Research in physics education can be useful in various ways but should not be the only source of help for teachers. Any answer to the question in the title depends upon what the questioner understands by research in physics education and by the purposes that such research may be assumed to serve. The author suggests that while physics teachers may learn much from research in physics education, the findings of educational research may not be the most obvious or important way of improving practice, or of raising the professional standing of science teachers. Such a suggestion does not devalue educational research or deny its importance to physics teachers' work. Rather, as the author hopes to show, it rests upon a more generous understanding of what is meant by educational research and demands a more realistic acknowledgment of the complex and mediated relationship between research and educational policy and practice. Because of that complexity and mediation, it is always going to be difficult to isolate or measure the impact of any research on how physics teachers think about, and conduct, their work in classrooms and laboratories.