The Fourth Dimension: And How to Get There

'Rucker calls this a "definitive account of what the fourth dimension means, both physically and spiritually." To help us visualize the fourth dimension, Rucker reasons by analogy: the fourth dimension is to the third as the third is to the second. Quoting from Flatland, a SF novel published in 1884 which tells the story of a two-dimensional square who meets a three-dimensional sphere and takes a trip into higher dimensions, Rucker introduces us to four-dimensional shapes like the hypercube, of which a drawing is provided, and proceeds to discuss spiritualism, Ouspensky, the aether, Einstein's relativity theories, curves and bumps in space, time and the possibility of time travel, the Unknowable One of the mystics, Jung and synchronicity, Hilberts theory of infinite dimensional spaces.' - Martin Gardner. (from the back cover)