Cosmos: Possible Worlds

By Ann Druyan, Neil deGrasse Tyson

643 ratings - 4.38* vote

11 hours and 30 minutesThis all-new and long-awaited sequel to Carl Sagan and Ann Druyan's international bestseller Cosmos takes readers to worlds only now emerging with the advent of new technologies.With lucid prose that recalls the best-selling and beloved Cosmos, Ann Druyan takes readers on an extraordinary journey through the vast and unexplored realms of Earth and sp 11 hours and 30 minutesThis all-new and long-awaited sequel to Carl Sagan and Ann Druyan's international bestseller

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Book details

Audible Audio, 0 pages
February 25th 2020 by Recorded Books

(first published December 2019)

1426219083 (ISBN13: 9781426219085)
Edition Language

Community Reviews

Gabriela Kozhuharova

Beautiful, poetic and very inspirational love letter to science, life and the human potential.

Kam Yung Soh

A fascinating and at times, personal, journey through time, space, and history by the author as she explores not the just the universe as we know it, but also the various stories of people throughout history who have placed the importance of science and other people above their own. The book is not only about 'Possible Worlds' but also, like the first Cosmos series by Carl Sagan, a 'Personal Journey' by the author who not only wants the readers to see the wonders the universe has to offer, but also some of the trials she has to go through to keep the ideas and ideals of Carl Sagan alive.

"Ladder to the stars" gives an overview of the journey with the Cosmic Calendar (that compresses all of time from the Big Bang to the present into one calendar year). Highlights from the calendar are presented, from the creation of Earth, the rise of life on Earth, the rise of humanity until human civilisation is established.

"Oh, Mighty King" shows humanity's struggle to understand the universe and the supernatural nature of good and evil in an unfeeling universe. The chapter begins with Zoroastrianism and ends with the story of the Indian Emperor Ashoka who started out being an embodiment of evil, yet was changed by Buddhism to become a paragon of good in India.

"Lost city of life" looks at how life might have developed on Earth, deep under the sea, in vast towers of minerals that sheltered and nurtured the first life forms. It then gives a brief look at the lives of some of the scientists who looked at chemistry and biochemistry and ends with a consideration of other worlds and moons in the Solar System that may well harbour life as we know it.

"Vavilov" tells the story of agriculture and the struggle to prevent hunger by growing better types of grains and other plants. It also tells the story of Nikolai Vavilov, a Russian scientist whose botanical skills would lead to the identification of the centre of origins for various agricultural plants. But his is not a happy story, for it takes place prior and during the Second World War and would involve Stalin and Trofim Lysenko.

"The cosmic connectome" looks at the brain and the mystery of its numerous connections that give us the ability to think and of awareness. Starting from how animals evolved the brain, the chapter also covers the history of brain research from recognising that the brain is the seat of thinking to the discovery of what different parts of the brain do, to detecting signals from the brain to current brain research that is revealing the large number of connections between neurons in the brain.

"The man of a trillion worlds" looks at the lives of two scientists during the period in the 20th century when the search for the beginnings of life on Earth and the possibility of life on other planets was being researched: Gerald Kuiper and Harold Urey. The chapter also looks at the graduate student who would be a bridge between them: Carl Sagan, who would also organise the first group to study how life might exist on other planets.

"The search for intelligent life on earth" considers the search for intelligent life in the universe by looking at what may be intelligent life on earth (besides us). From the web of fungi and plants to the 'dance' of bees, the examples chosen show what intelligent life might look like if we were consider the ways it expresses itself in the way communities of plants and animals live.

"The sacrifice of Cassini" gives an overview of what made the Cassini mission to Saturn possible. Starting with a history of the astronomical observations of Saturn, the chapter moves on to the story of the Russian who dreamed up the idea of gravitational assist, an idea that would make most interplanetary missions possible. The chapter ends with some of the discoveries made by the Cassini probe before it was commanded to end its mission by crashing into Saturn, to protect the moons of Saturn from possible contamination from Cassini.

"Magic without lies" looks at the strange nature of light. From the early arguments between Newton and Huygens over whether light is a wave or made up of particles, to the mysterious interference experiments of Thomas Young and the mysterious inner quantum nature of light shown by Bell's Theorem, the chapter offers a glimpse that we still don't really understand light, much like Flatlanders don't really grasp the nature of the third dimension.

"A tale of two atoms" tells the tale of two kinds of atoms. One is carbon, which is the basis for life as we know it, the other is uranium, from which some of the most destructive weapons would be created. The two kinds of atoms would meet when humanity would harness uranium for its destructive power.

"The fleeting grace of the habitable zone" looks at what will happen as the sun ages. At first, it will give off more light (and heat), forcing humanity (if it still exists far in the future) to abandon Earth to live on worlds further from the sun. But as the sun becomes a white dwarf and cools, humanity will have no choice but to move to another star system. Is this possible? The author imagines the journey our ancestors did to navigate the great unknown oceans of Earth and believes such an incredible journey to other stars may one day be possible.

"Coming of age in the Anthropocene" this chapters looks at what humanity has done to change the earth enough that we are now living in a human-caused age. The rise of hunting, agriculture and, ultimately, technology, has enabled humanity to change and modify the Earth. More than that, humanity has the ability to predict what will happen in the future (via examples like the ozone hole caused by Chlorofluorocarbon, or climate change caused by increasing amounts of Carbon dioxide). But the question is whether humanity is willing to act on it.

"A possible world" end the book the way it started: with a look at the World's Fair. While the introduction showed the 1939 World's Fair seen by Carl Sagan, the one featured here shows a World's Fair in the near future on a world recovering from the damage done by humanity. It is possible? Perhaps.


I love the original Cosmos more than just about anything in the world.

Ann does a superb job trying to captain the ship all by herself. And in truth she isn't alone. She had feedback including from her son Sam.

Hits the mark:

* Poetry and cosmic perspective; I wept several times
* Inspiring, relevant stories from the history of science

Misses the mark:

* Critical thinking and skepticism
* Scientific and historical accuracy

For example, the section about quantum mechanics gets a few things wrong.

1. It's implied that "free will" is a challenge to quantum super-determinism, which it's not. First of all, we can't start out by assuming our intuition that we have free will is correct. It's not. Libertarian free will is incoherent, even in an nondeterministic universe.

2. It's claimed that entangled particle pairs "communicate" with one another which is incorrect. There's a coincidence between their measured spin on a given axis, but that's merely a perfect correlation. Bell's inequalities show this doesn't arise through any "communication" as typically understood. Instead, it's just how the universe works. We can't use this to communicate faster than light, because knowledge of the coincidence has to be transmitted along some classical channel. This isn't me being pedantic. Her point was that the universe is spooky and allows for faster than light communication. Which is wrong.

3. It's claimed there is "no objective reality" under quantum mechanics. It's not even very clear in the context of the chapter what justification she intends to support this claim. It's just not true. There's nothing subjective (as opposed to "objective") in QM. There's nothing surreal or unreal as opposed to plain old "reality". Certainly the theory doesn't have local realism, which might be what she was getting at. But she goes on to use it in the context of spookiness about there being no objective reality, which is clearly antithetical to QM, which is a well-established physical theory of an objective, external physical reality. I don't forgive this as poetic license. Unfortunately, she was just lying.

But in the whole book these are the only three mistakes I found. That's not so bad.


Our universe began some 14 billion years ago when matter, energy, time, and space burst forth.

And the darkness was cold, and the light was hot, and the union of these extremes gave shape to matter and there was structure.
And there were great stars hundreds of times the mass of our sun. And these stars exploded, sending oxygen and carbon to the worlds to come and adorning them with gold and silver. And in their deaths, the stars became darkness and the weight of their darkness anchored the light. And new stars were born from their death shrouds. And they began to dance with each other and now there were galaxies.

And the galaxies made stars. And the stars made worlds. And on at least one of those worlds there came a time when heat shot out from its molten heart, and it warmed the waters. And the matter that had rained down from the stars came alive and that starstuff became aware.

And that life was sculpted by the earth, and its struggles with the other living things.
And a great tree grew up, one with many branches, and six times it was almost felled. But still it grows and we are but one small branch, one that cannot live without its tree.

And slowly, we learned to read the book of nature, to learn its laws, to nurture the tree. To find out where and when we are in the great ocean, to become a way for the cosmos to know itself and to return to the stars.

Meg - A Bookish Affair

4.5 stars. "Cosmos: Possible Worlds" is the sequel to Carl Sagan's book, "Cosmos" and it is a worthy follow-on. This book explores so many corners of our universe and highlights many people who took scientific exploration further than it has ever gone before and tried to figure out this big, amazing world.

Sometimes you just want a book that totally sucks you in and makes you mull over so many different things that you've never thought of before. This is that book. The book opens with the story of a young Carl Sagan being captivated by the World's Fair and how that experience set off a lifelong journey to explore the furthest most corners of the universe. I love the intimate picture that you get of Sagan through various life stages: this book was written by his wife, a noted scientist and scientific writer in her own right.

This is one of those books that can be read straight through or story-by-story. There is so much to ponder here and while Druyan gives the reader tons and tons of detail, the stories still feel accessible. The book also has some really gorgeous pictures in it that bring the stories even more to life. In a time where I am constantly looking for books that are fully engaging and take me away, this book certainly fit the bill. This book would be perfect for readers who love science and know all the doors that just having the willingness to explore can open!


This was an interesting book. I have read a few books by Carl Sagan, and also enjoyed the 2014 reboot of the show Cosmos which featured author Ann Druyan and Neil deGrasse Tyson.

Author Ann Druyan is the widow of Carl Sagan. She is an Emmy and Peabody Award-winning American writer, producer, and director specializing in the communication of science. She co-wrote the 1980 PBS documentary series Cosmos, hosted by Carl Sagan, whom she married in 1981. She is the creator, producer, and writer of the 2014 sequel, Cosmos: A Spacetime Odyssey and its sequel series, Cosmos: Possible Worlds, as well as the book of the same name. She is credited with directing episodes of both series as well, according to her Wikipedia page.

Ann Druyan and Carl Sagan, circa 1988 :

Cosmos: Possible Worlds opens by taking the reader through the Cosmic Calendar:


The scope of this book is quite broad, and many subjects and scientific disciplines are covered in these pages, including:
*Mendelian and Lamarckian inheritance
*Russian botanist Nikolay Vavilov
*Neuroscience of the brain
*The Cassini spacecraft
*The dual nature of light; wave and particle, and the related double-slit experiment
*Quantum entanglement
...and many others.

Cosmos: Possible Worlds is full of illustrations that help bring some context to the writing. There are also many historical photos here, which was a nice touch.

Although I did enjoy this one, I felt it did not quite meet the high water mark established by the original Cosmos that bears its namesake. I didn't find this one as captivating and interesting as the original, unfortunately...

There was also quite a long and somewhat ridiculous bit of writing about nuclear weapons that seemed to go beyond arguments for non-proliferation, and into the realm of their complete eradication. Much of her writing on this reads as though she is chastizing humanity for inventing Weapons of Mass Destruction. This indicates her naïveté to realpolitiks, as well as her ignorance of the important role atomic weapons have played in the establishment of both the "Long Peace", and the "New Peace".
A strong case has been made for the unprecedented stability and prosperity of a World established under Pax Americana that is not discussed in these pages.
Druyan cites Manhattan Project chief scientist Robert Oppenheimer's opposition to the usage of the bombs he helped bring to life. Many of the scientists of the Manhattan Project were opposed to the bombs being actually deployed in war. Thankfully these people do not dictate military policy. The world we know would look drastically different if that were the case.

She also insinuates that Oppenheimer was the victim of a witch-hunt of sorts, conveniently not mentioning that Oppenheimer had been close to members of the Communist Party, including his wife and brother. On June 7, 1949, Oppenheimer testified before the House Un-American Activities Committee, where he admitted that he had associations with the Communist Party in the 1930s. He also was a self-admitted "fellow traveller".
We fought a Cold War for the better part of ~50 years; against an ideology that had aims of global domination, and has brought unprecedented levels of wholesale human misery everywhere it has been implemented. To gloss over Oppenheimer's ties to Communism is dishonest.

Druyan also somewhat misses the mark on her discussion of quantum entanglement. She claims the entangled particles "communicate" with each other, which is not true, from what I have read. See Bell's inequalities for more.
She extrapolates this "communication" between entangled particles to make a tenuous case for the magical nature of the Universe, and a possible case for faster-than-light travel, which is still not thought to be possible...

Overall, this was still a decent book, worthy of the Cosmos brand.
I would recommend it to fans of Cosmos, or anyone else interested.
3.5 stars.

La Crosse County Library

“And slowly, we learned to read the book of nature, to learn its laws, to nurture the tree. To find out where and when we are in the great ocean, to become a way for the cosmos to know itself and to return to the stars.” -Ann Druyan (p. 370)

This book was an unexpected gem for me, in a year of doom and gloom where COVID-19 and a new economic recession have dominated the headlines. It was a welcome escape and, like the best books, whether or not they are fiction or nonfiction, reignited my sense of curiosity and wonder about our world and its many possibilities.

Based on the National Geographic TV series of the same name, Cosmos: Possible Worlds (2020) is a beautiful blend of science and storytelling. From the beginning of the universe around 14 billion years ago to today, Ann Druyan chronicles the emergence of life and the stories of the scientists and explorers who helped advance society to where it is today. She mentions the more famous of these scientists, such as the household names of Albert Einstein, Charles Darwin, Isaac Newton and the like, but also sheds light on the stories of lesser known scientific figures whose discoveries were no less important but may not get the credit they deserve (to name a few): Karl Von Frisch, bee whisperer; Nikolay Vavilov, whose collection of plant species from around the world served as a precursor to today’s Svalbard Global Seed Vault in Norway; and Aleksandr Shargei (aka Yuri Kondratyuk), whose insights on gravitational assists would be crucial for landing on the moon.

The lessons of all these stories of scientific explorers? For Druyan, it’s that humanity’s adaptiveness, assisted by high technology, has gotten us out of tight spots as a species before, such as the near destruction of the ozone layer. Druyan thinks we can apply these lessons to get us out of one of the biggest of pickles of our time, climate change, and notes we have the technological solutions there, but that to make a difference, technology must be married to massive collective action once again (à la the moon landing or fixing the ozone layer). Nature has given us the tools to secure a second chance for our species, but the ball is in our proverbial court now.

In her concluding chapter, Druyan gives readers a glimpse into a future in which the climate change problem has been solved and humanity is reaching farther into the stars. At a hypothetical World Fair in 2039, visitors are treated to a futuristic vista mostly fashioned out of materials derived from the excess carbon dioxide humanity pulled out of the atmosphere. It reminded me of the utopian vision of humanity’s future as presented in the sci-fi show “Star Trek.”

Is this merely a fantastical vision of the future?

Perhaps, but perhaps not. But I choose to hope.


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"The universe makes galaxies. Galaxies make stars. Stars make worlds."

Using the Cosmic Calendar as a guide, Ann Druyan takes us on a trip through time and space in Cosmos: Possible Worlds.  Written in a way for anyone to understand, Ann uses stories to make the science of the universe come alive.  Beginning with the start of life on Earth might seem like an impossible amount of information to fit into book,; however, only selected important advancements in science are highlighted throughout time.  Throughout all of these scientific advancements, humans quest for knowledge along with our ability to adapt to new situations is overwhelming. I was continually amazed at human's capability to wonder and explore beyond what we can see.  Throughout Cosmos the stage is set for human's capability to find and explore new worlds beyond our own.  Hope is given that other worlds exist that are capable of supporting life as well as human life, just as Carl Sagan imagined.  

Ace Boggess

I'm torn about this book. It was fascinating and captivating, but at same time not structurally coherent or what the subtitle implies. The book discusses science, history, and religions (much in the same way Bill Bryson does in A Short History of Nearly Everything, but without the humor). However, it does so tangentially, without really following a path. This is a book of tangents. They're all interesting tangents. I learned weird things, and I'm a lover a learning weird things. But if you're looking for more of that fantastic voyage to other worlds that the original Cosmos series offered, you will be disappointed.

That said, I enjoyed the book for what it is. I suspect that you, reader, will either love it or hate it.


The Cosmos brand has always been elevated over other exemplars of science writing for infusing scientific exploration with heartfelt wonder and reinforcement of joy over the never-ending quest of learning new things. Carl Sagan's amazing life partner, Ann Druyan, continues that unique tradition in this wonderful book. I learned a lot of things I hadn't thought of before, such as the possibility of consciousness among trees and of dreams among bees, and the desirable prospect of life in near-orbit of red dwarf stars. I liked the snippets into her life with Carl, and I liked that the scientific heroes she features throughout the book may be more obscure than the usual greats of science but are distinguished by their herculean effort through life hardship to pursue their dreams, even obsessions, of science, engineering or discovery.