Life at the Cosmic Scale

Even if we never find life beyond Earth, the very act of searching has already transformed our understanding of life on Earth. Looking for life elsewhere has forced us to reconceptualize our answer to the question: What is life? Life on other planets may not look like on this planet. And so scientists have had to think beyond “life as we know it” to “life as no one knows it,” in the words of astrobiologist Sara Imari Walker.

In trying to discover generalizations about life – where it comes from, what distinguishes it from non-life, how it sustains itself – we’ve come to see Earth’s living beings in a new light. By looking out to the stars, in order words, we actually revealed fundamental truths about ourselves.

Further exploration

Imagine that you are an alien seeing Earth for the first time. What would you notice about our planet? What strikes you as interesting? As notable? As odd? How does adopting this external, extraterrestrial viewpoint change your perspective on Earth, on what it means to be alive, and on what it means to be human?

Further reading

Adam Frank, Light of the Stars: Alien Worlds and the Fate of the Earth (2018)

Sara Imari Walker, Life As No One Knows It: The Physics of Life’s Emergence (2024)

Michael L. Wong, “What Searching For Aliens Reveals About Ourselves,” Noema Magazine (2025)