Cosmos

Throughout the entire book, the author emphasizes the importance of the human imagination. Without that imagination, exploration—of other countries, of the Earth, of the cosmos—would not be possible. Humanity’s early explorations on Earth and its later treks into the cosmos were due to our unquenchable thirst for adventure and to our creation of stories, including origin stories and cultural narratives. Basically, humankind is a storytelling species. This was and is a survival mechanism: “We are, almost all of us, descended from people who responded to the dangers of existence by inventing stories about unpredictable or disgruntled deities” (173).

The stories that humanity tells itself can be instructive or misleading, a contrast that foregrounds The Juxtaposition of Science and Religion. One example of an instructive story was told by Pythagoras: “It was he who first used the word Cosmos to denote a well-ordered and harmonious universe, a world amenable to human understanding” (183). This is certainly the view of the cosmos that predominates in Sagan’s own work—though this view of a harmonious universe is disrupted at times (quasars and black holes defy full explanation, at least at this point in scientific history). An example of a misleading story was the conviction that the world is a fundamentally flawed and inexplicable place: “Platonists and their Christian successors held the peculiar notion that the Earth was tainted and somehow nasty, while the heavens were perfect and divine. The fundamental idea that the Earth is a planet, that we are citizens of the Universe, was rejected and forgotten” (188). Clearly, the author’s entire project in Cosmos is to restore that forgotten notion: The Earth and the larger universe exist in harmony with each other, and humanity remains beholden to the laws and whims of the Cosmos.

Sagan examines the physics of interstellar travel and its potential impact on humanity—a narrow slice of the book’s more general interest in The Consequences of Human Impact. In his theories of relativity and special relativity, Albert Einstein articulated more fully the idea that “Space and time are interwoven” (198). Some of his theories unsettled established ideas about how the Cosmos works: “The more Einstein thought about such questions, the more troubling they became. Paradoxes seemed to emerge everywhere if you could travel at the speed of light” (199). These paradoxes went on to inspire artistic renderings of multiverses and wormholes that persist in the genre of science fiction to this day. Without wormholes, much of the Star Trek universe would be nullified. Einstein’s work also impacted how human beings saw other human beings. As the author explains, “This is what the word relativity means. The idea is very simple, despite its magical trappings: in viewing the universe, every place is as good as every other place” (200). Effectively, relativity invalidated the philosophies underpinning colonialism—that European values are superior to, say, African or South American values. Finally, Einstein’s discoveries also indicate that space travel and extremely long-range communication are possible: “Relativistic spaceflight makes the universe accessible to advanced civilizations, but only to those who go on the journey” (207). The implication is that an “advanced” civilization is not only technologically advanced but also culturally progressive.

To explain the makeup of the cosmos, Sagan uses an apple pie as a metaphor for how elements come together: “the hydrogen was made in the Big Bang, the explosion that began the Cosmos. If you wish to make an apple pie from scratch, you must first invent the universe” (218). Indeed, all of the elements that make up life were first stellar: “The origin and evolution of life are connected in the most intimate way with the origin and evolution of the stars” (233). Without the stars, there would be no life on Earth—one way for humans to resolve the question of Where in the Cosmos Do We Belong. As Sagan argues throughout the book, there is a “deep connection between life and the Cosmos” (243). Ultimately, Cosmos is not merely a study of interstellar space or astronomy, but also a statement about the origins and continuity of life itself.