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Writer's pictureJason Wang

Summary of "Cosmos"

Updated: Aug 24, 2020


Cosmos is a science classic published in 1980 by Carl Sagan, a scientist who focused on the universe and the public perception of science. Cosmos discusses humanity’s role in the Cosmos in a way both poetic and honest, which explains its popularity - it deserves to be so, for it is both witty and serious, accessible yet monumental in scope.

Sagan begins the book by writing in the introduction that science has revealed to humanity of its insignificance in the universe. To definitively answer the question as to whether reality is stranger than fiction, it can be possibly answered that that statement is true, for what we call “fiction” stems from our limited perceptions, which in turn have been fashioned by reality. Consequently, there are many unimaginable phenomena and events in space which fiction couldn’t have imagined before, as for most of humanity’s existence, the Cosmos was an absolute mystery. However, in the 20th century, humanity’s understanding of the universe has greatly improved. Sagan wrote that despite our newfound knowledge, “We have grown distant from the Cosmos. It has seemed remote and irrelevant to everyday concerns. But science has found not only that the universe has a reeling and ecstatic grandeur, not only that it is accessible to human understanding, but also that we are, in a very real and profound sense, a part of that Cosmos, born from it, our fate deeply connected with it” (xxiii). Sagan then talks about space travel, including the Voyagers 1 and 2, spacecrafts who had encountered Saturn and its largest moon, aptly named Titan. Science has revealed to humanity a tapestry of unparalleled size, and it is our responsibility, nay, our duty, to learn more and to act appropriately.


Sagan writes in the first chapter, “The Shores of the Cosmic Ocean,” of the infinite appeal of the universe: the Cosmos is all that is or ever was or ever will be. Our feeblest contemplations of the Cosmos stir us-there is a tingling in the spine, a catch in the voice, a faint sensation, as if a distant memory, of falling from a height. We know we are approaching the greatest of mysteries” (1). Sagan then discusses that the Cosmos is so large in scope and age that the human brain couldn’t comprehend it for what it really is, and that what we know so far is nothing compared to what is out there. Sagan then states that Earth, for us, is only the shore of the cosmic ocean, and that we wish to go into the deep end to explore and to undergo the process of self-actualization. Sagan states that space is so massive and monumental that it is measured in the speed of light: “In one second a beam of light travels 186,000 miles, nearly 300,000 kilometers or seven times around the Earth” (2). Sagan then writes that we are indeed very lucky to have the civilization we have when we look at the Cosmos as a whole, for “If we were randomly inserted into the Cosmos, the chance that we would find ourselves on or near a planet would be less than one in a billion trillion trillion” (3). Sagan continues with staggering statistics, revealing that there are more than a hundred billion galaxies, each with an average of a hundred billion stars. He hypothesizes that in most galaxies, there are as many planets as stars. He writes that he believes that the universe contains much life, and that we didn't discover any extraterrestrials yet because we inhabit “a tiny speck of rock and metal, shining feebly by reflected sunlight, and at this distance utterly lost” (4). The Local Group of galaxies is several million light-years long. The Milky Way has some 400 billion stars.

Sagan then writes that it took humanity some time for it to realize that the earth wasn’t the only thing in the galaxies. To begin, even the unaided eye can see, in a night sky devoid of smog and clouds, a wide plethora of stars. Despite being visually able to see into space, humanity as a whole was at a loss of what was truly out there. Eratosthenes, a scientist who lived more than 2,200 years ago, was able to measure the Earth very accurately using only “sticks, eyes, feet and brains, plus a taste for experiment” - reflecting sunlight and shadow, he noticed that shadows are longer when cast in certain directions. This caused him to hypothesize that the earth was a sphere hanging in space, and that the earth itself was curved. This demonstration of scientific genius and innovation is a clear example of what humanity can do, even with limited resources. Sagan soon discusses how humanity has evolved in our little corner - through natural selection, humans evolved from, in Sagan’s own words, “microbes and muck.” Sagan, to demonstrate the principle of natural selection, wrote how a certain lake in Japan had many crabs which appeared to have samurai faces. He describes that there was a legend of a young emperor who was defeated and killed at the lake, and afterwards, whenever crabs were fished out, they would first be inspected for human faces. Crabs which had exoskeletons that suggested a human face were thrown back in and flourished, while those which did not were eaten. Charles Darwin himself wrote in The Origin of Species that a great example of selection is seen in how humans domesticate animals for various reasons - we let (or make) animals with traits we like mate and produce offspring. Sagan then goes back to the very beginning of life on earth, writing how the Earth “condensed out of interstellar gas and dust some 4.6 billion years ago,” and that “We know from the fossil record that the origin of life happened soon after, perhaps around 4.0 billion years ago, in the ponds and oceans of the primitive Earth” (27). He then notes that the earliest organisms were not so complicated as to even qualify as a single-celled organism, for extreme environmental and atmospheric conditions produced molecules and “one day, quite by accident, a molecule arose that was able to make crude copies of itself, using as building blocks other molecules in the soup” (27).


Three billion years ago, multicellular organisms came into existence, while sexual behavior came into existence two billion years ago. The advantage of sexual reproduction was that diversity occurred much quicker, seen in how parents would combine their DNA to form an entirely new organism. By one billion years ago, plants had utterly transformed the earth’s atmosphere by introducing oxygen into the atmosphere. This kind of phenomena is seen best with the Great Oxidation Event, in which cyanobacteria almost wiped out life on Earth by pumping a previously unknown compound, oxygen, into the atmosphere in large quantities. Most organisms at the time, which were used to nitrogen, and completely unused to oxygen and an oxygen-rich atmosphere, promptly perished. The devastation was to such a degree that almost all life on earth went extinct. After this cataclysm, it became much easier for multicellular organisms to survive, as oxygen was better suited for that purpose. Sagan then wrote that oxygen “is fundamentally a poison for unprotected organic matter … The nitrogen in the Earth’s atmosphere is much more chemically inert and therefore much more benign than oxygen. But it too is biologically sustained. Thus, 99 percent of the Earth’s atmosphere is of biological origin. The sky is made by life” (29). Sagan then wrote that for most of the four billion years of life, the main form which life took was that of simple algae in the ocean. However, 600 million years ago, there was an explosion of biological forms. This is known today as the Cambrian explosion, and dinosaurs soon evolved. Then they were annihilated by the asteroid in the Triassic Extinction, and humans evolved. We owe our current society to all the aforementioned events, showing just how unlikely this whole affair is, for good or for ill.


Sagan soon notes that while astronomy is a relatively popular field, it is, statistically, more likely for someone in a grocery store to buy a book about astrology than one on astronomy. Sagan states that this is a pity, for astrology has no empirical evidence, and is therefore extremely unlikely to be accurate. Sagan then discusses people who innovated how we see the Cosmos, including Tycho Brahe and Johannes Kepler. Tycho observed the planets and held in high esteem an idealized, perfect universe. Kepler idolized Brahe, but upon meeting him, was disappointed to find that he was very inefficient with finances. Tycho was also unwilling to show him his data. Kepler, deciding to pursue his own research, soon came up with three laws that describe the motion of planets. Through his scientific laws, he made a groundbreaking discovery: previous Christian scientists viewed planets and spheres as moving in circles. Kepler realized that they moved in ellipses. Kepler’s three laws are as follows: (1) “A planet moves in an ellipse with the Sun at once focus,” (2) “Planets sweep out equal areas in equal times,” and (3) “the squares of the periods of the planets (the times for them to complete one orbit) are proportional to the cubes of their average distance from the Sun” (63). Kepler, after making his discoveries, had his life thrown into a crisis as the Thirty Years War, fought due to various alliances between many European Kingdoms and religious fanaticism between different Christian sects, raged - his wife and son died of a disease which the soldiers carried. He was forced to flee, was excommunicated by his church for having differing opinions, and lost whatever wealth he had. His mother was also threatened with torture on slim evidence, but Kepler was able to use the scientific method to clearly show that she was in fact not a witch. To specify, she was blamed for the bad health of some authority figures. Kepler illustrated that they were simply using her as a scapegoat, as there is no logical correlation between her and their ailments. Kepler spent the remainder of his life struggling with money; his grave was then destroyed during the Thirty Years War. The epitaph wrote beforehand by Kepler himself read “‘I measured the skies, now the shadows I measure. Sky-bound was the mind, Earth-bound the body rests,’” and Sagan notes that it would be fitting if it read “‘He preferred the hard truth to his dearest illusions’” (69).


Sagan then discusses Isaac Newton, writing that he greatly improved calculus and physics due to his genius. For instance, when a plague ravaged the city he was in, he stayed at school and revolutionized calculus as a personal project. Newton wrote about mathematics and space in his Principia, and right before he died, he wrote “‘I do not know what I may appear to the world; but to myself I seem to have been only like a boy, playing on the seashore, and diverting myself, in now and then finding a smoother pebble or a prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me’” (75). Sagan noted that Kepler and Newton were both revolutionary figures, for they illustrated that space and the laws of the universe, Physics, can indeed be understood by people through observational data. Sagan then discusses how volatile events can be when it comes to planetary spheres, as external stressors like asteroids and internal stressors like earthquakes can greatly change the fate of a planet. One needs to only look at the moon’s various craters to see the magnitude of cosmic bombardment, and Sagan writes that even though the space near Earth’s immediate vicinity is relatively clear today, “there may have been more interplanetary debris a few billion years ago than there is today” (89). Sagan then brilliantly describes that even though it is very likely that both the Earth and the moon were pummelled by cosmic debris billions of years ago, the reason Earth has “recovered” is due to it having an atmosphere and biological processes. Nietzsche once wrote that the largest mountains were once in fact at the bottom of the ocean, and this encapsulates what Sagan is trying to say: Earth was scarred like the moon many years ago, but millions of years of geographic processes slowly removed its scabs. Sagan put it himself, “The only possible explanation is that impact craters are formed at very similar rates on both the Earth and the Moon, but that on the airless, waterless Moon they are preserved for immense periods of time, while on the Earth slow erosion wipes them out or fills them in. Running water, windblown sand and mountain-building are very slow processes. But over millions or billions of years, they are capable of utterly erasing even very large impact scars” (92).


Sagan then speaks of the limits of human perception, for our eyes operate within a certain color range, and colors outside the range are effectively invisible to us; that is why astronomers use a variety of instruments to capture pictures from space. Sagan had done research on Venus before, and he warns of what it has to say about our society: we currently burn fossil fuels to generate energy. This poses various issues, ranging from pollution to the fact that there is only a limited amount of oil. Furthermore, oil takes millions of years to form, a process which humans don’t have the patience for. Sagan writes that Venus was once believed to be a planet like Earth, but upon closer inspection, it appeared to be a molten hell, for the temperatures were extremely high, making life all but impossible. Sagan elegantly describes that this is due to the greenhouse effect - while a little of the greenhouse effect helps keep the planet warm, too much can create a runaway greenhouse effect, effectively ending all life. “If the Earth were moved only a little closer to the Sun, the temperature would increase slightly. This would drive some of the CO2 out of the surface rocks, generating a stronger greenhouse effect, which would in turn incrementally heat the surface further … there would be the possibility of a runaway greenhouse effect to very high temperatures. This is just what we think happened in the early history of Venus, because of Venus’ proximity to the Sun. The surface environment of Venus is a warning: something disastrous can happen to a planet rather like our own” (105). Sagan then questioned humanity’s future, seeing how its behavior, from a large standpoint, is both immature and foolish: “Our intelligence and our technology have given us the power to affect the climate. How will we use this power? Are we willing to tolerate ignorance and complacency in matters that affect the entire human family? Do we value short-term advantages above the welfare of the Earth? Or will we think on longer time scales … to understand and protect the complex life-support systems of our planet? The Earth is a tiny and fragile world. It needs to be cherished” (107).


Sagan then moves on to discuss Mars, the red planet. He describes how people wanted to believe that Mars had life due to the fact that it looked like Earth. It also had popular appeal due to The War of the Worlds by H. G. Wells, published in 1897, which involves Martians from Mars invading earth in tripods. In 1984, a Bostonian, Percival Lowell, claimed that he had found canals on Mars. People were extremely excited, but this was shown to be inaccurate, as the “canals” were in fact natural formations of Mars’s geography. Sagan then described that the Voyager spacecraft, when it was sent to space, had no goal in mind - it will, for an extremely long period of time, move through space in a way similar to how the Flying Dutchman moves in the ocean: “the Voyager spacecraft will plunge on, penetrating the heliopause sometime in the middle of the twenty-first century, skimming through the ocean of space, never to enter another solar system, destined to wander through eternity far from the stellar islands and to complete its first circumnavigation of the massive center of the Milky Way a few hundred million years from now. We have embarked on epic voyages” (170). Attached to the voyager is the Golden Record, designed by Sagan himself, which is supposed to introduce humanity via pictures and sounds (we only show our desirable side, unsurprisingly, such as our curiosity and potential benevolence). The Golden Record symbolizes what humanity can truly do when cooperation is reached, and the fact that a project like this was only done once serves to show a major shortcoming of our species: we are capable of greatness, but petty differences divide us from doing what we could do.


Sagan then writes about great thinkers who paved the way for our idea of the Cosmos. They include Anaximander, who stated that “human beings arose from other animals with more self-reliant newborns: He proposed the spontaneous origin of life in mud, the first animals being fish covered with spines. Some descendants of these fishes eventually abandoned the water and moved to dry land, where they evolved into other animals by the transmutation of one form into another. He believed in an infinite number of worlds, all inhabited, and all subject to cycles of dissolution and regeneration” (185). Of course, while his latter idea cannot be supported or denied, his first idea was frighteningly accurate - the first microbes did indeed emerge from virtually nothing, and fish (including the walking fish, the Tiktaalik), became mammals after learning to walk on land and leaving the water. The “transmutation” of forms can be read as an old term for evolution. Aside from Anaximander, there was Empedocles, who was probably extremely smart, so smart that “He believed that light travels very fast, but not infinitely fast. He taught that there was once a much greater variety of living things on the Earth, but that many races of beings ‘must have been unable to beget and continue their kind. For in the case of every species that exists, either craft or courage or speed has from the beginning of its existence protected and preserved it’” (187). Empedocles, humorously, was said to have died by leaping into a volcano in an ecstatic fit, which Sagan attributes to pure carelessness: “sometimes I imagine that he merely slipped during a courageous and pioneering venture in observational geophysics” (188).


Then there was Democritus, who thought of worlds colliding before planetary collisions and asteroids became known to science. He was also the father of the word “atom,” which means “unable to be cut.” Atoms were the smallest units of nature, and Democritus effectively conveyed the subject by stating that when an apple is cut by a knife, there must be spaces between the atoms, for if there were no spaces for the knife to go through, the apple couldn’t be cut. Democritus was also a friend of Hippocrates, and although he was nervous about “Women, children and sex” because “they took time away from thinking,” he cherished the idea of friendship and enthusiasm (189). Interestingly, one time he went to Athens to see Socrates, but was too nervous to go through with it. He was also astounded by “the beauty and elegance of the physical world,” and “felt that poverty in a democracy was preferable to wealth in a tyranny. He believed that the prevailing religions of his time were evil and that neither immortal souls nor immortal gods exist: ‘Nothing exists, but atoms in the void’” (190). Anaxagoras was a Greek scientist who was rich but cared for science more than his wealth. He believed that the hands of humans made them more intelligent than other organisms, and he was also a firm believer of atoms. He was also “the first person to state clearly that the Moon shines by reflected light, and he accordingly devised a theory of the phases of the Moon” (191). This caused his findings to be circulated in secret, for it was believed at the time that the Sun and Moon were gods. Anaxogas, however, derided that they were “fiery stones” (191). While he wasn’t entirely accurate, his free spirit and inquiry are commendable. As Bertrand Russell said, “If fifty million people say a foolish thing, it is still a foolish thing.” The Pythagoreans came after Anaxagoras, and while the Ionians believed in experiments and hypotheses to be able to deduce the nature of the universe, the Pythagoreans were rationalists, believing that pure thought/reason could discern the nature of the Cosmos. The most famous Pythagorean was Pythagoras, who was humorously criticized by Bertrand Russell as being averse to beans and practicing the equivalent of a religion, if only in scientific terms. The Pythagoreans idolized numbers and geometry, hence the Pythagorean Theorem.


Sagan then wrote of how many philosophers, even Aristotle and Plato, disdained the practical. Sagan described that the “antiempirical taint of the Pythagoreans” directly stemmed from the desire of worldly wealth. A historian, Benjamin Farrington, wrote that an economy which thrived on slaves couldn’t possibly offer them arguments to free them in fear of offending the privileged few, which meant that all the talk of “democracy” and “freedom” in Athens applied to only the rich. While there was much room for technological progress, people greatly refrained from doing so, as there were a great number of slaves who could do the work for them. Sagan then wrote that “Plato and Aristotle were comfortable in a slave society. They offered justifications for oppression. They served tyrants. They taught the alienation of the body from the mind (a natural enough ideal in a slave society); they separated matter from thought; they divorced the Earth from the heavens-divisions that were to dominate Western thinking for more than twenty centuries. Plato, who believed that ‘all things are full of gods,’ actually used the metaphor of slavery to connect his politics with his cosmology. He is said to have urged the burning of all the books of Democritus … perhaps because Democritus did not acknowledge immortal souls or immortal gods or Pythagorean mysticism, or because he believed in an infinite number of worlds” (199). Even more damningly, of Democritus’s known seventy-three books, “covering all of human knowledge, not a single work survives. All we know is from fragments, chiefly on ethics, and secondhand accounts. The same is true of almost all the other ancient Ionian scientists” (199). Sagan then states that the Pythagoreans, Platonists, and the Christians have indeed separated the earth from the heavens, viewing the heavens as somehow immaculate and perfect, while seeing the earth as somehow corrupted and tainted. This has led to progress being stalled, a disservice to humanity: “In the recognition by Pythagoras and Plato that the Cosmos is knowable, that there is a mathematical underpinning to nature, they greatly advanced the cause of science. But in the suppression of disquieting facts, the sense that science should be kept for a small elite, the distaste for experiment, the embrace of mysticism and the easy acceptance of slave societies, they set back the human enterprise” (199).


Sagan soon states that there are more stars in the universe than all the grains of sand on the beaches of earth. He talks about constellations, and that they do change, but over long periods of time. The Big Dipper, for instance, looked like a spear a million years ago. Sagan then discusses travelling at the speed of light, writing that when travelling at a speed close to it, time operates differently, causing a person to age extremely slowly. Therefore, Sagan describes that “Traveling close to the speed of light is a kind of elixir of life. Because time slows down close to the speed of light, special relativity provides us with a means of going to the stars” (218). Sagan then writes that space travel is quite feasible in the future. He then remarks that if the Ionian spirit of experimentalism had only survived, humans might have gone to the stars already. That is, “what if the light that dawned in the eastern Mediterranean 2,500 years ago had not flickered out? What if science and the experimental method and the dignity of crafts and mechanical arts had been vigorously pursued 2,000 years before the Industrial Revolution?” (224). Sagan states that he believes that ten to twenty centuries would have been saved in time, and that “Perhaps the contributions of Leonardo would have been made a thousand years ago and those of Albert Einstein five hundred years ago. In such an alternate Earth, Leonardo and Einstein would, of course, never have been born” (224). Sagan then discusses probability, revealing that the chance of a person being born is infinitesimally small - all the events leading up to their birth has to be an exact way, and even if their parents are to meet and become romantically involved, they had to copulate in a certain manner, for “In every ejaculation there are hundreds of millions of sperm cells, only one of which can fertilize an egg and produce a member of the next generation … If even a little thing had gone differently 2,500 years ago, none of us would be here today. There would be billions of others living in our place” (225).


Sagan then writes that atoms are composed of three kinds of particles: protons, neutrons, and electrons. Sagan discusses the beginning of the universe, writing that in the beginning, all matter and energy were concentrated in one small point, and that when the Big Bang occurred, the energy in the small point began a rapid expansion that has never stopped since, not even once. Sagan writes it is inaccurate to view the expansion of the universe from the outside, for there is no outside, or at least no outside that we currently know of. Therefore, “It is better to think of it from the inside, perhaps with grid lines-imagined to adhere to the moving fabric of space-expanding uniformly in all directions” (257). Sagan talks about cosmic evolution, including the fact that galaxies commonly merge and change forms. He also talks about the Doppler Effect, which deals with sound and light, mandating that as a person approaches the source of the emitter, the frequency of what it emanates will increase. This is exemplified in how the blare of a siren will become much louder if it gets substantially closer to you, and this also applies in space when it comes to picking up waves in the observatory. Sagan writes that the Big Bang might not even be the beginning of the universe, for the universe might have always existed. Furthermore, many creation myths around the world, from India to China, are only byproducts of human imagination, not reasoned results that stem from evidence. Sagan continues to describe that the Big Bang might operate through oscillation, beginning with a Big Bang before collapsing in on itself (known as the “Big Crunch”), then experiencing a repeat of the cycle. It is also possible that the universe’s expansion will never end, and the Big Crunch is not going to happen. Sagan then talks about varying forms of perception, from the third dimension to the fourth. We are currently viewing objects from the third-dimensional perspective, but if it was possible to see the world from the fourth-dimensional perspective, as speculated by scientists, you could see both space and time.


Sagan soon writes of the wonder of life on earth, focusing on the blue whale. The blue whale still exists, but most of its members have been slaughtered by Homo Sapiens in the advent of naval technology. Blue whales are larger than even dinosaurs, seeing that an adult can be as long as thirty meters and weigh 150 tons. They are relatively passive hunters, opening their mouths to filter feed, and had evolved from land animals - “Over seventy million years ago their ancestors were carnivorous mammals who migrated in slow steps from the land into the ocean” (286). They have a remarkable communication system which utilizes sonar, allowing them to communicate anywhere in the world. They also have beautiful songs which they probably sing for socializing. When humans appeared, they were unprepared - for 99.9% of their history humans didn't exist, and they weren’t being used to being hunted. Furthermore, the noise pollution produced by humans, seen in boats and other pieces of technology, have effectively silenced these magnificent creatures, as their sonar waves are much harder to detect in a world full of noise: “Two hundred years ago, a typical distance across which finbacks could communicate was perhaps 10,000 kilometers. Today the corresponding number is perhaps a few hundred kilometers” (288). Despite having slaughtered most of the whales, humans continue to hunt them, for parts of their bodies are used for lipstick and lubricant. Sagan condemns our current behavior - we are so interested in meeting extraterrestrials, yet we treat intelligent organisms on the same planet with insensitivity, brutality, and utter stupidity: “Would not a good beginning be improved communication with terrestrial intelligence, with other human beings of different cultures and languages, with the great apes, with the dolphins, but particularly with those intelligent masters of the deep, the great whales” (289). Sagan then discusses how humanity’s cranium is a mix between our higher abilities and our primal drives, and of how civilization as we know it owes its existence to the cerebral cortex.


Sagan soon talks again of the evolution of humanity, noting that before the Triassic Extinction, dinosaurs reigned supreme. At the time of the dinosaurs, what would become humanity was a species of small mammals, “creatures with the size and intelligence of moles or tree shrews” (299). The Triassic Extinction destroyed the dinosaurs - the asteroid is a very popular theory, and it states that it wasn’t the asteroid itself that killed them, but the fact that the dust which was thrown into the air blocked out the sunlight, which caused the food chain to collapse. Dinosaurs, which needed large amounts of food to survive, starved to death. Our ancestors, being small in size, found enough to survive while larger organisms perished. Sagan writes that it is possible that up to 96% of all the species in the ocean went extinct. Sagan then describes that it is not entirely known what killed the dinosaurs, but the end result was the same - they died out. He continues to describe humanity’s evolution, clearly illustrating that Homo Sapiens formed by chance - the climate caused humans to leave the safety of the trees. Sagan then writes in the last chapter of humanity’s great potential, seeing that if we could only work together, we could travel into space. He then notes humanity’s follies, discussing the Cold War - if nuclear weapons were actually utilized, there would be a WWII every single second. Most of the devastation, indeed, would be done rapidly, as nuclear weapons are remarkably fast at reaching their targets. He included the testimony of a girl who survived the Hiroshima explosion: “Through a darkness like the bottom of hell, I could hear the voices of the other students calling for their mothers. And at the base of the bridge … a mother, weeping, holding above her head a naked baby that was burned bright red all over its body. And another mother was crying and sobbing as she gave her burned breast to her baby … And the singed hair on the heads of the people was frizzled and whitish and covered with dust” (339-40). Sagan then writes of the nuclear testing by world powers, seeing how on March 1, 1954, a nuclear weapon was tested at Bikini (a Spongebob Theory states that Bikini Bottom stems directly from this), which was located in the Marshall Islands. While no one was killed directly, those who were near the area were still exposed to the radiation, and “Two-thirds of the children and one-third of the adults later developed thyroid abnormalities, growth retardation or malignant tumors. In compensation, the Marshall Islands received expert medical care” (340).


Sagan then writes that at the time of his writing (and this still remains true today), if all the nuclear weapons were dispatched, Earth would be pummelled multiple times - there are more than enough bombs to wipe out humanity, not to mention other species. He then writes of the conflict between the Soviet Union and America, and that “deterrence,” while effective, still carries the terrible risk of nuclear annihilation. Furthermore, it doesn’t take a genius to invent a reason for a country to have nuclear weapons. Among the most commonly cited reasons include “self defence”: “Every nation seems to have its set of forbidden possibilities, which its citizenry and adherents must not at any cost be permitted to think seriously about. In the Soviet Union these include capitalism, God, and the surrender of national sovereignty; in the United States, socialism, atheism, and the surrender of national sovereignty. It is the same all over the world” (347). Sagan then appeals to humanity’s sense of responsibility, asking how we could justify our behavior to aliens. For all our intelligence (two-thirds of the mass of the brain is attributed to the cerebral cortex), we continue to behave in a manner unbecoming of our respect: “How would we explain the global arms race to a dispassionate extraterrestrial observer? How would we justify the most recent destabilizing developments of killer-satellites, particle beam weapons, lasers, neutron bombs, cruise missiles, and the proposed conversion of areas the size of modest countries to the enterprise of hiding each intercontinental ballistic missile among hundreds of decoys? Would we argue that ten thousand targeted nuclear warheads are likely to enhance the prospects for our survival? What account would we give of our stewardship of the planet Earth? We have heard the rationales offered by the nuclear superpowers. We know who speaks for the nations. But who speaks for the human species? Who speaks for Earth?” (347).


Sagan then writes of the relationship between violence and types of societies, and the results are jarring: societies that are tolerant towards premarital sexual affairs and don’t physically punish children have only a 2% chance of experiencing violent and undesirable behavior like slavery, torture, murder, and abuse. On the other hand, Sagan backs the neuropsychologist James W. Prescott who believes “that cultures with a predisposition for violence are composed of individuals who have been deprived-during at least one of two critical stages in life, infancy and adolescence-of the pleasures of the body. Where physical affection is encouraged, theft, organized religion and invidious displays of wealth are inconspicuous; where infants are physically punished, there tends to be slavery, frequent killing, torturing and mutiliation of enemies, a devotion to the inferiority of women, and a belief in one or more supernatural beings who intervene in daily life” (350). Sagan then states that child abuse and sexual repression should be viewed as crimes against humanity, for those who undergo those things are deformed mentally. Sagan then states that these findings, though morbid in the fact that humanity has made many errors, are also hopeful in that they offered the chance for improvement. Many terrible practices have been largely banned over the past few centuries. Slavery, once a prominent feature of civilizations like America, Rome, and Britain, has been almost completely outlawed. War crimes, seen in the wanton slaughter and abuse of civilian populations, are now largely viewed as heinous acts. The subjection of women to men, corresponding with the fact that they had little rights due to patriarchies, has decreased in magnitude to a massive extent in most societies. Disease, once misunderstood and unknown, has now been discerned by scientists - our treatments for disease shows what science can truly do if given the resources. Democracy, though fragile, has notably improved, as Europe, aristocratic for much of its history, has largely abandoned extremist ideologies such as Fascism. Germany, for instance, is now a first-world nation with a democracy and affordable health care system (unlike America), a remarkable improvement considering that less than a century ago it practiced totalitarianism and was headed by a lunatic. All of this points to one thing: the living standards of most humans have notably improved. Or as Steven Pinker would put it, the better angels of our nature are now winning over our inner demons.

Sagan ends his book by appealing to people to become more tolerant, kind, and curious. He mentions Hypatia of Alexandria, a brilliant scholar who was brutally murdered by religious fanatics, to represent what humanity could have achieved many years ago. He then states that if an extraterrestrial observer was to note the Earth, they would view our differences as insignificant, for we are almost completely identical. Sagan points out that the cost of having a large space program is next to nothing compared to the amount spended on the military, and that we have much to learn. Sagan ends his book with the following sentences: “For we are the local embodiment of a Cosmos grown to self-awareness. We have begun to contemplate our origins: starstuff pondering the stars; organized assemblages of ten billion billion billion atoms considering the evolution of atoms; tracing the long journey by which, here at least, consciousness arose. Our loyalties are to the species and the planet. We speak for Earth. Our obligation to survive is owed not just to ourselves but also to that Cosmos, ancient and vast, from which we spring” (364-5).


Personal thoughts:

Cosmos is a truly fantastic book. If there is only one book you have to read in your life, this is one of my top candidates. Cosmos is so stunning because it puts everything into perspective, as once we realize our place in the universe, we can truly start to act maturely. All of humanity’s rivalries, nationalistic sentiments, partisan politics, religious differences, racism, and class struggles are for naught when the big picture, the Cosmos, is truly observed. Sagan himself once stated that “If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.” As I reflect on the book now, my view of humanity is conflicted. As Sagan and many others wrote, humans could become truly great, yet we are still held back by our instincts, prejudices, and delusions. Regardless, it will be interesting to see how the human race does for the rest of our existence. Will we get along relatively well and explore other worlds, or will we stagnate and meet our end on Earth? It is truly impossible to tell through guessing alone, but we can each do our own part by practicing the traits Sagan himself proposed. Indeed, if we use Kant’s categorical imperative, if each person was tolerant, curious, and kind, the world would be a much better place to live in. I give my highest recommendations for Cosmos to anyone interested in humanity, space, the future, science, and ethics.


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