Dear Physics 24 students, I discovered last night that there is a 2nd edition of K&K, but I only have the 1st edition on my bookshelf. Three of the problems in homework 1 are listed by problem number in K&K 1st edition (problems 12.5, 12.6, and 12.10). These may or may not correspond to what is in K&K 2nd edition. To make it absolutely clear, here is where you can find the assigned problems from the first edition. http://hep.ucsb.edu/people/claudio/ph24-18/Old-KandK-1.jpg http://hep.ucsb.edu/people/claudio/ph24-18/Old-KandK-2.jpg If you have already done the problems from the 2nd edition, and they happen to be different from those in the 1st edition, you will get credit for them. Just indicate in the homework solutions that you turn in that you did the problems from the 2nd edition. You then do not need to do the problems from the 1st edition as well (but you probably should for your own good). On the other hand, if you have not started on the K&K problems yet, ignore the 2nd edition and do the problem from the 1st edition. I will try to get my hands on a 2nd edition of K&K on Monday to put a stop to this confusion. Also: the syllabus on the website refers to the K&K chapter numbers from the 1st edition. I will update the syllabus as soon as I get a 2nd edition, if the chapter numbers have changed. Sorry about all of this. C