Cosmos - Carl Sagan [129]
*Silicon is an atom. Silicone is a molecule, one of billions of different varieties containing silicon. Silicon and silicone have different properties and applications.
*The Earth is an exception, because our primordial hydrogen, only weakly bound by our planet’s comparatively feeble gravitational attraction, has by now largely escaped to space. Jupiter, with its more massive gravity, has retained at least much of its original complement of the lightest element.
*Stars more massive than the Sun achieve higher central temperatures and pressures in their late evolutionary stages. They are able to rise more than once from their ashes, using carbon and oxygen as fuel for synthesizing still heavier elements.
†The Aztecs foretold a time “when the Earth has become tired …, when the seed of Earth has ended.” On that day, they believed, the Sun will fall from the sky and the stars will be shaken from the heavens.
*Moslem observers noted it as well. But there is not a word about it in all the chronicles of Europe.
†Kepler published in 1606 a book called De Stella Nova, “On the New Star,” in which he wonders if a supernova is the result of some random concatenation of atoms in the heavens. He presents what he says is “… not my own opinion, but my wife’s: Yesterday, when weary with writing, I was called to supper, and a salad I had asked for was set before me. ‘It seems then,’ I said, ‘if pewter dishes, leaves of lettuce, grains of salt, drops of water, vinegar, oil and slices of eggs had been flying about in the air for all eternity, it might at last happen by chance that there would come a salad.’ ‘Yes,’ responded my lovely, ‘but not so nice as this one of mine.’ ”
*1 g is the acceleration experienced by falling objects on the Earth, almost 10 meters per second every second. A falling rock will reach a speed of 10 meters per second after one second of fall, 20 meters per second after two seconds, and so on until it strikes the ground or is slowed by friction with the air. On a world where the gravitational acceleration was much greater, falling bodies would increase their speed by correspondingly greater amounts. On a world with 10 g acceleration, a rock would travel 10 × 10 m/sec or almost 100 m/sec after the first second, 200 m/sec after the next second, and so on. A slight stumble could be fatal. The acceleration due to gravity should always be written with a lowercase g, to distinguish it from the Newtonian gravitational constant, G, which is a measure of the strength of gravity everywhere in the universe, not merely on whatever world or sun we are discussing. (The Newtonian relationship of the two quantities is F = mg = GMm/r2; g = GM/r2, where F is the gravitational force, M is the mass of the planet or star, m is the mass of the falling object, and r is the distance from the falling object to the center of the planet or star.)
*The early Sumerian pictograph for god was an asterisk, the symbol of the stars. The Aztec word for god was Teotl, and its glyph was a representation of the Sun. The heavens were called the Teoatl, the godsea, the cosmic ocean.
CHAPTER X
THE EDGE OF FOREVER
There is a way on high, conspicuous in the clear heavens, called the Milky Way, brilliant with its own brightness. By it the gods go to the dwelling of the great Thunderer and his royal abode … Here the famous and mighty inhabitants of heaven have their homes. This is the region which I might make bold to call the Palatine [Way] of the Great Sky.
—Ovid, Metamorphoses (Rome, first century)
Some foolish men declare that a Creator made the world. The doctrine that the world was created is ill-advised, and should be rejected.
If God created the world, where was He before creation?… How could God have made the world without any raw material? If you say He made this first, and then the world, you are faced with an endless regression … Know that the world is uncreated, as time itself