Does teleport maintain intertia?

[FuelDrop]

Starting a superheroes game. Using the Psionic powers rules from the book of the same name. One of our PCs is a teleporter.

Just curious if teleported objects maintain trajectory and velocity (thus allowing some amazing trick shots) or don't (thus allowing defensive teleporting to rob projectiles of momentum)?

[Sam Baughn]

As far as I know, the rules don't specify.
I think the least-abusable option, which is also the closest match to how teleportation works in fiction is to have the teleported maintain velocity relative to their immediate environment. So if you teleport from standing on the ground into an airplane, you end up standing in the plane. If you are falling and teleport to the ground, you hit at whatever velocity you had while falling. Teleporting a few miles across the surface of a planet isn't lethal, nor is teleporting to and from something in orbit. Teleporting to orbit without something to 'land' on only works for geosynchronous orbits.

[Varyon]

I think the thread was talking about teleportation via appropriate spells, but this Krommpost may be of use. The important thing is retaining relative velocity, not absolute velocity - maintaining the other would mean any long-range teleportation risks slamming you into the ground or flinging you into the air, thanks to the curvature and spin of the planet.

Alternatively, there's this, which quotes Psionic Powers (which I lack to check) as allowing you to shed relative velocity (with the example of teleporting safely to the ground during a fall). You're more likely to be disoriented from such a Warp than normal (-5 to the Body Sense roll), of course.

So, it's ultimately up to the GM. Personally, I'd typically be inclined to have you always just match velocity with your destination (so a teleport to ground while falling results in a safe landing, not a collision), but I'd allow a player to define his Warp as retaining relative velocity instead (I'd never allow for retaining absolute velocity, as that would be a headache). For a character who can choose, that would be an Enhancement of some sort - I'd roughly eyeball it at around +20%.

[FuelDrop]

Thanks guys, that's very helpful :)

[malloyd]

I probably wouldn't even allow an option to retain velocities. The answer needs to be no for teleportation to work as a transportation method for any but the most trivial purposes, and that's what the ability is priced for. Retaining velocities is the first step in converting it to an infinite power source and/or planet killing weapon - i.e. it's abusive trouble waiting to happen.

And do you really want to get into physics debates about a super power? Lots and lots of them are physically nonsensical, opening the issue for any one of them is going to spill over to the others, and while these sorts of things can make for fun internet threads, you really don't want them to eat into your gaming time do you?

[RGTraynor]

I've always portrayed it as such, to the degree that a teleporter being thrown off a cliff took that extra precious second to make his teleport facing upwards, so as to kill off downward momentum.

[whswhs]

It seems to me that, if you're specifying both an advantage and a disadvantage to momentum being conserved, you've made a case for saying that it might be either, for the same cost. Pick one as the standard form, and make the other a +0% "enhancement."

I have the impression that most portrayals of teleportation disregard conservation of momentum, so I'd probably make it "Conserves Momentum" that's the modification.

There's a Larry Niven story, published a long time ago, where a college professor figures out how to teleport. Two of his students are in a car that's about to get into a bad accident. The wife teleports to her bedroom—and hits the wall at something over 60 mph. Notably, earlier on they have problems with conservation of energy as well: teleporting downhill causes the lost gravitational potential energy to show up as heat, giving the teleporter a brief high fever.

[malloyd]

Originally Posted by RGTraynor

I've always portrayed it as such, to the degree that a teleporter being thrown off a cliff took that extra precious second to make his teleport facing upwards, so as to kill off downward momentum.

I think that's yet another form. If you can do that, what are you maintaining momentum relative too? It's not the teleporter (that's zero), it's not the Earth, or any other close to inertial reference frame (that always points in the same direction), it's some weird science that conserves the magnitude of momentum without preserving direction, even though it's a vector quantity.

[Varyon]

Originally Posted by malloyd

I think that's yet another form. If you can do that, what are you maintaining momentum relative too? It's not the teleporter (that's zero), it's not the Earth, or any other close to inertial reference frame (that always points in the same direction), it's some weird science that conserves the magnitude of momentum without preserving direction, even though it's a vector quantity.

It's sort of a combination of two things. First off, you set your velocity relative to your frame of reference - a person sitting in an airplane going 500 mph has a relative velocity of 0 (frame of reference is the plane), but if he jumps out and reaches terminal velocity of ~120 mph, he has a relative velocity of 120 mph (frame of reference is the planet). However, the actual velocity vector is based on body orientation - if the above jumper is falling in the supine position, then his velocity vector is facing forward relative to if he were in the standing position. So, if he teleports into a prone orientation, the velocity vector is now facing upwards relative to the frame of reference, so he gets flung up into the air (and will probably need to do another teleport to the ground at the apex of this, when his velocity reaches 0 - otherwise he hits the ground nearly as hard as he would have without the teleport). It makes an intuitive sort of sense, and at high velocities is necessary (unless teleportation comes with built-in inertial dampening) for a changed-orientation to not subject the target to extreme G-forces (you'd be going from falling "forward" to falling "backward," this would be roughly comparable in the above example to hitting a hard, unyielding surface at 240 mph), but doesn't really have any basis in physics... but then, that's already the case for usable teleportation, at least at human scales.

[RyanW]

Originally Posted by Varyon

It makes an intuitive sort of sense, and at high velocities is necessary (unless teleportation comes with built-in inertial dampening) for a changed-orientation to not subject the target to extreme G-forces (you'd be going from falling "forward" to falling "backward," this would be roughly comparable in the above example to hitting a hard, unyielding surface at 240 mph), but doesn't really have any basis in physics... but then, that's already the case for usable teleportation, at least at human scales.

That might not be so horrible as you might imagine. The reason acceleration is so hazardous is because not all the bits of you accelerate at different rates. Your skull stops but you brain keeps going, far example. If you suddenly experience a massive but completely even change in velocity, you might not even notice it. That doesn't happen in reality, but neither does teleportation.