The current topic of debate is: should I spend the fall in Paris? There's a semester-long program in number theory that a Berkeley professor whom I consider a possible advisor is going to. He's taking a bunch of his students, so I asked him what it would take for me to be able to go. He said, "Just show up."

Now before you say, "Who wouldn't want to spend a semester in Paris?" consider the drawbacks: (a) I may not want to study number theory, in which case I would come back a semester behind in terms of both learning math and finding an advisor. (b) Paris is very expensive. Especially with the dollar in its current state. (c) I won't have any friends there. (d) Can Paris really be that much better than the Bay Area?

On the other hand, it is Paris. And when else will I have the opportunity to spend four months there fully funded?

Thoughts?