How can an inter-dimensional rift between worlds prevent passengers from crossing back over?

Question

The book of Genesis tells of how God created the earth in six days, as well as the first humans. He created Adam and Eve in his image as pure and uncorrupted beings. However, Lucifer seduced and slept with Eve within the garden, unbeknownst to her husband, infecting the human race with original sin. Eve had two sons, Cain and Abel, with the latter being the son of Adam and the former being the son of Satan. This led to God rejecting Cain and embracing Abel, leading to jealous rivalries between the two which would culminate in the first murder. Adam and Eve would go on to have another son named Seth, while Cain was branded a murderer and forced to walk the earth alone. Therefore, while the elves of the world stem from the seed of Seth as pure and uncorrupted, the human race would stem from the seed of Cain, tainted with the stain of original sin that he had passed down from his mother.This was all part of Satan's grand scheme to screw over God's divine plan by making humans susceptible to his manipulations.

Human souls contain life energy that sustains an individual during life, and are instrumental in the usage of magic. Demon magic focuses on releasing this life energy in massive amounts to create altering reality affects. This is done through the process of causing pain and suffering, such as a mass human sacrifice or a battle costing large amounts of lives. Directing and focusing this buildup of energy in the right way can cause a rift between the worlds of Hell and the mortal plane. These demonic spirits can cross the boundaries of Hell into our world through these rifts that open up between realms that allow passage.

The taint of original sin has allowed for a " back door " within humans, allowing them to be possessed by demons. Through demonic possession, a demonic spirit can take full control of an individual, suppressing their free will and trapping their soul within themselves. Being in our world gives them the capability to forcefully take control of a victim, making them a slave to the demon's machinations. The body of that human eventually withers and decays from the demonic energy, forcing the demon to hop from human to human, allowing him to continue his master's goals on earth.

It stands to reason that if a massive amount of built-up life energy is required to summon a demon from Hell, it should also allow for a demon to cross back over. However, as things turn out, there is a chink in this master plan. Apparently, crossing over from Hell into the mortal plane is a one way trip. A demon who passes through a rift connecting realities becomes trapped on the mortal plane, unable to travel back even while these rifts remain open or a new one is created. The only way for a demon to re-enter Hell is through an exorcism by an ordained priest, who exorcises a demon from a host, forcing them back into the pit. Aside from this, they are stuck bouncing from human to human unable to return home.

How can a barrier be constructed in a way that allows things to pass through them in only one direction?

Answer 1

Polar Opposites:

In the weird celestial magnetic and energy relationship, Good and evil are states of being separate from positive and negative energy. Damned souls and demons are evil, and separately wicked deeds are negatively charged. Evil is attracted to negative charge, thus demons and evil souls are drawn to hell (the central concentration of negative energy). Conversely, holy people are good, and doing kind deeds creates positive energy. Good is drawn to heaven. Living beings are material, so like a piece of iron nailed to a board, a magnet can't move it until the person dies and it is no longer tied to the material world.

Demons are able to contain great amounts of negative energy, but are still evil. Like charges repel, so a demon in hell needs to have enough negative energy to overcome the attraction of its evil state to the huge concentration of negative energy in hell. Thus only the most negative beings can ever get out of hell.

Once out of hell, the negative energy of the demon keeps it repelled from hell, and attracts evil people to it. The demon above all else does NOT want to go back to hell (it is, after all, HELL) and works diligently to create as much negative energy as possible to maintain a repulsion from hell. A free-standing demon on Earth who is insufficiently negative is still evil, and would get dragged down to hell.

Possessing a person is like holding on to a rope binding the demon to the Earth: they can use the connection to shelter from being pulled back to hell. Unlike the human, this is a weak attachment. But like the human, they are partly attached to the material world and may find it difficult to return to hell if they desired to (which they most certainly do NOT want to). "Oh, sorry boss, I can't come back. Ah, shucks! I guess I'll go have a nice dinner and a smoke, maybe some tequila. I sure wish I could be suffering and eating ashes in hell with you guys."

Priests, conversely, are filled with positive energy. When a priest performs an exorcism, he/she pours positive energy into the demon. This cancels the negative energy in the demon, rendering it both evil (attracted to hell) and positive in charge (thus creating an unavoidable attraction to hell). The demon is thus drawn back to hell involuntarily.

The now neutralized demon must stay in hell until it has absorbed enough negative energy to overcome the attraction of its evil for hell before it can again return to the material world.

Answer 2

Making an inter-dimensional portal one-way is not hard, the hard part is making them two-way!

All universes, all dimensions have an inherent energy level. And wherever it is, energy only wants to flow from higher concentrations to lower concentrations. This is basic Entropy.

So as soon as you open a gateway between two different locations, whether they be locations within the same universe or in different universes or even different realities, inevitably energy will want to flow from one of these to the other.
Sending matter along in the same direction as the energy flow is easy.
Sending matter (which is really just another concentrated form of energy) against this natural flow is very, very hard.

Answer 3

It takes energy generated from Earthly pain and bloodshed to pull the demon to Earth, and it takes energy from heaven to send them back to hell. The priest during the exorcism is channelling this energy. What stops them from going back while the rift is open, is that they are pulled through, they don't move on their own, same went sent back. Perhaps their master determines who gets pulled through?

What I find more interesting, do the beings want to go back? Is there 'time' in hell better than on Earth. Would a demon thus actively seek out an exorcism?

Answer 4

Air pressure.

Earth and Hell were once connected by convenient rifts favored by D.C. commuters and the occasional adventurous gastronomist. Over time, bureaucrats had some of the rifts sealed off. Meanwhile, the political climate in Hell, uh, became heated. Those familiar with the Ideal Gas Law should understand that folks down there are now under a whole lot of pressure.

Exorcists, on the other hand, know that if you pray hard enough, you can make water flow uphill. How hard? Hard enough to make water flow uphill! Same thing applies to matters of air pressure.

Answer 5

An analogy to magma flow and volcanoes

Suppose that Hell and Earth are two metaphysical planes of existence, and the Earth is 'above' Hell (in a metaphysical sense).

Now, areas with a lot of "pain and bloodshed" can be said to be 'heavier', as they have more 'negative energy' than the nearby areas. So, they droop towards Hell, like a trampoline with a weight placed on it.

If the weight is heavy enough, it ruptures the Barrier between Hell and Earth, as if the metaphorical trampoline was punctured.

Now, though this area had a lot of negative energy, Hell has orders of orders of magnitude more. This hell of a lot of negative energy (pun totally intended) is compressed into Hell under great pressure, like magma under the crust of the Earth, by the Barrier between Earth and Hell.

As soon as there is a rift in the Barrier, the pressure forces the negative energy upwards through it, like a volcano exploding. Demons can sense this and position themselves such that they are 'erupted' out along with the flow (given that demons want to escape. If they do not, then maybe the demons that come out are the ones who were caught by surprise when the rift opened right above them.

Once into Earth, they can't really oppose the flow and go back down, as while the rift is open it is constantly erupting negative energy and pushing things outwards. (Maybe once enough negative energy has been erupted, it 'cools down' like magma does and forms 'crust' that repairs the Barrier).

Priests are able to exorcise demons because they borrow the energy of Heaven. When they open a gateway to hell to return a demon, they use that energy to keep the pent-up negative energy at bay, and push the demon through, closing the gateway.

(Another explanation can be that they trap the demon in pocket dimension, which is surrounded by the material of the barrier, and push that through. If this doesn't make sense, look up how cells push out waste through vacuoles, with the barrier acting as the cell membrane.)

Answer 6

They cannot return home. They never left.

Hell is here. As is Heaven. And possibly other states of reality. A demon which gains access to the mortal plane does so because its perceptual range expands. It understands the nature of things around it in an expanded way. These things have always been around it but have been ignored or not seen or interpreted in different ways.

One cannot unsee a thing once seen. Once a demon can perceive the reality that is the mortal plane, it cannot reduce itself to the ignorance it had before.

The same is true for mortals. Some already understand and perceive the coexistent reality that is heaven, or hell. Or both.