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Big History – Cynthia Brown
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PART I: The Depths of Time and Space
1. Expanding into Universe (13.7 Billion–4.6 Billion Years Ago)
o Our universe has at least four dimensions, three of space and one of time, meaning that time and space are interconnected. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 3.]
o Initially the universe was composed of “cosmic plasma,” a homogeneous substance so hot that it had no known structure at all. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 4.]
o Before one second had elapsed the four fundamental forces that govern matter had come into being: gravitational force, electromagnetic force, the strong nuclear force, and the weak nuclear force. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 5.]
o Scientists believe that all four forces must be aspects of one force, but they have not yet been able to create a unifying theory. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 5.]
o These four forces work in perfect balance to allow the universe to exist and expand at a sustainable rate. If the gravitational force were a tiny bit stronger, all matter would likely implode in on itself. If gravity were slightly weaker, stars could not form. If the temperature of the universe had dropped more slowly, the protons and neutrons might not have stopped at helium and lithium but continued to bond until they formed iron, too heavy to form galaxies and stars. The exquisite balance provided by the four forces seems to be the only way in which the universe can maintain itself. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 5, 6.]
o The newborn universe evolved with phenomenal speed, setting in place in a tiny fraction of a second the fundamental properties that have remained stable since. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 6.]
o the universe was filled with so many zigzagging particles, some negative, some positive, that light (consisting of subatomic particles called photons) could not move through the bath of charged particles. This was so because photons interact with electrically charged particles and are either deflected or absorbed. If anyone had been there to see it, the universe would have appeared as a dense fog or a blinding snowstorm. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 6.]
o If our eyes were sensitive to microwaves, which they are not, we would see a diffuse glow in the world around us. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 6.]
o In the spring of 1965 two radio astronomers, Arno A. Penzias and Robert W. Wilson, working for Bell Laboratories in New Jersey, accidentally detected this afterglow as a background hissing noise while they were testing a new microwave antenna to be used with communication satellites. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 6, 7.]
o In 1989 NASA sent up the Cosmic Background Explorer (COBE) satellite, which collected information that confirmed with high precision that there are about 400 million photons in every cubic meter of the universe—an invisible cosmic sea of microwave radiation, at 3 degrees above absolute, just as predicted by the theory of the big bang. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 7.]
o In 2002 NASA sent a sixteen-foot probe called the Wilkinson Microwave Anisotropy Probe, or WMAP, a million miles out from Earth. For a year WMAP took time exposures of the entire sky, showing in high resolution the map of the cosmic background radiation (CBR) from 380,000 years after the big bang and confirming again the big bang account of the universe. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 7.]
o We can never see the universe as it is today, only as it once was, because it takes millions and billions of years for the light of distant galaxies and stars, traveling at nearly 6 trillion miles a year, to reach us. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 7.]
o Most of the stars nearest us are red stars, but the one we know best, the sun, is a stable yellow star burning hydrogen, called hydrogen fusion as described earlier. When its hydrogen is used up, in about 5 billion years, our sun will switch to burning helium, called helium fusion. Since helium fusion is a hotter process with a greater energy output, the pressure from the extra energy will expand the sun until it becomes what is called a red giant. When the helium fuel is used up, the red giant will collapse to a white dwarf. Then it will slowly cool until it becomes a cinder called a black dwarf, about the size of Earth and 200,000 times its mass. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 9.]
o Some yellow stars, the ones that are larger than our sun at their inception, become larger red giants than our sun will. When their red-giant stage is over, they do not shrink into white dwarfs. In them heavier elements are created and burned: carbon, nitrogen, oxygen, magnesium, and finally iron. But iron cannot be used as a stellar fuel. Energy production stops and gravity takes over. The star’s core implodes and triggers an immense explosion of the outer layers that blasts most of the star to smithereens. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 9.]
o We quite literally are made of stardust. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 10.]
o Our Milky Way galaxy is a perfect spiral, the lucky accident of being in a non–congested area of the early universe about 12 billion years ago. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 10.]
o This sun was an average-sized star, distinguished by not having a companion star (about two-thirds of the stars in our section of the Milky Way are multiple-star systems). [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 11.]
o It takes about 225 to 250 million years to circle around the center of the galaxy in an elliptical, or oval, orbit, traveling about 200,000 miles a day. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 11.]
o As centers of concentration developed in these bands, the planets emerged, with the sun’s gravity making the inner four (Mercury, Venus, Earth, and Mars) heavier and rockier, while the outer ones (Jupiter, Saturn, Uranus, and Neptune) are lighter and more gaseous. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 11.]
o Only Earth has a size that produces a gravitational and electromagnetic balance, which allows a solid rock crust to form around a burning core. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 12.]
o Only Earth has a position in respect to the sun, a mean distance of 93 million miles, that establishes a temperature range in which complex molecules can form. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 12.]
o This tilt of our axis as we spin creates the seasons here on Earth, for if we spun on a vertical axis both hemispheres would receive the same amount of sunlight all year round. (All other planets revolve on a vertical axis except Uranus, which revolves on a nearly horizontal axis.) [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 12.]
o The moon is so small that it quickly lost its internal heat and preserved its original surface. Earth was sufficiently large—with a core hot enough that the heat of those early impacts kept it boiling day and night—that no imprints of the collisions could form. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 12.]
o Even the origin of our moon is uncertain. Some say it is a piece broken off from Earth, but most believe that the moon arose when a planetoid crashed against Earth, could not escape its gravity, and went into orbit, knocking Earth off its vertical axis to the slightly tilted one that creates our seasons. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 13.]
o More difficult questions come to mind, such as: “Why do mathematical equations work to account for things like the trajectory of the moon and of the Andromeda galaxy?” and “What came before the big bang?” To the first question, mathematicians just shrug and joke, “God is a mathematician.” It is simply amazing that we are able to understand anything about the universe, that our minds can create equations that correlate with reality. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 13.]
o What came before the big bang? No one knows what the initial conditions of the universe were. Some physicists believe the answers to this question lie forever beyond the grasp of the human mind and any of its theories. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 13.]
o In the last few decades physicists have learned that the expansion of the universe is not slowing down but rather is accelerating. Something unknown is pushing the universe farther apart. Scientists are calling this unknown antigravitational force “dark energy,” or the energy of nothingness. They also believe there is something called “dark matter,” unlike anything on Earth. No one knows yet what dark matter and energy are; scientists currently think that they may constitute more than 90 percent of the universe. The search has only just begun. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 15.]
2. Living Earth (4.6 Billion–5 Million Years Ago)
o Life on Earth is a shimmering mystery. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 16.]
o Earth has always managed to preserve a balance of its matter and its energy, not solidifying into coldness nor vaporizing into hotness. Helped, perhaps determined, by its size and its distance from the sun, Earth has maintained an ongoing but always changing composition. Scientists call this active self-maintenance autopoiesis (Greek for “self-making”). This is the most basic definition of life—that a living organism must be able to maintain its stability while undergoing change. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 16.]
o How did the chemicals of the early Earth come alive? Scientists cannot say for certain, since they have not yet been able to create life out of chemicals in a laboratory. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 17.]
o The oldest datable rocks come from Greenland, dating about 3.8 billion years old. Volcanoes erupted at cracks and spewed lava. Meteorites crashed. Electrical storms raged. Water began to condense; it rained torrentially for perhaps millions of years. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 18.]
o Scientists used to think that when lightning struck the oceans, it somehow triggered living cells out of the primordial chemical soup. Now it seems unlikely that small molecules in the soup could assemble themselves spontaneously, even with the help of lightning. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 18.]
o When nitrogen (N) entered the system, possibly as ammonia (NH3), a dramatic increase in complexity became possible, because nitrogen is necessary for two features of cellular life—catalysis and information storage. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 19.]
o The evidence for a single common ancestor is the fact that all life-forms share the same genetic code, the same biochemical network. This event is sometimes called the big birth. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 19.]
o These first living cells were enclosed in a membrane, had about 5,000 proteins, and had strands of both ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) floating around inside. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 19.]
o The details of how this final step to life happened are still mysterious, the chemical networks are so complex that new mathematical concepts are needed before they can be understood. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 19.]
o Early photosynthetic bacteria took hydrogen directly from the atmosphere to combine with carbon to form carbohydrates. This metabolic innovation by bacteria, not yet fully understood, ranks as one of the most important in the history of life on the planet. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 21.]
o In one of the great coups of all time, blue-green bacteria invented a way to breathe oxygen, using it in a controlled manner. They now carried out both photosynthesis, which generated oxygen, and respiration, which consumed it. The level of oxygen in the atmosphere stabilized at about 21 percent, which is the present level. How that level is maintained is still a mystery, but if the level of oxygen were a few percentage points higher, living organisms would combust; if it were a bit lower, organisms would asphyxiate. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 21, 22.]
o Eukaryotes appeared at the earliest 1.9 billion years ago. Between 1.7 and 1.5 billion years ago, the organisms formed by these cells with nuclei evolved a new way of reproducing, which required two partners. The sperm cell from one organism joined the egg cell from another. After they combined and divided, a new organism emerged with a complete set of chromosomes, half from each parent. This kind of sexual reproduction has continued unchanged to its current manifestations. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 22.]
o Five-sixths of the history of life is the story of one-celled creatures, bacteria. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 23.]
o the smaller a living entity, the easier it is to form and maintain because it is less complex. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 23.]
o The Earth is a huge electromagnetic dynamo. Its inner core is solid in the center, surrounded by liquid iron and nickel, still heated from the primordial creation of the planet. The magnetic field of Earth is generated by the rotating liquid iron swirling around its center. The solid core slowly increases in diameter two inches every five years because, like everything in the universe, Earth is cooling. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 24.]
o The continents of the Earth are carried along on its moving magma at speeds measured in inches per year. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 25.]
o The continental plates will keep moving as long as the Earth’s core is hot from the heat generated during its formation and sustained by decaying radioactive elements. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 25.]
o Trees, and other plants, played (and still play) a major role in keeping Earth cool for other life. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 25.]
o The atmosphere is only about .035 percent carbon dioxide, but this tiny percentage is critical to stabilizing the temperature on Earth. The photosynthesis of plants also releases oxygen into the atmosphere, helping to maintain the percentage at about 21 percent, critical for living organisms. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 26.]
o The only evidence available for verifying the story of ape/human development consists of extremely fragile fossilized bones and footprints that are millions of years old and scattered from place to place, without complete records anywhere. There is no way yet to present a complete family tree—too many gaps remain in the evidence, even though it has improved markedly in the past twenty years. There are two large gaps in the fossil record: from 31 to 22 million years ago, when gorillas, chimpanzees, and humans launched their careers, and from 12 to 5 million years ago, when the great apes and humans diverged. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 32.]
o In contrast to monkeys in other parts of the world, the monkey primates in the Americas never came down from the trees. The reasons for this remain unknown. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 33.]
o Chimps are quite unlike humans in many other distinctive ways. They take only ten to fifteen seconds to copulate, cannot distinguish between legal and illegal behavior, cannot speak, and, when they learn from humans to sign, they “converse” only at the level of a two-year-old human. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 35.]
3. Human Emergence: One Species (5 Million–35,000 Years Ago)
o To imagine time since the big bang, we can use the device of compressing all time into thirteen years. If we say the universe began thirteen years ago, Earth would have come into existence five years ago; the meteorite that killed the dinosaurs would have hit three weeks ago; the first bipedal apes (those that walked on two feet) would have appeared three days ago and the first Homo sapiens fifty-three minutes ago; and modern industrial societies would have existed for six seconds. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 38.]
o However, one represents it, the bare reality is that human history constitutes the tiniest fraction of planetary time—not to mention universe time. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 40.]
o Five to 7 million years ago some mutation occurred in an ape ancestor and survived, and from that single mutation other single mutations kept occurring in the branch called hominids, the bipedal apes. The mutations that bestowed advantage were preserved. These changes eventually led to modern Homo sapiens. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 40.]
o By comparing the genome of humans with that of chimpanzees, scientists have identified a partial list of the genes that make people human. They include genes for hearing and speech, genes that wire the developing brain, genes for detecting odors and for shaping bones. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 43.]
o The best-known Australopithicus is Lucy, whose less-than-half-complete skeleton was found in 1974 near Hadar, Ethiopia. She was named for the Beatles’ song, “Lucy in the Sky with Diamonds,” since the crews of excavators had this song playing as they worked. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 43.]
o As legs became stronger and heavier, the body’s center of gravity shifted downward, making an upright posture easier to maintain. Minor improvements may have begun to operate as a self-reinforcing system. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 44.]
o The advantages of this risky behavior proved enormously worthwhile. People could frighten off predators, set fires to drive prey into traps, cook and eat a wider range of food, preserve food for long periods, light up dark caves, and stay warm in colder weather. Bigger brains were really beginning to pay off. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 45.]
o Neanderthals are in the fossil record from about 130,000 to 28,000 years ago, originating before the start of the last ice age, about 90,000 years ago. They were the first humans to adapt successfully to life on the edge of an ice age world. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 46.]
o Their brains were at least as large as our own, although shaped differently. Their skulls were long and low, like those of earlier humans, with a notable ridge above the eyes and a massive nasal opening, larger than in any humans before or since. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 47.]
o There is no evidence of ornamentation until the very end of their existence, and no cave drawings. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 47.]
o Neanderthals definitely used fire. They scraped hides for clothing and shelter. They buried their dead—the first humans known to have done so. Bodies are found associated with tools, but there is no pattern of other burial goods or any clue to the possibility of ceremonies. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 47.]
o In 1912 a find was announced of a skull of a large-brained hominid that had been located in the Piltdown gravels of Sussex, England. Piltdown man was taken in the European and American scientific communities as proof that the first large-brained human ancestor had evolved in England. The Piltdown skull became the standard against which other skeletal evidence was judged and found wanting. Forty years after Piltdown man was found, it was proved to be a fake—an ingenious combination of fragments of a modern human skull and an orangutan jawbone, both doctored to look ancient. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 48.]
o This joke calls into question the credibility of the entire scientific enterprise. In the end, however, European archaeologists were able to defend their creed by unmasking this fraud, though it took them forty years to do so. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 48.]
o Our story can be summarized thus: Our universe began 13.7 billion years ago as a speck of incomprehensible energy, which burst into expansion that continues still. After sufficient cooling, matter appeared as hydrogen and helium and formed stars, in which heavier atoms were created. Some stars exploded as supernovas, scattering the heavier elements, which formed new star systems, including our solar system and Earth. With the help of energy sources, such as ultraviolet rays and lightning, the chemical building blocks of life developed on Earth, leading eventually to the first living cell 3.5 to 4 billion years ago. This cell divided and multiplied, and life has been evolving from it ever since. A mutation about 6 million years ago started the development of chimpanzees toward humans, who appeared as a species a mere 200,000 to 100,000 years ago, dominated other human types by 30,000 years ago, and inhabited the planet by 13,000 years ago. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 53, 54.]
o Modern humans evolved in Africa and radiated out from there to the rest of the world. This hypothesis is called Noah’s Ark (we were once all in one boat), Out of Africa, or Garden of Eden. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 54.]
o Some people in the Judeo-Christian world, as do people in other religious traditions, reject the findings of science and continue to believe that God created the world as it is just a few thousand years ago. These people are known as “creationists,” and their position is called “young earth creationism.” There are other creationist positions. “Old earth creationists” accept modern geology and astrophysics, but reject the findings of biology, specifically evolution. Other creationists accept some of evolution, but not the continuity between extremely different kinds of creatures, specifically that between humans and apes. Many Africans, being familiar with apes, believed that people were descended from them, but that idea was not acceptable to Christianity or to Islam. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 55.]
4. Advanced Hunting and Gathering (35,000–10,000 Years Ago)
o The first unmistakable human and animal figures date to 30,000 to 32,000 years ago, as does the earliest evidence of music—a wind instrument made from a bone with four holes on one side and two on the other. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 61.]
o Just how and when full symbolic speech developed is still not understood. Some think that something special happened in the networking of the human brain or in the structure of the larynx and tongue—rather suddenly about 60,000 to 40,000 years ago—that enabled full speech to arise. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 63.]
o Some linguists believe there must have been one original human language shared by the first group of Homo sapiens in Africa. Most, however, do not believe that this language can ever be reconstructed, because too much time has elapsed since it was spoken. [Cynthia Stokes Brown: Big History From the Big Bang to the Present, The New Press, London 2007, Page 63.]
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