papucisse

They are observables. You can measure anyone of them. you're right, it's S+ and S- that are not observables .

Yet Another Question: since Sx, Sy, Sz are not observables, are you sure their hermitian ?

[goodjob] Congratulations on your score, and on your offer from LSU. You should be partying by now [dance]

Kooki3, Most of those schools don't care much about you score after you reach the 70%; Indeed another "top" school (not caltech though) even told me that most of their admitted students in average score in the 40%, especially if you are an american student (or did your undergrad in the US), If you were from china and if you want to do Theory in grad-school it may be a different story. with that said, HOW THE HELL DID U SCORE 800 WITHOUT HAVING E&M? :crazy::crazy: This is unheard of! I know many graduating seniors who have taken Grad-level E&M and Quantum and have scored a lot less (they' re all going to some of the schools you may be considering, just to let you know). Since you seem to be good at this, you should definitely take it again after your first semester E&M, maybe you'll be our next yevgeny (for fun, and of course if you have $115 to spare for the GRE Fee). But I think all you need now is some research experience (possibly this summer through an REU) and a publication will be the icing on the cake. I also understand that nothing or noone is going to make you feel at ease with your "excellent" score, because just a few months ago I was in a similar situation hoping to get in the best school in my field and thinking that my GRE score was going to be an obstacle. But believe me, you have crossed the biggest obstacle by scoring over 70%; and I'm sure you'll be just fine. As for me I can't really tell you my score ( fear embarrasment :drunk:), but I am now attending the #1 graduate program in my field. Hope this note helps a little.

Hello, I m an international student too, studying in the US, with somewhat of a similar situation (different field though. The school I got in turned out to be the #1 in my field, and they're offering full financial coverage, so I guess there is no thinking twice.:p. I m a sole believer that things like that happen for a reason, so enjoy the lemonade you would have made out of life's lemons :cool: But coming back to your question, when you will do your interview (like I did, I dont know if the requirement is the same for your interview) the ambassador will only have information about the one I-20 from the University you will be attending because that's the Info that need to go on your visa... so I don't believe it would make a difference to the embassy if u recieved one I-20 or 20 I-20's because they won't know, and probably won't care:shy:.

This is a slight variation of problem#5 in chapter 3 of Kittel's Intro to solid State Physics (page 93); I modified the problem to adress the specific question I am trying to understand: Consider a line of 2N ions of alternating charge +/- q with a repulsive potential energy A/(R^n) between nearest neighbors (where R represents the distance between particles). determine the energy per particle and the total energy of the crystal. hint: energy per particle would be u®= (attractive term) +(repulsive term) I hope someone can help.

ok thanks ecm; another question: was it from the problem or is it a property of Spin (S)? (i m using griffiths "intro to QM", and Spin is on page 154 if you want to make a reference) Thanks

Hey ECM, welcome back! yeah it makes sense now, thanks; it sort of like the question what is the constant of a spring after the length has been cut in half. I sent you and yevgeny a PM about I will be going for grad school, have you recieved it?

a question: since S=Sx, shouldnt ==0 (no dependence on Sy, and Sz)?

the rest of your reasoning makes sense, but I have a hard time understanding why k' is greater than k, shouldnt it be k'=k*dq/L (since dq/L is the ratio by length representing the small piece) ?

I am not too familiar with this but here is what comes to my mind, perhaps it would be helpful perhaps not. 1- I would try to use the distance traveled (D2-D1) to determine the speed of the source relative to earth (or time if needed ). 2- I would use only D1 for the distance travelled by the radiation. Now, what am I assuming wrong? where can I read more on this?

I finally called ETS last night to get my resultsform the november 8th test. I did somewhat worse than I expected:drunk:, But I still did "OK"; I think I can officially say now that I m done with the physics GRE[dance]. Thanks Ecm and yevgeny for the multiple posts and for solving most of the difficult problems on this forum. I will still be arround cause solving other questions like the GRE's will be a good preparation for the prelims and qualifying exams in grad school. banana rules [banana]!

Read your pm yevgeny

I guess they already took "her" away ( It didnt occur to me to look up your profile and hers :shy:, so to be fair I also updated mine). But where are you ECM, we miss you already :( yevgeny, no I don't have a telescope?; but there is an observatory nearby. what is it in reference to?( or was it a joke that I missed :o)

Felicitaciones ECM[bounce]! I very very happy for you[dance]; For this offer to top going to caltech, it must be really really big! I want to know all about it! (or am I being too noisy? :o ), PM me! I also have something to tell you guys about, it's also a confusing good news :D