Michio Kaku’s Hyperspace, Bennett’s sources
It is worth looking at the physicist Michio Kaku’s Hyperspace which has some material on the episode of so-called Kaluza-Klein theory in the twenties. This was a five-dimensional extention to Einstein’s General Relativity that was stunningly original for its time, falling by the wayside for several decades, but now resurfacing in a more general form in the various forms of so-called string theory.
It was Bennett’s keen-eyed insight to pick up on Kaluza-Klein in the twenties, and proceed to his own version of that, the six-dimensional time-space version of an earlier idea in Ouspensky.
New Man, New Age, New Socialism 