Philip Ball writes: For centuries, scientists studied light to comprehend the visible world. Why are things colored? What is a rainbow? How do our eyes work? And what is light itself? These are questions that preoccupied scientists and philosophers since the time of Aristotle, including Roger Bacon, Isaac Newton, Michael Faraday, Thomas Young, and James Clerk Maxwell.
But in the late 19th century all that changed, and it was largely Maxwell’s doing. This was the period in which the whole focus of physics — then still emerging as a distinct scientific discipline — shifted from the visible to the invisible. Light itself was instrumental to that change. Not only were the components of light invisible “fields,” but light was revealed as merely a small slice of a rainbow extending far into the unseen.
Physics has never looked back. Today its theories and concepts are concerned largely with invisible entities: not only unseen force fields and insensible rays but particles too small to see even with the most advanced microscopes. We now know that our everyday perception grants us access to only a tiny fraction of reality. Telescopes responding to radio waves, infrared radiation, and X-rays have vastly expanded our view of the universe, while electron microscopes, X-ray beams, and other fine probes of nature’s granularity have unveiled the microworld hidden beyond our visual acuity. Theories at the speculative forefront of physics flesh out this unseen universe with parallel worlds and with mysterious entities named for their very invisibility: dark matter and dark energy.
This move beyond the visible has become a fundamental part of science’s narrative. But it’s a more complicated shift than we often appreciate. Making sense of what is unseen — of what lies “beyond the light” — has a much longer history in human experience. Before science had the means to explore that realm, we had to make do with stories that became enshrined in myth and folklore. Those stories aren’t banished as science advances; they are simply reinvented. Scientists working at the forefront of the invisible will always be confronted with gaps in knowledge, understanding, and experimental capability. In the face of those limits, they draw unconsciously on the imagery of the old stories. This is a necessary part of science, and these stories can sometimes suggest genuinely productive scientific ideas. But the danger is that we will start to believe them at face value, mistaking them for theories.
A backward glance at the history of the invisible shows how the narratives and tropes of myth and folklore can stimulate science, while showing that the truth will probably turn out to be far stranger and more unexpected than these old stories can accommodate. [Continue reading…]