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July/August 2007 -- (This is the fourth in a series of reviews of the seven best classic documentaries of broadcast television. The first review of the series , published in the April 2007 issue of TNI, was Civilisation by Kenneth Clark.
The second was The Ascent of Man by Jacob Bronowski; the third was Connections: An Alternative View by James Burke.)
Cosmos: A Personal Voyage written by Carl Sagan, with Ann Druyan and Steven Soter. Television series produced by Adrian Malone. First aired in 1980. The 7-disc, 13-part Emmy Award-winning series on a remastered DVD set with updated material is distributed by Cosmos Studios, retail price $129.95. The companion book was published in 1980 by Random House; current edition published 2002.
In 1969, after working as a high school intern at Goddard Space Flight Center on the Apollo 11 moon landing, I became an astronomy major in college, fired by a passion to understand the universe that we humans were only beginning to explore first-hand. I would return often to that facility for the Friday afternoon science lectures. One of my interests was life elsewhere in the universe. At that time, most popular discussions of the subject centered on UFOs; I had discounted the belief that they were visitors from other worlds.
The speaker one Friday was a young scientist who gave one of the most thoughtful yet entertaining lectures on that subject that I’d ever heard. He, too, rejected the space-alien explanation of flying saucers. He pointed out, among other things, that the best observed cases usually had natural explanations—stars, meteors, aircraft. For the most interesting ones—a saucer lands, an alien walks down a ramp, gives a flower to a stupefied lady, and then leaves—there was no physical evidence, only the testimony of the alleged observer.
But he also took us through the conditions necessary for life, how we might determine its likelihood elsewhere in the universe, and how observers might differentiate natural phenomena from signs of intelligence. I remember a slide of a herd of cows, taken from the air, about which he asked how an alien might determine if they were conscious creatures rather than weird natural formations.
With his 1980 PBS television series Cosmos, that scientist, Carl Sagan, became the world’s best-known and most beloved astronomer.
Sagan (1934–1996) was one of the most serious and innovative thinkers on Intelligent Life in the Universe (to use the title of his 1966 book, co-authored with I. S. Shklovskii). He followed this work with the 1973 publication of The Cosmic Connection, which presaged his ability to communicate complex matters in clear and imaginative ways. He was heavily involved in the Search for Extra-Terrestrial Intelligence (SETI) project to find advanced life forms in the universe.
Carl Sagan became the world’s best-known and most beloved astronomer.
Sagan was also a top planetary scientist. He postulated, correctly, that Venus would be a scorching furnace rather than a pleasant twin of the Earth. He worked on most major probes to Mars and other planets. And, knowing that some of these probes would find their way into interstellar space, where they might be found by intelligent aliens millennia in the future, he devised plaques and audio recordings to give any such creatures information about us, the probes’ makers, and our location in the galaxy.
But it was with Cosmos and its companion book, which contained this material and much more, that he brought astronomy and scientific thinking to a popular audience.
Each episode of the series offers us a theme—the planet Mars, space and time, stars, life in the cosmos—that integrates much information, presents it in imaginative ways, and shows us how humans came to such knowledge. Sagan was one of the first to use blue-screen special-effects techniques, so that we can see him stroll on the surface of other worlds or point to the parts of a DNA molecule a million times its actual size. He often uses actor dramatizations, with his voiceover explanations, of the key events in the lives of those individuals who helped establish our understanding of the nature of the universe and our place in it.
Sagan launches his series in his “spaceship of the imagination.” We sit in a simple craft with a large picture window that allows him to give us a cursory tour of the universe. He begins in the realm of distant galaxies, moving into our home galaxy, past nebulae and stars, into our solar system, and finally to Earth. (This is the reverse of the impressive opening sequence of the movie Contact, which was based on Sagan’s outstanding sci-fi novel of that title.)
One of his imaginative ways of showing us the scale of time is with a giant, one-year calendar that looks larger than a football field. Our sun formed on September 14; the most primitive life appeared around September 25th. In early November, sex emerged. Sagan speculates that since it was so late before advanced life came about on our planet, perhaps the universe might be populated by planets rich in lowly cells but with few more-developed creatures.
He walks along the calendar pointing to the highlights of Earth’s history. The earliest plants emerged on December 1st. The first fish and vertebrates appeared on December 19th. Plants took root on land on December 20th. Winged insects took flight on December 22. Trees and reptiles came the next day, with dinosaurs appearing on Christmas Eve. Mammals and birds came the day after Christmas. A few days later, the dinosaurs suddenly died out. The first true humans emerged only on the evening of the last day of the last month; all of human history is contained in the last ten seconds of New Year’s Eve. We see this as a tiny dot at the lower right corner of the giant calendar.
The universe has been around for a long time; we’re very recent residents. That’s the lesson that Sagan’s imaginative presentation helps us to put in perspective.
Later, he begins a discussion about the emergence of various life forms by showing us a crab with a design on its back that looks very much like the face of a samurai warrior. He narrates the story of a battle in medieval Japan between the forces of a child emperor and a rival samurai tribe. The emperor’s forces are outnumbered and lose badly. We see the child-ruler’s guardian taking him out in a boat, then stepping out into the water and to their doom.
In the years following that event, fisherman who captured crabs with markings on their backs resembling a human face just a little bit would throw them back, in commemoration of the doleful battle. Those crabs lived on to have lots of little baby crabs that inherited those face-like features. Over time, this process produced crabs that not only had human-looking faces on their backs but the faces of samurai warriors.
The lesson? We humans created those faces by our own selection process. And natural selection works in a similar manner to produce the diversity of life we find on this planet.
Sagan focuses not only on what we have discovered, but he also tells us the stories of the individuals who made those great discoveries.
For example, Johannes Kepler (1571-1630) had one foot in the old, mystical worldview of the past, but he ushered in the future age of science that uses rigorous observations and exact mathematical explanations. Kepler was a quiet introvert, failed theology student, and failed teacher. He mumbled, was impossible to follow, and thoroughly bored his very few students. At odds with the religious authorities, he found himself fleeing across central Europe for his own safety. Later, he spent years trying to keep his mother from being burned as a witch.
Kepler initially concocted theories based on his religious beliefs about the order of the universe. For example, he tried to explain the motion of the planets in terms of various perfect solids—spheres, cubes—nested inside one another. He then went to work in Prague with the extroverted, jovial party animal Tycho Brahe, who, before the invention of the telescope, was making the most accurate observations of the strange back-and-forth motion of planets across the sky. Their personalities clashed, but after Tycho’s death from over-partying, Kepler abandoned his commitment to explaining planetary motion in terms of perfect forms that had mystical meaning to him. Instead, he formulated a mathematical description that put the sun at one foci of an ellipse and that allowed us to make testable predictions.
The lesson? Humans often had to struggle to overcome their prejudices and religious preferences and allow reality to guide them to the truth.
Sagan tells the tale of Milton Humason, a mule-team driver who helped haul parts up Mount Wilson in California during the early twentieth century to build what was then the world’s largest telescope. Humason later became a janitor at the new observatory. Asked to help with the equipment, he became a virtuoso in the new technique of astro-photography. In the 1920s, with the observatory’s chief astronomer, Edwin Hubble, he helped discover that those dim smudges of light on long-exposure photos were actually gigantic, distant galaxies and that the entire universe is expanding, pointing back to a Big Bang that took place billions of years ago.
In the Italian countryside where a young Albert Einstein liked to walk and think, Sagan uses a young boy on a bike as a prop to show how the world would look and change if the youth peddled very fast—indeed, close to the speed of light. Time would actually slow down for the rider. When he returned to the piazza, he would find that his brother, who was a child like him when he left, was now an old man. Time and space, the demonstration shows, are relative.
Carl Sagan’s presentations also help us think about those areas where science and philosophy come together. In one of the best episodes, “Edge of Forever,” he surveys our best understanding and most provocative theories about the origins of the universe. One of the topics is the difficult problem of how to conceive of a “beginning” of space and time, when, one theory goes, all matter and energy existed at one infinitely small point. On this view, the universe did not explode into space in the Big Bang; space itself expanded. But into what?
Carl Sagan understood that to be human is to wonder.
Sagan helps us wrap our minds around this difficult concept. Imagine a sphere like the Earth, and imagine that we can only move along its surface. What is north of the North Pole? The question makes no sense. The Earth’s surface is finite but unbounded. We can move along it forever, but it is not infinite in area. Asking what happened before the Big Bang, “before time began,” might be a similar question. In recent decades, physicist and science popularizer Stephen Hawking has expanded on these sorts of issues. But most people were introduced to such concepts by Sagan.
In this series, we do get Sagan’s liberal political views—for example, about the dangers of nuclear war, and his concerns about pollution. But these opinions are not so intrusive as to take away from the enjoyment of the series by those who don’t share them.
A religious skeptic, Sagan shows us how faith has opposed science—such as the burning by Christians of the ancient library of Alexandria. But he also shows how religious thought often strives for explanations or symbolic representations of the subject matter of science, such as the beginning of the universe. We’re given a fascinating discussion of Hindu views on the cycles of the sleeping and waking of Brahma that, certainly through accident, coincide with the actual timescales of the universe. This is one of many parts of the series that appeals to the poetic in us. But, of course, it’s science that allows us to replace myth with knowledge.
The illustrations and images of the Cosmos series, even after two-and-a-half decades, hold up well. Most awe-inspiring are photos and graphic depictions of the natural wonders of the universe: planets, stars, globular clusters, nebulae, supernovae, and galaxies. (The DVD set provides updated material, as well.)
Carl Sagan understood that to be human is to wonder. It is to observe the seasons, the growth and death of plants and animals, and to wonder why things change. It is to stare at the stars at night and wonder what they are. It is to think about ourselves and to wonder whence we came. “Cosmos,” he reminds us, is the Greek word for the order of the universe, as opposed to “chaos.” And in this timeless series, Sagan helps us in our human quest to understand that underlying natural order.
愛德華·哈金斯（Edward Hudgins）是哈特蘭研究所（Heartland Institute）的研究主任，也是阿特拉斯協會（Atlas Society）的前宣傳主任和高級學者。
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