Ok, I've been giving some thought on the mechanics of the afterlife and other assorted random bits. Lots of conjecture here, but it makes sense on some levels.
Ok, we know that people when they die, they *usually (I'll explain the 'usually' in just a bit) end in either Heaven or Hell. Heaven has the habit of kicking a good portion of the souls who end up there out of heaven (usually those who won't mindlessly do what they're told). So, we know that there is some reason for where we end up. Now, if we are to go with the assumption that how you lead your life determines where you end up, then the actions/emotions/karma of our existence end up creating an imprint of some kind upon the soul which determines where it goes.
Now if this was the case of the soul having imprints, then it's very likely that people who have led passionate/emotional/action oriented lives are going to have a positive imprint upon their soul (positive does not always equate to "good" here people, just so you know). As Hell is said to be a realm of Chaos, Passion, and Wild Energies, then those with a positive charge are more likely to end up in Hell rather than Heaven. Now, you don't have to be evil to end up in hell, but 'evil' actions would in fact lead to a positive charge upon the soul more easily than 'good' actions. Therefore, Good and Evil do not play the defining role in where you end up in the afterlife, but they do play their role in things.
Now Heaven is thought to be a realm of inner peace, joy, serenity and all that rot. Now classically, these things have always been associated as being the opposite of the forces of action (essentially, the classical description would have been the word 'negative', but without the offensiveness or stigma that we currently associate with the word 'negative'). So, those who would live emotionally healthy lives, who would do 'good', or who had come to peace and/or serenity would likely have a negative charge, and end up in heaven. Whether they'd actually stay in heaven is a separate issue entirely though.
So, we know that at some point some higher dimensional being stepped through to Earth, and they did it without a beacon (Nephilim). A beacon of some kind to lock onto makes the trip much more easier to do. However, while the scientists could try to open a hole to heaven (by act of reversing the polarity!), without a beacon to lock onto, it would take a lot of trial and error as while they have the data for the hell portal, they don't know which part of the data is for opening the portal and which for is the beacon.
*Ok, to explain the usually. Humanity has been around for at least a hundred thousand years. It's an uncomfortable fact (as it implies that there is a HUGE amount of lost human history), but this is pretty much accepted by people who keep publishing genetics study reviews and the like. Now, in that one hundred thousand years, there have been at a minimum of one trillion souls of people who have been born and who have died. Heaven currently has somewhere between twenty billion to forty billion souls in it's possession (I couldn't find the post that said what the exact number was). Hell has somewhere around a hundred billion.
As there is one thousand billions in one trillion, there is a large number of missing souls here (about 850 billion to be more exact). Now, the story has implied that only
very recently has heaven and hell come into contact with earth, and given that this sort of daemonic and angelic mythology is pretty recent (I think we can figure out when by looking at the numbers of souls Heaven and Hell currently possess with their domains and working out how long back it would take to get those numbers), this means that souls were ending up somewhere else before 'the stars were right' (
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn?) for the forces of Heaven and Hell to walk upon the earth.
Now, a while back there was talk of what happens to someone who dies in hell. As we know that the soul contains energy, and as
energy cannot be destroyed, we know that death itself is kind of meaningless in the context it's being raised as. Now, energy can be redirected, siphoned, leeched, or allowed to atrophy, but energy cannot be destroyed. As there are about a hundred billion souls being tortured or whatnot in hell, we can reasonably say that the Baldricks get nothing from the deaths (I.E. destruction) of those souls, otherwise there would be about a hundred billion rotting faux corpses. So, we can assume one of a few things when a persons dies, or when the body of one of the dead is completely destroyed within hell. They either reappear somewhere else in hell, they end up taking in the energy of those being tortured alongside them and ascending to a level beyond that of Hell, or their souls can no longer hold onto that energy and they explode with the power of a nuclear bomb.
Actually, this raises another interesting question, what exactly is the soul? It's said within classical mythology that Demons and Angels do not have souls. Perhaps all the soul is is a way to tap into the energies of the universe. It would explain why the Angels and Demons would need the power provided by humanity, as they would be incapable of getting it on their own.
I digress though.
As for the issue of whether or not the damned can return to Earth, it would have some
serious repercussions in terms of physics if the dead can infact 'step through'. The dead in the afterlife are essentially composed of Faux Matter, I.E. Energy turned into Matter. If they can step through those portals, then that means there is some way to turn energy into matter within the laws of physics (or maybe it's a loophole of some kind in quantum mechanics or the like)

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An issue which might arise from one of the dead stepping back to Earth would be whether or now their bodies would start to fall apart (that is something which could go either way depending on what the author decides, though let's assume it will so I can type out this scenario). If the Faux Matter can survive within say... three to six months let's say, then this would also mean that there is a chance the dead could infact breed with the living and produce viable offspring (though that depends entirely on whether or not that when the bodies of the dead are (re)formed that they also accurately reform the genetic codes of their sperm/ovum). If that is the case, then with the Faux Matter being able to last for a couple months, it would give the fetus a MAJOR chance for survival as most of the Faux Matter would have been replaced with an exceptional amount of regular matter (mainly though the nutrients and proteins provided by the umbilical cord).
Ok, I've rambled enough for now.
