Sean Carroll in Scientific American:
I first heard of Joe Polchinski in 1988, when I was applying to various graduate schools in physics. During a visit to Harvard, I talked with Sidney Coleman, one of the leading thinkers in the esoteric world of quantum field theory. Although he was happy to sing the praises of his own institution, Sidney couldn’t help but add, “But I wouldn’t blame you if you went to the University of Texas. Whoever gets Joe Polchinski as an advisor will be fortunate indeed.”
I didn’t follow the advice, but I remembered the name, and a few years later I had the wonderful good fortune of being a postdoctoral researcher at the Kavli Institute for Theoretical Physics in Santa Barbara. Joe had moved there in 1992, and my office was just down the hall from his. I can’t tell you how often I would knock on his door to ask a question about physics. In a milieu packed with very smart people, he was the go-to guy, renowned for his carefulness and open-mindedness to new ideas. It wasn’t just me, either; countless students and colleagues sought out just a bit of his time. Eventually, as he worked to finish his giant two-volume textbook on string theory, he took to simply closing his door and pretending he wasn’t in the office. Once the book was finished, however, the door was open again, and the constant stream of visitors resumed.
Joe died at his home last week, age 63, after having been treated for brain cancer for a few years. His passing leaves a hole in the physics community, as his research was as innovative and impactful as ever. Looking over the countless memories and sympathies posted online, I don’t think I’ve ever seen such a large and heartfelt outpouring of grief at the passing of a great physicist.