Abstract Summary
If you can spray them then they are real” is Ian Hacking’s pithy answer to the question of when we should believe in the existence of microscopic entities we cannot see. Much history and philosophy of science has concerned the second half of Hacking’s slogan. Historians have investigated how scientists came to believe in things like electrons, neutrons, and photons. Philosophers have wondered what it means to build science around belief in unobservable entities. But the first half of the quote hints at other, more rarely told stories. When we spray electrons, or neutrons, or photons, how do we spray them? At what? To what end? The history and philosophy of science have said a great deal about the things we spray, but much less about how and why we spray them. This talk discusses the 20th-century tools that provided new insights into the characteristics of materials, and thereby redefined what scientist mean when they talk about materials. Materials are often distinguished from other matter because they can be or have been turned to human purposes. Nothing about that definition requires a robust scientific understanding of materials have useful properties. The proliferation of tools for characterizing materials brought that knowledge within grasp. These tools helped fuse the many traditions of materials research into a new, interdisciplinary field of materials science. In doing so, they made knowledge of the inner workings of matter essential to the concept of materials as the substances that humans use to achieve their aims and desires.
