Sandbox Discussions

[Alicorn]

Feel entirely free to make a post in Miscellanea about your character repertoire and see who bites, or strike up offsite conversations with amenable glowficcers whose characters you want to poke.

[DanielH]

OK. I'm pretty sure that's equivalent to my second hypothesis (assuming negative mass isn't a thing, which would already cause problems). I feel like that should be easier to prove than the proof I came up with, though, so I don't trust that the proof I came up with is correct.

So if she were in interstellar space she'd still count as in the gravity well of a nearby star, whichever one the very weak gravity most pulled towards. Being in actual zero g instead of almost zero g is, I believe, an unstable situation that happens almost never (in the mathematical sense where it is possible to point to such a state, but it has probability zero, and any slight disturbance would change that). If she were personally orbiting something without a planet or space ship joining her in the orbit, she might be stuck and unable to teleport, though.

With her Olympic jumping she could jump from Deimos (Mars's smaller moon) and teleport to the Martian surface, but she might need a running start. If she moved to Origin I imagine she'd ask her local alt for wishing, but in the meantime wouldn't be able to safely teleport within Saturn because the bubbles move.

[Alicorn]

I think you're overestimating the duration of "shortish time scale". If she's not close enough to a star to be noticeably, actively falling into it she is not in its grav well for her purpose.

[DanielH]

Oh, I missed that part.

If she’s not in a grav well, then can she just not teleport at all?

[Alicorn]

No. She cannot teleport out of a grav well she is in. She may teleport anywhere she can navigate to absolutely if she is not in a grav well. (No, I don't have a way to cash out absolute nav in space.)

[DanielH]

If “absolutely” modifies “teleport” instead of “anywhere” (as I think it does), then can you clarify what not-fully-cashed-out thing you mean by it? I expect you have a better understanding of how you mean that statement than I do even though it isn’t fully cashed out. Is this the same “absolute” that allows her to teleport to the northeast corner of Some Street and That Way, or to a given lat/long, but not to 123 Main St.?¹

If not, do you mean she can’t teleport “three meters that way” like she can in a grav well (she could do that on Earth, right?), or that it has to be in some sense stationary (multiple possibilities for what this means are reasonable), or what? If you can’t answer that because it isn’t cashed out enough, could you give examples like “She can teleport to the Pioneer 10 plaque, but she can’t teleport to ‘the closest nonhuman sentience’ even if such existed in her world”?

Perhaps most important for practical purposes, or perhaps completely unimportant practically, depending on whether anybody thinks of this and whether anybody can help: Assuming somebody else were to provide the rocketry, would this allow her to actually teleport home from Whately, or can she still only go intrauniverse?

In either case, how is she at changing her orientation? I assume that when she teleports to Italy she isn’t almost lying down because of the curvature of the Earth, but could she appear that way if she wanted to? Could she teleport across the room and be upside down or facing the other direction? Could she disappear standing up and appear sitting down instead of in some approximately straight posture? I’m guessing the answers are all yes, except that the last is a no; my secondary guess is that she has to remain oriented with the same part being down but facing in any direction and my tertiary is that the direction is also determined somehow.

¹ If so, then I’m pretty sure astronomers have already cashed this out for you at least within the Milky Way, and probably even outside it. I think, but am not sure, that they picked one direction perpendicular to the plane of the galaxy and called in galactic north, and that they somehow picked a zero point for angles within the disc of the galaxy², and that gives us cylindrical coordinates. I could be wrong about those details, but I’m still pretty sure we have some absolute system of coordinates for the Milky Way.

² I know at least one way to do that without privileging the Earth (which I don’t think would work), but I’d be surprised if they took that even if I’m right about using cylindrical coordinates.

[Alicorn]

She can't teleport to the Pioneer 10 plaque because she doesn't know where it is, but if there is a stationary coordinate system she might be able to use that; I didn't know there was one (but "the Milky Way" doesn't count as "a gravity well", so if it follows the Milky Way it won't work). She can teleport 3 meters in a chosen direction, but if she tried to use this for very long-distance travel she would get lost because important things like the entire planet earth move a lot. Her destination does have to be stationary relative to whatever grav well she's working with; in the absence of a well she's working with she will have to fall into her destination well before she can get anywhere specific within it. I am undecided on her ability to travel interdimensionally from space. She is capable of appearing in whatever orientation or posture she likes.

[DanielH]

So she can still only hit a stationary target when teleporting in space, but there is no convenient gravity well to define “stationary”. Is it stationary relative to whatever her old position and velocity were, or is it stationary in some more absolute sense? The latter makes little but nonzero physical sense, but if you need to go that route for some reason it is possible to say it’s stationary relative to the Cosmic Microwave Background. In other words, if she’s on the ISS, can she teleport to the next room over, or would that put her going at 700,000 to 900,000 of miles per hour relative to the station because that is how fast the Earth is going with respect to the CMB (and consequently mean it is not safe to teleport at all while aboard the ISS, even just three meters that way)?

From a physical standpoint, ignoring that twin superpowers are all physically impossible anyway, the first make a huge amount more sense.

I was wrong about there being a nice predefined stationary Milky Way coordinate system; the one I was thinking of is based on the Earth and the center of the galaxy, which isn’t very good because the Earth moves with respect to the Milky Way.

[Alicorn]

Iiiiiii don't know enough physics to follow these questions anymore

[DanielH]

The physics behind the questions isn’t complicated; it’s just not commonly taught. I’m going to try to explain what I meant in terms of the physics, by analogy to a more everyday situation, and by the results of a simple experiment; I hope that at least one of these will make sense so you can answer the question, but if not then I’ll just go with “it’s just unlikely to come up”.

It is impossible to define “stationary” in any meaningful way in space, when you are not near a gravity well or changing speeds. Sometimes people put this as “you cannot tell if you are moving or not”, but this isn’t quite right: there is no fact of the matter as to whether you are moving or not¹. This is similar to the more everyday question of whether or not you’re facing forward: if you’re on a train, or at a theater, or waiting in line, then this question makes sense and can be definitively answered the same way as the question of whether you’re facing the direction of the train’s motion, the stage/screen, or the person in front of you in line, respectively; however, if you’re in the middle of the desert, there’s no prefered way to define “forward”, so the question of whether you’re facing that direction literally has no answer. Somebody who had spent their whole lives always being on trains or in movie theaters (or, God help them, always waiting in line) might not easily understand that concept, and might instead simplify it to “you cannot tell if you are facing forward or not”, but this would be incorrect.

There are two ways you could mean “stationary” when refering to Flicker in space: stationary with respect to her (or equivalently, moving in the same direction as she is and with the same speed), or stationary with respect to the closest thing we have to an absolute reference frame, the Cosmic Microwave Background¹. In the “facing forward” analogy, the first would be like defining “forward” as whichever direction your body was pointed, such that it was the direction in which it was most natural to walk. There’s no reason to prefer that direction to any other, and it’s a bit awkward to define “forward” based on the person in this case but not other cases, but it’s convenient because you’re only looking at things in the desert to define this. The second would be like defining “forward” as “the direction that is overhead for whichever part of the equator is experiencing dawn”, as that is the direction the Earth is moving relative to the Sun. There’s no reason to prefer this direction either, and it’s a bit awkward to say “well, if you aren’t on a bus that has a forward direction, then we’ll just pretend the planet is a bus”, but it’s convenient because it’s the same everywhere.

And, for the simple experiment, if I explained that poorly: Flicker is in space, somewhere in the solar system, holding hands (or spacesuit gloves) with one of Alli, feeling like she isn’t moving. She teleports three meters “thataway” and waits a second. In the first case, where the definition of “stationary” is with respect to Flicker, she is still near her sister. She can wave at her, and she can teleport three meters in the opposite direction to be back in handholding range. On the other hand, this would hold true even if they were holding hands while floating next to the Pioneer 10, which is conventionally considered to be “moving”. In the second case, where the definition of “stationary” is with respect to the CMB, after she teleports and waits a second she is hundreds of thousands of miles away from her sister (because her sister, the solar system, and in fact the whole Milky Way Galaxy are moving). She could wave, but her sister wouldn’t see it without extremely superhuman vision. She could teleport three meters in the direction of her sister, but in the time it takes her to decide to do that, her sister’s already far more than three meters farther away. Relative to the Earth, she is going 200 times faster than any other human-originating object. In the sense that Pioneer 10 is generally considered “moving”, then she is now moving much faster.

From a physics perspective, having something like this have a preferred reference frame, even if that reference frame were the CMB, would be very surprising; that is, physically the first option makes a lot more sense⁴. If I’m still not making myself clear, or you don’t care to read that much clarification, then you can of course leave the answer at “don’t know” and I won’t bring it up again.


¹ This is true even in a gravity well, or when you are changing speed or direction, but in these situations it’s usually easier to define “stationary” in a meaningful way. Also, any time you hear “you can’t tell” in the context of physics, that usually means “there is no fact of the matter”.
² The CMB is light left over from the Big Bang. My understanding of physics is faulty in that I think it should not have a reference frame, but it does. There is absolutely no reason to prefer this reference frame over any other; the laws of physics work the same whether you’re moving with respect to it or not. However, the CMB is everywhere, and presumably moving at the same speed and direction everywhere, so it’s convenient to use it anyway.
³ It started “here”, and it is no longer here, and later it will be farther from here than it is now.
⁴ This is of course of utmost importance when dealing with nonlocal teleportation magic where every magic power can violate conservation of energy in some way.