Carl Sagan’s Cosmos is one of the best popular scientific books that I have read. It was written in parallel with developing a TV series with the same name, first broadcast in 1980. Although both astronomy and the world in general have developed since then, the book is still a fascinating journey through the universe and our place in it. Cosmos has a wider span than most popular scientific books and gives a vivid introduction to astronomy as well as to evolutionary biology, geology, and the history of science.
The book starts, as did all of the episodes of the TV series, with a journey through the universe. Beginning on the grand scale of the universe as a whole, the journey converges towards its final destination – our Earth. Putting our small planet, and our existence on it, into this stupefying perspective, Sagan continues to ask if ours is the only world in the universe that has life on it. To be able to at least speculate about life elsewhere he explains the prerequisites for life on Earth and how it evolved. He also describes the geological development of our sister planets in the solar system, explaining why they do not have life. The chemistry of life is described, and how life’s building blocks are known to spontaneously form in different parts of the universe.
The question about life on other worlds remains unanswered, but exploring the problem is a fascinating journey in itself. Throughout the book are scattered pieces of science history, relating how we came to know the world around us and how we expanded our horizon further and further into the cosmos. The book is an inspiring mix of objective accounts of science and personal speculations. It is filled with beautiful artwork from observatories and museums, as well as of imaginary distant worlds. Sagan concludes the book with his personal view: We are a part of the development of the universe and, intriguingly, a way for the universe to know itself. We have, he says, a moral responsibility to continue our exploration of the grand world we live in so long as we can. This book is pure inspiration for anyone who wonders about the universe and our place in it.
The original TV series is also available as a DVD boxed set. I bought it out of nostalgia and found that, although video technology has moved forward during the last decades, the inspiration is still very much there. After each episode there are updates explaining how science has developed since the production of the series. Still, in most places, it is surprisingly up to date. For example, when Sagan explains how Venus is a dead world because its atmosphere makes it too hot to sustain life, he continues to explain the threat that our emissions of carbon dioxide is to our planet. It is difficult to imagine that this was produced in the late 1970’s! I have read the book at least three times in my life, beginning in my early teens, and it has had something new to offer every time I have read it. I will certainly share both the book and the DVD-box with my son when he is old enough read or to understand English. If I am to choose one episode to represent the spirit of this production it would be “the backbone of night” that explores the dawn of scientific thought in ancient Greece. I have used it as discussion material with my Ph.D. students and it still raises relevant questions, not only about what scientific thinking is, but also about the fragility of the fruits of rational thought.