Of Time and Tides

It is maybe 20 minutes after sunrise, dead high tide on the West Passage of Passamaquoddy bay, at the southern edge of the Bay of Fundy. Despite the early hour the air is pleasantly warm, almost balmy, but when the wind blows just right, you can feel the cool breath of the North Atlantic, a short distance away. The air is perfumed with the scent of a hundred different types of flowers.

The Passage is busy this morning. An official-looking vessel flying a maple-leaf flag heads southeast down the channel at a good clip, hugging the far shore, taking obvious care not to cross the invisible line running down the middle, which separates the American political entity from the Canadian. A gathering of Minke whales and Harbor porpoises, scofflaws, are not so mindful. They meander about following no apparent plan, crossing and re-crossing the line, feeding or perhaps just goofing off. Here and there grey seals dive and resurface, dive and resurface in an endlessly repeated cycle. Birds of many types I am unable to discern float by, bobbing in the wavelets, continually taking off and landing. One bird, perched on a prominent snag near the shore, is easily identified, though. Its white head, black body, and bright yellow beak mark it as an American Bald Eagle.

Searching the far shore with binoculars, I realize with a start that there are two people there, looking back. The far side is thickly wooded, with few signs of human habitation, so they seem jarringly out of place. Like me, they have binoculars in hand and scan the Passage and far banks for anything of interest. At one point they seem to be looking in my direction, so I raise my hand in a wave. They do not respond.

For those of us used to life in lower latitudes, sunrise comes shockingly early in these parts. Geometry, latitude, and longitude all conspire to make it so. Because of the Earth’s twenty-three degrees and a fraction tilt, relative to its orbital plane about the sun, the northern half of the planet spends significantly more time in sunlight than in shadow this time of year. The farther north you go, the greater the ratio of light to dark. Here, at the 45th parallel, halfway between the Equator and the North Pole, the effect is fairly pronounced. Right now the days run about three hours longer than at latitude 30 degrees North, where I am from. Go another twenty-two degrees or so closer to the Pole, though, and the sun doesn’t set at all; look due North at midnight and you will see it hanging low over the horizon.

The effect is skewed by our far easterly longitude. As it turns out, another invisible line runs down the middle of the West Passage, separating two of the planet’s twenty-four time zones. On this side we observe the Eastern Time Zone. New Brunswick, a few hundred yards away, is in the Atlantic Time Zone, an hour later. Local cell phones, unable to decide which time zone to observe, switch randomly back and forth between the two.

Time zones are a human invention of course, enabling us to more easily synchronize our clocks–another invention–to the motions of the sun. Thus aligned, we are able to carry out no end of prearranged and coordinated activities, precisely “on time.” A twenty-four hour day necessitates a like number of time zones. The number twenty four is arbitrary, other than that it is about the right size to reasonably define a day, neither so large as to be unwieldy nor so small as to be useless. It is also easily divisible by multiples of two into smaller intervals, for measuring events of shorter duration.

The passing of time is often compared to the flow of a river, or if you wish, the tide. Although there is poetry in the analogy, the comparison is a misleading one because, in fact, time is the ultimate human invention, an illusion derived from the persistence of matter. In reality there is no past or future, only an eternal now; no was or will be, only a never-ending is. We perceive that time has passed because our minds retain impressions of events we experience and store them in something of a sequential order. We perceive that there is a future because we are able to imagine one, extrapolating “forward” the trajectories of our experience, as one might predict the path of a billiard ball. Without memory, without intelligence, there would be no such thing as time.

High tide, the intermission between rising and falling tide, is surprisingly brief, and harder to spot than you might suppose. Ten minutes ago the tide was indisputably incoming, its trace clearly visible as a tongue of turbulent water racing around Deer Island and up the Passage. But now the channel is a confused muddle of currents running this way and that, like a crowd milling about, awaiting a signal. That signal will arrive shortly. Over the next few minutes the milling about will gradually cease, and the waters of Passamaquoddy Bay will gather force and head seaward. In a fraction over six hours, give or take, the pattern will reverse.

Here, on on the West Passage, tides are a force to be reckoned with, averaging nearly twenty five feet from high to low. A hundred or so miles away, at the head of the Bay of Fundy, they are more than twice as large, pushing, some days, fifty five feet. In fact, the Bay of Fundy has the greatest average tidal range to be found anywhere on Planet Earth. Every day, twice a day, regular as a metronome, twenty-some trillion, with a T, gallons of water rush in and then spill back out. This gargantuan oscillation is driven, as are tides everywhere, by the moon’s gravitational attraction, combined with complex, planetary-scale inertial forces. But the Bay of Fundy’s unique location and geography concentrate the effect as nowhere else, with spectacular results.

Once the tidal current gets going, it moves with impressive speed, generating a clearly audible rushing sound and kicking up, in places, standing waves 5 or 6 feet high. Whirlpools a hundred feet across form and dissipate with clock-like regularity. Sometimes a bend in the shoreline or an obstruction on the bottom deflects some of the onrushing current so that it curves back on itself and runs, improbably, backward. Such imbalance cannot be long sustained, though. Inevitably, as though recognizing the futility of resistance, the errant plume falters, and is quickly absorbed back into the main stream.

If you examine a tidal calendar, you see that the tidal pulse forms an almost perfect sinusoidal wave. A sinusoidal wave mathematically describes the change in value or magnitude of a cyclic phenomenon, for example a swinging pendulum, a vibrating string, or a revolving planet. Like anything in nature, though, the reality imperfectly approximates the ideal. Wind, coastal geography, and perhaps a dozen other factors smear and nudge this way and that the peaks and valleys of the tidal cycle, adding bumps and dips to its otherwise smooth curves. Even the sun is a player, albeit a minor one, in this production, its slender gravitational pull by turns adding or subtracting a bit of tidal range. Notwithstanding minor irregularities, the tides are broadly predictable enough that they are easily tracked with simple mechanical devices. There is one in the living room of our temporary home. It is basically a clock without a minute hand, slightly modified with an extra gear tooth or two or a slightly heavier balance wheel, to slow it enough to approximate the tides’ twelve hour and twenty-something minute period.

On a larger scale, the apparent rising and falling of the sun over the course of a year, which drives the seasons, comprise yet another familiar, predictable cycle. Six months from now the place I stand will be covered in snow, the sun will arc low across the southern horizon, and the days will be short and frigid. Thick rafts of ice will jostle upon the tidal waters. Six months from that time, the land will be draped in green once again, the sun high in the sky, the air warm and redolent.

On an even larger scale, the cycle of glacial advance and retreat that has shaped and reshaped the landscape here continues unabated. At least fourteen times in the last seven hundred thousand years, vast sheets of ice many thousands of feet thick have swept over this landscape, grinding the surface into dust, obliterating every last trace of life. Each time the ice eventually melted away, leaving behind a moonscape of barren, sterile bedrock. And each time, Nature, neglecting to learn from her experience, has repopulated the wasteland, filled in the blank slate. There will be a fifteenth time. Someday, twenty or fifty or a hundred human lifetimes from now, after the minor carbon bubble our species has released is resorbed, the ice will return.

We humans are strongly attuned to the idea of cyclicity. Our brains, the product of millions of generations of steady refinement, are wired to extract meaningful patterns from the apparent chaos around us. And so we see cycles everywhere, an infinitude of clockworks large and small, all springing from a great cosmic wheel. To our remote ancestors, whose sense of wonder had not yet been blunted by the cold logic of science, the tides must have seemed like God’s own heartbeat.

But as  I contemplate this appealing scene, it occurs to me that in reality there is no such thing as a cycle; the relentlessly unidirectional nature of the universe forbids it. There is only motion in all its forms, always forward, sometimes so constrained as to resemble cyclicity. There is no exact repetition of anything, ever.




© 2013 By Scott P. Snell

Right of reuse is freely granted with proper attribution.

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