Einstein’s search for general relativity spanned eight years, 1907-1915. Some periods were quiet and some were more intense. The moments when the great transition occurred, came sometime between the late summer of 1912, when Einstein moved from Prague to Zurich, and early 1913. If we could choose one time at which to look over Einstein’s shoulder and watch him work on general relativity, it would be this time.
And that is just what we can do. For, found among his papers when Einstein died in 1955 was a small, brown notebook containing his private calculations from just this time. This is the Zurich notebook.
The technique used by Brand to create these pieces is not one of conventional holography. He meticulously controls the unique shape of thousands of tiny optical pieces placed on a surface creating a 3D effect when the light source or viewer moves. This is essentially a mathematical problem in differential geometry and combinatorial optimization. Brand was the first person to correctly describe this technique in 2008 even though it dates back as early as the 1930s (check out his paper for details).