The Heidi Klum of calculations

BEFORE THE BIG BANG:
The Prehistory of Our Universe
By Brian Clegg
St. Martin's, 320 pp., $25.99

E=mc{+2} is the supermodel of equations. It’s a fashion brand and a Mariah Carey album. Sculptures are made out of it; energy drinks are named for it. The formula is 104 years old, but it’s still sexy, if you know what I mean.

Actually, what do I mean? E=mc{+2}? Einstein wrote it down first; I’ve got that. But that’s about as far as I can get on my own. Thankfully, a couple of patient Englishmen have written “Why Does E=mc2: (And Why Should We Care?)’’ to help willing souls dig a bit deeper.

Brian Cox is a particle physicist. Jeff Forshaw is a theoretical physicist. Cox also is one of People magazine’s “sexiest men alive.’’ Forshaw, presumably, doesn’t let that get to him. Together the authors present a mild-mannered, digressive, mostly math-free walk-through of the world’s most famous equation.

“What E=mc{+2} says,’’ our guides tell us, “is that energy and mass are interchangeable, much like dollars and euros are interchangeable, and that the speed of light is the exchange rate.’’

Let’s say you had a kilogram of stuff. And let’s say I did something to your stuff to make it disappear. Now that your stuff is gone, Einstein’s equation demands that a kilogram’s worth of energy must remain behind. I’ve exchanged your mass for energy.

“Before Einstein,’’ Cox and Forshaw write, “no one had dreamed that mass could be destroyed and converted into energy because mass and energy seemed to be entirely disconnected entities.’’ Common sense suggests energy and mass are different things. Space and time seem to be, too. But common sense, the authors remind us, is often dead wrong.

One way to look at the history of modern science is to say that it represents a century-by-century reordering of common sense. Copernicus showed us we weren’t standing still at the center of the universe. Galileo showed us that all motion is relative depending on who observes it. Darwin showed us that our bodies and minds are the result of eons of natural selection. None of these things seemed true at first glance.

Then Einstein came along and proved that not only is motion relative, but so are space and time. No absolute, celestial clock ticks away in the sky. Not only that, but vast quantities of latent energy are locked away in mass. That’s how coal fires, atomic bombs, and the sun work.

The best thing “Why Does E=mc{+2}?’’ does is remind us that Einstein’s equation is not some esoteric idea best pondered by scientific supermen, but a profound insight that continues to change lives. Relativity has had implications for nuclear energy, gravitational theory, and how GPS systems work; it has also reverberated through moral philosophy, English literature, and visual art.

Cox and Forshaw’s enthusiasm for their material is plain. In their introduction they claim, “We do not assume any prior scientific knowledge and we avoid mathematics as much as possible.’’ For the most part they keep their promise. If you don’t mind plunging into the sort of mind-bending reasoning that sends you clawing backward through the occasional paragraph, you will find them accommodating escorts.

Another hole in my understanding of modern science has to do with the theory of the Big Bang. We know that the universe is expanding. And we know most cosmologists agree that 13.7 billion years ago there existed a primeval, zero-sized, unfathomably hot kernel of space, and out of it bloomed you, Paris Hilton, the Pacific Ocean, Mars, the Andromeda Galaxy, and everything else.

It probably wasn’t big and there certainly wasn’t anyone around to hear it, but that’s the Big Bang. Sounds crazy, doesn’t it? Even Einstein thought so, at least at first. But as observational evidence has mounted, and as challenging theories have fallen out of favor, gradually the Big Bang has become, in the words of science writer Brian Clegg, “the most widely accepted scientific theory for the origin of the universe.’’

So here’s my question: What came before the Big Bang?

In “Before the Big Bang: The Prehistory of Our Universe’’ Clegg surveys the current conjectures. Could it be there was a series of expansions and contractions, Big Bangs followed by Big Crunches? Or could it be that our whole universe condensed inside a black hole?

Or maybe before the Big Bang there was nothing at all?

Before he gets to the various origin hypotheses, Clegg spends most of his book drawing an elegant picture of the universe as we understand it, tracing how the Big Bang theory rose to prominence, and revealing its rather substantial flaws. He’s very good at reminding his reader of the speculative nature of cosmology. “It is not experimental,’’ he writes, “and there is no way to ever make it experimental.’’

Indeed, the existence of so many things, from dark matter to black holes to wormholes all has to be inferred. The Big Bang, too, is only provisional and seems to be waiting for a more graceful model to replace it. In Clegg’s words, the Big Bang theory “has the feeling of something held together with a Band-Aid.’’

Whether what came before our universe was another universe or nothing, or something else yet unconsidered, for now the most accurate answer might be: We just don’t know.

Anthony Doerr is the author of “The Shell Collector,’’ “About Grace,’’ and “Four Seasons in Rome.’’