Dennis Carr wrote:

Just a little curious, is anybody aware if there is a theory behind
hyperspace in the Tenchi Muyo universe?

AFAIK, no official theory.  You open a hole into hyperspace, enter, and
close the hole.  It might be wormhole - instant transit - or dimensional
shift, or any of a number of things.

Although, if Nobuyuki ever got his hands on said theory...well, his
architectural career might have a few interesting twists ahead.
(Especially if the source of the knowledge - which, frankly, could
plausibly be just about any of the non-humans, although Washu's lab,
Ayeka's guardians, and the Yagami's databanks would be the easiest
sources to justify - views Nobuyuki's method of learning as "theft".)