Zoom: From Atoms and Galaxies to Blizzards and Bees: How Everything Moves (13 page)

As for winged animals, their speed depends on their motives. Most cruise at twenty to thirty miles per hour, and this is true for small birds as well as large ones. Geese and hummingbirds fly at the same speed. Nearly all birds can tuck in their wings and dive much faster than they can fly should the need arise. Peregrine falcons are renowned as the very swiftest birds, able to achieve two hundred miles per hour in a dive, although half that is their usual behavior. However, even two hundred miles per hour is perhaps no “achievement”: a human skydiver reaches that same speed in a headfirst posture with his arms tucked to his sides. It’s the simple matter of terminal velocity; no skill required. A falcon cannot outrace a diving daredevil.

Nearly all birds fly between twenty and thirty miles per hour. But their wing-beat rates vary enormously: it’s 1,250 flaps per minute in hummingbirds but closer to one hundred flaps per minute in these greylag geese. (Michael Maggs, Wikimedia Commons)

Birds can catch field mice, squirrels, and chipmunks without batting an eye. Squirrels have the most visibly dramatic strategy of defense, routinely zigzagging so that a swooping hawk has a hard time aiming at the fleeing rodent. But birds can and do choose different speeds for different purposes. A hawk on reconnaissance patrol, loitering in the sky in search of prey, would want to maximize her endurance and move her wings leisurely to preserve energy and stay aloft for hours. But a seabird trying to reach a distant hunting ground would want to maximize her range. This doesn’t usually entail going fast or even flying long distances through the air; exploiting wind currents might be the key. And birds are sometimes forced to maximize speed, as they do when pursued by a predator.

Suffice it to say that nearly all birds fly between ten and forty miles per hour, and most cruise in the twenty-to-thirty range. Plenty fast enough to catch flying insects, few of which can attain twenty miles per hour.

But more is happening than meets the eye. What we see is, in many ways, not as fascinating as what we could potentially detect with X-ray vision (with which we could peer through bark) or time-lapse perception, because the most dramatic magic unfolding in spring is the act of growth.

Trees are classified according to a slow, medium, or fast growing rate. Slow means less than a foot a year. Fast means more than two feet. Medium is in between. Each species is distinct. Sugar maples barely alter their appearance year over year, while willows change shape quickly.

HOW FAST DO TREES GROW?

Fast (≥2 feet / yr) Medium Slow (≤1 foot / yr)

Elm Linden Balsam fir

Honey locust Norway maple Black walnut

Red maple Scotch pine White oak

Ash Red pine Butternut

Birch Spruce Sugar maple

Black locust White pine

Box elder

Cottonwood

Red oak

Silver maple

Willow

Spring brings the year’s fastest growth in trees and plants alike; shoots push up as much as an inch a day. None of it crosses the threshold of visible motion. The plants that come closest are some of the climbing ivies, which use almost spooky holdfasts, and the wraparound climbing stems of wisteria, which can extend ten feet per season and which seem science fiction–like when viewed through time-lapse photography.

Likewise, if we could peer through the ground, we would see snaking roots advancing by two inches to as much as two feet per week. The all-time growth winner, however, is not a plant most of us get to enjoy. It’s bamboo. This can emerge from the earth at its full thickness and then head upward at speeds just barely too slow to visually discern. The all-time record is a measured thirty-nine inches in a single day. That’s one and a half inches an hour.

So this single season, spring, reliably delivers nature’s outstanding hurry-up exhibits. Quick change is what’s dramatic, especially when clothed in vivid colors—and change is another word for motion.

CHAPTER 8: The Gang That Deciphered the Wind

A Desert Dweller’s Airy Spells Last for a Millennium, While Two Oddballs Dodge the Inquisition

Gray-eyed Athena sent them a favorable breeze,

A fresh west wind, singing over the wine-dark sea.

—HOMER, THE ODYSSEY (CA. EIGHTH CENTURY BCE)

In the Bible, John 3:8 says, “The wind bloweth… and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth.”

Blowing wind had started me on this quest to understand natural motion. Yet being harmed by the wind was hardly a unique experience. It’s a familiar scenario in global literature. The specter of an invisible entity that destroys houses has aroused fear through the ages.

But I knew where I must goeth. To the consistently windiest place in the hemisphere. Where anemometers measured the all-time fastest-ever wind gust in a record that stood for more than a half century. That blast duplicated the inside of an EF4 tornado.1

New Hampshire’s Mount Washington stands for more than mere Guinness-type record holding. Its famous gusts make people itch to experience the wind for themselves. To accommodate them, the state built a road to the summit back when Abraham Lincoln was in the White House. Families looking for a bit of adventure authenticated by a boastful bumper sticker have made the pilgrimage ever since.

Sure, I could lazily get in my old four-seater plane and fly myself over that 6,288-foot peak, but how would that bestow the experience of its famous winds? Besides, I was scared. Wind acts in violent ways around mountains, and Mount Washington possesses an odd configuration that funnels the air with the best of them. I remember reading about a Boeing 707 jetliner flying near Mount Fuji in Japan on March 5, 1966, that, tragically, had its tail torn off by orologically induced turbulence.2

Who in ancient times could have begun to understand swirly air? Who could visualize any mechanism by which Earth’s five thousand trillion tons of gas are set into perennial motion? None of the ancients tackled the whats, hows, or whys of the gaseous realm. The Westerner who went the furthest was Aristotle, who declared air to be an “element” that liked to rise.

Instead, people asked how moving air could benefit them: What’s in it for me? One of the first technological lightbulbs to go boing in the ancients’ minds was the idea of employing air as a free power source.

Air energy has been harnessed since earliest recorded history, even by a sparse human population that didn’t reach two hundred million until the time of Christ. As far back as 5000 BCE, wind propelled boats along the Nile. By biblical times, sailboats were a common sight.

It took an amazingly long time—fully five thousand years after the first canvas sails—before moving air was utilized mechanically. The Chinese did it first, around 200 BCE, when they erected windmills and fitted them with gears that pumped water for irrigation. Soon after, the idea spread to the Middle East, where inhabitants built windmills that had woven reed sails and were geared with a vertical revolving shaft for grinding grain.

The Persians were next in line to use wind power and introduced it to the European regions still under the rule of the Roman Empire by 250 CE. Another few centuries of achingly slow technological progress brought an upgrade to Windmills 2.1, which featured better materials, such as metal gears, and larger, more efficient vanes. These windmills appeared in Afghanistan in the seventh century and Holland by the 1200s. These bigger structures grandly drained marshes and fertilized fields and ultimately even pumped water for American settlers heading west in the 1800s.

For all that, no one seemed obsessed with figuring out what, exactly, is air. Or how far it extended upward, or why it should ever budge. No one guessed that it’s a blend of different gases, each with distinct properties. No one puzzled over the bizarre fact that—unlike the sun and moon and the habitual tides and the seasonal rains and the predictable cycles of crops and insects and such—the wind acted capriciously. Sometimes it didn’t waft at all, then it could howl destructively an hour later. Strong winds often accompanied thunderstorms. Yet equally ferocious winds could blow from cloudless skies. No other aspect of the everyday environment displayed such wild whimsy.

Even in the early twentieth century, no one knew about well-defined air masses. It wasn’t until after World War I, appropriately enough, that the word front was coined to describe this novel idea of warring globs of air that produce inclement weather along their boundaries.

The really juicy discoveries started in the eighteenth century and then accelerated in the nineteenth. But a few brilliant thinkers made laudable contributions much earlier.

It was Aristotle in 350 BCE who coined the word meteorology, which is simply Greek for the science of “high in the sky.” But the study of the atmosphere and its rich, vast, and varied antics perhaps began in earnest a half millennium earlier in India, when the ancient holy texts of the Upanishads were composed. These writings discuss at length the ways in which clouds form and rain is produced and even attribute the phenomenon to the seasonal cycles that result from the movement of Earth around the sun.3 Around the year 500 CE, Varāhamihira wrote the classical Sanskrit work Brihat Samhita, which expounds on complex atmospheric processes such as hydrolic cycles, cloud formation, and temperature transformations attributable to solar heating.

Another half millennium passed with the Western world sound asleep. It was the Dark Ages, when advancements—so promising during the glory days of the Greeks and in ancient India and China—simply stopped cold until the 1500s. Or so we are taught. What everyone forgets are the four wonderful centuries when knowledge was prized in Persia and the Middle East. This was the golden age of Arabic science. While one side was dark, another basked in the sun.

I have a hero from this era. Born in Basra in what is now Iraq in 965 CE, he was Abu Ali al-Hasan ibn al-Hasan ibn al-Haytham, familiarly called ibn-al Haytham in the Arab world. Let’s be gentle on ourselves and refer to him by his Latinized name—Alhazen.

He had extensive knowledge of the Greeks and wrote approvingly of Aristotle and disapprovingly of Ptolemy. In what was a groundbreaking approach, he did not merely theorize or speculate but performed careful experiments.

In 1021, Alhazen became the very first to accurately describe the way air bends, or refracts, light. He proved through rigorous observations how the atmosphere creates twilight and said that its very first traces begin when the sun is nineteen degrees below the horizon. Today’s modern figure is eighteen degrees.

More impressive—and this is why I applaud him—he was among the first (and likely the first person) to use the scientific method to get at the truth. Alhazen employed complex, accurate geometric calculations to determine that the height of Earth’s atmosphere is—drumroll, please—52,000 passuum.

You’re not impressed? That’s because you probably haven’t lately used that Latin unit of length. It was equal to five feet. Do the math and you’ll find that Alhazen’s figure for our atmosphere’s height was forty-nine miles.

Back then nobody—absolutely nobody—had the slightest clue how far up the air extends. Or whether it ever stops. For all anyone knew it could continue for four miles or four million. Alhazen said forty-nine miles. These days most authorities place the figure at fifty-two miles, the top of the mesosphere. And yet who in the West has even heard of Alhazen?4

If Alhazen has any fame at all in the West, it’s because he invented the pinhole camera, which I sincerely wish everyone would experience at some point because it’s amazing and fun. Once in a while you’ll witness something similar when a tiny bit of light enters a dark room through a hole in drawn shades. Exquisite, animated, filmlike details of the world get projected onto the walls and ceiling. It’s riveting. Alhazen’s fellow desert dwellers must have flipped. Alhazen also discovered the laws of refraction and was able to separate light into its constituent colors. He studied eclipses and optics and correctly figured out the math behind them.

How he had the time for so much study and experimentation is a story he probably loved to share with his analyst. It’s a strange tale that began when he still lived in Basra and would read about the Nile’s famous annual floods. In a moment of overconfidence he wrote that the river’s destructive autumn inundations could easily be controlled by a system of reservoirs and dikes, which might also serve to store the water for use during the long dry season. It was easy for him to imagine such technology, but these innocent published musings unwittingly set the stage for personal-life changes that would have ranked high on the modern Holmes and Rahe stress scale.

When Alhazen arrived in Cairo, the caliph, by all accounts a testy, unpleasant fellow who had heard about Alhazen’s claims, summoned him and said, “Okay, do it.” Alhazen was taken on a tour of the various floodplains. I wish I could have seen his reaction. He must have blanched. Observing the flood regions in person, the pragmatic Alhazen immediately knew that his plan could not possibly work, not in a million years.

But rather than admit his mistake and take a chance that the murderous caliph would have him executed on the spot, Alhazen tried a risky ploy. Using a technique later perfected by draftees evading the Vietnam War, he feigned madness. He figured the caliph would just have him tossed out on the street and that would be that.

He was wrong. The ruler instead ordered him locked up under permanent house arrest. He was not permitted to experience freedom or mingle with the public ever again.

This good-news-and-bad-news story resulted in Alhazen having ten full years, starting in 1011, to do nothing but immerse himself in the writing of innumerable brilliant treatises, including a notable work on optics that ranks with that of Newton seven centuries in the future. He was finally set free when the caliph died in 1021, at which point he could finally shake off the crazy act that he had probably gotten pretty good at.

The next unfolding of air’s secrets arrived more than half a millennium later and involved various aspects that probably should be considered separately. Consider, for example, the pressure, or weight, of the air. Each square inch of Earth’s surface is, famously, pressed against by a column of air weighing nearly fifteen pounds. In modern times we experience this in a fast-moving elevator or when an airplane descends. Our ears pop.