Stanford University's microwave research program offers an interesting perspective on the interaction of electrical engineering and physics. Beginning with the invention of the klystron by William Hansen and the Varian brothers in the 1930s, Stanford's departments of physics and electrical engineering worked together closely in exploring the science and technology of microwaves. On the engineering side, this knowledge led to a series of important electronics devices for communication and defense. On the scientific side, it became the heart of the Stanford Linear Accelerator Center, one of the most expensive and productive scientific facilities of its time. What made Stanford's program so productive were physicists and electrical engineers--William Hansen, Edward Ginzton, Frederick Terman--who combined an appreciation of the scientific and technical potential of microwave research with an entrepreneurial talent for assembling the intellectual and financial resources crucial for success. They brought together electrical engineering and physics not so much by collapsing disciplinary boundaries as by opening up opportunities in the spaces between them.