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by Bob Berman

  It is true that, in prehistory, a fierce tsunami devastated the Norwegian Sea around 6000 BCE, but no records existed to warn Middle Eastern, Persian, and Mediterranean civilizations of tsunamis’ devastating power. And nearly the entire island of Thera, now called Santorini, was destroyed by an explosive eruption around 1650 BCE that created a tsunami so strong it wiped out the advanced Minoan civilization on nearby Crete. Yet a millennium later, when parts of the Bible were penned and the first thinkers of classical Greece were observing nature, this, too, had been essentially forgotten. A thousand years is, after all, a long time.

  This lack of awareness changed in the summer of 426 BCE, when a modest tsunami startled the sailors in the ships armed for the Peloponnesian War. In his written history of that conflict, the Greek historian Thucydides openly mused about what could possibly cause the ocean to behave so strangely and correctly concluded that it must have been an undersea earthquake. He thus became the first to link the movement of solid earth with that of the liquid seas.

  A half century later, in 373 BCE, a tsunami permanently submerged the town of Helike in Greece, obliterating its population and perhaps inspiring Plato, who was in his midfifties at the time, to speculate about a lost civilization that he called Atlantis. And yet this, too, was a largely localized event.

  The same was not true 738 years later.

  On July 21, 365 CE, an enormous undersea quake, the likes of which occurs only every few thousand years, struck the eastern Mediterranean between Crete and Egypt. Although everyone in the region felt the ground shake violently, it passed without widespread destruction—except on Crete, which received no warning that an astonishing hundred-foot-high wall of water was radiating outward. When we recall the eighty-foot tidal wave of the 2004 tsunami that killed a quarter million people in places such as Banda Aceh, Indonesia, or the seventy-seven-foot-high tsunami that wiped out Japan’s Fukushima Daiichi nuclear power plant in 2011 (thanks to the back-up diesel generators having been sited, bewilderingly, on the ground floor), we can appreciate how horrible a hundred-foot—ten-story—wall of water must be.

  We have an actual eyewitness account of the 365 CE tsunami from a survivor. And not just any survivor but the Roman historian Ammianus Marcellinus, known for his accurate, unembellished accounts of the everyday life of his time. It was he who watched in astonishment as an event that was anything but everyday unfolded and recounted it almost matter-of-factly in Book 26 of his epic, Res Gestae:

  Slightly after daybreak… the solidity of the whole earth was made to shake and shudder, and the sea was driven away… and it disappeared, so that the abyss of the depths was uncovered and many-shaped varieties of sea creatures were seen stuck in the slime.… Many ships, then, were stranded as if on dry land, and people wandered at will… to collect fish and the like in their hands; then the roaring sea… rises back in turn, and through the teeming shoals dashed itself violently on islands and extensive tracts of the mainland, and flattened innumerable buildings in towns.… For the mass of waters returning when least expected killed many thousands by drowning.… [H]uge ships, thrust out by the mad blasts, perched on the roofs of houses… others were hurled nearly two miles from the shore.

  Another historian, Thucydides, said that “without an earthquake it does not appear to me that such a thing could happen.”

  He was not entirely correct. Any large mass, such as a meteorite, hitting the sea can displace enough water to do the job. The largest wave ever recorded, an astonishing 1,720 feet tall, or about 50 percent higher than the Empire State Building, raged through Alaska’s Lituya Bay on July 9, 1958. This was the tallest tsunami in history. It did begin with an earthquake, but not a particularly big one; yet the tremor knocked loose a mass of rock that plunged three thousand feet into the Gilbert Inlet, displacing enough water to create the monster wave. The sheer scale of such motion defies visualization. After all, each cubic mile of the ocean weighs five billion tons.

  The 365 CE tsunami went on to annihilate much of Alexandria, Egypt; Crete; and coastal Libya, and marched up the Nile River delta, hurling ships two miles inland. The quake permanently raised the coast of Crete by thirty feet—to this day the record elevation gain resulting from a single sudden event. This sunrise tsunami was so devastating that its anniversary was commemorated each year in Alexandria as “the day of horror”—for the next two centuries! It was quietly forgotten only at the end of the sixth century.7

  Observing waves is everyone’s idle pastime. Waves have many cool attributes, as people such as Otis Redding have perenially noticed while they’re “sitting on the dock of the bay, watching the tide roll away.” One favorite attribute involves diffraction. We experience this principle when we turn on the car radio and the FM stations fade in and out as we pass close to hills or buildings. But the AM signals are much steadier and don’t vanish so readily. This is due to the bending of electromagnetic radiation around obstacles—diffraction. Longer wavelengths diffract more readily. AM stations broadcast waves hundreds of times longer than those on the FM band, so they bend around obstacles much more easily and are therefore not as readily blocked by obstructions. In other words, we don’t get into radio shadows as easily when we listen to AM’s widely spaced waves.

  Now back to the ocean, whose waves are also pretty long—hundreds of feet—so they’re not easily stopped by a small obstacle. Notice how waves encountering a little rocky lighthouse island soon fill in again behind the island and continue on their way. If the sea waves were closer together, there’d be more of a “shadow” zone behind small islands in which the ocean is permanently calm. By noticing this phenomenon behind jetties, docks, and other obstructions of various sizes you can see the diffraction effect in action.

  Major mysteries of maritime motion remain. For example, south of New York City, much of the coastline as far down as Florida is peppered with barrier islands—low offshore sand ridges that run parallel to the coast. Waves crash onto them, and thus they shield the tranquil lagoons behind them, where boaters enjoy miles of protected sailing without having to take to the rough open sea.

  The question is: Why should barrier islands endure? All shorelines suffer major modifications from the relentless pounding of the sea and storms. Logic tells us that these barrier islands should not last long. Their continued existence is a mystery, although this doesn’t stop oceanographers from guessing.

  Do breakers heap up sand scoured from the bottom of the sea and continually deposit it on the shore, replenishing the islands? Their sands are much higher than the high-tide mark, so any sand must be deposited during extreme storms. But such storms might just as well wash away these long, narrow, fragile islands, so we’re back to square one. Or are the islands perhaps remnants of giant sand dunes, maybe deposited during the last glaciation period? If so, then perhaps it’s the calm sea between them and the mainland that requires explanation—does it conceal a lowland running parallel to the dune ridges that got submerged when the sea level rose?

  This lone example—and one could easily find hundreds—illustrates that even some simple aspects of the powerful moving sea and its relation to the long-suffering coastline remain uncertain. Our current science is not always up to the task of fully appreciating the ceaseless aquatic pageants.

  Perhaps, as so many before us did, it’s sometimes better to simply sit “on the dock of the bay,” wasting time by watching the waves.

  CHAPTER 13: Invisible Companions

  The Odd Entities Zooming Through Our Bodies

  Yesterday, upon the stair,

  I met a man who wasn’t there…

  —HUGHES MEARNS, “ANTIGONISH” (1899)

  Before the twentieth century, most people believed in ghosts or spirits. Yet no one in all of history suspected that tiny invisible entities zoom right through our bodies 24-7. Expressing such a belief would have gotten you thrown into a medieval insane asylum, where they probably didn’t even accept MediSerf.

  This invisible stuff is part of our ever
yday lives. It’s not entirely harmless. Yet there’s nothing we can do to get rid of it unless we ask a real-estate agent to find us a nice two-bedroom deep in a mine.

  This story begins in 1800. That’s when William Herschel discovered a form of light nobody can see. Invisible light? If anything ever came from left field, it was this. It fit nowhere in mankind’s evolving models of the cosmos. The discovery would have surely been doubted and ridiculed except that Herschel was then the world’s most respected scientist, famous for having found the first-ever new planet, Uranus, nineteen years earlier. (Nobody had seen that one coming, either.)

  Since light can be regarded as a stream of particles, we can truly say that countless unseen bullets continually zoom around us. This first-known invisible form of light doesn’t quite go unnoticed, though. Our skin detects Herschel’s “calorific rays” (eventually called infrared radiation) as the sensation of heat. Nearly half the sun’s emissions are infrared. So when we look around us, an equal mix of visible and invisible particles are bouncing off the rocks and rabbits.

  You may imagine that heat moves slowly. It takes a while to warm up a frying pan. But infrared rays, which create heat on our skin by making its molecules move faster, are light-speed swift. You experience this when gathered around a campfire on a chilly night. If a big person steps in front of you, you instantly feel the effect because that person blocks the invisible infrared rays from hitting you. He’s creating infrared shadows.

  A year after Herschel’s discovery, in 1801, the sad-sack German Johann Ritter discovered ultraviolet light but failed to publicize it sufficiently. He had a tendency to ramble on about extraneous matters, such as his belief in ghosts, so he ended up ignored and impoverished. He wasn’t credited with his discovery until after his death—the glory, appropriately, awarded to his disembodied spirit.

  Things took an even more disquieting turn near the end of that century. On November 8, 1895, another German—Wilhelm Röntgen—discovered X-rays. As we all know, these waves or particles do not stop when they reach the skin. They can fully penetrate our bodies, although many are absorbed by dense material such as bones and teeth. When, two weeks after his discovery, Röntgen took the very first X-ray pictures, showing the hand of his wife, Anna Bertha, she stared with horror at the image of her skeleton and exclaimed, “I am seeing my death!” (Given the then-unknown deadly potential of shortwave radiation such as X-rays, which ultimately took the life of Marie Curie—the first person to win two separate Nobel Prizes—and many thousands more in places such as Chernobyl and Hiroshima, Anna Bertha’s comment may seem eerily prescient.)

  In 1896, the Dutch physicist Hendrik Lorentz posited the existence of a totally different invisible speedster: the first-ever subatomic particle, the electron, even tinier than the theoretical atoms suggested by Democritus 2,300 years earlier. Lorentz had plunged deeper than any other physicist before him and brilliantly figured out the origin of all light! He said that light comes into existence solely because of the motions of a tiny, negatively charged object. When the electron was duly discovered soon thereafter, Lorentz’s prescience earned him the 1902 Nobel Prize in Physics.

  This was a productive time for finding invisible entities. The pace didn’t let up. Also in 1896, French physicist Henri Becquerel got swept up in the global excitement of Röntgen’s X-ray discovery of the previous year. Becquerel’s interest was in materials that glow, so he thought phosphorescent substances such as uranium salts might emit X-rays after basking in sunlight. By May of that year, however, he correctly realized that the uranium emitted some new and unknown form of “radiation,” as it was starting to be called. Seven years later, in 1903, Becquerel won the Nobel Prize in Physics, sharing it with Pierre and Marie Curie, who had taken Becquerel’s ideas and run with them.

  The newly married couple was fascinated by substances that emitted what Marie called uranium rays. After years of watching these strange rocks produce smatterings of light on photographic film, the Curies realized that the most intense radiation flew out from two brand-new elements. She named the first polonium, after her native land, Poland, and the second radium, for the mere act of radiating. This latter element was her baby, her darling; she called it “my beautiful radium,” for she possessed no inkling that it would someday kill her and many others with its sizzling emissions. It was three thousand times more radioactive than uranium.

  So now, quite suddenly, nineteenth-century scientists had revealed a motley crew of five invisible entities flying around or through us.

  Ultraviolet photons can burn us at the beach and set the stage for skin cancer, but they are also beneficial, even vital; the body creates vitamin D when struck by them.

  X-rays are scarcely present naturally here on Earth.

  Infrared rays are commonplace but harmless.

  So are electrons, streams of which were used for decades in the old-style TV picture tubes to conjure Mister Rogers and Lucy Ricardo.

  But Becquerel’s and the Curies’ uranium-and radium-based “radiation” would prove far more dangerous, even if radium was initially believed to be a healthful substance, a tonic. (To this end, it was marketed as an elixir, mixed with sparkling spa waters and touted as a rejuvenating agent. Millions of bottles were sold and drunk. Later came radium watches with their glowing numbers and dials, painted in factories mostly by young women who suffered horrible early deaths before the peril was recognized.)1

  The spooky quest for unseen phantoms soon got even spookier. In 1909 Theodor Wulf created an early equivalent of a Geiger counter—an instrument called an electroscope, which revealed whether atoms inside a sealed container were being broken apart. It showed higher levels of radiation at the top of the Eiffel Tower than at its base. Because this made no sense—the device was then farther from the ground’s uranium and radium sources—his paper was ignored. But on August 7, 1912, Austrian physicist Victor Hess personally took improved versions of the electroscope up in a hydrogen balloon to 17,400 feet, and it revealed radiation levels twice as intense as those on the ground. He correctly attributed this to a radiation source arriving from outer space.

  Hess soon eliminated the sun as the cause: he flew a balloon during a solar eclipse, when the moon blocked nearly all the sun’s incoming energy. He also, perilously, conducted some flights at night. The conclusion was amazing, if disquieting. He announced, “A radiation of very great penetrating power enters our atmosphere from above.” For this discovery—which still has ominous ongoing implications for pilots, in addition to posing a serious hazard to any future human colonies on other worlds—Hess won the 1936 Nobel Prize in Physics.2

  By amazing coincidence, precisely one century to the day after Hess’s balloon flight, on August 7, 2012, the newly landed Mars rover Curiosity began measuring this radiation on another planet for the first time.

  Physicists initially believed these invisible outer-space invaders were some kind of wave, an electromagnetic phenomenon, which is why they were—and mostly still are—called cosmic rays. Each of those two words tingles with sci-fi creepiness and vaguely implies a bizarre peril from beyond the stars, thus awarding cosmic rays the scariest and perhaps coolest name of all the tiny, streaking, high-speed entities.

  But they aren’t rays at all. Meaning they’re not a form of light. Their incoming paths are bent by our planet’s magnetic field, and light never changes direction in response to magnetism. Cosmic rays simply couldn’t be another electromagnetic phenomenon, as X-rays are. Before the start of World War II, everyone realized they must be electrically charged particles, like the ones that stream (as we finally recognize) from uranium and radium.

  The truth, the denouement, is both powerful and anticlimactic. Cosmic rays are mostly protons. Ordinary, plain-vanilla protons, the nucleus of hydrogen, the positively charged particle found in every atom’s heart. They’re violently ejected in supernova explosions and wander the universe like homeless high-speed swashbucklers.

  But why is 90 percent of this incomin
g substance protons? Why does it include just a negligible sprinkling of electrons (1 percent)? There are just as many electrons as protons in the universe. Why are electrons so underrepresented?

  Befitting their spooky name, cosmic rays are thus puzzling even today, thanks to their illogically proton-heavy composition and the fact that a small percentage of them scream into our atmosphere at bewilderingly high, near-speed-of-light velocities. Cosmic rays even include a bit of antimatter.

  Protons weigh 1,836 times more than electrons, so they pack a wallop when they hit anything. Fortunately our atmosphere and our magnetic field block most of them. While you and I do get penetrated regularly, they’re a medical problem mostly for astronauts, which is why the twenty-seven Apollo adventurers all saw spurious bright streaks cross their visual fields every minute, as protons ripped through their brains.

  Moreover, as in a game of billiards, protons typically strike air atoms thirty-five miles up and knock loose a cascading shower of smaller stuff. One of these is the muon, which decays rapidly but not before it, too, penetrates our poor pincushion bodies.

  At least two hundred muons per second zip through each of us. They weigh 208 times more than electrons, so they’re not exactly harmless if they crash through and alter a gene in one of our chromosomes. You can avoid them only if you live underground, in a place like Zion, the city in the Matrix films. The mutations they induce keep plants and animals evolving and help explain why today’s cats and cabbages look different from their analogues from a hundred million years ago.