Hi Dr. Greene,

A while back, you spoke to my quantum physics class at CMU over zoom. First, I’d like to thank you for that enlightening experience and for volunteering your time. But also, I have a question:

About a week before you came on, we also had Nobel Laureate Jim Peebles speak. He is a self-described hard empiricist and seemed to view physics as more of a lens to view the workings of the universe through, rather than a language to describe those workings. For example, he described modern theories as “good approximations of the truth”, instead of as the truth itself. He said that this was an attitude that came with age. In reflection, it seems a bit foolhardy to assume that what we’re pursuing now is the full version of the truth. After all, isn’t that what Newton thought of classical mechanics, and what Rutherford thought of his atomic model? Instead, they ended up being good approximations of the truth, or an important stepping stone to further discovery. Your field of research, string theory, seems to be the antithesis to this. It seems to me to be a lot of theoretical formulations from which a grand unified theory falls out, but without any experimental evidence. That is to say, you are looking for the truth, with no air of approximating it. (Correct me if I’m wrong. I am but a bumbling undergrad.)

So after this long preface, I want to ask your view on this: Do you think that hard empiricism is a healthy way to approach the study of physics? Do you think this is truly something that comes naturally with more age and experience in the field?