking's celebrity -- this book makes clear there are other brilliant minds and strong competitors in the theoretical cosmology that is his field -- stems in no small part from this personal story, and in turn that engenders more curiosity concerning his private life than scientists usually expect.

Ferguson, clearly a Hawking admirer, will have little of that. Hawking's two divorces are treated matter-of-factly and summarily, with mention of extramarital romances on both sides perhaps included mostly because Hawking's first wife of 25 years, Jane, has written about them herself in her own memoirs.

To be sure, Ferguson tells enough of Jane's own remarkable story to evoke admiration for her accomplishments and for her devotion to an increasingly disabled husband.

But this is a mental biography of Hawking, not a physical one; even more perfunctory treatment is given to a later police investigation (which went nowhere) of Hawking as a possible victim of physical abuse.

What this book is, is a remarkable tale of a brilliant mind.

Hawking's physical condition could not derail some of the most astounding mental gymnastics of our time, the kind of theoretical fireworks that could only be set off by a genius with the ability to imagine nearly unimaginable scenarios of space and time.

And therein lies the value of this book; Ferguson patiently incorporates readable (if on rare occasions somewhat condescending) explanations of cutting-edge physics into her tale of Hawking's progress from young iconoclast in an emergent specialty to gray eminence engaging another generation of iconoclasts at the same or higher levels of energy and ideas.

Welcome to multiverses, Hawking's pioneering work in melding general relativity and quantum mechanics, and a host of theories that have been tested and discarded in an attempt to reach a Theory of Everything that Hawking now thinks may be beyond our reach.

Along the way, Ferguson does devote quite a bit of discussion to the implications of this work to belief in the existence of God, a discussion that Hawking's quest "to understand the mind of God" has always engendered.

Hawking himself, who has been surrounded by believers in both his personal and professional lives throughout his career, sees no need for God in the machinations of the universe, but also does not see that as a reason to deny the existence of God. He notes that his efforts seek to understand the how and what of existence, but cannot answer why. It's a nuanced stance often lost in the popular press, but the discussion here is interesting.

Hawking, Ferguson notes, does not see his disability-defying rise to eminence in the world of science at the border of philosophy -- or, for that matter, his intense travel and lecture schedule -- as an act of courage. He says he simply took the paths that were open to him, and he was indeed fortunate that cosmology's mental landscapes were opening so fully just as he embarked on his academic career.

And he adds a key observation, that his condition weaned him away from blackboard and computer-screen equations and into a geometry-based way of calculating and envisioning concepts dealing with basic questions of the origin, development and fate of the physical universe.

The man in the wheelchair has opened unimaginable vistas to the rest of us. Ferguson tells that story well.

Pull up a chair and enjoy some physics.

Mike Vogel is the retired editor of the News Editorial Page and a lifelong student of scientific breakthroughs and a devotee of scientific literature.


Stephen Hawking: An Unfettered Mind

By Kitty Ferguson

Palgrave Macmillan

270 pages, $27