I adore Brian Greene because he’s smarter than me but he still thinks I deserve to understand what the hell he’s talking about. Charles Whelan, the author of a book called Naked Economics, called his own book—which is wonderful—not “economics for laymen,” but “economics for smart, educated people who just never took Economics.” For people who know they’re never gonna be Larry Summers but are still interested in knowing how exactly the Fed controls the money supply. Brian Greene does the same thing for theoretical physics. I liked physics in high school, got As even, but that’s about as far as my scientific training went: I majored in history and philosophy in college and my distribution-requirement courses tended to focus on animal behavior and geology and stuff like that. However, I owe my deep fascination with cosmology to my dad—he used to sit with me on our stoop in Brooklyn and point out the stars we could see through the New York smog; when he told me that when we gazed at the moon, we were seeing it as it was about a minute and a half ago, it blew my seven-year-old mind. (It still does, actually.)
Then, freshman year of high school, I read a book called Flatland, by Edwin Abbot, that explained the concept of extra spatial dimensions better than anyone or anything else I’ve ever encountered (even Brian Greene). The book describes life in Flatland, a two-dimensional world. The protagonist is a square, and other citizens of Flatland appear to him only as lines. When a sphere invades Flatland and invites the square to experience life in three dimensions, he realizes how limited his worldview really is. To the sphere, Flatland appears as shapes drawn on a piece of paper, which we can easily visualize. The square dreams of Lineland, a one-dimensional world, where the two people living to the fore and rear of you would appear merely as points; and Pointland, the land of zero dimensions, where, in a world that is perhaps infinitesimally big and overly populated, the Point believes himself to be alone and dominant, simply because he is unable to see anybody else. What’s even more fascinating is how Abbot describes the concept of a fourth special dimension (incidentally, the Sphere is equally as ignorant about the finite nature of his own perspective as most residents of Flatland are about theirs): Inhabitants of a fourth dimension would be able to see the back of your head and your face simultaneously; they would also be able to see the outside and inside of your body, akin to those complementary diagrams you see in pediatrician’s offices or in second-grade classrooms.
The concept of extra dimensions makes intuitive sense to me, and I believe they exist. The existence of ten spatial dimensions (plus time, for a total of 11) is built into string theory, of which Greene is a pioneer. I read his book, The Elegant Universe, which outlines string theory, two years ago, and The Fabric of the Cosmos a year before that, which gave a more comprehensive overview of the laws governing the cosmos and the search for a Grand Unified Theory to reconcile Einstein’s theory of relativity with quantum mechanics. (Because relativity applies to vast expanses and quantum theory to the microscopic realm, the two can be applied separately until you hit the Planck Length, where the equations break down. So basically, there’s no theory to explain arenas where a huge mass is packed into an unimaginably tiny area—in other words, the Big Bang and the origin of our universe.) This latest book also focuses on string theory and its implications for parallel worlds (of which there are a few, out of the nine “multiverse proposals” he analyzes in the book), which I’ve always found very intriguing.
String theory, in essence, posits that the entire known universe is made up not of particles but of tiny vibrating open-and-closed-loop strings; the vibrational patterns of these strings are what constitutes what we think of as “particle properties” in classical physics. Particles, then, aren’t really particles at all, but they appear as such because the strings are so ridiculously tiny. The strings are said to vibrate through all ten spatial dimensions, all but three of which are tiny and coiled up so that they are undetectable to humans. It gets way more complex, of course, most of which I don’t really understand in full (there are five varieties of string theory, united into what is known as M-Theory; string theory should imply a supersymmetrical universe, which they still haven’t found proof of, etc. etc.) As for what lies outside our known universe, there are a bunch of different multiverse hypotheses, which must gel with the widely-accepted story of creation: that is, the Big Bang followed by inflationary expansion. The Big Bang was essentially proved in 1993 after the discovery of cosmic microwave background radiation, which is a relic of about 400,000 years after the bang, when temperatures had cooled to the extent that atoms could form and photons (light) could travel unimpeded through the cosmos. So basically, parts of the electromagnetic spectrum that we see today (like TV or radio waves) have been around since the beginning of the universe. How cool is that? Anyway, basically scientists discovered fluctuations in the CMBR waves that gelled perfectly with predictions of density levels in the beginning of the universe, proving that the Big Bang led to our current formation of stars, galaxies, planets, etc. As for what set off the Big Bang, as I understand it, energy fluctuations in a much larger, probably infinite, multiverse caused the burst of space-expansion that constitutes our known universe. And if the multiverse is infinite, then the implications are especially interesting, since an infinite multiverse means an infinite number of possible universes, which means an infinite number of possible yous, living in that universe. So in one universe, you may be sitting a foot to the left, in one you may have brown hair instead of blonde, in one you may be an evil totalitarian dictator—you get the point.
Digressing slightly, the most moving manifestation of the parallel-worlds theory that I’ve seen was a play I saw on Broadway a few years ago, starring Cynthia Nixon (always Miranda Hobbes in my eyes), called “Rabbit Hole.” (Nixon won a Tony for the role.) Basically, she plays one half of a bourgeois married couple whose four-year-old son is killed by a speeding car; at the end of the play, the teenager who had been driving the car comes to see her, and he’s a science geek. He tells her about the Rabbit Hole theory (the same idea of an infinite number of scenarios playing out in an infinite number of universes), and tells her that somewhere out there, in a world she cannot see, her son is still alive, sitting next to her as she reads to him, or playing with his blocks on the floor while she reads, or holding her hand in the playground. It’s extremely affecting. I cried.
Anyway, to bring this back full-circle, Brian Greene is incredible because he elucidates the wonders of theoretical physics in a way that’s accessible to the unschooled reader who wants to know them. I’ve read other books of this kind (including Lisa Randall’s Warped Passages, which I highly recommend) but no one has as good a style or a better feel for how to translate very complicated theories into a lucid view of reality as Greene. Reading his books has enriched my life immeasurably, and he better write more.