We had a lengthy, in-depth conversation of the potential possibilities of gateways back on wotmania.

The close issues I had addressed were what happens when a) the pressure on either side of the gateway is different, or, especially, the gravitational field is different on either side of the gateway.

Imagine (for the sake of it) that you're floating in outer space, looking at earth. You open up a gateway directly in front of you, and the gateway's other opening is much closer to earth--say, one-half the distance. The question now is, do you feel the pull of the earth through the gateway? I assume you would, since Rand feels cold air through Aviendha's gateway to Seanchan. So here's the question: gravity's force of attraction is proportional to the inverse square of the distance. Thus, from the gateway's entrance point, one should feel a force of, say, 2 newtons. At the gateway's exit point, one should feel a force of 8 newtons. So, can you feel the 8 newtons of gravitational pull through the gateway? Does it add to the 2 newtons that you already feel outside of the gateway?

You could make this more complicated by placing multiple gateways such that you get gravity-feedback, and essentially feel an infinite amount of force.