Notes from Cosmos by Carl Sagan

Reading Note Convention

This is the convention being followed for all reading notes exported after January 31, 2023 (and some previous exports):

KOReader/Exported Kindle Meaning
Lighten/Normal Yellow Quotables, concepts, and general ideas.
Underline Orange Further thought is required on this for clarity.
Highlighted/Bold Blue Something strikingly novel/Deeply moving/Highly thought-provoking.
Strikeout Pink In discord with this opinion.


by Carl Sagan

CHAPTER II : One Voice in the Cosmic Fugue

Page 47 @ March 24, 2016

we do not yet know how to assemble alternative sequences of nucleotides to make alternative kinds of human beings. In the future we may well be able to assemble nucleotides in any desired sequence, to produce whatever characteristics we think desirable - a sobering and disquieting prospect.

হয়ত পারবো, কিন্তু বোরিং হবে, না?

CHAPTER III : The Harmony of Worlds

Page 59 @ March 25, 2016

In contemporary Western society, buying a magazine on astrology - at a newsstand, say - is easy; it is much harder to find one on astronomy. Virtually every newspaper in America has a daily column on astrology; there are hardly any that have even a weekly column on astronomy. There are ten times more astrologers in the United States than astronomers.

আর কনটেম্পরারি বাঙলা কালচারে এস্ট্রোনমার পাওয়াই যায় না আর এস্ট্রোলজাররা সবাই “স্বর্ণপদকপ্রাপ্ত”!

Page 64 @ March 25, 2016

‘Mortal as I am,’ he wrote, ‘I know that I am born for a day. But when I follow at my pleasure the serried multitude of the stars in their circular course, my feet no longer touch the Earth…’

Ptolemy's Quote.

Page 67 @ March 25, 2016

Geometry existed before the Creation. It is co-eternal with the mind of God … Geometry provided God with a model for the Creation … Geometry is God Himself.

Kepler on Geometry.

CHAPTER IV : Heaven and Hell

Page 108 @ March 26, 2016

But science is a self-correcting enterprise. To be accepted, all new ideas must survive rigorous standards of evidence. The worst aspect of the Velikovsky affair is not that his hypotheses were wrong or in contradiction to firmly established facts, but that some who called themselves scientists attempted to suppress Velikovsky’s work. 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 it is not the path to knowledge; it has no place in the endeavor of science. We do not know in advance who will discover fundamental new insights.


CHAPTER VI : Travelers’ Tales

Page 175 @ April 02, 2016

How does a picture from the outer solar system get to us? Sunlight shines on Europa in its orbit around Jupiter and is reflected back to space, where some of it strikes the phosphors of the Voyager television cameras, generating an image. The image is read by the Voyager computers, radioed back across the

Digital photography?

CHAPTER VII : The Backbone of Night

Page 189 @ April 03, 2016

Bur Aristarchus of Samos

First one to say The Earth revolves around The Sun?

Page 210 @ April 03, 2016

He held that the Sun was so huge that it was probably larger than the Peloponnesus, roughly the southern third of Greece. His critics thought this estimate excessive and absurd.

Such Critics, Much Wow! "D

Page 212 @ April 03, 2016

Alcmaeon, is the first person known to have dissected a human body; he distinguished between arteries and veins, was the first to discover the optic nerve and the eustachian tubes, and identified the brain as the seat of the intellect (a contention later denied by Aristotle, who placed intelligence in the heart, and then revived by Herophilus of Chalcedon).

Okay, Aristotle was one bloody Jackass!

CHAPTER VIII : Travels in Space and Time

Page 231 @ April 03, 2016

you might have come upon a somewhat long-haired teenage high school dropout on the road to Pavia. His teachers in Germany had told him that he would never amount to anything, that his questions destroyed classroom discipline, that he would be better off out of school. So he left and wandered, delighting in the freedom of Northern Italy, where he could ruminate on matters remote from the subjects he had been force-fed in his highly disciplined Prussian schoolroom. His name was Albert Einstein, and his ruminations changed the world.

Here comes the making of Einstein. :D

Page 235 @ April 03, 2016

(There are no penalties for breaking laws of Nature, because there are no crimes: Nature is self-regulating and merely arranges things so that its prohibitions are impossible to transgress.)

That means: তুমি মানো বা না মানো, সায়েন্সের ছেঁড়া যায় না।

CHAPTER X : The Edge of Forever

Page 294 @ April 07, 2016

Before heaven and earth had taken form all was vague and amorphous …

This Chinese creation myth is far much compatible with big bang than Hindu or Abrahamic myths.

Page 296 @ April 07, 2016

The dates on Mayan inscriptions also range deep into the past and occasionally far into the future. One inscription refers to a time more than a million years ago and another perhaps refers to events of 400 million years ago, although this is in some dispute among Mayan scholars. The events memorialized may be mythical, but the time scales are prodigious. A millennium before Europeans were willing to divest themselves of the Biblical idea that the world was a few thousand years old, the Mayans were thinking of millions, and the Indians of billions.

Culture and geology effect society, therefore freethinking span of a single man. India, being diverse in nature and culture can embrace different ideas easily. On the contrary this is not so easy in semitic or Semitism driven culture.

CHAPTER XIII : Who Speaks for Earth?

Page 371 @ April 08, 2016

Who speaks for Earth?

No one is worthy till today

Page 376 @ April 08, 2016

There is no other species on Earth that does science. It is, so far, entirely a human invention, evolved by natural selection in the cerebral cortex for one simple reason: it works. It is not perfect. It can be misused. It is only a tool. But it is by far the best tool we have, self-correcting, ongoing, applicable to everything. It has two rules. First: there are no sacred truths; all assumptions must be critically examined; arguments from authority are worthless. Second: whatever is inconsistent with the facts must be discarded or revised. We must understand the Cosmos as it is and not confuse how it is with how we wish it to be. The obvious is sometimes false; the unexpected is sometimes true.


Page 384 @ April 08, 2016

But the Darwinian lesson is clear: There will be no humans elsewhere. Only here. Only on this small planet. We are a rare as well as an endangered species. Every one of us is, in the cosmic perspective, precious. If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.

This is how science provide ethics.

Page 385 @ April 20, 2016

The choice is stark and ironic. The same rocket boosters used to launch probes to the planets are poised to send nuclear warheads to the nations. The radioactive power sources on Viking and Voyager derive from the same technology that makes nuclear weapons. The radio and radar techniques employed to track and guide ballistic missiles and defend against attack are also used to monitor and command the spacecraft on the planets and to listen for signals from civilizations near other stars. If we use these technologies to destroy ourselves, we surely will venture no more to the planets and the stars. But the converse is also true. If we continue to the planets and the stars, our chauvinisms will be shaken further. We will gain a cosmic perspective. We will recognize that our explorations can

And another on ethics and humanity