I'm a bit nervous. I now have two offers on the table for PhDs in two countries. Both with industry funding. For the last one, in Germany with 75% civil service salary I'll get an answer next week. And now I'm getting cold feet.
The two I find most interesting, the one in Germany and another one involve some knowledge on programming and will involve using simulator software whose background consists of more differential equations that I've ever seen anywhere. Basically, I understand nothing of this and I'm not quite sure I ever will. Are these thoughts normal before you start out?