Nature: “Millions of students are returning to US universities in a vast unplanned pandemic experiment”

At the University of California, Irvine, campus managers will keep an eye on how crowded buildings are, using a system that has been under development for years with a grant from the US Defense Advanced Research Projects Agency. As students’ phones and laptops search for Wi-Fi signals in buildings, they generate ‘probe events’ that will be used to estimate how many people are in each area.