Comment on Which is it Lemmy?
Bytemeister@lemmy.world 3 days agoperspective that encompasses all of the objects involved” is not a thing in reality.
Actually it is, that’s exactly what a perspective, or r fence is, it’s either this, or you are arguing that there is a universal reference point. There isn’t a universal reference point though, all motion is relative to other objects. The problem with using B as the result of this experiment is it draws a conclusion on the relative motion of the box, without considering the relative motion of everything on the other side of the portal. B only makes “sense” in a system where only the position and motion of the box and the orange portal are considered, any conclusion regarding motion outside this system are invalid when you use a perspective thar excludes everything except the box and the orange portal.
ericwdhs@discuss.online 3 days ago
Maybe I’m misinterpreting your use of the phrase, but it seems you’re arguing from applied Newtonian mechanics where objects define a reference frame. A reference frame in that sense is a useful convention but doesn’t actually signify something in reality, hence my comment. Objects don’t care about their velocity relative to other objects or about reference frames suddenly shifting as measured that way. An object’s motion is encoded as an entirely local property in spacetime itself, AKA its worldline. This distinction between object-based reference frames and local reference frames is usually not worthwhile, because they’re usually entirely consistent with each other. The convention just happens to break in situations where worldlines cease to be continuous and consistently differentiated, as in the case of portals.
Bytemeister@lemmy.world 3 days ago
Worldline is just a way to describe how an object or point moves in spacetime, since relatively makes everything kinda fucky and hard to follow using newtonian laws of motion, it does not appear to be a replacement for an inertial frame of reference.
ericwdhs@discuss.online 3 days ago
Lol. Serious /uj question: Are you deliberately misreading me to do the rage bait thing? I’m using “worldline” in the first sense you gave. I’ll avoid it and reword the actual main point as this is good practice for me anyway:
Local spacetime is the ultimate thing all velocity maps onto, so any examination of this problem needs to respect spacetime as the primary driver of behavior. Answer A ignores the spacetime the cube is being moved into on the exit side of the portal as a real thing it must maintain inertia within (the critical detail also overlooked in the “Buster Keaton” answers).
Bytemeister@lemmy.world 3 days ago
No, I’ve been serious since I acknowledged that I was supposed to ragebait people.
Okay, let’s step through this slowly for you, if local spacetime is what all velocity maps to, then it sounds like each object has its own velocity that is independent of other objects (IE, in a universe with a single object in it, it could have a velocity), correct?