Charles Yu has written a lot about the nature of reality, how we understand what is real, and the assumptions we make about each other and the universe we live in. Yu’s first novel, “How to live Safely in a Science Fictional Universe,” follows a time machine repairman who is searching for his father who is lost in time and memory. His latest book, National Book Award winning “Interior Chinatown,” takes place in a Chinese restaurant that’s also the set for a police procedural TV show and a sendup of stereotypes of Asian American characters. Yu talks to us in front of an audience of students from Ida B. Wells High School.