I am going to be a high school math teacher and I know I will be asked questions like, "When am I ever going to use this?" or "Why do we have to learn this?" So going along with these questions I wanted to find out where primes are used outside of number theory. In this way, I would be prepared to answer questions like these in my classroom.

I went on Wikipedia and found that the following fact:

"In his science fiction novel Contact, later made into a film of the same name, the NASA scientist Carl Sagan suggested that **prime numbers** could be used as a means of communicating with aliens, an idea that he had first developed informally with American astronomer Frank Drake in 1975. [26]" (Wikipedia) I thought this was interesting. :)

Also, I found that they can even be used in the world of music. Here is what it says…

"Prime numbers have influenced many artists and writers. The French composer Olivier Messiaen used prime numbers to create ametrical music through "natural phenomena". In works such as La Nativité du Seigneur (1935) and Quatre études de rythme (1949-50), he simultaneously employs motifs with lengths given by different **prime numbers** to create unpredictable rhythms: the primes 41, 43, 47 and 53 appear in one of the études. According to Messiaen this way of composing was "inspired by the movements of nature, movements of free and unequal durations". [25] (Wikipedia)

Does anyone else have any other examples of where primes are used outside of number theory?