A Blank Wall Can Show How Many People Are in a Room and What They’re Doing
A Blank Wall Can Show How Many People Are in a Room and What They’re Doing
Oct 9, 2021, 9:17am UTC
https://www.scientificamerican.com/article/a-blank-wall-can-show-how-many-people-are-in-a-room-and-what-theyre-doing/