by David Brooks
If the multiverse idea is correct, then the historic mission of physics to explain all the properties of our universe in terms of fundamental principles—to explain why the properties of our universe must necessarily be what they are—is futile, a beautiful philosophical dream that simply isn’t true. Our universe is what it is because we are here. The situation could be likened to a school of intelligent fish who one day began wondering why their world is completely filled with water. Many of the fish, the theorists, hope to prove that the entire cosmos necessarily has to be filled with water. For years, they put their minds to the task but can never quite seem to prove their assertion. Then, a wizened group of fish postulate that maybe they are fooling themselves. Maybe there are, they suggest, many other worlds, some of them completely dry, and everything in between.
The most striking example of fine-tuning, and one that practically demands the multiverse to explain it, is the unexpected detection of what scientists call dark energy. Little more than a decade ago, using robotic telescopes in Arizona, Chile, Hawaii, and outer space that can comb through nearly a million galaxies a night, astronomers discovered that the expansion of the universe is accelerating. As mentioned previously, it has been known since the late 1920s that the universe is expanding; it’s a central feature of the Big Bang model. Orthodox cosmological thought held that the expansion is slowing down. After all, gravity is an attractive force; it pulls masses closer together. So it was quite a surprise in 1998 when two teams of astronomers announced that some unknown force appears to be jamming its foot down on the cosmic accelerator. The expansion is speeding up. Galaxies are flying away from each other as if repelled by antigravity. Says Robert Kirshner, one of the team members who made the discovery: “This is not your father’s universe.” (In October, members of both teams were awarded the Nobel Prize in Physics.)
Physicists have named the energy associated with this cosmological force dark energy. No one knows what it is. Not only invisible, dark energy apparently hides out in empty space. Yet, based on our observations of the accelerating rate of expansion, dark energy constitutes a whopping three-quarters of the total energy of the universe. It is the invisible elephant in the room of science.
The amount of dark energy, or more precisely the amount of dark energy in every cubic centimeter of space, has been calculated to be about one hundred-millionth (10−8) of an erg per cubic centimeter. (For comparison, a penny dropped from waist high hits the floor with an energy of about three hundred thousand—that is, 3 x 105—ergs.) This may not seem like much, but it adds up in the vast volumes of outer space. Astronomers were able to determine this number by measuring the rate of expansion of the universe at different epochs—if the universe is accelerating, then its rate of expansion was slower in the past. From the amount of acceleration, astronomers can calculate the amount of dark energy in the universe.
Theoretical physicists have several hypotheses about the identity of dark energy. It may be the energy of ghostly subatomic particles that can briefly appear out of nothing before self-annihilating and slipping back into the vacuum. According to quantum physics, empty space is a pandemonium of subatomic particles rushing about and then vanishing before they can be seen. Dark energy may also be associated with an as-yet-unobserved force field called the Higgs field, which is sometimes invoked to explain why certain kinds of matter have mass. (Theoretical physicists ponder things that other people do not.) And in the models proposed by string theory, dark energy may be associated with the way in which extra dimensions of space—beyond the usual length, width, and breadth—get compressed down to sizes much smaller than atoms, so that we do not notice them.
These various hypotheses give a fantastically large range for the theoretically possible amounts of dark energy in a universe, from something like 10115 ergs per cubic centimeter to –10115 ergs per cubic centimeter. (A negative value for dark energy would mean that it acts to decelerate the universe, in contrast to what is observed.) Thus, in absolute magnitude, the amount of dark energy actually present in our universe is either very, very small or very, very large compared with what it could be. This fact alone is surprising. If the theoretically possible positive values for dark energy were marked out on a ruler stretching from here to the sun, with zero at one end of the ruler and 10115 ergs per cubic centimeter at the other end, the value of dark energy actually found in our universe (10−8 ergs per cubic centimeter) would be closer to the zero end than the width of an atom.
On one thing most physicists agree: if the amount of dark energy in our universe were only a little bit different than what it actually is, then life could never have emerged. A little more and the universe would accelerate so rapidly that the matter in the young cosmos could never pull itself together to form stars and thence form the complex atoms made in stars. And, going into negative values of dark energy, a little less and the universe would decelerate so rapidly that it would recollapse before there was time to form even the simplest atoms.
Here we have a clear example of fine-tuning: out of all the possible amounts of dark energy that our universe might have, the actual amount lies in the tiny sliver of the range that allows life. There is little argument on this point. It does not depend on assumptions about whether we need liquid water for life or oxygen or particular biochemistries. As before, one is compelled to ask the question: why does such fine-tuning occur? And the answer many physicists now believe: the multiverse. A vast number of universes may exist, with many different values of the amount of dark energy. Our particular universe is one of the universes with a small value, permitting the emergence of life. We are here, so our universe must be such a universe. We are an accident. From the cosmic lottery hat containing zillions of universes, we happened to draw a universe that allowed life. But then again, if we had not drawn such a ticket, we would not be here to ponder the odds.
The concept of the multiverse is compelling not only because it explains the problem of fine-tuning. As I mentioned earlier, the possibility of the multiverse is actually predicted by modern theories of physics. One such theory, called eternal inflation, is a revision of Guth’s inflation theory developed by Andrei Linde, Paul Steinhardt, and Alex Vilenkin in the early and mid-1980s. In regular inflation theory, the very rapid expansion of the infant universe is caused by an energy field, like dark energy, that is temporarily trapped in a condition that does not represent the lowest possible energy for the universe as a whole—like a marble sitting in a small dent on a table. The marble can stay there, but if it is jostled it will roll out of the dent, roll across the table, and then fall to the floor (which represents the lowest possible energy level). In the theory of eternal inflation, the dark energy field has many different values at different points of space, analogous to lots of marbles sitting in lots of dents on the cosmic table. Moreover, as space expands rapidly, the number of marbles increases. Each of these marbles is jostled by the random processes inherent in quantum mechanics, and some of the marbles will begin rolling across the table and onto the floor. Each marble starts a new Big Bang, essentially a new universe. Thus, the original, rapidly expanding universe spawns a multitude of new universes, in a never-ending process.
String theory, too, predicts the possibility of the multiverse. Originally conceived in the late 1960s as a theory of the strong nuclear force but soon enlarged far beyond that ambition, string theory postulates that the smallest constituents of matter are not subatomic particles like the electron but extremely tiny one-dimensional “strings” of energy. These elemental strings can vibrate at different frequencies, like the strings of a violin, and the different modes of vibration correspond to different fundamental particles and forces. String theories typically require seven dimensions of space in addition to the usual three, which are compacted down to such small sizes that we never experience them, like a three-dimensional garden hose that appears as a one-dimensional line when seen from a great distance. There are, in fact, a vast number of ways that the extra dimensions in string th
eory can be folded up, and each of the different ways corresponds to a different universe with different physical properties.
It was originally hoped that from a theory of these strings, with very few additional parameters, physicists would be able to explain all the forces and particles of nature—all of reality would be a manifestation of the vibrations of elemental strings. String theory would then be the ultimate realization of the Platonic ideal of a fully explicable cosmos. In the past few years, however, physicists have discovered that string theory predicts not a unique universe but a huge number of possible universes with different properties. It has been estimated that the “string landscape” contains 10500 different possible universes. For all practical purposes, that number is infinite.
It is important to point out that neither eternal inflation nor string theory has anywhere near the experimental support of many previous theories in physics, such as special relativity or quantum electrodynamics, mentioned earlier. Eternal inflation or string theory, or both, could turn out to be wrong. However, some of the world’s leading physicists have devoted their careers to the study of these two theories.
Back to the intelligent fish. The wizened old fish conjecture that there are many other worlds, some with dry land and some with water. Some of the fish grudgingly accept this explanation. Some feel relieved. Some feel like their lifelong ruminations have been pointless. And some remain deeply concerned. Because there is no way they can prove this conjecture. That same uncertainty disturbs many physicists who are adjusting to the idea of the multiverse. Not only must we accept that basic properties of our universe are accidental and incalculable. In addition, we must believe in the existence of many other universes. But we have no conceivable way of observing these other universes and cannot prove their existence. Thus, to explain what we see in the world and in our mental deductions, we must believe in what we cannot prove.
Sound familiar? Theologians are accustomed to taking some beliefs on faith. Scientists are not. All we can do is hope that the same theories that predict the multiverse also produce many other predictions that we can test here in our own universe. But the other universes themselves will almost certainly remain a conjecture.
“We had a lot more confidence in our intuition before the discovery of dark energy and the multiverse idea,” says Guth. “There will still be a lot for us to understand, but we will miss out on the fun of figuring everything out from first principles.”
One wonders whether a young Alan Guth, considering a career in science today, would choose theoretical physics.
SANDRA TSING LOH
The Bitch Is Back
FROM The Atlantic
DURING MENOPAUSE, A woman can feel like the only way she can continue to exist for ten more seconds inside her crawling, burning skin is to walk screaming into the sea—grandly, epically, and terrifyingly, like a fifteen-foot-tall Greek tragic figure wearing a giant, pop-eyed wooden mask. Or she may remain in the kitchen and begin hurling objects at her family: telephones, coffee cups, plates. Or, as my mother did in the 1970s, she may just eerily disappear into her bedroom, like a tide washing out—curtains drawn, door locked, dead to the world, for days, weeks, months (some moms went silent for years). Oh, for a tribal cauldron to dive into, a harvest moon to howl at, or even an online service that provides—here’s an idea!—demon gypsy lovers.
But no, this is twenty-first-century America, so there is no ancient womyn’s magic for us but rather, as usual for female passages, a stack of medically themed self-help books. (I ask you: Where are the vampire novels for perimenopausal women? Werewolf tales? Pirate movies?) That’s right—to fully get our crone on, we’re supposed to read, even though it may feel, what with the giant Greek chthonic headpiece, that one can barely see out the eyeholes. (Who can focus on words on a page? Who can even remember where she left her giant octagonal Medea-size reading glasses?) Rest assured, though: I’m here to help. Gentle reader, if you are a female of transitional age, which can apparently be anywhere from thirty-five to sixty-five these days, let me be your Virgil to the literature of menopause. Long have I wandered through the dry riverbeds, long have I suffered; now I’ve come back to share my wisdom.
To set the stage, here is a selection of titles from my local bookstore’s women’s section: Could It Be . . . Perimenopause?; Before Your Time: The Early Menopause Survival Guide; The Natural Menopause Plan; Second Spring; Menopause Reset!: Reverse Weight Gain, Speed Fat Loss, and Get Your Body Back in 3 Simple Steps; and the slightly ominously titled What Nurses Know . . . Menopause (two words: atrophic vaginitis). On the cover of a typical menopause book, instead of the perhaps more-to-the-point fanged woman with the Medusa do, one is far more likely to see a lone flower—a poppy, perhaps a daisy. Curious choice? Well, no, because as one begins to read the war stories of the MD, PhD, and RN (atrophic vaginitis!) authors who dominate this genre, one sees narratives that are indeed Stuart Smalley–esque. Here’s a pastiche:
Mary Anne, age forty-eight, came into my office feeling overweight and bloated. She hadn’t been sleeping, work was stressful, her husband had just gone on disability, and he required daily care. Mary Anne complained to me of lower-back problems and gastritis, and also cramping during sex, which had become more and more infrequent. She was extremely depressed about moving her eighty-four-year-old mother to a nursing home, and upon examination I noticed vaginal inflammation.
As unappetizing as that just was to read, be glad you saw only one such passage—I must have read a hundred. Because clearly, from the medical-professional point of view, menopause, or really the run-up to it called perimenopause, is a parade of baleful, bloated middle-aged women (“Lisa, fifty-two,” “Carolyn, forty-seven,” “Suzanne, sixty-one”) trudging into their doctors’ offices complaining of lower-back pain and family caregiving issues and diminished libidos and personal dryness and corns. As they sit wanly on the tables in their paper gowns, they arduously count out their irregular periods—from thirty-five days to forty-four days to fifty-seven, going heavy to light, light to heavy, sometimes with spotting, sometimes with flooding, sometimes flood-spotting, sometimes spot-flooding. Why this variation? So easy to understand, really. The simple science: ovarian production of the estrogens and progesterone becomes erratic during perimenopause, with unpredictable fluctuations in levels, which in turn can result in many different symptoms, including major mood swings. But sometimes not. You may never feel any of this! Because here’s the key: all women are different.
And yet, even though we all are different, the list of prescriptions for us seems to be very much the same, and none of it’s fun. If one must tinker with hormone replacement therapy, one may—briefly, in moderation. But from this point on, the Change is about a healthy lifestyle. We’re all to get more exercise, drink more water, do yoga stretches before bed, cut out alcohol and caffeine, and yet (and how does this follow?) reduce stress. Even the flirty exhortations to have more sex feel like yet another job on life’s chore wheel (given that it’s supposed to be with your mate of twenty years rather than with Johnny Depp). And don’t forget all the deep sensory pleasures of a reduced-calorie diet. Menopause Reset! at least initially seemed to promise a nutritional miracle cure for that mysterious spare beach floaty that arrives after forty. I for one was excited to see that, instead of Black Swan–ing it until dinner, as apparently so many of us women do (in order to heap our measly fifteen hundred calories together into one meal a person might actually want to eat), you’re supposed to eat many tiny meals constantly. Hurray! But alas, after reading much dietary advice for menopausal women, I concluded that, in the horrible new metrics of midlife, each of the following constitutes a meal:
Meal No. 1 (8:00 A.M. )
2 tsp. nonfat yogurt
Meal No. 2 (10:00 A.M. )
3 almonds (unsalted)
Meal No. 3 (12:00 P.M. )
2 oz. low-fat barley soufflé (see Appendix D)
Meal No. 4 (2:00 P.M. )
small bell pepper
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br /> 1 tsp. flaxseed
Just staying awake all day to eat the food—while of course getting in those fifteen reps an hour of sex with your fiftysomething husband—seems a challenge. No wine, though: best to pair vaginal dryness with buckwheat tempeh. Oh! Oh! Oh! Where is the plate-glass window to hurl the phone through? Why is life worth living? Ouch, my corns!
So that’s the basic physiological landscape of menopause. Dry as the riverbeds can seem, though, one menopause book does rise like Mount Etna above the rest. Now celebrating its tenth anniversary, it is the bible of middle-aged womanhood: The Wisdom of Menopause, by Christiane Northrup, MD. Having recently spent (twenty? fifty? eighty?) hours with it, I’ve come to believe that The Wisdom of Menopause is a masterwork. Weighing in at two pounds and 656 pages, it is an astonishingly complete, mind-bogglingly detailed orrery of the achingly complex, wheels-and-dials-filled Ptolemaic universe that is Womanhood. Featuring, arch-conventionally, its smiling doctor/author on a soothing pastel cover, the book is very much of the genre, and yet explodes it. Northrup presents both a celebration of Western medical practice and a revolt against it. Three times as big as the others, Wisdom is no less than the Jupiter in the menopause-book solar system, our Gravity’s Rainbow.
Let me now gloriously unbutton my too-tight mom jeans, wave my Hadassah arms (even more hideous term heard recently—bat wings), and wax on. Are you grasping, yet, the scope of this thing? Wisdom is a Homeric poem of modern femalehood. No stone from Western or Eastern (or Southern or Northern) medicine is left unturned, from folic acid to breast exams to personal dancing to selenium to feng shui to cosmetic surgery (Northrup allows it, while counseling discretion as a protection against judgmental friends). Woo-woo passages on Motherpeace Tarot cards and the chakra work of the astrologer Barbara Hand Clow alternate with biological analyses of an almost kidney-squeezing complexity. Which is not to say there isn’t tons of news you can use:
