Pale Blue Dot: A Vision of the Human Future in Space by the famed scientist Carl Sagan was published in 1994 and discusses the universe and potential space travel. A remarkable work of facts and prose, Pale Blue Dot, like Cosmos, should be read by every human being, for it clearly demonstrates that every member of Homo Sapiens should cooperate, as we are on the same planet: our political, racial, religious, and socioeconomic rivalries mean nothing in the grand scheme.
Sagan begins the book with a passage that can be read as an eloquent speech. This speech can be found in an abridged version on Youtube, titled “Wanderers” (attached below). Sagan narrates humanity’s history as hunter-gatherers, detailing that we are by nature a nomadic species. He writes that “for 99.9 percent of the time since our species came to be, we were hunters and foragers, wanderers on the savannahs and the steppes … The frontier was everywhere. We were bound only by the Earth and the ocean and the sky-plus occasional grumpy neighbors” (xiv). Sagan details that agriculture occurred by mere chance, and civilization is only ten-thousand-years old. Sagan writes that even though the adventurers largely stay at home now, they still thirst for travel, for the desire for exploration was instilled into us by natural selection. He then writes of climate change, describing that if nothing is done, it can create an extremely large number of refugees. He proceeds to discuss his grandfather, whose name was Leib Gruber. He grew up in a town, Sassow, in the Austro-Hungarian Empire and made his living by carrying customers across the river Bug, for there was no other way to get across. He details that while he stayed in the village for much of his life, he eventually left for the New World to avoid a potential murder (at the very least, that’s what Carl Sagan detailed). Carl Sagan’s grandmother, Clara, died from complications involving birth. When Carl Sagan’s mother had him, she named him after his grandmother. Sagan then details humanity’s potential for interplanetary travel, saying that at the moment, “No one on Earth, not the richest among us, can afford the passage; so we can’t pick up and leave for Mars or Titan on a whim, or because we’re bored, or out of work, or drafted into the army, or oppressed, or because, justly or unjustly, we’ve been accused of a crime. There does not seem to be sufficient short-term profit to motivate private industry” (xx).
Sagan writes that a picture was taken of Earth by a machine that was traveling 40,000 miles per hour. In February of 1990, it was commanded to take a photo of the Earth. Complying, it did as it was instructed, and it took 5.5 hours for the photograph to reach humanity. On the picture, the Earth was a pale blue dot, unimaginably small, almost indistinguishable from the nearby planets (and at that point in time the machine was barely into space). As Sagan wrote, “there is no sign of humans in this picture, not our reworking of the Earth’s surface, not our machines, not ourselves: We are too small and our statecraft is too feeble to be seen by a spacecraft between the Earth and the Moon. From this vantage point, our obsession with nationalism is nowhere in evidence … On the scale of worlds-to say nothing of stars or galaxies-humans are inconsequential, a thin film of life on an obscure and solitary lump of rock and metal” (3). Sagan describes that even though the Earth is insignificant, it’s different for us: “Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ‘superstar,’ every ‘supreme leader,’ every saint and sinner in the history of our species lived there-on a mote of dust suspended in a sunbeam” (6). Sagan then talks about the stupidity of war and genocide, for humans share infinitely more in common than the few differences which we acquired through both nature and nurture. Furthermore, the picture of Earth demonstrates that humans are not important at all and that it is very unlikely for other life forms to come and save us from our own follies, stupidities, short-sightedness, greed, indifference, callousness, and cruelty. Regardless, Sagan calls for the readers to be decent people and to treat each other with respect: “astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known” (7).
Sagan then states that religion is extremely inaccurate, for the notion that some sort of divine entity created the entire universe for only one species is preposterous. Sagan introduces a hilarious thought experiment: how would humanity react upon learning of some other lifeform in the universe which believes the world was created just for them? Sagan then discusses telescopes, calling them time machines, as every light year between a star and Earth allows us to look one year back in time when it comes to the state of the planet (if a star is one-hundred-million light-years away, we see it as it was one-hundred-million light-years ago). Sagan then writes of Earth, detailing that “Long ago, when an early galaxy began to pour light out into the surrounding darkness, no witness could have known that billions of years later some remote clumps of rock and metal, ice and organic molecules would fall together to make a place called Earth; or that life would rise and thinking beings evolve who would one day capture a little of that galactic light, and try to puzzle out what had sent it on its way. And after the Earth dies, some 5 billion years from now, after it is burned to a crisp or even swallowed by the Sun, there will be other worlds and stars and galaxies coming into being-and they will know nothing of a place once called Earth” (10). Sagan states that prejudice is absolutely stupid, as it is an instance of tribalism. Furthermore, he writes of Ptolemy, who wrote thousands of years ago that although the Earth was indeed only a small point, it was in the center of the universe. People believed this to comfort their egos, for that offered the human species a favorable position in the cosmos. It was also believed by many famed minds such as Plato that humans were extremely important. Sagan writes that if an intelligent and responsible alien form was to see us, they would view us as the patients of a madhouse. Regardless, various philosophies and many religions believed the Heavens to be perfect, despite people like Democritus and Epicurus writing that they may not exist (they don’t: beyond Earth is space, not some imaginary kingdom where everything is supposedly perfect). Sagan details that some philosophies and religions commanded others to be humble while themselves lacking any kind of humility, which is quite ironic. Sagan describes that religion requires ignorance to function, which was the exact reason why scientists like Copernicus and Galileo were afraid to publish their research. This uninventive, dogmatic attitude is seen very well in how a clergyman said that only evidence which was in line with Christianity should be allowed and that the freedom to experiment and examine evidence should be banned. Regardless, science won various victories, clearly demoting the arrogance of humans (although it is still unaccepted by a variety of groups, such as those against vaccination, those who believe in a flat Earth, and those who stick to outdated religious dogma). Sagan wrote that just as how his grandfather was amazed to see large cities upon coming from his small village, humans may be filled with wonder upon exploring the universe and realizing our limitations. In his own words, “The country bumpkins know almost nothing about what else is possible. They fail to grasp the insignificance of their province or the diversity of the Empire. With ease, they apply their own standards and customs to the rest of the planet. But popped down in Vienna, say, or Hamburg, or New York, ruefully they recognize how limited their perspective has been. They become ‘deprovincialized.’ Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home” (19).
Sagan moves on to be more specific when it comes to the ruination of the arrogance of many Homo Sapiens, writing that at the beginning, people viewed Earth as being unique. He then states that when people realized Earth wasn’t at the center of the universe, they comforted themselves by stating that the sun was. This was proven to be false upon examining other stars. Next, people believed that the Milky Way was the only galaxy. This was proven to be erroneous too, for there are “perhaps hundreds of billions of galaxies … Some modern deep-sky photographs show more galaxies beyond the Milky Way than stars within the Milky Way. Every one of them is an island universe containing perhaps a hundred billion suns” (21). Next, people sought to rescue their egos by believing that our galaxy was at the center of the universe. Sagan details that the universe is constantly expanding, demonstrating that there is no center of space. People then tried to imagine that Earth was the only planet in the universe. This was proven wrong too, as “Today we have firm evidence for at least three planets orbiting an extremely dense star … Other planetary systems now look to be a cosmic commonplace, maybe even worlds something like the Earth. We should be able, in the next few decades, to inventory at least the larger planets, if they exist, or hundreds of nearby stars” (22-3). Sagan then counteracts religious claims, writing that religions generally ascribe a certain age for the beginning of the universe, which is empirically preposterous: if Christianity is true, then the Earth is approximately 6,000 years old. However, we have evidence through carbon dating and other practices that that is fantastically inaccurate. In fact, Sagan tellingly details that humans are an extremely new species, for the universe is around 15 billion years old while the Earth is 4.5 billion years old. In his own words, “As for humans, we’re latecomers. We appear in the last instant of cosmic time. The history of the Universe till now was 99.998 percent over before our species arrived on the scene. In that vast sweep of aeons, we could not have assumed any special responsibilities for our planet, or life, or anything else. We were not here” (25). Sagan then states that claims that Earth’s velocity and movement are unique are untrue, for the whole idea of humanity having “a privileged reference frame” is false: “Our preferences don’t count” (26). Furthermore, claims based on religious grounds that humans are somewhat unique can be easily done away with when Darwin’s ingenious theory of natural selection is applied: there is no need for a creator. As Sagan described, “Charles Darwin showed convincingly how one species can evolve into another by entirely natural processes, which come down to the heartless business of Nature saving the heredities that work and rejecting those that don’t. ‘Man in his arrogance thinks himself a great work worthy [of] the interposition of a deity,’ Darwin wrote telegraphically in his notebook. ‘More humble and I think truer to consider him created from animals.’ The profound and intimate connections of humans with other life forms on Earth have been compellingly demonstrated in the late twentieth century by the new science of molecular biology” (27).
All in all, many of humanity’s past delusions and false notions of grandeur have been debunked on a logical, empirical basis. For instance, the claims that humans are “unique” in regards to other animals have their weaknesses, for other animals are capable of cognition (albeit not to a large enough degree to build complex machinery and tools, but still impressive) and attributes once thought to be only for humans. For instance, “Chimps reason, are self-conscious, make tools, show devotion, and so on. Chimps and humans have 99.6 percent of their active genes in common” (27). Sagan states that animism, the belief that objects have human-like attributes, is ridiculous and inaccurate, for they are inanimate. He describes that the reason that animism is so popular is that humans have tendencies to project ourselves into other things. He then writes that there may indeed be intelligent life in the universe, taking away our claims as being the sole “smart” species. Sagan also mentions that the universe may hypothetically be infinitely old: it may have gone through previous fluctuations, contractions and expansions, as seen in the Big Bang and the potential Big Crunch. Sagan states that as our technology improves, we can learn more things about the universe, which will reveal even more information to us. He then ends the chapter by writing that “A Principle of Mediocrity seems to apply to all our circumstances. We could not have known beforehand that the evidence would be, so repeatedly and thoroughly, incompatible with the proposition that human beings are at center stage in the Universe … We have not been given the lead in the cosmic drama. Perhaps someone else has. Perhaps no one else has. In either case, we have good reason for humility” (36-7).
Sagan proceeds to discuss the follies of man-made doctrines that profess our “importance.” He discusses how the Roman Catholic Church tried to prevent the accumulation of knowledge (including astronomy, accurate history, opposing philosophies, geology, and anatomy), encapsulated very well in how they threatened Galileo with brutal torture for maintaining that the Earth wasn’t at the center of the universe. Unsurprisingly, it took the Roman Catholic Church almost two centuries to remove Galileo’s book from the Index, which Sagan hilariously described as a “list of books which Catholics were forbidden to read at the risk of dire punishment of their immortal souls” (40). When Pope John Paul II gave a speech about Galileo in 1992, he said that the Roman Catholic Church was not as bad as they have been portrayed to be. But as Carl Sagan wrote, “But surely the Holy Inquisition ushering the elderly and infirm Galileo in to inspect the instruments of torture in the dungeons of the Church not only admits but requires such an interpretation. This was not mere scientific caution and restraint, a reluctance to shift a paradigm until compelling evidence, such as the annual parallax, was available. This was fear of discussion and debate. Censoring alternative views and threatening to torture their proponents betray a lack of faith in the very doctrine and parishioners that are ostensibly being protected. Why were threats and Galileo’s house arrest needed? Cannot truth defend itself in its confrontation with error?” (42). Sagan writes that prejudice must not be confused with facts and that facts don’t care about one’s feelings: what’s true should be known, and what’s inaccurate should be willingly discarded. Sagan writes that many have complained of science in that it took away the justifications of man’s outrageously inflated ego. Even though it is somewhat lamentable for people to realize our complete unimportance in regards to the universe, the alternative is worse: as Carl Sagan maintained, better by far to embrace the hard truth than a reassuring fable. Sagan, however, acknowledges the human desire to have purpose, detailing that “We long to be here for a purpose, even though, despite much self-deception, none is evident. ‘The meaningless absurdity of life,’ wrote Leo Tolstoy, ‘is the only incontestable knowledge accessible to man.’ Our time is burdened under the cumulative weight of successive debunkings of our conceits: We’re Johnny-come-latelies. We live in the cosmic boondocks. We emerged from microbes and muck. Apes are our cousins. Our thoughts and feelings are not fully under our own control. There may be much smarter and very different beings elsewhere. And on top of all this, we’re making a mess of our planet and becoming a danger to ourselves” (51). Sagan writes that once we overcome our fear of being insignificant, we can truly appreciate the universe and better our technology. Therefore, science is very inspiring, and should be honored and pursued. Sagan calls for the audience to become better people, writing that even though there is no evidence at all for some sort of conscious designer, “The significance of our lives and our fragile planet is then determined only by our wisdom and courage. We are the custodians of life’s meaning … but knowledge is preferable to ignorance. Better by far to embrace the hard truth than a reassuring fable. If we crave some cosmic purpose, then let us find ourselves a worthy goal” (55).
Sagan then discusses how an extraterrestrial may view Earth and human civilization. If, hypothetically, an alien civilization that is both intelligent and cooperative found the planet, they would initially strain to find the markings of human civilization. Once they recognize the fact that humans are inhabiting the planet, they are initially surprised. However, upon closer inspection, they find the effects of climate change and mass extinction, and are terribly shocked to find that the “complex” civilization is doing nothing to stop it. That is, “from your orbital perspective, you can see that something has unmistakably gone wrong. The dominant organisms, whoever they are-who have gone to so much trouble to rework the surface-are simultaneously destroying their ozone layer and their forests, eroding their topsoil, and performing massive, uncontrolled experiments on their planet’s climate. Haven’t they noticed what’s happening? Are they oblivious to their fate? Are they unable to work together on behalf of the environment that sustains them all? Perhaps, you think, it’s time to reassess the conjecture that there’s intelligent life on Earth” (65-6). Sagan writes of the Galileo, a spacecraft designed by NASA to analyze Jupiter and the moons orbiting around it. The mission found no signs of life. Later, he discusses Voyager 1 and Voyager 2, two spacecraft which explored nearby planets. They both attested to the strength of Jupiter’s gravity, and Voyager 2 was able to reach the Uranus system, detailing in just a few hours much information that revolutionized what we know of the planet, its 15 moons, its rings, and its particles. In total, the two spacecraft “have returned four trillion bits of information to Earth, the equivalent of about 100,000 encyclopedia volumes” (75). All in all, the Voyagers were successes: though they were in need of repair multiple times, there were no major malfunctions. Sagan writes that the mission has “cost each American less than a penny a year from launch to Neptune encounter,” clearly showing that these missions are affordable and illuminating, thereby making them worthwhile (82).
Sagan writes of Titan, Jupiter’s largest moon. Titan has low temperatures and “rain” which involves molecules. One of Sagan’s mentors, the astronomer Gerard P. Kuiper, discovered that Titan had an atmosphere. Sagan mentions that the days of the week were named after planets. For instance, Saturday was named after Saturn, Sunday for the Sun, and Monday for the moon. Also, Tuesday, Wednesday, Thursday, and Friday were named after various gods. To specify, Tuesday was inspired by Tyr (god of war), Wednesday was named after Odin (otherwise known as Wodin), Thursday paid homage to Thor, and Friday honored Freya (goddess of love). Sagan states that these names have had a massive influence in history before proceeding to discuss Jupiter and Saturn: in both of these planets, “the pressures are so great that atoms sweat electrons, and the air becomes a metal. That does not seem to happen on less massive Uranus, because the pressures at depth are less. Still deeper, discovered only by its subtle tugs on Uranus’ moons, wholly inaccessible to view, under the crushing weight of the overlying atmosphere, is a rocky surface. A big Earthlike planet is hiding down there, swathed in an immense blanket of air” (104). Uranus, unlike the earth, lacks the heat to sustain life. Sagan mentions that Uranus is so far from the Sun that from its vantage point the Sun is much smaller in size and influence. Furthermore, since Neptune was discovered in 1846, it has not yet completed a single full rotation around the Sun (a Neptunian year - the entire orbit involves 23 billion miles). Furthermore, Neptune is “so far away that it cannot be seen with the naked eye. It’s so far away that it takes light-faster than which nothing can go-more than five hours to get from Neptune to Earth” (110). Neptune is also four times larger than Earth. Its atmosphere covers its entire exterior when viewed from an outside angle: the surface of Neptune has not been clearly discerned. Furthermore, “the atmosphere is made mainly of hydrogen and helium, with a little methane and traces of other hydrocarbons. There may also be some nitrogen … From the motion of the clouds we discovered fierce winds, approaching the local speed of sound. A Great Dark Spot was found, curiously at almost the same latitude as the Greek Red Spot on Jupiter'' (110-1). Neptune also has rings, though they aren’t believed to be longlasting due to gravity and solar radiation. Sagan then details that Triton is the biggest moon in the Neptune system, and, like Titan, has an atmosphere full of nitrogen. However, unlike Titan, its surface can be discerned: “The landscapes are varied and splendid. This is a world of ices-nitrogen ice, methane ice, probably underlain by more familiar water ice and rock. There are impact basins, which seems to have been flooded with liquid before refreezing … impact craters; long crisscrossing valleys; vast plains covered by freshly fallen nitrogen snow; puckered terrain that resembles the skin of a cantaloupe” (111).
It is also worth mentioning that Triton’s atmosphere is 1/10000 as thick as that of the Earth, and its weather is similar in nature yet different than Earth in regards to time: “In local winter, layers of ice build up on the surface. (Our winters, mercifully, are only 4 percent as long.) Through the spring … more and more reddish organic molecules accumulating. By summertime, the ice and snow have evaporated; the gases so released migrate halfway across the planet to the winter hemisphere and there cover the surface with ice and snow again. But the reddish organic molecules do not vaporize and are not transported-a lag deposit, they are next winter covered over by new snows, which are in turn irradiated, and by the following summer the accumulation is thicker. As time goes on, substantial amounts of organic matter are built up … which may account for its delicate color markings” (113). Sagan details that Triton may have polar caps. He says that Triton’s atmosphere is extremely thin because of its distance from the sun: if it was any closer, the polar caps would melt, creating a denser atmosphere. Sagan, after discussing various other planets, stated that the Voyager carried a golden disk which recorded many of humanity’s experiences, including “59 human languages and one whale language; a 12-minute sound essay including a kiss, a baby’s cry, and an EEG record of the meditations of a young woman in love; 116 encoded pictures, on our science, our civilizations, and ourselves; and 90 minutes of the Earth’s greatest hits-Eastern and Western, classical and folk, including a Navajo night chant, a Japanese shakuhachi piece, a Pygmy girl’s initiation song, a Peruvian wedding song, a 3000-year-old composition for the ch’in called ‘Flowing Streams,’ Bach, Beethoven, Mozart, Stravinsky, Louis Armstrong, Blind Willie Johnson, and Chuck Berry’s ‘Johnny B. Goode.’” (124). Sagan then writes that space is almost completely empty, meaning that the chance that the Voyagers will happen on another solar system is basically nil. However, both Voyagers will encircle the Milky Way Galaxy for an extremely long time, meaning that it is at least possible for it to be found by an extraterrestrial civilization (if they exist). It is worthy to note that the Voyagers didn't include any of humanity’s negative attributes (ex. war, genocide, massacre, rape, strife, nationalistic, racial, religious, and socioeconomic rivalries, stupidity, selfishness, egoism, climate change, habitat destruction, pollution), which can easily be explained in that Sagan and his colleagues wanted to make a good impression on any potential extraterrestrials (which is, of course, completely understandable).
Sagan continues to discuss the skies of various planets, writing that the colors of the horizons of various worlds do indeed differ. For instance, Jupiter’s sky is mostly black near the top, while multicolored clouds (yellow and brown) appear at the bottom layer. On the other hand, “Uranus and especially Neptune have an uncanny, austere blue color through which clouds-some of them a little whiter-are carried by high-speed winds. Sunlight reaches a comparatively clean atmosphere composed mainly of hydrogen and helium but also rich in methane. Long paths of methane absorb yellow and especially red light and let the green and blue filter through. A thin hydrocarbon haze removes a little blue. There may be a depth where the sky is greenish” (135). Sagan then talks about Mariners 1 and 2, two American spaceships which went to Venus. Two decades later, another spaceship, the Galileo, was sent there as well. It was structurally superior to the Mariners due to it having higher resolution and sensitivity.
Additionally, it helped scientists realize that Venus was in fact not hospitable to life due to the sweltering heat: beforehand, many speculated and honestly believed that it was home to various life forms. Later, when Venus was analyzed, it was discovered that, like Earth, it had volcanoes (albeit in the past). Scientists also discovered “plains features ranging to over 200 kilometers in size … circular depressions surrounded by concentric rings, while long, spindly surface cracks extend radially out from the center. Odd, flat ‘pancake domes’-a geological feature unknown on Earth, but probably a kind of volcano-are perhaps formed by thick, viscous lava slowly flowing uniformly in all directions … Curious ring structures called ‘coronae’ range up to some 2,000 kilometers across” (156). Furthermore, the surface temperature of Venus is almost 470°C, or 900°F. Consequently, the hot temperature causes rocks to soften, making them capable of flowing like a liquid. Venus also has craters, though it is less scarred than the moon. Sagan then mentions Apollo 11, the spaceship which went to the moon. He points out that the moon was named as such (as well as “month” and “Monday”) due to the menstruation of women: “Folklore and popular songs celebrate a mysterious connection between the Moon and love … Its waxing and warning-from crescent to full to crescent to new-was widely understood as a celestial metaphor of death and rebirth. It was connected with the ovulation cycle of women, which has nearly the same period-as the word ‘menstruation’ (Latin mensis = month, from the word ‘to measure’) reminds us. Those who sleep in moonlight go mad; the connection is preserved in the English word ‘lunatic.’” (164).
The Moon, for most of humanity’s history, was a symbol for what was impossible to obtain. However, less than a century ago such a feat became not only feasible but possible. Sagan details that the main motivation for Apollo 11 and other spaceships was political: the twelve people who walked on the moon were all Americans. That is, America wanted to show the Soviet Union it was superior to it when it came to technology: what better way to demonstrate this than to go to the moon? As predicted, once the feat was reached and the Soviet Union was relatively cowed, space travel greatly decreased in popularity, as it no longer served a political agenda. Humanity’s hypocrisy is excellently encapsulated in the following incidence: “the most ironic token of that moment in history is the plaque signed by President Richard M. Nixon that Apollo 11 took to the Moon. It reads: ‘We came in peace for all mankind.’ As the United States was dropping 7½ megatons of conventional explosives on small nations in Southeast Asia, we congratulated ourselves on our humanity: We would harm no one on a lifeless rock. That plaque is there still, attached to the base of the Apollo 11 Lunar Module, on the airless desolation of the Sea of Tranquility. If no one disturbs it, it will still be readable a million years from now” (169-70). It is also worth noting that the last space mission involving the moon, Apollo 17, saw a scientist stepping on its surface. Despite the multitude of flaws behind the motivations for its creation, it was still optimistic, as what was previously thought unachievable was in fact reached. Space missions like Apollo 17 also provided people with an excellent view of Earth, demonstrating our vulnerability as a species: “From Earth orbit, you are struck by the tender blue arc of the horizon-the Earth’s thin atmosphere seen tangentially. You can understand why there is no longer such a thing as a local environmental problem … Industrial poisons, greenhouse gases, and substances that attack the protective ozone layer, because of their abysmal ignorance, do not respect borders. They are oblivious of the notion of national sovereignty. And so, due to the almost mythic powers of our technology (and the prevalence of short-term thinking), we are beginning-on continental and on planetary scales-to pose a danger to ourselves. Plainly, if these problems are to be solved, it will require many nations acting in concert over many years. I’m struck again by the irony that spaceflight-conceived in the cauldron of nationalist rivalries and hatreds-brings with it a stunning transnational vision. You spend even a little time contemplating the Earth from orbit and the most deeply engrained nationalisms begin to erode. They seem the squabbles of mites on a plum” (175).
Sagan then details the catastrophic effects of global warming, as the reason Venus is so hot is due to a runaway greenhouse effect (a greenhouse effect that has gone haywire). Sagan states that if nuclear weapons are to be used, most of humanity will perish from nuclear winter. Nuclear winter is the direct result of nuclear bombs: so much dust and smoke particles will be sent into the atmosphere that those who have survived the explosion and the radiation will be unable to grow food (sunlight can’t reach the ground layer of said planet), consequently starving to death. This is connected to the demise of the dinosaurs: most of those which survived the initial impact of the asteroid starved to death, seeing their large size and the sudden interruption of the food chain. Sagan scathingly writes that the behavior of the world at the time of the writing (and to some extent today) is completely ridiculous and stupid, as there were more than 60,000 nuclear warheads. Sagan writes that colonizing other planets is a great investment for humanity and that Mars is a fantastic option, seeing that it has frozen water. Mars may have begun like Earth, but 3.8 billion years ago things took a turn for the worse from a biological standpoint. Sagan states that if the scientists of the Soviet Union and America had worked together, much could have been achieved. Furthermore, very few robots were sent to investigate Mars due to the sheer cost: it costs a lot of money for transportation via shuttles. Sagan details that the reason Mars is the best candidate for interplanetary exploration is that it was likely to have been like Earth in the past, not to mention that it has “weather … its own moons, volcanos, polar ice caps, peculiar landforms, ancient river valleys, and evidence of massive climatic change on a once-Earthlike world” (204). The reason the Moon is a poor candidate is that there is literally no atmosphere, making survival impossible. Furthermore, there are basically no resources to work with, as there is an utter lack of water. Sagan elaborates that even though travel to Mars is currently absurdly expensive (too much for any nation to do on its own), it can definitely happen in the future: technology can advance very quickly when people have the motivation to improve it. He writes that one day humans could go to Mars: “I am sure-unless we destroy ourselves first-that the day will come when we humans set foot on Mars. It is only a matter of when” (207).
Sagan then discusses that many criticisms of space travel are valid: we have enough problems on one planet alone. However, it should be noted that space travel is far from useless, because not only does it put things into perspective, but it increases the data and scope of science. One of the major problems hindering space travel is public opinion: a large number of Americans believed at the time the book was published that the budget of NASA was equal to that of defense. However, “In fact, the entire NASA budget, including human and robotic missions and aeronautics, is about 5 percent of the U.S. defense budget,” clearly showing that even if space travel is entirely canceled, it will barely free up any money (217). In the end, the justifications for space travel are not monetary, but humanistic: while it is possible for space travel to make up for its costs (ex. expensive minerals can be found on the planets), that is not guaranteed. As Bertrand Russell noted in 1959, visions of potential futures “which are now left mainly to unfounded fantasy, could be more soberly treated without ceasing to be interesting and could show to even the most adventurous of the young that a world without war need not be a world without adventurous and hazardous glory. To this kind of contest there is no limit. Each victory is only a prelude to another, and no boundaries can be set to rational hope” (230). Sagan adds to Russell’s quote that “Every time humanity stretches itself and turns a new corner, it receives a jolt of productive vitality that can carry it for centuries. There’s a new world next door. And we know how to get there” (231).
Sagan states that planetary bodies commonly interact with each other violently and that craters and other deformities are testimonies to the possibilities which can occur in space. To demonstrate, four billion years ago, when the planets in the solar system had barely formed, lunar impacts were very frequent. While the planets in our local region were still forming 4.5 billion years ago, “collisions happened perhaps a billion times more often than in our becalmed epoch” (237). Furthermore, Earth was created by accident as these massive collisions occurred: if anything was different, Earth’s biological life forms (if they even exist, that is) will be undergoing an entirely different situation. Sagan then tellingly writes of asteroids that are near Earth. Their names are accordingly: “Orpheus, Hathor, Icarus, Adonis, Apollo, Cerberus, Khufu, Amor, Tantalus, Aten, Midas, Ra-Shalom, Phaethon, Toutatis, Quetzalcoatl. There are a few of special exploratory potential-for example, Nereus. In general, it’s much easier to get onto and off of near-Earth asteroids than the Moon. Nereus, a tiny world about a kilometer across, is one of the easiest. It would be real exploration of a truly new world” (247). Sagan then proceeds to discuss the marsh of Camarina. The city of Camarina was located in southern Sicily (founded by people from Syracuse in 598 B.C.) and some time after the initial colonization, a disease sprung up (probably from the marsh). The disease killed many, so the settlers decided to drain the marsh against the consultation of the oracle. After draining the marsh, the epidemic was briefly subdued. However, they had avoided one trouble only to expose themselves to a greater one: the marsh of Camarina had protected them from foreign invaders, so without it, they were doomed. That is, “As in America 2,300 years later, the colonists had quarreled with the mother country. In 552 B.C., a Syracusan force crossed over the dry land where the marsh had been, slaughtered every man, woman, and child, and razed the city. The marsh of Camarina became proverbial for eliminating a danger in such a way as to usher in another, much worse” (250). Sagan ties this cautionary tale to mass extinctions, especially the Cretaceous-Tertiary Collision. Sagan details that when disasters follow each other in quick succession, organisms may not be able to survive, hence the lethality of mass extinctions. To be specific, “On average, once every few hundred years the Earth is hit by an object about 70 meters in diameter; the resulting energy released is equivalent to the largest nuclear weapons explosion ever detonated. Every 10,000 years, we’re hit by a 200-meter object that might induce serious regional climatic effects. Every million years, an impact by a body over 2 kilometers in diameter occurs, equivalent to nearly a million megatons of TNT-an explosion that would work a global catastrophe, killing (unless unprecedented precautions were taken) a significant fraction of the human species. A million megatons of TNT is 100 times the explosive yield of all the nuclear weapons on the planet, if simultaneously blown up” (251).
The Cretaceous-Tertiary Collision involved an asteroid even worse than a million megatons of TNT, as an event like that occurs once every hundred-million-years. The asteroid involved here is wider than 10 kilometers, making it capable of great damage. Sagan writes that if human civilization is still present when an asteroid of sizable proportion comes towards Earth, then it could be a good idea for humanity to come up with the technology to deflect the dangerous asteroid. Despite the vast potential of this procedure, it is also dangerous, illustrating a modern-day dilemma which reminds us of the lesson of the Marsh of Camarina: evil, insane people exist, and if they are able to get their hands on technology which are capable of deflecting or moving asteroids, they can commit terrible atrocities. Sagan writes that sometimes horrendous human beings “achieve the highest levels of political power in modern industrial nations. This is the century of Hitler and Stalin, tyrants who posed the gravest dangers not just to the human family, but to their own people as well. In the winter and spring of 1945, Hitler ordered Germany to be destroyed-even ‘what the people need for elementary survival’-because the surviving Germans had ‘betrayed’ him, and at any rate were ‘inferior’ to those who had already died. If Hitler had had nuclear weapons, the threat of a counterstrike by Allied nuclear weapons, had there been any, is unlikely to have dissuaded him. It might have encouraged him” (259). Of course, besides Hitler, there are despotic leaders like Mao, Tojo, Stalin, and Pol Pot who might have done similar things. Stalin, whom Sagan mentioned, was also almost unbelievably vile: he didn't hesitate to have millions of innocent Russians tortured, sent to labor camps (Gulags), and shot on a whim, as well as initiating collectivization which led to millions dying of starvation in what became known as the Holodomor (literally translates to “to kill by hunger”). During WWII, he carelessly sacrificed the lives of millions of soldiers, and when the war was over, he had most of the POWs and many regular soldiers executed and sent to the Gulags to prevent outside influences from seeping in. Indeed, such technology is truly very risky, for there are indeed human beings who will grossly misuse them for their own ends. As he elaborates further, “Can we humans be trusted with civilization-threatening technologies? If the chance is almost one in a thousand that much of the human population will be killed by an impact in the next century, isn’t it more likely that asteroid deflection technology will get into the wrong hands in another century-some misanthropic sociopath like a Hitler or a Stalin eager to kill everybody, a megalomaniac lusting after ‘greatness’ and ‘glory,’ a victim of ethnic violence bent on revenge, someone in the grip of unusually severe testosterone poisoning, some religious fanatic hastening the Day of Judgement, or just technicians incompetent or insufficiently vigilant in handling the controls and safeguards? Such people exist. The risks seem far worse than the benefits, the cure worse than the disease. The cloud of near-Earth asteroids through which the Earth plows may constitute a modern Camarine marsh” (259). Sagan then states that due to the massive unreliability of the current political system, even if such technology is invented, it could take decades or centuries to change the political system appropriately to deal with the massive responsibility of handling something of this magnitude.
Sagan discusses anti-matter and its potential to possibly move asteroids. He moves on to detail terraforming amid various planets. For instance, terraforming as of yet cannot be done to Venus, which has undergone a runaway greenhouse effect, due to the lack of options: one of the few choices is making asteroids and comets collide with it. Sagan also wrote, “We could use a giant artificial sunshade in orbit around Venus to cool the surface; but it would be enormously expensive, as well as having many of the deficiencies of the dust layer … Thus all proposals for terraforming Venus are still brute-force, inelegant, and absurdly expensive. The desired planetary metamorphosis may be beyond our reach for a very long time, even if we thought it was desirable and responsible” (279). As for Mars, the greenhouse effect is not present enough, making the surface extremely cold. Therefore, terraforming Mars is likely to include the introduction of greenhouse gases and even ammonia. Although the terraforming of Mars is much easier than transforming Venus, “it is still very expensive by present standards, and environmentally destructive. If there were sufficient justification, though, perhaps the terraforming of Mars could be under way by the twenty-second century” (281). Sagan states that Titan is a good candidate for terraforming because it already has an atmosphere composed mainly of N2 like Earth, not to mention that its atmospheric pressure is not extreme. Furthermore, greenhouse gases are frozen on its surface, making releasing them into the atmosphere easy. Sagan details that the “Manufacture of initial greenhouse gases that do not freeze out at present Titan temperatures plus direct warming of the surface by nuclear fusion could, it seems, be the key early steps to one day terraform Titan” (282). Sagan states that even though terraforming may sound ludicrous today, it is very possible in the future: our technology has advanced extremely rapidly in the last century. The twentieth century saw great leaps in medicine, physics, and other sciences, not to mention the inventions of methods of transportation that was unimaginable some time before (seen very well in the airplane). The twenty-first century has already seen the prominence of the internet, which connects many people to a vast amount of knowledge and resources to improve their lives. Sagan details that if terraforming is indeed done, humans on other worlds may view Earth as being its mother country, as they are likely to be independent when it comes to their own needs.
SETI is eventually discussed: it was a project to use radio waves in an attempt to connect with an alien species. Sagan criticizes the government for saying that it’s a waste of money, for it costs people a measly 12 million dollars a year (even though it is a large number when looked at from an absolute angle, compare that with the billions spent on military weapons that are largely unused - for now). Sagan then states that even if the chance of contacting an extraterrestrial civilization is low, there is no way to truly know: “But how, before we have found extraterrestrial intelligence, can we ‘guarantee’ that we will find it? How, on the other hand, can we know that the chances of success are ‘remote’? And if we find extraterrestrial intelligence, are the benefits really likely to be ‘so limited’? As in all great exploratory ventures, we do not know what we will find and we don’t know the probability of finding it. If we did, we would not have to look” (299). Sagan also discusses Drake’s equation, a formula which provides a way to know (if the values of the multiple variables are known) the prevalence of life in the universe. All in all, Sagan acknowledges that we truly don’t know how prevalent or rare life is in the universe, for it is possible that life is extremely improbable. On the other hand, it is also likely that life does indeed occur quite often, though in ways greatly varied: if this is indeed true, a likely reason as to why we have not detected any alien civilizations yet is because they may have destroyed themselves due to their irresponsible behavior (like humans: think of potential nuclear war, climate change, and overpopulation/excessive resource consumption). Sagan also mentions BETA, which stands for “Billion-channel ExtraTerrestrial Assay.” Sagan then talks about programs like SETI and BETA in the big picture: they can serve to unite us as a species if people look at it the right way. In his own words, “The realization that such beings exist and that, as the evolutionary process requires, they must be very different from us, would have a striking implication: Whatever differences divide us down here on Earth are trivial compared to the differences between any of us and any of them. Maybe it’s a long shot, but the discovery of extraterrestrial intelligence might play a role in unifying our squabbling and divided planet. It would be the last of the Great Demotions, a rite of passage for our species and a transforming event in the ancient quest to discover our place in the Universe” (301). Sagan ends the chapter by stating that when it comes to the search for extraterrestrial intelligence, ambiguity, skepticism, and an open-mind must be maintained: science involves people to be willing to change their minds, which allows for growth and positive change in the long-run.
Sagan provides a summary for the dangers which may threaten humanity’s future. They are, accordingly: fossil fuels (climate change - little to nothing is being done in this regard, even today), CFCs (chlorofluorocarbons which damage the ozone layer - is largely banned though), nuclear weapons (numbers have decreased drastically since 1992), asteroids (first discovered in 1801), biological warfare (especially dangerous when coupled with molecular biology), and the sixth extinction (due to our overconsumption, massive population - maximum amount of humans is commonly held to be 10 billion, resource depletion, and environmental degradation). Sagan writes that the current moment for Homo Sapiens is pivotal, as we currently have the technology to potentially destroy ourselves. On the other hand, we could become responsible and mature as a species, though this process will be exceedingly difficult, like many previous endeavors. J. Richard Gott, an astrophysicist at Princeton, used the Copernican principle to calculate that “at the 97.5 percent confidence level … there will be humans for no more than 8 million years. That’s his upper limit, about the same as the average lifetime of many mammalian species. In that case, our technology neither harms nor helps. But Gott’s lower limit, with the same claimed reliability, is only 12 years … If Gott is right, not only may we never be out among the stars; there’s a fair chance we may not be around long enough even to make the first football on another planet” (307). Sagan states that if humanity is in trouble, we have the amazing potential to cooperate and to save ourselves if we react correctly. Sagan states that if humanity does indeed travel to other planets, we should not repeat the previous colonial experiences (seen in the exploitation of Native Americans, the massacre of those who disagreed with the colonists, and the enslavement of African Americans), seeing that acting barbarously and stupidly would be a recipe for disaster. Sagan states that even though humanity has caused itself a myriad of disasters and has conducted itself largely irresponsibly and in an ignorant manner, it is because of the fact that we “have become powerful without becoming commensurately wise. The world-altering powers that technology has delivered into our hands now require a degree of consideration and foresight that has never before been asked of us” (317). To deal with this issue, if we decide that long-term survival is our goal, we have to drastically revise many of our current institutions. Sagan then quotes and adds to the words of Voltaire: “As Voltaire put it in his Memnon, ‘our little terraqueous globe is the madhouse of those hundred thousand millions of worlds.’ We, who cannot even put our own planetary home in order, riven with rivalries and hatreds, despoiling our environment, murdering one another through irritation and inattention as well as on deadly purpose, and moreover a species that until only recently was convinced that the Universe was made for its sole benefit-are we to venture out into space, move worlds, reengineer planets, spread to neighboring star systems?” (329). Sagan answers his question, describing that those who will travel and colonize other planets will be better versions of ourselves. That is, “If we continue to accumulate only power and not wisdom, we will surely destroy ourselves. Our very existence in that distant time requires that we will have changed our institutions and ourselves. How can I dare to guess about humans in the far future? It is, I think, only a matter of natural selection. If we become even slightly more violent, shortsighted, ignorant, and selfish than we are now, almost certainly we will have no future” (329).
Sagan continues with his previous response, elaborating that current humans will not be the ones who reach Alpha Centauri. On the other hand, “It will be a species very like us, but with more of our strengths and fewer of our weaknesses, a species returned to circumstances more like those for which it was originally evolved, more confident, farseeing, capable, and prudent-the sorts of beings we would want to represent us in a Universe that, for all we know, is filled with species much older, much more powerful, and very different” (329). Following this logic, the difficulty of interstellar travel is in itself a sort of test: a species which only wars against itself will lack the unity, knowledge, and decency to be able to conduct such a feat. Sagan soon talks about dark matter: matter which we consider normal make up only a minority of the universe. Sagan, after discussing humanity’s potential future, summarizes our history as life forms: “Two billion years ago our ancestors were microbes; a half-billion years ago, fish; a hundred million years ago, something like mice; ten million years ago, arboreal apes; and a million years ago, proto-humans puzzling out the taming of fire. Our evolutionary lineage is marked by mastery of change. In our time, the pace is quickening” (332). When fish first began walking on land, many died. This clearly demonstrates that key transitions in evolution for our species were frequently dangerous and costly. Furthermore, the processes “took millions of years, and were imperceptible to those involved” (332). On the other hand, our current situation involves a technological transition that “occupies only a few generations, and with only a handful of lives lost. The pace is so swift that we are still barely able to grasp what is happening” (333). Sagan then brings humanity back to Earth, stating that even though we have great potential, we are still fragile and fallible. He ends his book with the following segment: “The Cosmos extends, for all practical purposes, forever. After a brief sedentary hiatus, we are resuming our ancient nomadic way of life. Our remote descendants, safely arrayed on many worlds through the Solar System and beyond, will be unified by their common heritage, by their regard for their home planet, and by the knowledge that, whatever other life may be, the only humans in all the Universe come from Earth. They will gaze up and strain to find the blue dot in their skies. They will love it no less for its obscurity and fragility. They will marvel at how vulnerable the repository of all our potential once was, how perilous our infancy, how humble our beginnings, how many rivers we had to cross before we found our way” (334).
Personal thoughts:
Pale Blue Dot: A Vision of the Human Future in Space by Carl Sagan is an astounding, fantastic, enlightening, and beautiful book. It elegantly shows the human condition from both a humanistic and a scientific perspective. It is optimistic while being rational and sane, a rare achievement on its own. Furthermore, it provides a large amount of scientific facts and hypothetical scenarios which are virtually guaranteed to broaden the horizons of the readers. Pale Blue Dot should be read by every Homo Sapiens due to its calls for humanity, decency, knowledge, and cooperation. I highly recommend it to anyone interested in space, science, the big picture, and history.
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