Does this explanation of "one way" world traversing make sense?

Question

I basically have a mechanism in my universe that allows humans to travel to different worlds (called offworlds) filled with different creatures and systems of magic, and this is very integral to the plot of the story. Currently I have things set up in such a way that humans are allowed to go to these worlds, but not vice versa because the human world and system of magic present within it acts as a "veil" making it undetectable by outside worlds and magical systems. My only concern is that this seems a bit conflicting with the fact that while humans can go to these worlds they can also come back.

My current idea to explain this is that they use a combination of magic and technology to make "gates" which allow them to link themselves to them using a device they carry with them to these other worlds. Basically the device maintains connection to the gate and (for lack of a better word) "yanks" people back to the gate when activated in most circumstances. Is this a good enough justification for a workaround to a system which is otherwise impervious to outside magical forces, or is there more details I should look to add in the general sense to make it seem less gimmicky?

Answer 1

I think that two simple rules could provide a mechanism for this:

Rule 1: You are a part of the world you originate from, and you can always let yourself be pulled back there.

Rule 2: Earth is 'veiled', and cannot be discovered or located from the outside.

This way, even though people from Earth who travel to a different world cannot locate it from outside, they are innately able to let themselves be transported back there due to the affinity every being has for their homeworld.

Another possibility is that the Earth is "odd" compared to the rest of the worlds in the multiverse. It doesn't fit into any understanding that outsiders have for the shape of the wider multiverse, so they have never noticed it before. This would be less a case that they can't go there, and more that they just haven't so far. Could be narratively interesting then if human exploration of other worlds tips off the outsiders that there's another world to find.

Answer 2

Earth can be veiled, but the humans already KNOW where it is, so they can magically access Earth just like any other world. It's like they know a secret combination, or the coordinates of something that appears invisible.

Think of it like Star Trek's Transporter system. They would never transport themselves into solid rock, but if they know there is a secret room under all that rock and its exact coordinates, they can beam into it. (Apparently beaming into solid air is not as big a problem as beaming into solid rock.)

Your system is the same; nobody off-world risks transporting themselves into empty space, it is lethal. And space is too big to explore that way, even if you could survive for a second before transporting back. But the humans know the incantation, or combination, or thought-image, or whatever you want to call it, for getting to Earth.

Then you don't need a device or gimmick or anything else, you hardly even have to explain this. A thought-image of where you want to be might work well, a mental image is not the kind of thing that can be extracted by torture. (But maybe by magic.)

Answer 3

My current idea to explain this is that they use a combination of magic and technology to make "gates" which allow them to link themselves to them using a device they carry with them to these other worlds.

Instead of a 'device', every human carries an inbuilt password in the form of human DNA. DNA is present in every cell of the body and this is what is needed for the transport system to work. Even if other beings manage to duplicate some human DNA, they can't change every single cell in their own body in order to be transported. In fact Earth DNA is unique to Earth so any earth creature can be transported in either direction if required.

Answer 4

Earth is on the "highest" plane of worlds. Meaning that you get a lot of energy if you send something to "lower" planes/worlds and require a lot to reach there.

Since its almost impossible to create that much energy from scratch, the only viable travel is to go down, and come back by using the energy created by that later (storing it in the meantime).

That would explain the need for technology and magic to come together to build the gates: The energy (magic) released from sending someone down needs to be stored in order to be able to get them back.

This would also give interesting options such as being able to bring back other things (while abandoning whatever you sent "down"), or a really really powerful "lower" civilisation getting close to the capability to push "up".

Answer 5

An asymetric membrane between worlds:

Earthlings can push the membrane too reach other worlds (they still are on the membrane) trough actively expending energy. Whenever they stop actively expending efforts to push the membrane they are pushed back by the same membrane back to his world.

Forcing the membrane to the other direction (direction earth) could be much more costy, or even impossible.

Answer 6

For some reason while reading this I thought of Stargate sg-1.

The Stargate can connect to any world with a Stargate and allows near instantaneous transportation.

Similar to your words teleporting wizards.

Because of an attack against them thru the Stargate, The sgc created an eyeris that apps people from traveling thru the Stargate unless they send a code to let the sgc know their are coming so that the eyeris can be opened for them.

What if earth is protected by a magical "eyeris" that prevents people without the proper authentication from teleporting to it. Perhaps it is a spell set up by the old wise ones (or whoever) that scans travelers as they apparate in, and returns them to sender if they do not have the righr code stamped on their soul (or something).