I particularly like this, in the 5D section:

"Seeing time as the fourth dimension made sense of Einstein's special relativity. The German mathematician Theodor Kaluza had even grander designs. In 1919, he sent a paper to Einstein in which he argued that by adding a fifth dimension to space-time, it was possible to show that gravity and electromagnetism were two aspects of one and the same force."

...because I've always had an inkling that gravity is a half-twist of magnetism.