Today’s invention is a way for an office worker in a dark cubicle to experience the time of day more viscerally than via a clock.
A small projector plugs into one’s laptop and shines a bright disc on the wall of the windowless office. The position and approximate size of the disc correspond to the Sun’s appearance from the worker’s position -if there were any windows.
A smart system might even scan the geometry of the room and adjust the apparent shape of the projected sun to remain always circular (rather than eg an ellipsoid on an oblique wall).
This might well be enough to keep the worker’s biorhythms intact throughout the year (which is believed to influence strongly one’s body’s responses to drugs and one’s immunity to disease).