The Birth of Modern Cosmology

In the history of science few developments have been more important than the advent of the new heliocentric cosmology in the sixteenth and seventeenth centuries. Whereas most of the ancient Greeks and European medievals had believed the earth was at the center of the universe - with the sun, moon, planets, and stars orbiting around us - in the sixteenth century a new idea began to emerge. According to this new way of thinking, it was not the earth but the sun that was at the center of the cosmic system. This revolutionary idea was famously proposed by Nicholas Copernicus in his book "On the Revolution of the Heavenly Spheres", published in 1543.

In the early seventeenth century, Copernicus' concept of a heliocentric universe was further developed by the great German mathematician Johannes Kepler - the first true astrophysicist. It is to Kepler that we owe the discovery that all the planets revolve around the sun in ellipses. This was the first of his three famous laws of planetary motion, which describe mathematically how the planets move through the sky. Moreover, with truly prescient insight, Kepler suggested that the planets were kept in orbit by a force emanating from the sun itself. This radical idea was eventually demonstrated by Isaac Newton later in the century. With his own law of gravity Newton showed that the same force which keeps our feet anchored to the ground was also responsible for keeping the moon in orbit around the earth, and the planets in orbit around the sun. Thus the heavens and the earth were united by one grand universal force.

From the point of view of religion what is important here is that all three founders of modern cosmology saw their new vision of the heavens as an offshoot of their theology. Kepler had originally intended to become a Lutheran minister before he discovered his lifelong passion for the stars. But in his own eyes the two fields were both different forms of worship. As he wrote in 1595: "for a long time I wanted to become a theologian ... now, however, behold how through my efforts God is being celebrated in astronomy."

In the same vein Isaac Newton has been accurately described as a "religious fanatic", and indeed his whole life work can be seen as a search for God. He wanted nothing more than that his science, especially his cosmology, would help to convince people of the existence of God. In answer to a question from a young clergyman on this subject he responded: "When I wrote my treatise about our system, I had my eye upon such principles as might work with considering men for the belief of a deity; and nothing can rejoice me more than to find it useful for that purpose."

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