“It is a very beautiful thing, and most gratifying to the sight, to behold the body of the moon….” At the beginning of the 17th century, Galileo gazed up at the dark expanse above, eyes meandering through lenses and tubes, and looked at the moon in a way no one in Europe had done before. In his “Starry Messengers,” Galileo published his findings that the moon was not a smooth sphere as had been previously thought by Catholic traditions, but was instead irregular, bumpy, and filled with valleys and mountains. He describes watching the sunrise on the moon from afar: “When I had observed [the moon] for a long time and had seen it completely dark, a bright peak began to emerge… Around it three other small points soon began to shine… when the moon was about to set, this triangular shape joined with the rest of the illuminated region and suddenly burst into the gulf of shadow like a vast promontory of light.” From this he deduced that, just like the sunrise on Earth first touches the mountains before reaching the valleys, the light on the moon must first be falling onto some great lunar peaks before delving into its vast, dark expanses. Where most people looked at the moon and saw variously colored splotches, Galileo saw a topographical wonderland. This was not revealed to Galileo through science.
Science is all about interactions. When scientists make observations, they record how an object of study interacts with a tool for measurement. Galileo was looking at the interactions between the moon and his eyes, aided by his telescope. If we are to be epistemologically rigorous (if we’re going to be real sticklers about what we can know for sure), all a scientist can observe are interactions, not objects.
If you are holding a newspaper in your hands (digital readers, please take a moment to grieve print journalism here), if you’re feeling rather scientific you might ask yourself, “what is this thing made of?” If you look really close, you can probably see the wood pulp fibers that make up the newsprint. But let’s say you want to learn about what those fibers are made of. Well, this gets harder. You could put the newspaper under a microscope and start looking at the fibers, but if you really want to know what it’s made of on a molecular level, sooner or later you would probably want to start doing some experiments. When you conduct a scientific experiment, you’re always looking at an interaction. Maybe you could burn the newspaper and learn that it’s made of something combustible. Perhaps leaving the newspaper in different solvents can tell you something about what sorts of bonds hold the newspaper together. Always, however, you’re only observing an interaction – between the newspaper and the solvent, the fire, the microscope, or your eyes. The newspaper itself — its substance, what it’s made of — is not something that science can measure.
Galileo can know how the moon looks, but he cannot know what the moon is, at least not by using science alone. He can watch the interactions between sun and moon with his telescope, but if he wants to understand what the moon is, if he wants to claim knowledge on an object and not an interaction, Galileo must go beyond science and craft a theory. When Galileo looked at the sun’s light encroaching on the lunar landscape, he saw something familiar. He looked at the earthly landscape that was readily available to him, he looked to that great alien body above, and he recognized that in many ways the two were the same. Any scientist like Galileo has to reach beyond science to craft and imagine their theories. Science can observe interactions and map them out so that we can use them to test our theories, but to come up with a theory, to see the mountains and valleys in the shadow and light, one must reach beyond what science can tell them. They must find new possibilities. Dive into the sea of interactions and hope that they can imagine an explanation that will hold water for long enough to expand their understanding. They must look to the sky, and make that great and impossible leap to the moon.