The new frontiers of discovery are the hidden worlds we're in but don't even know it.
"In my Father's house are many mansions"
There are worlds within worlds.
We've discovered, explored and mapped every square inch of our physical world, and almost everything in it from the plants and animals to the elements with their molecules, electrons and quarks. The new territories for discovery are the hidden worlds and planes which we occupy and don't even know it.
We're already in Eternity -- NOW -- we just don't realize it. Somehow we think eternity is something that comes after death, but we're always in eternity. Eternity is all there is. (How could it be otherwise?) The physical world creates the illusion that we are outside of eternity while in a single lifetime with it's seeming finiteness, it's beginning and ending.
Similarly, we're also in planes of existence which are coming to be named the "Astral" and the "Etheric". Sensory awareness of the physical world blocks out most people's ability to perceive these planes, despite how completely and immediately they are connected to us. Our body, mind, heart and soul could have no existence without the etheric and astral because these planes provide much of the interface between the physical and spiritual realms.
I can imagine that other spiritual realms
could go on infinitely. However, all I know about from
personal experience is that we're currently in the "Astral Plane",
which is a spiritual arena which connects the spiritual human heart
directly to other spiritual dimensions (or worlds--which may include
both the heavenly and hellish). The Astral Plane is a "meeting
ground for souls" and the inspirational birthplace for the arts,
sciences and inventions, visions and spiritual guidance.
It appears that the jinn share both the astral and etheric planes with humanity. This would account for their abilities to both materialize physically and to appear in visions and dreams. The Koran states that the jinn are made from "smokeless fire". This appears to be a way of describing matter as it exists in the etheric state.
Physical "stuff" is transmutable through the etheric level. This is the real secret of alchemy. The science of the future will hopefully use this to wonderful advantage.
This doesn't seem so fantastic when you're aware of
the tangible reality of the etheric plane as an essential corollary
of the physical plane.
The World's Greatest Hoax Introduction: Alien beings claiming they come from other planets may be the greatest hoax ever.