I asked this question over at Math, but it was deleted. I am having an argument with some of my friends. For the sake of this question let's accept that the foreskin can be expanded with tension and ...
I am working through Zwiebach's a first course in string theory. It's been a while since I did any math (or physics!), and I am stuck on the following problem (quick calculation 2.5 in the book): ...
I went to a lecture a few weeks ago and was told the following: The world sheet of a closed string is a normal, standing cylinder. The world sheet of an open string is a cylinder on its side. This ...