Cosmic evolution is the scientific study of universal change. It is an intellectual framework that offers a grand synthesis of the many varied changes in the assembly and composition of radiation, matter, and life throughout the history of the universe. While engaging the time-honored queries of who we are and whence we came, this interdisciplinary subject attempts to unify the sciences within the entirety of natural history—a single broad scientific narrative of a possible origin and evolution of all material things, from an inferred big bang to humankind. (Closely related subjects include epic of evolution, big history, and astrobiology).
We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time.
Eliot did not have space exploration in mind (the lines were written in 1942), but the sentiment poetically captures one of the most important reasons we explore space. NASA’s exploration of the universe, and that of other nations, reveals humanity’s place in nature in the broadest possible sense. That view of ourselves has changed dramatically over the last century. One hundred years ago most astronomers considered the universe to be about 3600 light years in extent, less than a billion years old, and with our solar system near its center. Astronomers today have seen objects 13 billion light years away in a universe 13.7 billion years old containing hundreds of billions of galaxies. We are peripherally located in one of those galaxies, known as the Milky Way.
“Nothing, however, has been more revolutionary than the idea that this entire universe is in a state of constant change, as planets, stars and galaxies are born and die. This story of the life of the universe, and our place in it, is known as cosmic evolution. Although the idea has roots in the 19th century, and was occasionally invoked in the first half of the 20th century by astronomers such as George Ellery Hale, it really came into its own only in the Space Age.”