Not sure if gravity is transmitted (no black holes in the game, so it doesn’t really come up) but light does go through the portal, so maybe gravity does too. I believe your string scenario would be entirely possible, yes. When you’re playing the game, the portal looks more like a window with no glass than anything else. You just look at it, and through it, you see the area where the other side is. Then you walk through, and you’re there, as if the two locations were literally right next to each other.
I think it would be fun to put the two portals on the floor and ceiling of a room, then drop a string through the floor, holding onto the other end. When it comes out of the ceiling, tie the two ends together and just let go.
I don’t know about this one. If there were an outgoing portal on the floor, and an incoming one on the ceiling, anything dropped into the portal would accelerate until it reaches its terminal velocity, which would be really damned fast for a sizable rock, perhaps supersonic? I’d think the object might burn up, or cause an appreciable sonic boom on each transit. The containing building might be blown apart by shock waves. I’m looking at the math on Wiki, and am unsure how to calculate the terminal velocity of (say) a 100lb rock of a specific size, but I bet its a fairly large number.
Create a portal at home in your backyard. Then, late at night, you could take your portal gun and place portals underneath vending machines and parking meters! Imagine all the change that will be waiting for you back home!
From playing the game, I would say that the portal does not transmit gravity. Passing next to a portal that faces toward the ground does not alter your trajectory, for one thing. That is, if you place a portal on the ceiling that is linked to a portal on the adjacent wall, then arrange to fall out of the ceiling portal, passing near the wall portal will not introduce a deflection.
Also, your movements seem to be affected strictly by local gravity, and only once you’re at least halfway through the portal–if you place two portals on the ground and jump into one, you’ll bob up through the other one, then fall back in as local gravity takes effect. Practically speaking, air resistance would eventually slow you to an equilibrium point partway through the portal. (So all the generator schemes would require an evacuated chamber for the magnet, at least.)
I think I’d contract out to NASA to build that moonbase they want.
Maybe I’m just unimagintive, but I’d set one end at my place and the other end at my grandmother’s - no more driving for SIX freaking HOURS. And if I can have two going at the same time, I’d set one between home and RenFaire. Freaking four hour drive, bleep that. =^.^=
The fact that you can’t establish an initial portal on a moving object in-game indicates that the problem is not movement relative to the other end of the portal. Nor does moving near a portal disrupt it. That suggests the disruption is caused by movement relative to the planet, presumably mediated by gravity or the magnetic field. The fact that some of the walls are covered with “portal-proof” metallic cladding inclines me to suspect magnetic disruption, although we can’t necessarily rule out some other mechanism. Since the dominant gravity well on the moon would be that of the moon itself, and given that the moon has no magnetosphere, an interplanetary portal might be possible. It would be worth further investigation, at any rate.
If the portal disruption effect is, in fact, magnetic in nature, it might even be possible to have moving portals on the moon. Of course, it’s equally possible that the tech relies on a substantial environmental magnetic field to operate, and no portal could be formed at all.