Whats the difference between an object moving and everything else moving? For an observer on the sun every one of us has huge momentum which would be preserved when entering a portal. Momentum is always relative to some frame of reference. Momentum ‘toward’ the portal would be conserved and mirrored through the other portal.
Comment on Which is it Lemmy?
Kolanaki@pawb.social 1 month ago
The object’s momentum is preserved. Movement of the entrance portal does nothing.
tomi000@lemmy.world 1 month ago
Kolanaki@pawb.social 1 month ago
The difference in this case is that the object has 0 momentum and the portal doesn’t impart its momentum to the cube because you can’t collide with the portal.
tomi000@lemmy.world 1 month ago
Of course it has momentum relative to the portal.
Kolanaki@pawb.social 1 month ago
That is not how either relativity or momentum work. The cube is still inert and the portal’s movement would have no effect on it unless it has some acting force that pushes it when passing through. Even if the exit portal was moving, the cube would remain stationary unless it had nothing to rest upon and gravity pulled it down.
berber@feddit.org 1 month ago
well, in my opinion it is a bit of a paradox. i think you are partially correct.
your door analogy may be right from the perspective of the platform on which the cube is. however, one flaw is that the whole space is moving, not just the door. as soon as the cube enters that door, it will be inside that space, and if you consider the cube part of it, moving that space “downward”, then due the cube being held by the platform, you could consider the cube moving “upward” in the space behind the orange portal. if you consider preserving momentum there, then as soon as the apparatus stops moving, the cube should not stop its momentum and move further up in the space.
or look at it like this: if you are behind the orange portal, meaning you are looking at the blue portal, you will see a cube moving towards you. then as soon as the platform hits the wall of the orange portal, the preserved momentum should make the cube “fly”.
the change of perspective leads to two different conclusions, therefore i think it is a paradox.
the problem sort of is that there are two “spacetimes” that are kind of being changed. one could interpret it as both of these effects “pulling” against each other since when the cube has partially passed the portal, one part of the cube is “in one of the spacetimes”, ant the other part in the other. ultimately though, the cube then would actually fly because in the limit (infinitesinally close to when the platform hits the portal wall) the cube is completely on the other side of the portal, so from the view of that spacetime, the cube does get pushed and should fly.
i don’t even remember if it is possible in the video game for walls with portals that move. a video game would probablt have some kind of “center of mass”, like a single vector of coordinates where describing the position of the object. there is no notion of “partially” being somewhere (except for collision boxes, but i don’t mean that). so also from that view the box would fly. however, in most video games (with or without portals), if a platform moves up and suddenly stops, the object won’t travel further in that direction anyway, especially not ulwards (even sideways usually not).
Elgenzay@lemmy.ml 1 month ago
As for the portals moving in the game, portals are destroyed if the panel they’re on is moved except for one specific part, where you can put a portal on a panel moving laterally to get a laser to cut the tubes connecting to the neurotoxin tank. That part needed to be explicitly programmed to allow it, and it’s not possible without cheating to physically reach that portal.
Master@sh.itjust.works 1 month ago
It would move really fast through the portal then slide down from stand still. So yea B is correct.
jacksilver@lemmy.world 1 month ago
What if the portal on the moving platform had a wall right in front of it, so moving though the portal would cause the box to run into the wall. You’d have a scenario where the box wouldn’t be able to move through the portal, but you’d have energy being generated by the moving arm “pushing down” on the box. The only way that could work is if the moving portal is transferring energy to the box, and therefore require option B.
Although that being said, portals break the laws of physics, so there probably can’t be a “right” answer.
MrNesser@lemmy.world 1 month ago
More like a hole in the wall with you standing perfectly still while the wall moves past you.
ThatWeirdGuy1001@lemmy.world 1 month ago
I brought this up on another comment that’s for some reason now deleted but, if the universe moves around you, would you not perceive it as modernity?
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Derpenheim@lemmy.zip 1 month ago
There is no such thing as an absolute inertial frame of reference. If you are in free fall on earth, you would experience the same sensation as being in space. The only things that would tell you otherwise are the air resistance hitting you and what you can see.
So no, you would not be able to tell the universe is moving around you unless something else in the universe hit you.
tomi000@lemmy.world 1 month ago
The first part made sense, then you contradicted yourself at the end^^ If the universe moves around you, you could literally see things moving. It would be the same as you moving relative to everything else
crapwittyname@feddit.uk 1 month ago
Seeing things counts as something hitting you: photons.
Derpenheim@lemmy.zip 1 month ago
Think about it more fundamentally. Instead of a person with senses, think of an object experiencing forces. Thats what an inertial reference frame means.