I took my first physics class ever at Stanford University in January 1960. The professor was Leonard Schiff, then also the chairman of the physics department. The lecture hall was full of mostly freshmen, some excited and some terrified at the thought of calculus-based physics taught by one of the most distinguished members of the department.
Leonard began by talking about the difference between basic and applied research, perhaps not a topic calculated to excite the group. But one guy (not I, let me assure you) raised his hand to stop the lecturer for a question: “Yes, but what is physics?” Leonard stopped in his tracks. I doubt he had ever been asked that question that way.
After thinking for a few moments, he responded, “Why, physics is whatever physicists do.” In the 61 years of my career as a physicist, I’ve never heard a definition I liked better. Physics isn’t the manipulation of mass and energy and the measurement of ever-more-precise quantities. Instead, it’s whatever the people trained in those arts decide to do.
That’s a definition I’ve used more than once as I’ve wandered from MeV- to GeV-range nuclear and particle physics, to planetary orbital mechanics, to strategic arms control, and to diplomacy with Chinese and Soviet colleagues. As long as I’m using the mental attitudes of a physicist, I’m doing physics and need not apologize for my changing interests and skills.
And so, my thanks for the February 2021 issue, which demonstrates and encourages the enormous range of activities that we can collectively call “physics”: from neutrinos to rare-earth magnets, lunar exploration, tech transfer, and measurable differences between whisky and whiskey. I think Leonard would have been charmed and delighted. I wish I had a hundred copies to give to high school seniors, mid-degree undergraduate physics majors, grad students, and physicists who have left the lab for other careers.
