If you replaced the people with a pole on a roller, you wouldn't expect the pole to get sucked into the portal or to roll towards the tram as it advanced, right?

That is what would happen if people were launched out of the other side of portal. The part of the pole that has been launched would drag the remainder of the pole with it.

But that wouldn't happen.

The pole would just lay there until the tram passed it by, so the answer must be A. There's no momentum added to the pole as the tram passes it by. The only thing that changed is the location of the pole.

[–] pankuleczkapl@lemmy.dbzer0.com 3 points 1 year ago

You almost arrived at the correct answer. The problem is that would happen. More specifically we know that four fundamental interactions can pass through the portals, e.g. a thing that is whole before passing through portals is still whole after passing through them, though for any pair of particles, atoms, neutrons and protons etc. there was a moment in time where they were separated by the portal. If you imagine the portal moving towards the pole at some speed and in the middle of it suddenly stopping, the momentum of the part on the other side would slightly pull on it, and the pole would still be moving at a reduced speed. The momentum of the second part cannot disappear and will pull on the first part. The only other reasonable option is that the pole gets split, but that obviously is not the case. So B it is

[–] ponfriend@sh.itjust.works 3 points 1 year ago* (last edited 1 year ago) (1 children)

If the pole is entering the portal at the rate of 60 miles per hour, it must exit the portal at the same rate. After a minute, 1 mile of pole has entered the portal, and 1 mile has exited it. If it exits more slowly than it enters, where is the missing part of the pole?

[–] Natanael@slrpnk.net 3 points 1 year ago* (last edited 1 year ago)

And if it exits at the speed it enters, does it lack momentum despite clearly being in motion outside the second portal? Does it magically halt when all of it has passed through?

[–] aggelalex@lemmy.world 1 points 1 year ago

The front part of the pole wouldn't pull the back part of the pole more so than in any normal contiguous space. If you send a pole flying from the front and catch it mid-flight from the back stopping its motion, you'll have to apply a force opposite in direction to the motion of the pole, and by Newton's third law (every action has an equal and opposite reaction) it's gonna pull you towards the direction it's moving by reactionary force while decelerating.

In the case if moving portals, it might be a bit confusing, but what it comes to teleportation through the portals, the portals are absolutely stationary the world around them moves. And in the case only one of the two portals move relative to the ground, not only does the world move relative to both portals, it also deforms in a non-euclidean manner. That is why the pole that was stationary relative to the ground suddenly started moving after coming out the portal. And yes, it would require massive amounts of energy for the portal to function like that and keep its own momentum relative to the ground after teleporting things, but tbh that's a woe for Aperture science, not mine 🙂