The universe in a nutshell

LEONARD SUSSKIND was a plumber before he reinvented himself as a physicist, a fact that may explain why he is inspired to write about the eye-crossing and mind-boggling complexities of modern science in language that a layperson can understand. In “The Cosmic Landscape,” he offers nothing less than an insider’s guided tour of theoretical physics over the last century or so, moving from Albert Einstein’s theory of relativity to Susskind’s own cutting-edge scientific theories.

Susskind has not picked up a pipe wrench in a long time. The Stanford scientist is credited with revolutionary discoveries in virtually every aspect of theoretical physics, including the invention of string theory (although he graciously credits a couple of colleagues for their independent work in the same field) and advanced work on quarks and black holes. Who, then, is better equipped to answer such cosmic questions as how our world came into existence and why intelligent life exists here? “[O]ur own universe is an extraordinary place that appears to be fantastically well-designed for our own existence,” he muses. “This specialness is not something that we can attribute to lucky accidents, which is far too unlikely. The apparent coincidences cry out for an explanation.”

One answer is rooted in religious belief and finds its most recent expression in the dogma of intelligent design -- which states that the planet Earth and everything that lives here are the handiwork of a “superarchitect” whom we might as well call God. Even though Susskind’s book is not devoted to debunking intelligent design -- indeed, the opportunistic subtitle of the book is slightly misleading -- he feels obliged to pause now and then to disabuse the reader of any such notion.

To summarize at the risk of oversimplifying Susskind’s argument, we live in a tiny pocket of what he calls a megaverse, “a huge Landscape of possibilities -- an enormously rich space of possible designs.” If the Earth contains 300,000 species of beetles, he observes, then the number of “pocket universes” in the cosmos must be vastly greater: “The numbers are so big that, statistically, some of them will be intelligent or conducive to intelligent life.” God, however, has nothing to do with it. “There is no magic, no supernatural designer,” he concludes, “just the laws of very large numbers.”

Susskind also finds himself compelled to address what is called the anthropic principle, a scientific theory based on the idea that “the laws of physics that we observe are determined not by fundamental laws, but instead by the requirement that intelligent life can exist to observe them.” Starting with such a deceptively simple definition, it is all too easy to jump to the conclusion that some “intelligent designer” devised the laws of physics for the convenience of humankind. That’s not what the advocates of the anthropic principle mean, as Susskind explains, but that’s why some physicists “refer to the Anthropic Principle as religion or superstition or ‘the A word’ and claim that it is ‘giving up.’ ”

The bulk of Susskind’s book, however, has nothing to do with intelligent design or the current culture war between science and religion. Rather, he walks us through the strange world of physics and cosmology, starting with the big bang and ending with his own groundbreaking notion of looking at the cosmos as a landscape of possible worlds rather than a single universe that is bounded in space and time. Along the way, he has something to say about everything from “absorption lines” to the “Z-boson,” the first and last entries in his glossary of scientific terms. But Susskind is always aware of how tough and even treacherous it can be to explain such abstract and complex ideas to the lay reader.

“My main purpose in writing this book is not primarily to convince the reader of my own point of view; scientific arguments are best fought on the pages of technical journals and the blackboards of seminar rooms,” he allows. “My purpose is to explain the struggle of ideas that is about to take front-and-center place in the mainstream of science so that ordinary readers can follow the ideas as they unfold and experience the drama and excitement that I feel.”

To accomplish his goal, Susskind resorts to analogies and metaphors, anecdotes and hypotheticals, imaginary worlds and fanciful words and phrases. Thus, for example, he imagines a planet inhabited by big-brained fish whose scientists are called “fyshicists” and “codmologists.” He conjures up overstuffed bagels and funhouse mirrors, pizza chefs spinning wads of dough and children with jump ropes. He borrows from Kurt Vonnegut’s science-fiction novel “Cat’s Cradle” to help us understand the “metastability of the vacuum,” and he shows us one of M.C. Escher’s mind-bending woodcuts to illustrate the curvature of space.

But Susskind always cautions us against taking his examples and his theories too literally. “[P]lease don’t get the idea that I think that universes or black holes are alive, engage in Darwinian competition, or have sex,” he pleads. He points out that his landscape is not a real place: “Think of it as a list of all the possible designs of hypothetical universes.” And, as if to acknowledge how the study of science can tax the attention, imagination and patience of the ordinary reader, he wryly quotes a poem by Walt Whitman: “When I sitting heard the astronomer where he lectured with much applause in the lecture room, / How soon unaccountable I became tired and sick.”

At one telling moment in “The Cosmic Landscape,” Susskind shares the contents of an e-mail from one of his fellow theoretical physicists: “Nobody could really explain to me what it means that string theory has 10,100 vacuum states,” wrote Gerardus ‘t Hooft. “Before you can say such a thing you must first give a rigorous definition of what string theory is, and we haven’t got such a definition.” Truth be told, I was enormously relieved to learn that the abstractions of theoretical physics are capable of perplexing the physicists too.

Susskind also admits to moments of perplexity. “I often feel a discomfort, a kind of embarrassment, when I explain elementary-particle physics to laypeople,” he confides. “It all seems so arbitrary -- the ridiculous collection of fundamental particles, the lack of pattern to their masses.”

And he disdains all the prattle of his fellow scientists who regard beauty, order and elegance as the benchmarks of a successful scientific theory. “Is the universe ‘elegant’ as Brian Greene tells us? Not as far as I can tell, not the usual laws of particle physics anyway,” he boldly announces. “I think I might find the universal principles of String Theory most elegant -- if I only knew what they were.”

A scientist takes a real risk whenever he or she tries to address a lay readership. Stephen Hawking’s “A Brief History of Time,” for example, has been called the least-read bestseller in history because, though it was brief, it was baffling. By contrast, the work of nonscientists such as Bill Bryson (“A Short History of Nearly Everything”) and K.C. Cole (“Mind Over Matter”) are illuminating and entertaining at the same time because these authors are so gifted at explaining to the rest of us what working scientists think, know and do.

“The Cosmic Universe” falls somewhere in between. At its best moments, the book allows us to see the world of science from the inside out: “[T]he thirty-five-year history of String Theory suggests that as long as someone will pay them,” he cracks, “theoretical physicists will continue to push the mathematical frontiers until the end of time.” But at other moments, the book’s scope and detail can be overwhelming. Thus, for example, when he observes in passing that proof of the existence of the so-called “cosmological constant” is “a real shocker,” I suddenly realized that I had not grasped enough of what Susskind had told me about the concept to be shocked at all. *