Time as a faculty member is a more precious resource than I ever imagined. As such, I can be kind of hard to contact. If you are trying to find me to talk about something, email is my preferred method --- it gives me a chance to defer answering until I have a chance to respond thoughtfully to whatever you might be asking.
Some more general contact notes:
If you would like to speak on the phone, please send me an email and set up an appointment first. I hate acting like such a prima donna, but I can't get anything done unless I control my schedule very carefully. (As one of my colleagues likes to say "I have lots of free time; it just all comes in 5 minute blocks.")
I'm a high school student doing a report on black holes. If you could help me to understand the following thing I read about, I would really appreciate it.
A bad example is
Hey dude, I was wondering about black holes. Could you like tell me about them? Oh, and could you send me a 1 page single spaced answer by like tomorrow at 8 am? That's when my report is due.
I'm very sad to report that the bad example is based on a real email I received (albeit I've improved the spelling and grammar).
I sometimes get queries about coming to MIT. If time permits, I can sometimes answer general questions, but please bear in mind that I'm not officially connected to admissions (undergraduate or graduate). The people who can tell you about admissions are here. (Specific information about the MIT physics Ph.D. program is here.)
Sometimes people from outside MIT write to me asking if they can join my research group for a "summer internship," or for a similar short term research project. The answer is always, unequivocally, no. To be blunt, such a short time frame is not long enough for someone to make a meaningful contribution to my group's research program. And, if I have time to supervise a student, I will work with an MIT student. As an MIT professor, working with MIT students is my top priority.
Please bear in mind I don't enforce these rules to be a jerk; my time is seriously limited. Telephone interruptions and questions of various sorts really do take a lot of time out of my day. I'm happy to talk with just about anyone reasonable, but I must insist on keeping access somewhat limited. Otherwise, I'd get nothing done, and I wouldn't be someone you'd care to speak with...