Princeton University.
Edward Witten's departure had a huge impact, leaving many people dizzy with busyness.
Edward Witten was a professor at the Institute for Advanced Study at Princeton and also taught courses and supervised doctoral students at Princeton University. He was a core leader in several mathematics projects at the institute, and many things couldn't be done without him.
Now Edward Witten had suddenly left, and many things were left without any buffer time.
First were the courses, projects, and conferences.
The courses taught by Edward Witten couldn't be interrupted, so someone else had to take responsibility for teaching them. However, his courses were very deep and complicated, and not just anyone could teach them. A mathematician who was an expert in the relevant field had to be found to replace him.
The projects were relatively easier to handle; they could be suspended temporarily if they couldn't be carried out.