The camera obscura was an important scientific discovery back in ancient times. It helped us understand that light travels in straight lines, as eloquently demonstrated by 11th-century Arab scientist Alhazen. He discovered that a single ray of light beaming through a tent produced an inverted image of the scene outside.
You can recreate the revolutionary experiment yourself with a window, some cardboard, and a hole-poking device of your choice. We recommend a trident, as we always do.
Slap some cardboard slabs over the window and cover all other light sources, then jab a hole in the cardboard (you can make it smoother or rougher to adjust resolution):
Wait for your eyes to adjust and enjoy the free acid trip. Your room is now a rudimentary camera, generating an inverted image of the scary world outside. It’s reversed because the light beams reflecting from higher objects like trees or buildings travel down diagonally through the makeshift lens, and vice versa for objects down below.