On our physical plane of existence we can detect only about 100 octaves of electromagnetic radiation, ranging from radio waves through visible light to x-rays and gamma rays, the electromagnetic spectrum covers an infinite range of frequencies – or at least we have no reason to believe otherwise.
What to us is ‘empty’ space is simply those regions of space containing no grade of matter that is perceptible to our physical senses.
An important property of electromagnetic energy is that waves of sufficiently different frequencies do not interfere or interact. If physical matter is condensed energy as science now maintains, it seems reasonable to suppose that the infinite spectrum of energy gives rise to infinite grades of matter, and that grades of matter of sufficiently differing densities or rates of vibration can pass through one another without noticeably interacting.
although physical matter is condensed energy, what is energy would be matter for beings on a higher plane than ours, as is suggested by the fact that energy does not exist in a continuous flow but is composed of discrete units or quanta.
If that is the case, then it is reasonable to suggest that our physical universe could be just one octave in an infinite spectrum of matter-energy, and be interpenetrated by innumerable other invisible non-physical worlds, both denser and also more aethereal than our own, but beyond our physical range of perception. The concept of worlds within worlds is therefore entirely reasonable if we pursue some of the basic concepts of science to their logical conclusion.
Waves by the way, imply motion and there is no motion that is independent of substance whether the substance is physical or aethereal. In other words, waves have to wave in some medium otherwise they are simply abstractions.
Space is not 'empty' either, it is constituted by different grades of energy-substance otherwise waves could not be propagated through it.
Our Universe is seen by what is considered an infinite spectrum of vibration or density but it consist of one substance
this substance is called aether and its a vibrating like energy that permeates space. matter as we know its created moment-by-moment as a standing wave in the aether. this wave particle paradox is not a big deal, once you consider the particle is a wave packet-----a packet of standing waves in the aether of space.
our bodies have shape and possess solidity only because it is being renewed each time at a quick rate so we are basically a composite of physical/non-physical waves at different wavelengths, frequencies and vibration that exceeds beyond that of the range of physical electromagnetic spectrum of energy.