Comment on Which is it Lemmy?
Bytemeister@lemmy.world 3 days agoSerious /uj question: Are you deliberately misreading me to do the rage bait thing?
No, I’ve been serious since I acknowledged that I was supposed to ragebait people.
Local spacetime is the ultimate thing all velocity maps onto,
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?
ericwdhs@discuss.online 3 days ago
Yes, it would have velocity, or at least all the mechanical properties of it. That velocity would be undefined from our perspective since all possible ways you could define it (0, 5 m/s to the right, etc.) would be equally valid depending on the coordinates you choose to put at rest, but that’s a measurement problem, not anything intrinsic to reality.
The important bits are: 1) inertia exists as long as you have the minimum ingredients, an object in spacetime, 2) all possible inertial reference frames are still meaningfully distinct from each other and stay as such, 3) any change in velocity of the object would show up in all possible inertial reference frames, and 4) any such change will stay logically consistent regardless of which inertial reference frame you choose to measure the velocity change in.
Bytemeister@lemmy.world 3 days ago
Okay, so since we have established (in your framework of understanding) that the cube has its own velocity, if the portal is moving towards the cube at 1m/s, how fast is the cube moving?
ericwdhs@discuss.online 3 days ago
I think I see exactly where you’re going with this, but let’s just say the cube is defined to be at rest with the portal approaching at 1 m/s.
Bytemeister@lemmy.world 3 days ago
Alright. Cube is moving at 0 m/s (or at rest) and the portal moves over the cube. How fast is the cube moving?