11) What two types of strings are present in string theory?
12) What are the three main theories within string theory?
13) What is a brane?
14) What type of forces are described by string theory?
15) How many dimensions does string theory exist in?
16) What is the name of the model within M-theory which has been proposed to explain the universe?
17) String Theory is a branch of physics that primarily deals with what?
18) What is the name of the hypothetical particle thought to be a loop of string in String Theory?
19) How many fundamental forces of nature are there in String Theory?
20) What is the name of the theory proposed by Edward Witten that combines the five different string theories?