Whatever your manner of repose while reading this article—sitting, standing, lying down—you most likely feel firmly anchored to the earth. The force of gravity, as you experience it, seems impressively strong.
That is not exactly how Lisa Randall, a theoretical physicist at Harvard, views the matter. Like many other scientists, Randall thinks of gravity as a profoundly weak thing—“feeble,” as she puts it. Indeed, particle for particle, as it were, gravity is the puniest of the fundamental forces governing the activity of matter in the universe, by a staggering margin.
In recent years, Randall has shot to science stardom thanks to her proposed explanation about why this is so. We are living, Randall has suggested, in a universe containing at least one extra dimension beyond those we can perceive. Gravity, she argues, is weak because it has been diluted into this extra space. Moreover, the universe’s center of gravity, so to speak, may lie elsewhere; what we feel is just a small spillover of this force.
“Imagine a warped universe where we’re just sitting some place off-center,” Randall says, explaining her work at a cafe near Harvard Square on a recent afternoon. “We’re not exactly where gravity peaks.” And don’t squint if you can only see three dimensions. Randall suggests we may be living in an isolated neighborhood of the cosmos, with fewer dimensions than exist in other parts of the universe.
Granted, these days, exotic-sounding theories about the cosmos are seemingly a dime a dimension. String theorists insist we live in a 10-dimensional universe—the extra ones are very, very small—while cosmologists ponder “multiverses” in which our own universe is but one of many that have existed. Still, because of the compelling logic of her theory and the suggestive cosmic structure it contains, Randall’s papers on the subject (some of which she produced with colleagues Raman Sundrum and Andras Karch) are among the most-cited in contemporary physics, the equivalent of chart-topping hits.
“Her work is very original, very significant,” says Mark Wise, a professor of physics at Caltech who has studied problems relating to Randall’s theories. “She is one of the very top researchers of her generation.”
And should the idea of, say, a five-dimensional universe still seem a bit outlandish to nonscientists, they can explore matters further in Randall’s new book, “Warped Passages: Unraveling the Mysteries of the Universe’s Hidden Dimensions,” published by Ecco Press this month. “Warped Passages” is by turns engrossing and demanding, as Randall outlines her own ideas and details the impasses in physics which have given rise to mind-bending theories like her own. “The cosmos could be larger, richer, and more varied than anything we imagined before,” writes Randall.