Soul of the World (21 page)

The end will come in one of two ways: cosmic “heat death” (which is really more like the “big freeze”) or the “big crunch.” Science can’t tell
us which one will win out because the weight of the universe is at the borderline between the two possibilities; it might continue to expand indefinitely, overcoming the contracting effects of gravity, or it might stop expanding and begin to collapse. The first scenario, heat death (or death from lack of heat), sees the stars snuff out one by one, and matter itself disintegrating until the temperature of the empty universe reaches absolute zero in the final darkness. The second, the big crunch, is the reverse of the Big Bang. Here gravity prevails. After expanding for billions of years, the universe starts to contract and ultimately collapses upon itself, imploding in a fiery annihilation that will be the mirror image of its birth.

If, as Thomas Gold proposed, time begins to run backwards in a contracting universe, then for its inhabitants birth will become the final moment of life. But these inhabitants won’t know time is reversed. Their thoughts will flow logically and naturally in the new direction of time as our own do, and the universe will appear to be expanding, just as our own does. But its end will come all the same.

T
HE
E
NDGAME

Worlds may freeze, and suns may perish, but there stirs something within us now that can never die again.

—
H. G. Wells

Can total annihilation be deferred, or even avoided? How do we snatch eternity from the jaws of a finite universe? Hans Moravec, among others, has wrestled with cosmic mortality and come up with an ingenious solution that just might work. It all hinges on the paradox of Zeno’s Arrow—if you keep halving the distance that the arrow has yet
to travel, the arrow will never arrive. This turns out to have practible applications. What if, Moravec asks, the universe is headed for heat death? How could an infinite amount of time be squeezed from a finite amount of matter and energy?

Moravec’s answer is clever. He says that our descendants could build a tremendous battery consisting of two giant mirrors that faced each other. Moravec proposes that a beam of photons be endlessly reflected between the two mirrors to harness the energy of light. The photons would push the mirrors farther apart and the energy from the moving mirrors would power civilization. Moravec writes, “The idea is to use about half the energy in the battery to do
T
amount of thinking, then wait until the universe is cold enough to permit half the
remaining
energy to support another
T
, and so on indefinitely.”

But what if the universe contracted instead? In this case Moravec again proposes mirrors, only now they would surround a stored vacuum. As the universe contracted, the vacuum would yield increasing amounts of energy. He writes, “A subjective infinity of thought might be done in the finite time to collapse by using this growing power to think faster and faster as the end draws nigh. The trick here is to repeatedly do an amount of thinking
T
in half the remaining
time.
” Of course, when Moravec refers to “thinking,” he means the complex information-processing that it would take to maintain such advanced beings within their real and virtual worlds.

Freeman Dyson has also contemplated how the endgame might play out is. Dyson is famous for his visions of fantastic engineering projects in the distant future. Perhaps his best-known scheme is the Dyson sphere, where a living star is enclosed within a giant globe and all the star’s energy is harvested for the benefit of a civilization living on the sphere. When first proposed, this idea was so compelling and so logically inevitable that astronomers began looking for Dyson spheres as a
method of determining whether there was intelligent life elsewhere in the universe. Occasionally, they argued, stars should sporadically dim and then wink out, evidence that an advanced civilization had reached the Dyson-sphere stage. So far, no such stars have been found.

But even Dyson spheres would not save a dying civilization at the end of the universe—stars will run out of fuel long before that. If heat death is indeed the ultimate fate of the universe, then Freeman Dyson has another trick up his sleeve. He proposes using the cooling temperature as a way to defer mortality. Our descendants, either superbeings or some sort of ultra-intelligences, would have to radically conserve energy in order to carry on. If they could, then they might be able to survive in a “subjective infinity,” as Moravec calls this sleight-of-hand immortality, but only if they were able to speed up their thought processes. Dyson maintains that the cold could be used to dissipate the heat inevitably generated by such vast information processing—thinking generates heat. But as available resources dwindled, these beings would have to ration their energy. He suggests that they might go into long periods of hibernation. Subjectively, they’d never be aware of their downtime, their thoughts would resume without interruption as soon as they reawakened, and the increasingly longer periods of hibernation would go unnoticed.

Frank Tipler, one of the co-authors of
The Anthropic Cosmological Principle
, has also wrestled with these questions. In his 1994 book
The Physics of Immortality
, he suggests that a superbeing who had grown to encompass the entire universe would use all available energy to process its thoughts, which would themselves include simulations of all possible worlds. But, appreciating that its own fate was tied to that of the universe, what would the ultra-brain do to survive? As we now know, even
it
wouldn’t be able to supervene the second law of thermodynamics, no matter how intelligent or omniscient it was.

Tipler’s answer is not unlike Moravec’s: the faster you think, the faster you act, and the more living you can fit into a smaller slice of time. The race does go to the quick, and it is inevitable that the cognitive speed of beings in the future will certainly outpace anything today. Since the longevity of existence is equivalent to the speed of thought (a Femtonian lives a million years during one of our seconds), Tipler argues that as the thinking process of the ultra-brain sped up, it could use the immense energies and unusual physics of a collapsing universe to increase the subjective speed of thought infinitely—the ultimate escape. If time is indeed infinite inwards, and the femtosecond within the nanosecond has an endless series of smaller and smaller divisions within it, then perhaps that inward abyss of time might be the key to our future, and our survival.

Even before the end of the universe, there are other pitfalls along the way that might end it prematurely. There is some speculation that when the first black hole evaporates through Hawking radiation, it might destroy the universe. This is because each black hole contains the end of time. It’s possible that if space-time collapses in the singularity of a black hole that completely evaporates, the collapse will spread outwards and destroy everything else along with it. To forestall such a catastrophe, Barrow and Tipler suggest that future intelligences could simply keep dumping matter into those black holes that were teetering at the brink of complete evaporation. They write, “Thus ultimately life exists in order to prevent the Universe from destroying itself!”

In the end, the interlocked fates of life and the universe hinge on life’s immortality. It is our only hope. But then a new dilemma arises, one that takes me back to my childhood bedroom, where I wrestled with the opposed fates of mortality and immortality. The idea of existence without end is pretty frightening, so much so that, for some, extinction might seem preferable.

T
HE
D
EEP
F
UTURE

The timeline for our universe, if it keeps expanding and ends in eventual heat death, has been worked out in detail by physicists, astronomers and cosmologists. Regardless of whether or not our progeny expand to fill it, the universe will run down. Tipler and Barrow (who refer to the universe that contains not only our visible universe but also all possible universes with a capitalized “Universe”) predict that in one thousand billion years, new stars will cease to form. Billions of years after that—or ten billion billion years from now—90 percent of the stars in the universe will have evaporated, while the remainder will have been sucked into massive black holes. In ten million, billion, billion, billion years, all carbon-based life forms will become extinct.

You’d think that would pretty much be the end of things, but within the barren, dark emptiness of this future cosmos, inside matter itself, non-carbon-based life would be blazing its own bright future. From now on, the universe’s timeline becomes so staggering that we have to convert to trillions in order to economize on words. In a trillion, trillion, trillion, trillion, trillion, billion years, the massive black holes that once formed the centre of galaxies will evaporate. Yet there will still be plenty of matter and energy available to sustain whatever beings exist.

Long after black holes have evaporated, if they don’t take the rest of the universe with them, the timeline becomes so incomprehensibly huge that we have to resort to powers of ten to write out the numbers. The black hole deadline that I mentioned above would be written as ten to the power of ninety-nine, or in notation, 10
⁹⁹
. The next major event in our timeline would be during the early middle age of our universe. Trillions of years after the lights have gone out, a strange encounter might take place.

According to the mathematics of the Anthropic Cosmological
Principle, in 10
⁸⁰⁰
years, our descendants will encounter the descendants of
Homo sapiens
that have arisen elsewhere in the universe. It seems Carl Sagan was a bit optimistic about the abundance of extraterrestrial beings. When this poignant meeting happens, intelligent life will be close to saturating the entire universe, though the endgame will still be trillions of years ahead.

The final years of the universe, when the temperature has dropped to absolute zero, will likely occur sometime after 10
¹⁵⁰⁰
years, though here the timeline becomes speculative. This is indeed a long-lived universe. But if, instead of expanding, the universe begins to contract and is ultimately annihilated in the “big crunch,” there might not be so much time left. If gravity wins the tug-of-war, the universe might last only twenty to thirty billion years longer. Hardly any time at all. What is certain is that, at 13.7 billion years old, our universe is young. And still, human life has already arisen, perhaps precisely because we need the rest of this time, these potential billions or trillions of years, to expand and to occupy the universe and all parallel universes that make up the Universe.

Our history has been marked by expansion and discovery. The urge to explore oceans and cross nameless deserts has constantly spurred us on. Ultimately, it seems, we will visit the stars and the galaxies beyond, and when we do, we will become the gardeners of the universe. But the tending will be mutual, for it appears that the universe is both garden and gardener itself.

The management and use of time may turn out to be our greatest achievement, far outshadowing any giant engineering projects of the distant future. Time is the final resource, and the universe, railing against the end of time, has put all its chips into our eventual ability to cheat death, not just for our heirs, but for the universe itself.

Nothing in the world lasts,

Save eternal change.

—
Honorat de Bueil

Last week, on a dark, cold afternoon, an ambulance pulled up in front of George’s house. The attendants went in with a gurney and soon reemerged with George. He was walking, with some difficulty, his arm braced by one of the paramedics. I realized that he had refused to lie on the stretcher. They got into the ambulance and left. Since then the lights in George’s house have been off, and I fear things did not go well at the hospital.

This week a For Sale sign appeared in front of my Portuguese neighbours’ house, and yesterday morning their real estate agent slipped a brochure under my porch door. The neighbourhood is changing. Even the houses are transforming. Several neighbours with young children have expanded their homes with additions and new decks. On most days one or two contractors’ vans are parked on the street.

It snowed last night, as this morning the roofs of the houses and the cars were dusted with white. By noon the snow had melted, though it was gloomy and cold all day. But just before evening fell, the sun came out. Its rays were almost horizontal as it crested the roofs of the buildings
in the west. The sunlight had a warm tinge, and the bricks of the houses across the street were lit up as if they were glowing red-hot, fresh from the kiln. My Austrian pine (I must admit to proprietary feelings, even if it isn’t on my property) was also lit up, its thickly set combs of needles as green as any June forest. It radiated a timeless calm and seemed to harbour daydreams in its lobed canopy.

R
ADIANT
T
IME

Because time’s flow has no three-dimensional direction, it’s hard to picture how time ramifies, how it slides from past to future. Yet time moves neither up nor down, left nor right, east nor west. Trying to grasp time’s motion, or lack of motion, has been one of the most difficult things I’ve ever tried to conceive. The best I can do is create metaphors, which may not accurately reflect what time is, but which at least lead me towards a more essential grasp of its intrinsic nature.

Last March, when I stood beside the rustling bamboo, time felt like a wind that blew through everything. That sensation captured the ubiquitous nature of time, how it manages to insinuate itself into the smallest atom and the largest galaxy at once. It also revealed time’s invisibility and its power to change the fabric and shape of whatever it blows through, like waves of wind rippling fields of summer grass. But the metaphor didn’t get at the unidimensional character of time, the fact that time doesn’t actually move through this world at all. Or, if it
does
move, it moves unlike anything else in our universe.

This afternoon, though, looking out at the old Austrian pine across the street, watching the sunlight that seemed to incandesce its foliage, I had another sensation of time. It came to me in an image of rain falling on a still pond. The ripples spread from each drop in a randomly even
pattern of overlapping, expanding rings. Then I imagined the surface of this pond doubled, so that there were two transparent surfaces, one just above the other. I could see the rain splashing on the second pond as well, with its own pattern of ripples. Then I pictured another surface laid over the first two, and then another and another, until they were countless and filled all space. Now the ripples from each drop propagated not in flat rings but in expanding, transparent spheres within spheres, radiating through all the layers. Time, I thought, didn’t flow from the past towards the future, but from inside of everything, at once, everywhere.

It was the old pine that congealed this vision. In the sunlight it looked dusty, almost pointillistic. Just for an instant, I could see the millions of expanding, transparent circles of time spreading out of the tree before they became microscopic and invisible. As they faded, they merged into the world—into the other trees, the buildings, the clouds, the sky and the earth. A purple finch flew into the pine and started up its melodious song while a tabby, stalking beneath, paused to look up at the bird. These creatures, both wild and tame, myself, these buildings, all joined in the net of time.

Everything sheds time in a steady emission that swells out of every atom, every leaf, every human being—even out of empty space. That’s why the old pine, with its evergreen halo of sun-soaked needles, seems beyond time. It, and me, and all of us, are soaked in Chronos. Perhaps time is more like a sourceless, uniform inner light. Its outward-flowing ripples are so small, so fine, they are undetectable. Perhaps the fountain at the heart of time is the infinitely divisible “now,” the “now” that is a billion billion “nows” within itself. Every second is infinite—a millisecond in the second, a nanosecond in the millisecond and a femtosecond in the nanosecond. It all blossoms, swells out from the centre of everything at once. We shine with time. True, time’s arrow points
in one direction, just as the needles of the pine radiate outwards from their branches or rays from the sun point in one direction, but time’s grain is directionless. Time’s arrow points everywhere at once, and all of creation glows with time.

It is here that our future lies, not ahead but within. If each second contains a near eternity, then are we not, in one very real sense, already immortal? And even though we are as unconscious of our immortality as an elephant is of the ants that crawl over its hide, we nonetheless exist within eternity, and our lives, however brief, stretch for countless eons within each minute, infinities within each hour.