egg illusions

Even though I'm not very good at it I find art a very important part of the playful part of math and science.  I've bemoaned the narrow-minded focus on STEM in schools enough, so here's a delightful example.

 

Before film it was discovered we have a persistence of vision - the mind stitches together smooth motion by combing something like 25 still images per second.¹  In the early 1800s the zoetrope was invented.  A drum with image frames painted on the inside would be spun.  It had a series of slits around the periphery that you would look through to watch the short animation.  These became toys of the Victorian era leading to more sophisticated design.  

 

Stitching moving still frames into an illusion of motion led to something of the inverse.   A blurry vibrating guitar string viewed using a bright light that flashes with a regular frequency appears to stop.  The stroboscope has a wide range of application - you've probably used one in a high school science class and electronic versions that only display the repeating parts of a signal are fundamental to electrical engineering.

 

You can write on the surface of a spinning object and by picking the right frequency of a flashing strobe light motion will appear.  Now what if you could do this on a complex surface?

 

The EggBot is a delightful little piece of tech.  A computer controlled printer that draws on spherical and roughly spherical shapes. Balls and, well, even eggs.  Jiri Zemanek at the Czech Technical University in Prague generates interesting patterns in Matlab which was used to drive his Eggbot.  Then he spins the eggs and adjusts the frequency of a strobe light.  Art, math, science and engineering and a bit of time for your imagination to take flight.

 

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¹ At least most of us think persistence of vision is what allows us to view motion in film.  It turns out to be more complicated and a combination of persistence of vision and the phi phenomenon.  Persistence of vision is why you don't see the black spaces that come before each frame in a film.  The phi phenomenon is the apparent motion of a sequence of still images.  

 

Comments

[Jheri]

Wow! I may order an eggbit. My heritage is Belarusian and beautifully painted eggs are a famous folkcraft.