During China’s Han dynasty, artisans began casting solid bronze mirrors with a perplexing property. The front of each mirror was a polished, reflective surface, and the back featured a design that had been cast into the bronze. But if light were cast from the mirrored side onto a wall, the design would appear there as if by magic.
The mirrors first came to the attention of the West in the early 19th century, and their secret eluded investigators for 100 years until British physicist William Bragg worked it out in 1932. Each mirror had been cast flat with the design on the reverse side, giving the disk a varying thickness. As the front was polished to produce a convex mirror, the thinner parts of the disk bulged outward slightly. These imperfections are invisible to direct inspection; as Bragg wrote, “Only the magnifying effect of reflection makes them plain.”
Joseph Needham, the historian of ancient Chinese science, calls this “the first step on the road to knowledge about the minute structure of metal surfaces.”
This is the most interested I’ve ever been in sports.
Completed through airbrushing and ridges that hide the different colors.
What made Buster Keaton so unforgettable?
Brain At 30 Years
Volume Rendering of an MRI scan of the brain
This is a stereogram, to be viewed in crossview technique: cross your eyes, relax your vision until there are three images, then focus on the center image.
Stereoscopic cross view photos can be viewed in three dimension (3D) without special glasses. Most people can learn how to view a cross view photo in just a few minutes: HOW TO VIEW A CROSS-EYE PAIR
Redmer Hoekstra creatively merges animals and other objects into one illustration, encouraging you to really look and think about the images. They are all very well and thoughtfully done. The unusual combinations have to be done just right to be pulled off, and the detail and realistic style really makes it work.
This is the view up a university stairwell where every floor is a different color.
Henry Kettle painted this pyramid anamorphosis around 1770. If a mirrored pyramid is placed at the center of the canvas, then each of its sides reflects a portion of one of the four distorted heads … producing a true hidden portrait when viewed from above.