You Are Here: A Portable History of the Universe, by Christopher Potter, HarperCollins, 304 pages ARC, $29.90

In one of the most straightforwardly honest introductions I've come across in a popular science book, Christopher Potter tells of a childhood attempt to write down his "full cosmic address" - in his case, 225 Rushgreen Road, Lymn, Cheshire, England, The United Kingdom, The World, The Solar System, The Galaxy, The Universe - his "childish handwriting getting larger and larger" as he moves up the cosmic ladder.

As young Christopher's attempt to pinpoint his celestial address shows, we know, or think we know, a good deal about how the universe is put together.

Indeed, a bright fourth-grader today probably knows significantly more about the structure of the cosmos than the greatest thinkers just a few centuries ago could have imagined.

But how did we come to know it, and why are we so confident in our proclamations? And what role, exactly, do puny Homo sapiens play in this mind-bogglingly vast universe?

These are the questions that motivate Potter, a London-based journalist and publisher, as he outlines what science has revealed about our place in the cosmos over the past 2,500 years.

To be sure, he is hardly the first to take on this challenge - Bill Bryson's A Short History of Nearly Everything comes to mind, along with recent titles from Timothy Ferris, Peter Atkins and others. Still, Potter does an admirable job, making centuries-old questions seem fresh, even urgent.

Where most authors take a historical approach (here's what we discovered when), Potter organizes the text by scale - here are things that are our size; here are things that are really big; here are things that are really small - along with a brief history of the universe, from the big bang to the present.

But it's not just physics. Potter is equally interested in our struggle to understand our place in the biological world, a quest that made significant headway only with the work of Darwin, a mere 150 years ago. (If anything, the realization that apes are our cousins may have been an even greater shock than the discovery that our planet is not at the centre of the universe. The discomfort can be glimpsed in an anecdote involving a visit by Queen Victoria to the London Zoo. There, as Potter notes, she observed an orangutan named Jenny. She later reflected in her diary that the creature was "frightful, and painfully and disagreeably human.")

Potter covers a lot of ground; hardly a surprise, considering his subject matter. Among the dangers of attempting such a broad synthesis is the tendency to drift into encyclopedia-style recounting of facts, and in several places he seems to do just that. ("Triassic period [251 to 200 million years ago] The first trees [conifers]appear. Some lizards evolve into crocodiles and others into dinosaurs. There are bees. There is another major extinction at then end of this period.")

There are also occasional stumbles when Potter wades into the toughest science: His explanations of Mach's principle and quantum entanglement - admittedly among the most difficult concepts in modern physics - are a bit confusing. Most of the time, however, his writing is crisp and authoritative, and the story is a compelling one. He is at his best when he steps back and examines the "big picture," exploring the philosophical implications of what the scientists have found, particularly in the final chapters.

Most rewarding is Potter's treatment of the underpinnings of science itself. He reminds us, for example, that our observations of the universe are constrained by the very fact that they are made by us, from our particular vantage point in both time and space. The simple matter of our perspective can mislead us, and has indeed misled us many times in the past. (It certainly looked like the sun went around the Earth - until Copernicus came along.)

As Potter observes, interpreting the data - figuring out what it means - can lag decades or even centuries behind the observations and experiments; witness today's struggle over the apparent "fine tuning" of the cosmos, and the controversy over the "anthropic principle" and the "Multiverse." (On that last issue - the idea of "multiple universes" - Potter asks: If this is where our mathematics is leading us, "what now divides the mystic and the materialist?")

Toward the end of the book, Potter wrestles with the deepest questions of all: We live on an ordinary world orbiting an ordinary star in an ordinary galaxy; we are not special. And yet we have these melon-sized lumps of grey matter in our heads that are so very special that they allow us to comprehend (at least to some degree) our surroundings. What, then, is the role of consciousness? Here, he wanders into speculative metaphysics: "Rather than being separate from what we experience, the physical world itself becomes part of the experience. … We are not apart from the world. The physical world is a manifestation of the act of perceiving it."

Some readers may bristle at his conclusion that science and mysticism have much in common. A few passages struck me as New-Agey. "If it is something about our brain that appears to grant us privilege in the universe, we might wonder if there is any meaningful separation to be made between brain and universe," he writes. "Ultimately we might wonder if there is any meaningful separation to be made between anything."

This is a little too "out there" for my taste. But feel free to disagree - the universe is big enough for more than one opinion.

Dan Falk is a Toronto science journalist and the author, most recently, of In Search of Time: Journeys along a Curious Dimension.