It really seems to depend on who you are working for. My adviser was pretty lenient...I could come in and leave when I liked (during the day), and so I was free to travel around that part of the country with my fellow REU students on the weekends once or twice if we asked for a Monday or Friday...
I'm going to graduate school for chemistry without ever taking a chemistry class (physics/math major)...but I did an REU at that university in the the chem dept.
Probably not typical, but it's possible. Probably going to be doing theoretical chemistry/physical chem, fwiw
I definitely agree with mgiddy that the main benefit is simply the exposure. Upper level physics classes espescially will be a lot easier if you already know the math and don't have to settle for the sometimes inadequate expositions given in physics texts. It also puts the math you already...
Well I don't know about Caltech, but there were definitely a few freshman in my REU at Cornell (Materials Science). As far as I know they all had research experience, though. I had a little research experience, but it was in no way related to Materials Science. I was a junior at the time...
Having just completed an REU this past summer and since I just sat down to work on my personal statements for various graduate schools, I feel like I can actually say something helpful here. So here goes:
Having read your personal statement, I see that you and I were kind of in a similar...