A Remarkably Simple Demonstration On Diffraction

I spotted a remarkably simple demonstration of optical diffraction the other night, from looking across at the far away lights on the otherside of the train tracks from a balcony. I noticed they looked quite different dependng on whether the flyscreen was open, or closed. Take a look: Open Closed See those beautiful points? Like a four pointed star? (Like in the ✨ Emoji). Those are the "diffraction effects", the result of the light waves taking slightly different paths through each of the tiny holes in my flyscreen, and then overlapping and interfering by the time they get to my eyeballs (or camera). Thomas Young described this effect using ripples / waves in a water tank, showing that the waves would interfere and add up to higher peaks in some areas, and flats in others. Credit: Public Domain — Thomas Young's sketch of two-slit diffraction for water ripple tank from his 1807 Lectures The exact pattern for each of these lights could be calculated by a second year physics student (I…