A Phoenix of Human Nature By Sara Schechner, Curator of the collection of Historical Scientific Instruments, Harvard University Since ancient times, people have marvelled at the night sky and sought answers to profound questions there. What are the heavenly bodies? What moves them? How do they affect one another? Where are they? And how do they affect us? These are questions of cosmology, and each age and culture has produced its own answers. To the modern astronomer, acceptable answers come from physics. But if I may point my telescope not just towards deep space but also back in time, I would suggest that modern answers continue to draw upon deep-seated cultural values. Religion, social practices and observational astronomy have long been intertwined in the development of cosmological beliefs. The ancient Egyptians observed the dawn risings of key stars and from them established not only their agricultural calendar and civil timekeeping, but also their religious rites. Two thousand years of observations gathered by Babylonian astronomer-priests gave rise to mathematical planetary astronomy, which Greek philosophers such as Aristotle used as the basis for their physical models of the cosmos. Aristotle’s cosmos was structured, hierarchical, finite, and compatible with the tenets of Christianity, Judaism, and Islam. God was Prime Mover of the planets and the unmoved foundation of a stable world system. In the 17th century, the Aristotelian cosmos gave way to the Newtonian world view. Looking out into an infinite universe, Isaac Newton showed how the motions of the stars, planets, and comets were all governed by universal gravitation. Comets circulated vital spirits and fuel to the stars, but could also slam into worlds, causing mass extinctions and global destruction. In 1755, Immanuel Kant offered a physical theory on the origin and evolution of the universe. He described how universal forces of attraction and repulsion, acting on matter diffused throughout space, gave rise to instabilities in the chaos, leading to physical and chemical complexity. Denser regions gravitationally attracted lesser ones, while the action of repulsive forces caused in-falling matter to swirl around the dense centres. Over time, these vortices collapsed into stellar systems containing suns, planets, and comets. Creation thus spread out from a central point into the chaos and animated the whole region of infinite space. But Kant observed, “whatever has a beginning and origin, has the mark of its limited nature in itself; it must perish and have an end.” When a world-system exhausted all the manifold variations that its structure could embrace, it perished in a violent conflagration. The universe was, Kant envisioned, a “phoenix of nature, which burns itself only in order to revive again in restored youth from its ashes, through all the infinity of times and spaces.” Kant’s book was one of the earliest attempts to describe the origin and evolution of the cosmos under the influence of universal natural laws. Prior to Kant, it was commonly held that creation was fixed and the universe was maintained in a steady state. So where did Kant’s modern evolutionary ideas come from? From popular culture as remade by Newton. Until the 17th century, people believed that comets were divine signs heralding imminent world change. Newton appropriated this popular belief when he portrayed comets as natural agents deployed by God to create, renovate, or destroy heavenly bodies, thus melding popular beliefs with physics. This new approach gave license to those who held that material forces created new solar systems and the universe evolved according to natural laws. If popular beliefs were formative in the early development of modern cosmology, should we be worried that they continue to sully current science? Not at all. We can still celebrate the ways our diverse cultural heritages have shaped our scientific inquiries. Cosmology is ultimately a human endeavour. In asking questions about the deep past and distant future, it draws from many rich traditions and brings us closer together as human beings.