Gotta be B, right? But then if the victims had no momentum… ah this hurts my brain
I think it would have to be B due to the laws of relative motion. It was easier for me to think about when I considered the opposite case. Imagine someone is on a vehicle, for example a boat, with one portal on the boat and the other on the shore. You wouldn’t expect someone casually walking through the portal on the boat while it’s moving to suddenly experience the momentum of the boat after exiting. This is because the person and the portal are both experiencing the same motion.
Going back to the original scenario, the relative motion of the people entering the portal is as fast as the trolly is moving. If there was no portal, they would experience the same force if the trolly ran into them as they would if they ran into a stationary trolly at the same speed.
You have to do funny things with the conservation of momentum when dealing with hypothetical portals because the portals allow you to abruptly change the frame of reference.
Well in the portal games I don’t think portals have ever moved
But the way I see it the “distance” you travel through the portal is the same. You don’t go through a tunnel it’s instantaneous. But one portal is moving so I think just and endpoint is moving
I’m thinking of it like a normal door
If a run through a door I will inherit my momentum like in the portal games
But if a door is quickly coming at me and I’m standing still the frame just goes around me I’m still
A, because the portal has the momentum not the people on the tracks?
The people have to exit the portal at the same speed they enter, otherwise they’d have to be squished or something weird.
If 1cm of person enters in 1 second, 1cm of person needs to leave in that second, the only other options are that part of the person disappears or gets compressed to less than 1cm.
Motion is relative though. Both the portal and the people are presumably on earth (or any other planet) and will thus be moving around in space at a fast pace. So the people have momentum, just not relative to the earth (or I guess more specifically not relative to the specific patch of earth they’re on).
So there’s 2 options:
- Portals do not respect the laws of relative motion -> the people will get yeeted in some direction because the earth they’re on goes very fast through space and the portals are not pointing in the same direction
- Portals do respect the laws of relative motion, in which case the people will get yeeted with the speed of the train
As per the games own physics it’s A.
Speedy thing goes in. Speedy thing comes out. It doesn’t matter if the portals are moving even in the game. The only thing that matters is the momentum of the object moving through the portals.
All y’all physics nerds can take your degrees and shove em cause it’s video game logic not real life.
The only reason the portal velocity isn’t considered in the game is because the portal velocity is always 0. Moving portals just isn’t something they programmed it to do. If they had, I imagine it would be B, if only because it creates more interesting gameplay options.
I heard in shift’s stream there is a console option for portals on moving objects. I’m with you, i guess it might not be implemented fully. And it is not enabled in the original game.
The fact that people say A honestly makes me a little bit worried about the state of physics education
Like… they enter at speed, why would they not exit at that speed?
Because they don’t “enter at speed”. The portal is moving ; not them. To them, they haven’t actually moved.
So like i said, i worry about the state of physics education.
Motion is relative, things don’t have some magical hidden speed variable tracked by god, all that matters is how things move relative to other things. This is fundamental physics.
No need to be insufferable. I’d rather a good explanation, if all you have are indirect insults you can keep those for yourself.
I will however admit I wasn’t always the most focused student in physics class, and so my perspective may be flawed.
In any case, I don’t quite see how a portal is different from an empty window frame. It’s just a hole. The hole going towards the cube, and the cube “going through” the hole, should not create any motion relative to me. And yet, it does ?
Even relative to the blue portal, the cube went from 0 motion to have motion. How does that work ?
I’m guessing this will all boil down to “portals aren’t possible” but idk.
But if you draw out the velocity vectors, the portal and people would have a would have a positive differential.
Imagine a building comes flying at you and but you barely jump into the window. To you, you’re not moving, but everything else around you is. It would be the same principle if a moving portal came flying at you.
What happens to a pole?
If the portal approach you as you hold it then the other end needs to be moving in it’s local space outside the second portal. That means it is given momentum which must come from the portal, likely taken from the momentum of the first portal which is moving. Also, the far end of the pole will likely experience a degree of inertia and push on the end you’re holding (at an equivalent of half the speed of the portal).
Whoopsie. Maybe take another look at how portals are handled in the game. Then extrapolate that to this "conundrum "
The answer is neither. They wouldn’t be ejected at all theyd just fall right back into the portal. Which would make them fall back through the orange back and forth forever. Until someone grabs the blue portal wall and pulls them out.
So you’re saying that Portal is an accurate physical simulation of reality that should be used to base proper scientific conclusions on?
You’re saying that there should be such a thing as a “proper scientific conclusion” to this meme about a video game physics engine? The only definition of these portals that we have to work with is the definition in the Portal physics engine. There is no definition of anything that behaves like these portals in the scientific study of physics. It is meaningless to try to draw a scientific conclusion about something that does not have a scientific definition.
Yeah, I’d be a bit more careful about making statements on physics education. The setup in itself is breaking physics itself. Arguing about what would happen is like saying “if we ignore the rules, what would happen according to the rules?”. It’s theoretical either way and there’s no correct answer.
B, even as the people do not have momentum, the portal does. Think of it this way, the first person coming out of the portal, let’s say they are having zero speed, but he is right infront of the portal, the second person to exit will exert a force on the first person to move and create space so that the second person can be next to the portal. What speed is this second person coming through the portal, why that will be similar speed to the moving portal. Only if the second portal is moving away at a similar speed will the people experience a situation like A, but as can be seen portal A is fixed to an angled block
