The behavior of atoms, molecules and ions determines the sort of world we live in, our shapes and sizes, and even how we feel on a given day. Chemists who understand these phenomena are well equipped to tackle problems faced by our modern society. Chemists may study the mechanism of the recombination of DNA molecules, measure the amount of insecticide in drinking water, compare the protein content of meats, develop a new antibiotic or analyze a moon rock.
Understanding chemicals and chemical processes provides insight into the physical universe we inhabit. Chemistry plays an essential role in physics, biology and medicine, and earth and environmental science.
Physics is the study of the mechanical universe. It aims to uncover the basic rules of the behavior of matter and energy on every scale: from the interaction of subatomic particles, to the motion of everyday objects, to the evolution of galaxies. Physics is essential to understanding all of the natural sciences.