Cosmos

Cosmos, Carl Sagan

Introduction

• Science is delightful; evolution has arranged that we take pleasure in understanding—those who better understand are more likely to survive.

  Chapter 1: The shore of the cosmic ocean

  Chapter 2: One voice in cosmic fugue

• On the plant and animal relationship: “What a marvellous cooperative arrangement—plants and animals each inhaling each other’s exhalations, a kind of planet wide mouth-to-stoma resuscitation, the entire elegant cycle powered by a star 150 million kilometres away.”
• DNA knows what to do, RNA conveys the instructions of the DNA to the rest of the cell (to make proteins?)
• If the mutation rate is too high, we lose the inheritance of four billion years of painstaking evolution. If too low, variation may be too low to adapt to a changing environment. Life requires a precious balance between mutation and selection
• In all life, nucleic acid is used for heredity (DNA), proteins are used for the enzymes that control cell chemistry (as per messenger RNA instructions received from DNA).
  • Nucleic acid information is translated into protein information

    Chapter 3: The harmony of worlds

• Martin Luther described Copernicus as “an upstart astrologer…[who] wishes to reverse the science of astronomy. But sacred scripture tells us that Joshua commanded the Sun to stand still, and not the Earth.”

  Chapter 4: Heaven and Hell

• Planets in our solar system have near circular orbits—not as elliptical as comets, say—because of a sort of planetary selection. Elliptical orbits would have had higher likelihood of collision, stymying the formation of planets. Wider, more circular orbits allowed amalgamation of matter with lower likelihood of collision.
• “Science is generated by and devoted to free inquiry: the idea that any hypothesis, no matter how strange, deserves to be considered on its merits.”
• “The suppression of uncomfortable ideas may be common in religion and politics, but is not the path to knowledge.”

  Chapter 5: Blues for a red planet

• Strong passions fray the tolerance for ambiguity, which is essential for science
• “The twin human passions for Euclidean geometry and territoriality.”

  Chapter 6: Travelers’ tales

• Leuwenhook and Huygens, products of Netherlands explorative and entrepreneurial era, were early discoverers of microscopic organisms (animalcules). Their work grandfathered germ theory and much of modern medicine, but their motives were merely related to tinkering with recently developed technology
  • The benefits a technology brings need not be realized upon the technology’s discovery. Technology can bring about unforeseen downstream effects, which can be beneficial or harmful.
• Jupiter is nearly a star and may as well be considered one if we consider its infrared radiation. Jupiter generates 2x more energy than it receives from the sun.
  • If there were two stars in our solar system, we could have had no night-time. In this kind of world, would sleep be required? Would sleep-states be rationed throughout “days”? The notion of day would change to whatever salient energy patterns arise due to our planet’s rotation and translation. How would evolution unfurl without night-time?

    Chapter 7: The backbone of night

• “When…he ascribes to his gods the production of some phenomenon…does he, in fact, do anything more than substitute for the darkness of his own mind, a sound to which he has been accustomed to listen with reverential awe?” - Paul Heinrich Dietrich
• Early Greeks believed the first being was Chaos (corresponding to the phrase in Genesis “without form”). Then, Ionians argued Nature exhibits order: there are regularities in Nature that permit its secrets to be unveiled. This ordered character of the universe was called Cosmos.
• “Men think epilepsy divine, merely because they do not understand it. But if they called everything divine which they do not understand, why, there would be no end of divine things.” -Hippocrates, ~500BC

  Chapter 8: Travels in space and time

• “Space and time are interwoven. We cannot look out into space without looking back into time.”

  Chapter 9: The lives of the stars

• Supernovae occur at the end of a star’s life, where stellar mass is violently ejected into space. During this ejection, thermonuclear reactions in the stellar interior fuse smaller atoms into larger atoms—this is where hydrogen combines into helium, then carbon, then oxygen, and so on until silicon and iron. We are formed by these atoms as well—we were birthed by the death of a star once located somewhere in our galaxy.
• Heavier atoms, like gold and uranium, are formed in the violent explosions of supernova. This high local pressure and temperature can fuse heavier atoms together. Embedded in uranium is the energy of a distant supernova that birthed the matter that forms Earth. Incredible.
• Almost all life is solar powered. Even mutation itself is solar powered—cosmic rays create mutations which cause hereditary variation
• Normally atoms in kind are repelled by their electron fields and protons. Why don’t the protons in their nucleus repel each other? Neutrons apparently serve to bind the protons together, like a nuclear clamp
• When temperatures and pressures are high enough, enough energy is provided to overcome the nuclear aversion between atoms and fuse them together, creating larger atoms
• Larger stars (3-5x) than the sun experience higher pressure and temperatures, thus consuming nuclear fuel at a higher rate. The lifetimes of larger stars tend to be much shorter (order of a few million years) until they die, explode, and fraction into smaller solar systems with smaller stars. Our sun is one of those smaller stars, and its long life is one of the reasons life has been able to evolve to a point where we can understand the stars themselves.
• When even larger stars (>10x sun) die, their implosion generates a black hole, whose gravity is so immense that even light cannot escape. The gravity causes three-dimensional space time to sink within itself, generating a fourth dimension unbeknownst to us.

  Chapter 10: The edge of forever

• If the universe is expanding, as observed by prevalent elongated—red—spectra, then why aren’t we the center about which everything is expanding? The answer may lie in a fourth dimension.
• Say the three dimensions observable to us are akin to a two-dimensional plane on a sphere, observable to two-dimensional folk. We may occupy a surface of a four-dimensional hypersphere, unaware of the fourth dimension as the 2D folk are unaware of the third. And if our hypersphere is expanding, the surface fabric of space time we occupy would be expanding in all directions.

  Chapter 11: The persistence of memory

• The brain is a very big place in a very small space. It has the informational equivalent of 10^14 bits, information which could fill some twenty million volumes, as many as the world’s largest libraries

  Chapter 12: Encyclopedia galactica

  Chapter 13: Who speaks for earth?

• Subtle consequences of nuclear war (beyond immediate blast and radiation)
  • Ozone depletion in high atmosphere due to combustion of nitrogen, increasing solar UV radiation. Skin cancer risk increase, crops decimated, and microorganisms killed—some of which could sit at the base of the ecological pyramid
  • Dust and ash would reflect sunlight, cooling the planet and disrupting agricultural crops
  • Birds are more vulnerable to radiation than insects. With less insectivores, plagues would be imminent as insect populations explode
  • Immunological function is hindered by radiation, making the few survivors more vulnerable to diseases
• When our well-being is threatened and our illusions challenge, some of us fly into a murderous rage. Sagan suggests the same thing happens at the nation scale, and that conflict is coerced by a few power/profit hungry entities
• Some estimate that roughly half of scientists and high technologists are employed full or part time on military matters. They’re offered power, money, accolades, and secrecy, which obviously attracts
• This secrecy is a challenge, however, because not even civilians can monitor the going-ons of their militaries. If we do not know what our militaries do, how can we stop them? “And with the rewards so substantial, with the hostile military establishments beholden to each other in some ghastly mutual embrace, the world finds itself drifting toward the ultimate undoing of the human enterprise.”
• Every major power has a justification for its production and stockpiling of weapons. These justifications often presume cultural defects of enemies (as opposed to us fine fellows) or the intentions of others (but never ourselves) to conquer the world.
• “Superstition is cowardice in the face of the Divine.” - Theophrastus
• To not confuse what things are with how we wish they’d be
• Only here, on this planet, do humans likely exist. We are a raw as well as an endangered (due to ourselves) species. In the cosmic perspective, humans are precious. So, if a human disagrees with you, let them live. In a hundred billion galaxies, you will not find another
• If we are to survive, our loyalties must be broadened to include the entire global human community. Many nations will find this unpleasant, fearing the loss of power. But it is this or extinction.