Because the continents float on a sea of molten magma, the land mass that now makes up Michigan and southern Ontario was once very far from where it is now. Six hundred million years ago, it was parked just south of the equator and covered with a tropical sea not unlike today’s Caribbean Sea. But deep beneath the continental crust, a storm was brewing. A convection current launched from the centre of the earth began to spin the magma directly under this sea into a giant vortex. Like a cataclysmic version of Edgar Allen Poe’s maelstrom, the magma whirlpool deepened and widened, drawing the rocky crust above down into it (imagine a thin film of plastic covering the vortex of a drain). Except that this was no transient event: the whirlpool lasted for millions of years. Eventually it created a bowl-shaped depression in the earth’s crust that was overlaid with limestone deposits.
At its greatest extent, the lava vortex was eight hundred kilometres across, and it exerted its downward pull for three hundred million years. Then, mysteriously, it stopped. Afterwards, in a geothermal rebound, the bowl-shaped deposits began to rise for an additional two hundred million years. Finally the whole process ended.
The continent, with its slightly elevated limestone bowl, continued to drift northwards, and over millions of years the layers of limestone that formed the edge of the bowl eroded. Because they were canted up at a shallow angle, and because the top layer of limestone was composed of hard dolomite, a cliff face emerged over eons. At the time of the dinosaurs it was barely high enough to trip a baby Tyrannosaurus rex, but by the beginning of the ice age a million years ago, the escarpment was tall enough to make continental glaciers stumble.
“Time will tell,” as the saying goes. It will, indeed. Geological time-lapse tells us truths that were once unimaginable. Everything around us, even the seemingly unmoving rock beneath our feet, is in transition. It is when we time-travel in our minds, animating inert landscapes, that the drama of life speaks to us.
A SEASONAL TIME MACHINE
When I was a child, every July and August resurrected for me the primeval, eternal summer of the age of reptiles. Snakes basked in the sun on forest paths near my home, and lizards with bright blue tails slipped through the ferns. In the pond, giant, antediluvian snapping turtles lurked. I was ten years old when I imagined that the seasons were like a Grand Canyon of time, that the journey from March to November took me through the same nine hundred million years as the geological journey from bottom to top of the world’s deepest canyon.
Everything began on March 21. This was the first day of spring and, according to my dual calendar, the beginning of the Neoproterozoic eon. Here, at the dawn of life, the first unicellular animals arose. The pond was mostly clear of ice, and tiny, single-celled organisms proliferated invisibly in the shallows. I knew about them because the year before I had taken home a sample of pond water, put it under my brother’s microscope and seen sleek, transparent creatures that used whips and moving bristles to propel themselves.
April was the beginning of the Paleozoic era, when the first crustaceans and fish began to stir in the ancient oceans. On bright, warm afternoons, schools of wild goldfish sunned themselves near the surface of the pond, and at night, in the shallows, the eyes of crayfish glowed like twin embers in the beam from my flashlight. Plants colonized the land during the Paleozoic, and, right on schedule, the first green shoots of wildflowers stuck up through the leaf litter in the woods.
Amphibians entered the scene during the Carboniferous period—in late April and early May by my calendar. The frogs began their mating trills, and I could hear them through my bedroom window on the first warm nights of May. The fiddleheads emerging in early May evoked the giant tree ferns of the late Carboniferous. By June tadpoles were wriggling by the hundreds in the pond, and even they obeyed the evolutionary edict of my geological calendar: they grew legs and dropped their tails in late June, transforming from aquatic to land animals. Amphibians gradually evolved into dinosaurs, and summer became the age of reptiles—July the Jurassic, August the Cretaceous.
Autumn, naturally, became the Cenozoic era, the age of mammals. The fat squirrels that buried walnuts in our backyard were glossy, and the neighbourhood cats looked sleeker and quicker as they stalked migratory birds in the hedges. All mammals seemed invigorated by the fall weather. Within the Cenozoic era, the late Tertiary period marked the height of the age of mammals. Some of these extinct behemoths reached extraordinary sizes, larger than elephants. The giant megathurium of South America, a kind of sloth, stood twenty feet tall. The glyptodon, from the armadillo family, was the size of an armoured vehicle. But global conditions were starting to cool. November and December brought the age of the glaciers, and then our own period of history, the Quaternary. During the first snowfalls in late November, I imagined herds of woolly mammoths gathering in the frosty gloom at the foot of glaciers.
Winter ended the yearly cycle, bracketing the beginning and the end of the journey of life through time, just as it did in prehistory seven hundred million years ago, when a glacial age almost ended the beginning of life on earth. This glacial age was apocalyptic; compared to it, later glacial ages were more like spring thaws. Simple multicellular organisms had barely gotten a foothold when glaciers spread out from the poles, just as they did only a few thousand years ago, but they didn’t stop. They continued southwards until they covered the entire planet. All the oceans froze, capped with a kilometre-thick icy layer. If there had been intelligent life on Mars at that time, scientists there would never have bothered sending a rover to look for life on earth. Earth, as seen through their telescopes, would have been a brilliant white sphere, a barren planet that had been locked in a deep-freeze for millions of years.
And yet, life, hardly given the warmest of welcomes, survived. Bacteria, algae and prokaryotic organisms living near geothermal deepsea vents and in hot springs, continued to exist for millions of years until, finally, in a great thaw, the icy clutch of winter was broken. After that cosmic spring, life was reanimated in a renaissance that eventually changed the face of the earth. On my time-travel calendar, March 21 is like all the annual holidays rolled into one. It is nothing less than the celebration of the tenacity of life and its endurance over time. Now, in us, life can look back at its beginnings. If life was matter’s dream, then consciousness was life’s dream. It was only a matter of time.
TIME MACHINES AND WORMHOLES
If you haven’t found something strange during the day it hasn’t been much of a day.
—John Wheeler, physicist
Don’t let anyone tell you there’s no such thing as a time machine. I’ve seen one. It’s the size of small city and it sits beside the Bay of Naples, in Italy. A few years ago, when I stepped through the northern gate of Pompeii, I stepped two thousand years back in time.
What astonished me was that Pompeii didn’t look old—far from it. It was a surprisingly modern city, lacking only the voices of its citizens, the rasp of metal-clad wheels on cobblestone, and barking dogs. The architecture was elegant and sophisticated. The city blocks, or insulae, as the Romans called them, were laid out in grids identical to any North American city. And they had plumbing! Aside from electric light and internal combustion engines, Pompeii lacked nothing. At one point I lost track of the other tourists and spent at least half an hour alone, wandering through the streets, peering through the gates of marbleclad villas or investigating corner wine bars that looked as if their patrons had just gone down the street to watch some civic spectacle.
Even Vesuvius, the volcano that both destroyed and preserved Pompeii, still looms in the distance, a plume of smoke issuing from its peak. I couldn’t get over the immediacy of the place; I became giddy with the sense of time travel. Later, after glutting my vision with impluviums, atriums, columns and statuary, I went to the train station and ate a grilled eggplant and cheese panini at a small café next door. It was there that I realized I had a feeling like jet lag, only this jet lag wasn’t from crossing a time zone or two—it was from being transport
ed through millennia. Perhaps, in my own way, I had experienced the same delirium that H. G. Wells’ time traveller described.
Curiously enough, science doesn’t rule out the idea of time travel, especially into the future. In fact, the theory of relativity predicts it; if an object can attain speeds even half the speed of light, it will experience time warp. (As we know from our twin sisters, the twin who travelled into space and reached a high enough velocity returned to earth in the future.) But the notion of travelling backwards in time faces the seemingly insurmountable obstacle of time paradoxes, including the famous “grandmother paradox,” which says that if you go back in time and murder your grandmother, you will never be born. This and other paradoxes, in and of themselves, seem to completely rule out time travel, and yet some contemporary physicists have neatly sidestepped them. Dr. Igor Dmitrievich Novikov, professor of astrophysics at Copenhagen University, has come up with an eponymous self-consistency principle asserting that a time traveller will never be able to create paradoxes because her actions in the past will be “over constrained” by the laws of space-time. Novikov believes that a time traveller would be prevented from murdering her grandmother, even if she made every effort to, by coincidental events that would always intercede.
Others, like Stephen Hawking, still believe that time travel to the past is not possible, given what we now know. Hawking has written a “chronology protection hypothesis” in which he argues that nature will always prevent travel into the past, much like the conservation of energy prevents energy from disappearing. Also, he points out, somewhat tongue-in-cheek, that we would already know if time travel into the past will be discovered in the future because we “have not been invaded by hordes of tourists from the future.” Yet even Hawking does not absolutely rule out time travel to the past, and other physicists are even more enthusiastic about the possibility.
The American physicist John Wheeler had always been fascinated by Einstein’s theory of relativity. Even when his academic career at Princeton was interrupted by his participation in the Manhattan Project and Project Matterhorn B (the building of the atomic and hydrogen bombs respectively), he kept a corner of his mind busy tinkering with extensions to Einstein’s formulae. When he returned to Princeton to teach full-time in the mid-1950s, he was able to devote much more speculative time to these ideas. Wheeler was particularly interested in the curvature of space-time, and in 1957 he realized that under special gravitational conditions, the structure of space might be able to form a passageway—a kind of shortcut—between two disparate regions. He called this passageway a “wormhole.” Space-time physics hasn’t been the same since.
Many of his colleagues scoffed at his theory, saying his wormholes contradicted some of the basic laws of physics. They cited Einstein and pointed out that wormholes were impossible because of the intimate relation between space and time. After all, they insisted, if the “shortcut” were long enough, it could conceivably permit faster-than-light travel, which was clearly an impossibility. But as the years went on, Wheeler’s math held up. Yet wormholes remained a theoretical possibility only until the ultimate discovery of “black holes” (a name Wheeler coined as well) a little over a decade later. Black holes were mesmerizing for physicists, particularly when it came to how gravity and light behaved around them. Here all bets were off, at least as far as the laws of conventional physics went. Physicists soon recognized that because black holes bent space-time so radically, they could themselves be the entrances to wormholes connecting distant regions of space. But black holes annihilate everything that falls into them, and, even if they were an entrance to a wormhole, where would the exit be—a billion miles away? Or in some unthinkable, parallel universe?
The idea of wormholes has continued to fascinate scientists. Might wormholes someday be tamed? Might starships use them? Igor Novikov thought so, and he even went further. In his book The River of Time, Novikov speculates that at some point in the future it might be possible to build two huge gravitational fields that would create a wormhole between them. Why would we want to do this? Because, Novikov claims, a wormhole, after a bit of ingenious tinkering, could be turned into a time machine. And then he conjectures that there might be an even easier way to capture a wormhole, and it’s right under our noses.
According to recent cosmological theories, our four-dimensional space-time universe is not what it appears to be. Apparently it has many other dimensions “curled up” inside the “quantum foam” (sub-atomic space-time) that underlies all matter. These are failed dimensions that, unlike the other four dimensions, didn’t unfurl after the Big Bang. They survived, invisibly locked within matter throughout the universe, suppressed by the dominant dimensions of classical space-time. Like dimensional viruses suppressed by a cosmic immune system, they are biding their time until something or someone unlocks their potential. As well as holding these potential new dimensions, the matrix of the “quantum foam” contains some other surprises—tiny black holes. And wormholes.
Cosmic engineers could pluck a wormhole out of the quantum foam in our own backyard. In 1988, in a paper published by Michael Morris, Kip Thorne and Ulvi Yurtsever, the authors wrote, “One can imagine an advanced civilization pulling such a wormhole out of the quantum foam and enlarging it to classical size.” Then, as Novikov blithely suggests, the wormhole could be stabilized and towed towards a large gravitational body, like a neutron star. (Attaching grappling hooks to such a will-o’-the-wisp would be one of the minor problems, no doubt.) Novikov would then park the wormhole vertically over the neutron star. One mouth of the wormhole would be lowered till it almost touched the surface, while the other would be raised hundreds of miles above the star.
Here’s the clincher. Because gravity affects time—passing more slowly near the surface of a large planet and more quickly away from it—Novikov argues that eventually the two mouths of the tunnel would get out of synch. The greater the gravity and the longer the wormhole was left to develop its time differential, the greater the difference in time between one mouth and the other. Eventually, when enough of a temporal disparity had developed, Novikov proposes that the wormhole be dragged away and parked in an empty region of space. If the time difference between the two mouths was, say, two days, then as soon as the wormhole was parked, someone entering the mouth leading to the past would be transported two days backwards in time.
The main limitation to the idea of wormhole time travel is that you could never travel farther back in time than the date at which the wormhole started to operate. Sadly, visits to the Jurassic era would be out of the question. But Stephen Hawking’s tourists from the future might well become a reality. In fact, I suspect that as soon as the wormhole was parked, maybe even before, tourists and who knows what else would begin to emerge from it. After all, the scientists of the future would have a leg up on the scientists who built the wormhole. They’d be able to look back over years of observations of the behaviour of the wormhole. Perhaps they would find ways of tweaking its performance, of extending its temporal range. The point is, the normal causal relationship between the building of knowledge over time from experience and observation could be inverted in a second. Cronos would be stymied.
This brings us back to our paradoxes. What if a mischievous scientist from the future were to explain a Nobel Prize–winning technology to a scientist from an earlier age and the earlier-age scientist went on to win the prize? From the perspective of the future scientist, with access to history books, she knew that the earlier scientist was going to invent this technology anyway, but she short-circuited the process. She might not have been changing history, but she was subverting it. Both scientists would rely on future history being fed back into the past without any causality. Talk about intellectual property. And what if the scientist from the future gave the idea to someone else, and he or she got the Nobel Prize instead, altering history as in the grandmother paradox? Perhaps, as Novikov and some other physicists believe, none of these events could occur; something wo
uld always intervene to ensure that the law of causality would never be contravened retroactively. But there are other problems with time travel.
RIGHT TIME, WRONG PLACE
The intimate relationship between time and space is something that rarely occurs to novelists and filmmakers dealing with time travel. In H. G. Wells’ The Time Machine, the world transforms around the protagonist while he remains stationary. If you think about it, though, time is also place. The co-ordinates of a specific time—say, Italy during the reign of Augustus—always include a place. But the fact that place and time are so inextricably connected presents an even more complicated problem for a time machine like the one Wells imagined.
Let’s say you have built the first time machine, something the size of a phone booth. Because it’s a prototype, it has a very limited range—something like twenty-four hours. Imagine that on a Wednesday afternoon, October 6 at 4:00 p.m., you decide to test your time machine for the first time. You step into the machine, strap on your harness and seat belt, make sure the airtight seals around the door are locked, and set the dials for 4:00 p.m. the day before: October 5. Then you cross your fingers, activate the chronological drive and wham—suddenly you’re floating in space. The laboratory is gone, the city is gone, and the earth is gone. You look at the master clock in your time machine and, indeed, it does register 4:00 p.m. on October 5. But where is the earth?
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