Friday, July 17, 2009

Cosmos

Carl Sagan--Cosmos

This one is a fascinating book. Carl Sagan writes beautifully, and the topics being discussed are some of the most fascinating questions about everything around us, from galaxies, to planets, to life on Earth (and eventually on other planets, and to human the limits of human knowledge. The book is divided in thirteen chapters: (1) The shores of the cosmic ocean (2) One voice in the cosmic fugue (3) The harmony of worlds (4) Heaven and hell (5) Blues for a red planet (6) Travelers' tales (7) The backbone of night (8) Travels in space and time (9) The lives of the stars (10) The edge of forever (11) The persistence of memory (12) Encyclopaedia galactica (13) Who speaks for Earth?.

I am jotting down here the passages that I liked the most.


For Ann Druyan. In the vastness of space and the immensity of time, it is my joy to share a planet and an epoch with Annie. (dedication)

Occasionally someone remarks on what a lucky coincidence it is that Earth is perfectly suitable for life--moderate temperatures, liquid water, oxygen atmosphere, and so on. But this is, at least in part, a confusion of cause and effect. (pg.14)

Many hypotheses proposed by scientists as well as by non-scientists turn out to be wrong. But science is a self-correcting enterprise. To be accepted all new ideas must survive rigorous standards of evidence. (pg.73)

"No one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as and yet as mortal as his own; that as men busied themselves about their various concerns, they were scrutinized and studied, perhaps almost as narrowly as a man with a microscope might scrutinize the transient creatures that swarm and multiply in a drop of water." (pg. 86, quoting O.H.Wells, The war of the worlds)

I am a collection of water, calcium and organic molecules called Carl Sagan. You are a collection of almost identical molecules with a different collective label. But is that all? Is there nothing in here but molecules? Some people find this idea demeaning to human dignity. For myself, I find it elevating that our universe permits the evolutions of molecular machines as intricate and subtle as we. (pg. 105)

[About Huygens] "The world is my country," he said "science is my religion." (pg. 117)

"If a faithful account was rendered of Man's idea upon Divinity, he would be obliged to acknowledge that for the most part the word 'gods' has been used to express the concealed, remote, unknown causes of the effects he witnessed; that he applies this term when the spring of the natural, the source of known causes, ceases to be visible: as soon as he looses the thread of these causes, or as soon as his mind can no longer follow the chain, he solves the difficulty, terminates his research by ascribing it to his gods..." (pg. 133, quoting P.H.Dietrich, Systeme de la Nature)

The two Voyager interstellar spacecraft, the fastest machines ever launched from Earth, are now traveling at one ten-thousandth the speed of light. They would need 40,000 years to go the distance to the nearest star. [...] What is magic about the speed of light? Might we someday be able to go faster than that? (pg.166)

Europeans around the turn of the century generally believed in privileged frames of reference: that German, or French, or British culture and political organization were better than those of other countries; that Europeans were superior to other peoples who were fortunate enough to be colonized. The social and political application of the ideas of Aristharcus and Copernicus was rejected or ignored. The young Einstein rebelled against the notion of privileged frames of reference in physics as much as he did in politics. (pg.167)

Compared to a star, we are like mayflies, fleeting ephemeral creatures who live out their whole lives in the course of a single day. From the point of view of a mayfly, human beings are stolid, boring, almost entirely immovable, offering hardly a hint that they ever do anything. From the point of view of a star, a human being is a tiny flash, one of billions of brief lives flickering tenously on the surface of a strangely cold, anoumalously solid, exotically remote sphere of silicate and iron. (pg.178)

"We had the sky up there, all speckled with stars, and we used to lay on our backs and look up at them, and discuss whether they was made, or only just happened." (pg. 179, quoting M.Twain, Huckleberry Finn)

"I have...a terrible need...shall I say the word?...if religion. Then I go out at night and paint the stars." (pg.179, quoting V.Van Gogh)

The relative abundance of the chemical elements found in the Cosmos matches the relative abundance of atoms generated in stars so well as to leave little doubt that red giants and supernovae are the ovens and cricibles in which matter has been forged. The Sun is a second- or third-generation star. All the matter in it, all the matter you see around you, has been through one or two previous cycles of stellar alchemy. (pg. 191)

Ten or twenty billion years ago, something happened--the Big Bang, the event that began our universe. Why it happened is the greatest mystery we know. That it happened is reasonably clear.[...] The remnants of that fireball, the cosmic background radiation, emanating from all parts of the sky can be detected by radio telescopes today. (pg. 201)

Where is the center of the Cosmos? Is there an edge to the universe? What lies beyond that? In a two dimensional universe curved through a third dimension, there is no center--at least not on the surface of the sphere. The center of such a universe is not in that universe; it lies, inaccessible, in the third dimension, inside the sphere. While there is only so much area on the surface of the sphere, there is no edge to this universe--it is finite but unbounded. And the question of what lies beyond is meaningless. Flat creatures cannot, on their own, escape their two dimensions. (pg. 220)

There is an idea--strange, haunting, evocative--one of the most exquisite conjectures in science or religion. It is entirely undemonstrated; it may never be proved. But it stirs the blood. There is, we are told, and infinite hierarchy of universes, so that an elementary particle, such an electron, in our universe would, if penetrated, reveal itself to be an entire closed universe.[...] Our familiar universe of galaxies and stars, planets and people, would be a single elementary particle in the next universe up, the first step of an entire infinite regress. (pg 221)

To specify whether a lamp is on or off requires a single bit of information. To designate one letter out of the twenty-six in the Latin alphabet takes five bits (2^5 = 2 x 2 x 2 x 2 x 2 = 32, which is more than 26). The verbal information content of this book is a little less than ten million bits, 10^7. The total number of bits that characterizes an hour-long television program is about 10^12. The information in the words and pictures of different books in all the libraries on Earth is something like 10^16 or 10^17 bits. O f course much of it is redundant. Such a number calibrates crudely what humans know. But elsewhere, on older worlds, where life has has evolved billions of years earlier than on Earth, perhaps they know 10^20 bits or 10^30--not just more information, but significantly different information. (pg. 224)

"How vast those orbs must be, and how inconsiderable this Earth, the theatre upon which all our mighty designs, all our navigations, and all our wars are transacted, is when compared to them. S very fit consideration, and matter of reflection, for those kings and princes who sacrifice the lives of so many people, only to flatter their ambition in being masters of some pitiful corner of this small spot." (pg. 263, quoting C.Huygens, New conjectures concerning the planetary worlds)

"[...] A day will come, a day in the unending succession of days, when beings, beings who are now latent in our thoughts and hidden in our loins, shall stand upon this earth as one stands upon a footstool, and shall laugh and reach out their hands amidst the stars." (pg. 264, quoting H.G.Wells, The discovery of the future, Nature, 1902)

About two thirds of the mass of the human brain is in the cerebral cortex, devoted to intuition and reason. Humans have evolved gregariously. We delight in each other's company; we care for one another. We cooperate. Altruism is built into us. We have brilliantly deciphered some of the patterns of Nature. We have sufficient motivation to work together and the ability to figure out how to do it. If we are willing to contemplate nuclear war and the wholesale destruction of our emerging global society, should we not also be willing to contemplate a wholesale restructuring of our societies? (pg. 272)

We must learn the science and technology that provide he only conceivable tools for our survival. We must be willing to challenge courageously the conventional social, political, economical and religious wisdom. We must make every effort to understand that our fellow humans, all over the worlds, are human. (pg. 273)

The ash of stellar alchemy was now emerging into our consciousness. At an ever-accelerating pace, it in vented writing, cities, art and science, and sent spaceships to the planets and the stars. These are some of the things that hydrogen atoms do, given fifteen billion years of cosmic evolution. (pg. 283)

If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another. (pg. 283)