Zoom: From Atoms and Galaxies to Blizzards and Bees: How Everything Moves (5 page)

Enough fooling around. Here are the truly slow-flowing fluids:

VISCOSITY OF COMMON FLUIDS

Olive oil 81

Honey 2,000–10,000

Molasses 5,000–10,000

Ketchup 50,000–100,000

Molten glass 10,000–1 million

Peanut butter 250,000

So forget molasses. “Slow as peanut butter” would better designate a refusal to flow. However, most people might not regard a jar’s worth of Skippy as a liquid and would thus disqualify it from the motion contest. When bored kids can use a spoon to create firm peaks in a substance, it’s hard to deem it a fluid.

Molasses did have its fifteen minutes of fame. That’s when it dramatically defied its reputation for sluggishness. The most spectacular molasses event in world history happened in Boston on an unusually mild January day in 1919, just after noon. At forty-three degrees Fahrenheit, it was ten degrees warmer than normal for that time of year. That’s when an enormous, poorly welded six-story-high cylindrical tank suddenly ruptured on Commercial Street, near North End Park. Two and a half million gallons of molasses burst out. People fled, and it would have been a funny sight had it not been for the tragic loss of twenty-one lives as men, women, teens, and several horses were engulfed and drowned in the sticky tidal wave.

Above the disaster scene, a packed elevated train had just passed, its incredulous passengers witnessing the collapsing tank and the approaching black wall of ooze. The viscous fluid broke the steel supports of the elevated train structure. When the trestle snapped, the tracks collapsed nearly to the ground—but the train had already sufficiently advanced to remain safely aloft a few hundred yards farther along.

The expression slow as molasses was already firmly in the public lexicon in 1919, and even the estimated thirty-five-mile-per-hour speed of the four-story wave of fluid, which—only because it had been piled so high—caught up to everyone trying to flee from it, failed to erase molasses’s clichéd reputation as the epitome of lethargy. The idiom remains.

Of course, when we think of peril instigated by a sluggish liquid, molasses doesn’t usually spring to mind first. Lava does.

And when it comes to cataclysm, no event before or since has remained as rooted in the collective consciousness as the total destruction of Pompeii and Herculaneum.

Let’s place ourselves in the mind-set of ancient Rome during the year when Titus became emperor, 79 CE. This was a tumultuous time, because before assuming the throne, during the brief reign of his father, Titus had simultaneously led the successful war against the Jews and destroyed Jerusalem and had a scandalous affair with the Jewish queen Berenice. Talk about having it both ways. Then, just two months later, Vesuvius blackened the skies. Few at the time failed to link that cataclysm with the gods’ apparent opinion of the seemingly dubious character of the new emperor. And his troubles were just beginning.

Of course, we may wonder why even today anyone in his or her right mind would choose to live in, say, Naples, just five miles from an active volcano whose tendency is toward explosive, Plinian-type eruptions. Let alone purchase real estate on its very slopes—the location of the unfortunate Pompeii and Herculaneum.

The 79 CE eruption of Monte Vesuvio (or, in Latin, Mons Vesuvius) changed the course of the Sarno River and raised the ocean beach, plunging property values in several ways. Afterward, Pompeii was no longer either on the river or adjacent to the coast.

Science lets us look back to the mountain’s genesis. Modern core samples drilled 6,600 feet into its flanks and dated using potassium-argon techniques show that Vesuvius was born from the Codola Plinian eruption just twenty-five thousand years ago, even if the entire region had known general volcanic activity for about a half million years.

The mountain was then built up in a series of lava flows, with some smaller explosive eruptions interspersed between them. The game perilously changed about nineteen thousand years ago, when Vesuvius’s regular eruptions became more explosive, or Plinian, events.

Before Pompeii, the Avellino eruption, about 3,800 years ago, destroyed several Bronze Age settlements. Archaeologists studying this in 2001 uncovered thousands of preserved footprints of people who were all apparently trying to flee northward, toward the Apennine Mountains, abandoning a village that, like Pompeii, was to be entombed beneath countless tons of ash and pumice. Fast-flowing pyroclastic surges were deposited ten miles away, where modern Naples has, unfortunately, now been built.

Any resident of Pompeii and Herculaneum who could read the classics would have had ample reason for concern about that location. A Plinian eruption a mere three centuries earlier, in 217 BCE, had produced earthquakes throughout Italy, and Plutarch wrote of the sky being on fire near Naples.

But by 79 CE, the lower slopes of the mountain were covered with gardens and vineyards nourished by the rich volcanic soil, with its high levels of nitrogen, phosphorus, potassium, and iron. It was a thriving, popular place. On flat areas near the summit, guarded by steep cliffs, Spartacus’s rebel army had their encampment just a few years earlier, in 73 BCE.

Then came the ascension of Titus to the throne and, a mere eight weeks later, the cataclysm that killed at least ten thousand people. We don’t have to guess what happened. In a letter to the Roman historian Tacitus, Pliny the Younger gave a gripping firsthand account:

[A] black and dreadful cloud, broken with rapid, zigzag flashes, revealed behind it variously shaped masses of flame.… Soon afterwards, the cloud began to descend, and cover the sea. It had already surrounded and concealed the island of Capreae and the promontory of Misenum.… The ashes now began to fall upon us, though in no great quantity. I looked back; a dense, dark mist seemed to be following us, spreading itself over the country like a cloud. “Let us turn out of the high-road,” I said, “while we can still see, for fear that, should we fall in the road, we should be pressed to death in the dark, by the crowds that are following us.”

Pliny continued:

We had scarcely sat down when night came upon us, not such as we have when the sky is cloudy, or when there is no moon, but that of a room when it is shut up, and all the lights put out. You might hear the shrieks of women, the screams of children, and the shouts of men; some calling for their children, others for their parents, others for their husbands, and seeking to recognize each other by the voices that replied…4

One hundred and fifty miles (by road) to the north in Rome, the clouds from the eruption as well as frantic word of it arrived almost immediately. Titus responded quickly.

Although the Roman imperial administration hardly has the reputation today of having been a compassionate FEMA-type agency, many emperors actually did react generously to natural disasters. Facing a great calamity, Titus appointed two ex-consuls to organize an impressive relief effort and donated large sums of money from the imperial treasury to aid the volcano’s victims. Moreover, he visited the buried cities soon after the eruption and again in 80 CE. It should have been enough to assure his popularity, but he couldn’t keep up with the plagues.

Calamities kept arriving. The Vesuvius disaster was followed the very next year by a major fire in Rome. Then, in a pattern radiating outward from the fire-ravaged area, no doubt following the paths of the escaping rats, came a deadly outbreak of bubonic plague. Even omen interpreters who liked Titus could find no way to get him off the hook. It seemed the empire would continue to be stricken as long as he sat on the throne. He then made it easy on everyone. He contracted a sudden fever the next year and died at the age of forty-two. Following Titus’s brief, frenzied reign, the mountain remained tranquil for more than a full human life span.

The peace was, of course, temporary. In December of 1631, following more than three centuries of total inactivity, a Vesuvius eruption caused widespread damage, and the focus on the mountain was renewed, albeit through the lens of modern scientific inquiry. This inspired many scholarly papers, especially from the numerous academies of Naples, as Renaissance scientists tried to learn how Earth metamorphoses from cold and stable to fluid and fiery. It was only then that science began to pin down the facts of the destructive events of August 24 and 25, 79 CE; something approaching absolute knowledge was not achieved until the 1990s.

Today we know that the eruption was a two-act tragedy. First came the Plinian phase, in which hot matter explosively blew upward in a tall column only to spread out and fall like hailstones. This initial mushroom cloud of material resembled a modern-day nuclear explosion. It began at midday on August 24 and quickly rose to a height of 66,000 feet. During the next eighteen hours it produced a dark, ominous rain of ash and pumice—mostly south of Vesuvius, thanks to the direction of that day’s winds. All told, the falling pumice stones, each about a half inch wide, buried Pompeii to a depth of eight feet and yet posed little initial danger to human life.

The eruption’s first few hours unfolded in slow motion. Many people, huddling in homes that were being rapidly buried by the fallout, held out hope of survival while keeping their fingers crossed that their roofs might bear the weight even as structures around them began to cave in. Modern estimates show that roofs of that era would start to fail when sixteen inches of pumice settled on them, which would produce a load of fifty-one pounds per square foot. Even the rare, super-well-built timber roof would collapse under the full weight of the pumice layer, at which point it would be asked to bear the impossible load of 476 pounds per square foot. This far exceeds current building codes for concrete warehouses. Thus no structure in Pompeii could have survived the initial, Plinian phase of the eruption, and, we must expect, residents would have been forced to flee, thus making it likely that they did not even witness the next stage, in which another four feet of heavier gray pumice was added, like the frosting on a sadistic cake.

By the next morning, August 25, eighteen thousand Pompeii residents were running for their lives. We know this because only some two thousand bodies were found in the buried ruins of the collapsed roofs and floors. Now came the tragedy’s superlethal Peléan phase.

Unfortunately for the residents who hadn’t already been killed, this deadly second act featured pyroclastic flows and surges—avalanches of scorching gas and dust plummeting down the mountain at sixty miles per hour, hugging the ground.5

These gases—superheated to 750 degrees and intermingled with nearly red-hot dust particles—produced most of the fatalities. The gas-and-dust mixture seared lungs. A single breath was lethal. There was no possible defense. The intense heat, exceeding that of an oven, turned much of the area’s organic material into carbon. Many of the victims were found with the tops of their heads missing because their brains boiled and exploded in their skulls.

Thus slow-moving lava—which later killed more than one hundred people in 1906, when a Vesuvius eruption produced the most lava ever recorded, and which continues to destroy property on Hawaii, thanks to Kilauea—was not the main culprit in the 79 CE Pompeii event.

But “slow-moving” doesn’t automatically mean “benign,” as bacteria show. Indeed, motions too leisurely to perceive are today causing ongoing worry for millions. And one such motion unfolds in a place few have ever visited—a location that might not even exist tomorrow.

They’re Really Shifting – Are We Toast?

At the still point of the turning world.

—T. S. ELIOT, “BURNT NORTON” (1935)

Four inches a minute.

You’d think that would be too sluggish to bother anyone. And yet no natural motion generates more paranoia than POLES ARE SHIFTING headlines, a rare marriage of New Age scare literature and mainstream science. Not content to worry about high blood pressure, some people fear we may be on the brink of a global cataclysm whose fault lies not even in the stars but in Mother Earth.

Here are true, measurable changes with a bread-crumb trail that all can follow. It’s not a question of if or when. The poles are shifting. And they’ve never moved faster than they do today. Is this concerning?

It’s fun and easy to become the neighborhood shifting-poles expert. There are just a few things to learn. One of the facts, a basic one, entered our cerebral cortices in fourth-grade earth science. This is the knowledge that our planet has two sets of poles. They bear no resemblance to each other. Both are always in motion, yet their effects are utterly different.

The poles that are moving wildly and with unprecedented speed and that generate all the “what does it mean?” anxiety—those are the magnetic poles. But let’s begin with their competitors, the poles of rotation, a.k.a. the geographic poles.

These poles are where our planet’s spin axis intersects the surface. They’re where meridians of longitude converge into a pinprick. The addresses are latitude 90° north and latitude 90° south. These are the only places that have no longitude.1 The northern address is where Santa lives. When you stand at the North Pole, every direction, any step you take, is south. No other direction has any meaning. You can turn off your car’s GPS.

At the poles, and only at the poles, you’re not carried along by our planet’s spin.

If you live on the equator, you whiz eastward with the earth’s rotation (which is separate from our planet’s devilishly fast 66,600-mile-per-hour orbital motion) at 1,038 miles per hour. This barely changes as you travel—at first. Go five degrees, or 350 miles, north, and the spin speed lessens by a negligible four miles per hour. But the next 350 miles brings it down by twelve miles per hour. By the time you reach Boulder or Brooklyn you’re moving at just 795 miles per hour, and a further 350-mile jump slows you another sixty miles per hour, taking you below the speed of sound for the first time.

(Where on earth would you be rotating at exactly the speed of sound? Woodstock, New York. The laid-back hippie place, still into music. Who says irony isn’t everywhere?)2