The world’s costliest painting depicts a glass sphere with curious optical properties. Computer scientists figured out what the artist was getting at.
After comparing their renderings with the original, they have concluded that the orb is not solid at all. Instead, they show that the painting is a realistic physical representation of a hollow sphere with a radius of 6.8 centimeters but a thickness of just 1.3 millimeters.
Gregor J. Rothfuss 