Tens of thousands of students are converging in concentrated locations from all over the state, nation and even the world. They are moving into tight dorm rooms and setting up apartments with new roommates. They’re sitting in classrooms, eating cafeteria-style, socializing and studying in the library. Many California college campuses appear to be havens from the coronavirus, with strict safety practices that include mandatory vaccinations for students and staff, weekly testing and required masking for all indoor and some outdoor activities. Positive cases will prompt quarantines and contact tracing. But amid the surge of the highly contagious Delta variant, it’s unclear whether “almost back to normal” will last this fall, as students redefine the centerpiece of college life: togetherness.