How to produce fractals without a computer

Via the BB Submitterator, TheOtherMichael points us to a nifty YouTube video of…

Computer-free fractals using "light on a wall as memory and the physical geometry of the path taken by the light into the camera and out from the projector as the processor to calculate the appropriate affine transformations." A lot of familiar fractal patterns show up — and the universe itself is the computer.

Blew my mind. I hope Mandelbrot got to see something like this before he died.

From the video description, by YouTube user YummyFuture:

Video feedback is a well-known phenomenon. If you hook a camera up to a TV and then point it at the TV, you get an infinite regression of images. However, you can use the same feedback phenomenon with multiple displays to make fractals. By displaying multiple smaller copies of what the camera sees, photographing that cluster of copies, and then repeating the process, you essentially create the self-similar structure seen in fractals. By moving and rotating the camera and projectors, you can create a very wide variety of fractal images.

The images seen in this video are not software-processed in any way. The camera is plugged in directly to the projectors. The pulsing and color shifting comes from the white balance and gain control of the camera.

In this setup, we're "computing" the fractal by using light on a wall as memory and the physical geometry of the path taken by the light into the camera and out from the projector as the processor to calculate the appropriate affine transformations. Given that both TV cameras and video projectors were around back in the late 1940s, it's possible that someone could have done this sort of setup at the dawn of the computer age.