The books in The Chronicles of the Covenant take place in either Einsteinian Space/Time (our “real” world) or in Planck Space/Time, which is also called “The Mists”.
Katherehtak describes Planck Space/Time to Rebecca Cubis this way: <Did you know, lass, that mortals consider time to be immutable? Your Planck and Einstein came the closest to understanding time if they’d only have had more…time. Ironic, isn’t it? The very thing that kept them from knowledge was the thing itself. You like numbers; I’m sure you will appreciate this: Planck time is the amount of time for light to travel one Planck length. A Planck length is the distance light travels in one unit of Planck time. Isn’t it delicious? He uses the terms to describe themselves. Only a true philosopher of numbers can get away with that.> Basically, it is a place where time has no meaning.
When Katherehtak sends Rebecca back from the Mists, he says: <…but now, it is time to return you to the mortal world. Only a ‘Planck time unit’ will have passed, and no one will notice that you were absent…>