I'm not exactly sure by what you mean by physical barriers of communication, but if I had to take a guess at this, here's how I would answer. There are a few different barriers which one could face, depending on how they were raised, someone may not speak with someone of a specific ethnicity. Others may feel uncomfortable speaking with those who are very physically attractive.
While others may feel they are better or above those which are speaking to them. Hope this helps you out, Google is always a great place to look as well.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.