I just got this from MIT

The entire problem of the original is that bfags think a stationary object creates momentum out of nothing or somehow not only inherits a non-interacting object’s momentum, but does in the complete opposite direction.
Here the object has momentum as a given, it’s an entirely different situation.

>Can't have portals on moving objects.
They had them in portal 2.

In both cases the A argument is that the portal's speed doesn't add to whatever's traveling through it, while B says it does.
This is a different problem with the same rules, it's just easier to see why the A argument is wrong.

We don't really know how portals work to make the definitive answer.

Attached: 7bc9dd635922cabd72be33b66cdf8493.jpg (1368x1688, 240K)

The speed never changes. See the MJ example. There is no acceleration. The cube is travelling relative to the portal, and everything on the other side of it. It continues doing so upon passing through.

>Can't have portals on moving objects
Except that one.

Attached: the moon.jpg (590x332, 16K)

wow MIT must be full of retards then holy shit

and this one

Attached: file.png (1100x618, 793K)

A fag in denial.

By the time I've written this out, 10 other people will have given you a (You) and moved on, but B is correct.

The object traveling towards the entry portal has a relative speed to the portal. In this example, 1000m/s - 999 m/s = 1 m/s. Relatively speaking, the rocket is traveling at 1 meter per second. From that side, the space that exists on the other side of the portal is also traveling at 999 m/s. So once it goes through, assuming transportation is instantaneous and no additional forces apply to the object mid transportation, the end result is a 1 m/s ship.

You already see this in action in airports and shopping malls, on escalators/travelators. Assuming you don't trip and eat shit, if you are running at 3 m/s onto a conveyor belt moving at 1 m/s in the opposite direction, your speed relative to the area around you becomes 2 m/s. Scenario B is exactly the same as this, except the conveyor belt is the space on the other side of the portal.

>a moving object will continue moving
wow good job the cube wasn't moving though

you know theoretically the building you are placing portals in is moving with the tectonic plates it's build upon. Those tectonic plates are moving with the planet as it rotates on its axis, or as it rotates around the sun. The entire solar system is moving, rotating around the center of our galaxy, Sagittarius A*. Our entire galaxy is constantly moving further and further away from the origin of the universe, the Big Bang. Theoretically... every portal is moving.

If this were true, the core that was teleported to the moon in portal 2 would've been ripped apart because of the difference of speed between earth and moon surface. It didn't, and preserved its speed, so B is correct.

So is it just that anyone who picks b has never played portal before?

That is if you continue to be on that conveyor belt. But the scenario in OP have you exit the portal. Where did all that speed and energy go when the rocket exit? Up your ass?

And both of them are different to all other portals in the game because they are portals you cannot normally interact with, and are just cutscenes.

the portal isnt physically acting upon the rocket though

Portals existing already break a lot of physics, but it's manageable while the portals never move relative to each other.
They can move together anywhere, with the planet, on a plane, anything.

A fuckton of additional physics get broken if you try to move one of them relative to the other.

>boo hoo preservation of energy doesn't work
No shit, every retard made a perpetual engine by putting one portal over another and then dropping something into it. Our entire way of thinking about energy is irrelevant if portals exist.

portals can't move that way so the question is invalid but yeah, otherwise it's B

>The object traveling towards the entry portal has a relative speed to the portal.
But it also has a relative speed to environment in which the portal exists. If we assume that both portals exist in the same environment, the relative speed is the same.

In the context of the orange portal, the rocket's portal-relative speed is 1m/s and environment-relative speed is 1000m/s. In the context of the blue portal, the rocket's portal-relative speed is 1000m/s and the rocket's environment-relative speed is 1000m/s. The environment relative speed must remain constant because portals conserve momentum. You can think of the environment-relative speed as the observer-relative speed but it's easier to conceptualise if you think of it as speed relative to the environment in which both portals and the rocket exist in.

So if an object exits a portal (portal-relative exit speed) faster than it enters one (portal-relative enter speed) the only thing that can happen is that it tears itself apart, because the environment-relative speed cannot change.

>From that side, the space that exists on the other side of the portal is also traveling at 999 m/s.
This is your mistake. The space on the orange side and the space on the blue side of the portal are the same space. The portals are not doors between worlds, but teleporters inside the same world. That's why the environment-relative speed can't change.

not that guy but the environment that portal transports the object to is, if it's just another vacuum momentum would be preserved but if conditions are different it could show depending on the given parameters

I don't understand how "where does the energy come from" is the part people get hung up on. Portals, by the nature of their function, create energy from nowhere. Moving an object from one point to another instantly requires an infinite amount of energy. That old troll science thing of using portals and falling water to generate electricity is the portal creating infinite energy. There's no version of portal physics where they don't break the conservation of energy, I don't know why you insist they break several other fundamental laws to try and preserve it.

right but the environment would just be the air in the space outside of the blue portal which wouldnt decrease the speed of the rocket to 1 m/s

yeah you're right, you'd have to calculate air composition, aerodynamics and drag to figure out the trajectory for the decrease in momentum

The problem isn't "where does the energy come from," the problem is that in Portal 1 we are explicitly told that portals conserve momentum. That makes B impossible.

Portals are not real.

There is no energy. The object is applying no additional thrust, it's just inertia. The inertia doesn't change as it passes through the portal. Lets propose a scenario where the object is only halfway through the portal. Half of its mass is in space A, the other in space B. In space B, it's motion was 1000m/s, but that force is negated by a 999m/s entry portal. The exit portal is going nowhere, that doesn't mean the ship suddenly re-accelerates to 1000m/s. It's speed is still relative to the entry portal which is sapping away the ship's speed.

Your mistake is assuming that the portal applies force in a positive manner. In reality, it applies a negative amount of force. A portal cannot sustain itself anyway if it adhered to the laws of physics as we know it, as it's own mass would cause it's collapse.

Attached: tegaki.png (400x400, 7K)

Portals aren't real and literally cannot exist the way the game portrays them. I'm not saying there is no point in discussing this, but there will never be a 100% correct answer.

They don't preserve momentum at all. If you jump in a portal on the floor and fly out a portal on the wall, your downward momentum is turned into sideways momentum, which is not preservation. Either GLaDOS is correct, portals preserve momentum, and portals don't work the way we observe them to work in both games, OR GLaDOS is wrong because the writers didn't know what momentum is.

There will always be some relative movement between the portals just due to the fact that most atoms have some sort of swinging motion.

she actually says they don't preserve. To be more precise, she says "They do, but they don't".

That is to say, she says they appear to preserve momentum, but what they actually preserve is inertia.

maybe they have a slim rugged back surface which evens those out, if portals move relative to each other, then it could only work if there are two different universes on the both sides of the portal, and in that case it would work like B.

Attached: portals.jpg (1600x1020, 231K)

after reading the thread i think it's A

the relative speed of the object compared to the orange portal says nothing about it's inherent inertia so while the difference in speed does account for a gradual transition the object should just come out going 1000m/s

what if the portal gradually evens out the differences in relative speed as the object passes through, gradually getting weighted towards the side that has more of the object sticking out

Any portals will be moving since the earth is spinning. Like points on a CD, they're moving at different speeds. This applies to earth's rotation. It applies to our orbiting the sun. It applies to our solar system orbiting through our galaxy. Yet they don't affect your speed. It applies to the portal to the moon scene. You always exit at the speed you entered. You don't go flying off at the speed the moon orbits us. You exit at the speed you enter. If the exit is moving, you move with it. If the entrance is moving, you move against it. If you're moving, well, you keep moving.

>"Spectacular. You appear to understand how a portal affects forward momentum. Or, to be more precise, how it does not. Momentum, a function of mass and velocity, is conserved between portals. In layman's terms: speedy thing goes in, speedy thing comes out."
But, as you astutely point out, it doesn't conserve the velocity because your direction changes. Except your direction relative to the portal doesn't change. So portals must conserve velocity relative to themselves, not relative to the environment.

Which makes B correct.

So I guess you were right.

Inertia is what makes the most sense, which in my mind supports B. In OP's picture, if you were in the rocket and A were true, you'd feel the ship slow down or accelerate or whatever it specifically does to maintain this external reference frame. If you're on the rocket in OP's picture and B is true, you feel no changes in how fast you're going, but would observe the rest of the universe slowing down. Ironically it's A where you would feel the portals generating "phantom force" on your ship.

What now?

Attached: stupid argument generator.jpg (1000x520, 60K)

clearly it would get flung upwards and chopped in half on the portal edge according to A-utists

If you're having trouble making sense of it, just envision yourself piloting it, looking out the front window at and through the portal.

A fags are thinking portals are some magical thing. Instead of thinking of them as some magical doorway connecting distant objects together... think of it like this.

In space, there is a flat, plastic wall with a hole in it. On one side it is painted orange, the other it is painted blue. If you were standing on the orange side, and could see a planet moving away from you at 999m/s, you know that either that planet is moving 999m/s away from you, or you are moving 999m/s away from it. On the blue side, you see nothing. As far as you know, you aren't moving at all. From the orange side, you see a rock flying towards the hole at 1000m/s. You know it's 1000m/s because you have a frame of reference: that planet you saw, and/or somehow magically knowing you are traveling at that speed.

On the blue side, you see the rock come out of the hole very slowly, at 1m/s. You think you aren't going anywhere, so you naturally assume it's speed is 1m/s.

The answer to this problem is both A and B. The question isn't "does the ship move at X speed or Y speed", the question is "from what perspective do we observe the speed of the ship?"

Portals conserve velocity relative to themselves, 10 m/s horizontal is all you get.

same result. Think about how jets refuel in the air.

>Can't have portals on moving objects.
Rather, portals cannot move relative to each other.

Only one is actually confirmed canon by Valve, and it's not B. Eat shit

To clarify this... if you are standing in the ship you are judging all objects speeds relative to you. As far as you are concerned, the orange portal is moving 1m/s towards you, and the blue 1m/s away once you are through.

From the orange portal, the ship is coming 1m/s towards you.

Because portals are tied together, the blue portal will observe the same thing as the orange portal.

No wonder they don't make games anymore.

Right? The rocket moves at either 1000 or 1m/s depending on whether you're observing through the portal or just the environment. In a way observing the world through a moving portal gives everything in the universe the portal's kinetic energy.

Attached: 1515216281009.png (1000x1104, 277K)

Why exactly can't you have them on moving objects? Especially considering we are moving right now as we speak. Portal 2 had 1 instance with somewhat fake portals moving around, but I can't see how anything in real life would restrict portals from simply moving.

>portals can't move that way
why?

he's referring to the fact that the game does not support moving players through moving portals. The engine doesnt even trigger portal effects unless the player is in motion or standing over an open portal.