Why do we study composites?

Whether or not we make a conscious notice of them, composites are all around us, from materials in our own bodies (e.g., bones and teeth) to most of the objects in our everyday use (wood, concrete, ceramics, even some chocolates). Composites are made in specific ways combining two or more materials (at larger-than-atomic length scales), each contributing beneficial properties so that the resulting composite of the two ingredient materials exhibits an optimized set of properties that are otherwise complementary, for example, strength and ductility. This is the usual answer one would normally hear when you ask a materials scientist. Here is a more intriguing, and perhaps a more philosophical, answer given by Graeme Milton in the book The Theory of Composites:

“… a second, equally important reason is that what we learn from the field of composites could have far-reaching implications in many fields of science. Significant progress in improving our understanding of how microscopic behavior influence macroscopic behavior could impact our understanding of turbulence, of phase transitions involving many length scales, of how quantum behavior influences behavior on classical length scales, or, at the more extreme level, of how behavior on the Plank length scale influences behavior on the atomic scale.”

While the transfer of tactics from the understandings of macroscopic-microscopic thermomechanical behavior to the classical-quantum behavior may seem unlikely, he argues in favor saying “… it is hard to deny the impact that our understanding of classical physics had on the development of quantum mechanics. Therefore, it is conceivable that a better understanding of classical questions involving multiple length scales could have large reverberations.”