Probable impossibilities, p.12
Probable Impossibilities, page 12
I realize that there is a certain amount of circularity in the above comments. For meaning is relevant, perhaps, only in the context of minds and intelligence. If the minds don’t exist, then neither does meaning. However, the fact is that we do exist. And we have minds. We have thoughts. The physicists may contemplate billions of self-consistent universes that do not have planets or stars or living material, but we should not neglect our own modest universe and the fact of our own existence. And even though I have argued that our bodies and brains are nothing more than material atoms and molecules, we have created our own cosmos of meaning. We make societies. We create values. We make cities. We make science and art. And we have done so as far back as recorded history.
As I mentioned in the chapter “One Hundred Billion,” the British philosopher Colin McGinn argues that it is impossible to understand the phenomenon of consciousness because we cannot get outside of our minds to discuss it. We are inescapably trapped within the network of neurons whose mysterious experience we attempt to analyze. Likewise, I would argue that we are imprisoned within our own cosmos of meaning. We cannot imagine a universe without meaning. I am not talking necessarily about some grand cosmic meaning, or a divine meaning, or even a lasting, eternal meaning—just the simple, particular meaning of everyday events, fleeting events like the momentary play of light on a lake, or the birth of a child. For better or for worse, meaning is part of the way we exist in the world.
And given our existence, our universe must have meaning, big and small meanings. I have not met any of the life-forms living out there in the vast cosmos beyond Earth. But I would be astonished if none of them were intelligent, as I define intelligence. And I would be further astonished if those intelligences were not, like us, making science and art and attempting to take stock and record this cosmic panorama of existence. We share with those other beings not the mysterious, transcendent essence of vitalism, but the highly improbable fact of being alive.
INFINITY
Cosmic Biocentrism
In 1979, the late distinguished theoretical physicist Freeman Dyson indulged himself in one of the more daring speculations of the scientific imagination: the fate of the universe and intelligent life in the extremely remote future. We’re not talking just hundreds of thousands of years in the future, when the next ice age occurs. Or even billions of years, when the Sun expands, turns into a “red giant” star, and incinerates the Earth. We’re talking millions of billions of years, when all the stars in space have burned out and planets have been tossed from their solar systems by chance encounters with wandering stars. And even beyond. Somewhat surprisingly, physicist Dyson writes, “It is impossible to calculate in detail the long-range future of the universe without including the effects of life and intelligence.” He then goes on to describe a scheme whereby intelligent life might survive in this grim future—by relocating consciousness and memory from flesh-and-blood bodies to large structures of particles, like floating clouds. To survive, these “intelligent structures” must go into long periods of hibernation between active periods of cautious nibbling at the dwindling supplies of energy.
Dyson’s paper, brimming with mathematical computations, was published under the title “Time Without End: Physics and Biology in an Open Universe.” The physicist was not unaware of the speculative nature of his predictions. Partly as cover, he quotes another great theoretical physicist, Steven Weinberg, who had recently published a book titled The First Three Minutes. Weinberg’s book did for the very beginning of time what Dyson was hoping to do for the very end. “This is often the way it is in physics,” wrote Weinberg. “Our mistake is not that we take our theories too seriously, but that we do not take them seriously enough.”
Dyson, who died in February 2020 at age ninety-six, was a shy, small, elf-like man. Born in England to a musical composer father and lawyer mother, he demonstrated a high talent for mathematics at an early age. His older sister Alice remembers her little brother surrounded by encyclopedias and sheets of paper on which he was calculating things. In World War II, not quite twenty years old, Dyson was recruited by the RAF Bomber Command to compute the ideal pattern of bomber formations for the Royal Air Force. He studied mathematics at Trinity College, Cambridge, but never bothered to get a PhD. In 1947, Dyson moved to the United States and, a few years later, took up a permanent post at the famous Institute for Advanced Study in Princeton. Many physicists think that Dyson should have shared the 1965 Nobel Prize for his work in understanding how light interacts with matter, taking into account both quantum physics and Einstein’s relativity.
Dyson was always a visionary. In the late 1950s, he led Project Orion, which proposed that spacecraft could be propelled by detonating a series of atomic bombs in their tail sections. A few years later, in 1960, he outlined something now called Dyson spheres, describing how an advanced civilization could utilize most of the energy of a star by building a light-collecting sphere around it. The Dyson tree is a genetically engineered plant, living in the open spaces in a comet and providing a sustainable atmosphere for human habitation.
Dyson’s idea about the continuing survival of intelligent life in the infinite future was dubbed “Dyson’s eternal intelligence.” Like many of his other futuristic speculations, these new ideas were batted about in the scientific community, considered interesting and controversial and possibly useless, and grabbed up by science fiction writers.
A natural question about all such cosmic ruminations, of course, is: Are they just intellectual amusement, or do they tell us anything important about ourselves here and now, on planet Earth in the twenty-first century? Certainly, Copernicus’s idea that the Sun, not the Earth, lies at the center of the solar system has had profound philosophical and theological impact in the here and now. Likewise, the recent discovery that a large fraction of stars have habitable planets, at the right distance from their central stars for liquid water.
Dyson’s eternal intelligence percolated along with varying degrees of interest for twenty years. Then, in 1998, a new scientific discovery shook everything up. Astronomers found that the universe is not expanding at the leisurely rate accepted for over a half century and assumed in Dyson’s calculations. Instead, the universe is expanding at an accelerating rate. That is, galaxies are flying away from one another at a speed increasing exponentially in time. As a result, in a mere hundred billion years, we and our local group of galaxies will be permanently cut off from the rest of the universe, as if we had fallen into a black hole. No light, energy, or anything else from the rest of the universe will ever reach us. (Our own Sun will have burned out long before this time, around ten billion years from now.) We will be imprisoned within a cell of limited size—large by Earthly standards but small in cosmic terms—preventing Dyson’s intelligent structures from continually growing and storing information in ever larger domains. The night sky will become completely black, space will become colder and colder, and all remaining available energy will diminish to nothing. At some point thereafter, perhaps in another few hundred billion years, that will be the end of life—not just life like ours or even the life embodied by Dyson’s “intelligent structures,” but all life. Such a final demise will occur not only in our cosmic neck of the woods, but everywhere in the universe. The universe will continue to churn along forever, for infinite time, but the “era of life” will have passed. That result and its implications, I suggest, could be even more profound than Dyson’s eternal intelligence.
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In the previous chapter, I discussed the rarity of life in material terms. To contemplate its rarity in terms of the “era of life,” one needs first to understand something of the enormous scales of distance and time in the universe. Seldom does daily existence afford any sense of our place in the cosmos, but eclipses provide a slight inkling. Like many Americans, I watched the solar eclipse of August 2017. My daughter and son-in-law and their two children were visiting my wife and me in coastal Maine, not the perfect location but a 58 percent eclipse according to the estimates. A couple of days before the event, we realized that we didn’t have the proper equipment, so we began calling around to procure eclipse sunglasses. All the nearby stores were completely sold out. Eventually, my wife located a tiny library in a town called China, Maine, about an hour and a half’s drive away, that had a good supply. She got a woman on the phone who said that they were closing soon, but she would leave a stock of eclipse sunglasses out in front of the library in a cooler, with a sign saying “Take only as many as you need.” My wife made the trip.
Meanwhile, our four-year-old granddaughter got wind that something important was in the works and asked me to explain eclipses. I took out several pieces of fruit, one being the Earth, one the Moon, and one the Sun, and put them in front of her in an arrangement such that the fruit moon obscured the fruit sun. “Can you show me that on the computer?” she asked.
My son-in-law was not satisfied with the fruit analogue demonstration, or the computer simulation, or the real-time direct eclipse-sunglass experience. He got out a food colander and projected a hundred crescent Suns on the deck.
During the eclipse, as the light dimmed, the animals around us began behaving strangely. The birds’ squawking didn’t seem normal. The squirrels scampered in unnatural ways—or at least it seemed so to us. The monarch butterflies hovering about the chives in our garden swooped and fluttered as if in a trance. After a half hour of the eclipse, we’d had enough. We put down our sunglasses and colanders and got on with the rest of our day.
But something profound had happened to us. For a moment, we were aware of ourselves in the universe. We were aware of the cosmic nature of things, of the Moon as an enormous round ball orbiting the Earth, and the Earth as another ball orbiting the Sun and spinning about on its axis. And the immensity of space. Spectacular things are occurring out there, whether we notice or not.
My granddaughter asked me how far away the Sun is. That question I couldn’t answer with apples and oranges. But if you traveled to the Sun on a high-speed train, say at two hundred miles per hour, it would take about fifty years. She nodded.
To get to the nearest star beyond the Sun on the same train would take about fifteen million years. It was Isaac Newton who first managed to estimate that distance, scribbling his calculations in a spidery script with a quill dipped in the ink of oak galls. (Only someone as extraordinary as Newton could have been the first to perform such a calculation and have it go almost unnoticed among his other achievements.) If one assumes that stars are similar things to our Sun, Newton asked, how far away would our Sun have to be in order to appear as faint as nearby stars? The challenge in such a calculation is how to compare the brightness of the Sun to that of a star. In the mid-seventeenth century, Newton didn’t have electronic photocells at his disposal. He did, however, know that at certain times of the year the planet Saturn appears about as bright as a bright star. That planet glows because of reflected light from the Sun. Figuring out the fraction of the Sun’s light that Saturn intercepts, Newton was able to get his answer: about thirty million million miles to the closest stars. His calculation, titled “On the Distance of the Stars,” occupies only a single page in his masterwork, the Principia.
To deal with such huge distances and even larger ones, astronomers use a unit of distance called the light-year, the distance that light can travel in one year. In these terms, the nearest star, called Alpha Centauri, is about five light-years away. In other words, a light ray emitted from that star and traveling through space at 186,000 miles per second would take five years to reach the Earth.
Newton’s estimate of this distance was far larger than any distance imagined in human history—fantastically larger than the circumference of the Earth or even the distance to the Sun (which the ancient Greeks had estimated). One should think of ants in an anthill in Cincinnati trying to imagine the distance to San Francisco.
But we’re just getting started, astronomically speaking. When we look up on a dark and clear night, we see a beautiful white sash overhead. That’s our galaxy, the Milky Way, a swarm of about a hundred billion stars. How to measure its size? For almost 250 years after Newton, no one knew. Then, in 1912, a mostly deaf astronomer named Henrietta Leavitt, working at the Harvard College Observatory, devised a completely new method to determine the distances to faraway stars. Certain stars, called Cepheid variables, were known to oscillate in brightness. Leavitt discovered that the cycle times of such stars are closely related to their intrinsic luminosities (wattages). More luminous stars have longer cycle times. Measure the cycle time of such a star and you know its intrinsic luminosity. Then, by comparing its intrinsic luminosity to how bright it appears in the sky, you can infer its distance, just as you can gauge the distance to an approaching car in the night if you know the wattage of its headlights. Cepheid variables are scattered throughout the cosmos and conveniently serve as cosmic distance signs in the highways of space. Leavitt, always referred to as “Miss Leavitt,” received no honors and little recognition during her lifetime and is almost unknown outside the astronomical community.
In the 1920s, using Leavitt’s results, astronomers were able to measure the size of the white sash of the Milky Way, which we now know to be a hundred thousand light-years across. At the time, there was a strong debate about other astronomical apparitions: Were the faint, nebulous smudges seen through telescopes part of our Milky Way, or something else? By identifying Cepheid variable stars in these smudges, the astronomer Edwin Hubble was able to determine that many of them are entire galaxies. The nearest large one, called Andromeda, is a couple of million light-years away. On average, each galaxy is separated from the nearest neighboring galaxy by ten or twenty galaxy diameters.
This picture of deep space was conceived by creatures roughly two meters in height, pondering the cosmos from one planet on the outskirts of one galaxy in the plentitude of galaxies. On January 22, 1926, The New York Times published a brief and blasé note about Hubble’s discovery, under the headline “Another Universe Seen by Astronomer”:
For many years, astronomers have speculated as to whether various nebulous formations in the heavens belong to this universe or were “island” universes of their own, immeasurable distances away…Evidence that another universe really exists is offered by Dr. Edwin Hubble in a study today published by the University of Chicago in the Astrophysical Journal. He found that this external galaxy, similar in many ways to our own, although entirely outside the Earth’s galactic system, is 700,000 light-years away [an underestimate but still much larger than the Milky Way].
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Human beings have done better at contemplating very long periods of time. In ancient Hinduism, the life span of a deva (minor god) was thought to be about 10,000 deva years, each deva year about 100 Earthly years, for a total of a million years. One day in the life of Brahma, the Creator God, was 1,000 deva lifetimes, estimated at about 4 billion years. That long time unit was called a kalpa. Evidently, these successively longer time scales were arrived at simply by multiplying the previous time scale by a few factors of ten, without any knowledge of the physical world.
The Hindus believed in a cyclic universe. The life cycle of the entire universe was thought to be a hundred years in the life of Brahma, working out to be about three hundred thousand billion years. By accident, this time period is about the time required for all stars to burn out.
Buddhists also used the kalpa as a unit of cosmic time, but the Buddha demurred from specifying the length of the kalpa in human years. However, he did give a vivid illustration: Suppose you have a very large mountain 16 miles in height and 16 miles in width. If you swipe the mountain with a piece of silk once every hundred years, the mountain will be completely worn away before the end of a kalpa. (This conjecture has not been verified.)
The first very long time period determined scientifically and fairly accurately occurred in the 1920s, when geologists used the rate of disintegration of uranium and other radioactive elements to estimate that the Earth is several billion years old. Then, in the 1930s and 1940s, with the realization that our Sun and all stars are powered by nuclear fusion at their centers, astronomers and physicists estimated the age of our Sun: about five billion years.
In 1929, Edwin Hubble, again analyzing data from the giant telescope at Mount Wilson, California, discovered evidence that the universe is expanding—probably the most important cosmic discovery of all time. According to the Big Bang model and recent observations of the cosmos, we expect that the universe will keep expanding forever, growing colder and increasingly dilute. It was in such a context that Dyson considered how life could survive into the remote future, and perhaps forever.
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We have now arrived at the point to reconsider the rarity of life, both in space and in time. One of the first people to propose the existence of life beyond planet Earth was the early Roman poet Lucretius (ca. 50 BC). In his great book On the Nature of Things, in which he espouses a purely materialist view of the cosmos in order to combat the supernatural power of the gods, Lucretius writes: “It is in the highest degree unlikely that this Earth and sky is the only one to have been created…Nothing in the universe is the only one of its kind, unique and solitary in its birth and growth…You are bound therefore to acknowledge that in other regions there are other Earths and various tribes of men and breeds of beasts.”
