Portals

Did you even play portal, portals cant be placed on moving objects

>>8974252
This question makes no sense because portals don't exist.

>>8974256
Ask how I know you never completed Portal 2...

>>8974271
I dont remember a single puzzle that allows you put a portal on a moving object in p2

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>>8974252
I have had it with you dumbass brainlets saying the answer is "A" or "there is no answer xD".

I am going to make a video, a documentary PROVING once and for all you all you braindead morons that the answer is undeniably B.

All of you make me so mad but this video documentary will be uploaded to my popular YouTube channel where I will have my revenge on everyone who says "A" or "there is no answer xD".

>>8974274
>shoot portal on the moon
>moon is moving in respect to earth

Box is at rest -> box goes through portal -> unbalanced force acts upon it(gravity on a not flat surface) thus B. Reasoned with the first law

>>8974252
Imma say this again, even though I say it every time:
>Non-trivial space time
>Can't apply standard conservation rules
It is quite literally unsolvable.

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>>8974252
It's A. The collision force due to the platform is negligible.

The world would have ftl travel if it weren't for schmucks like y'all.

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>>8974252
If A were to happen, with what velocity does the object come out of the portal? It just moves quickly then comes to a stop without being strapped down or anything? Where does the momentum of its motion upward and to the right go?

If B were to happen, where does the momentum come from? When the piston smashes the lower plate, does some of the piston's momentum transfer to the object? If so, how does this work in cases where the piston has very low mass and the object has very high mass? If the object's momentum came from the piston, how would such an object come out with more momentum than the piston had to start out with? Where does the extra momentum come from?

>>8974281

Math or gtfo.

>>8974282
Sorry to break your immersion but you shoot an event trigger

>>8974256
How do you know an object is moving, anon?

>>8974252
Should momentum be conserved from both frames of reference, the one of the cube and the one of the portal?

If you believe it's A, I have to assume you are mentally handicapped.

>>8974456
Then explain why it is b.

>>8974256
/thread/

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>>8974311

LOOK AT IT FROM THE ORANGE PORTAL'S PERSPECTIVE YOU WANG

THE CUBE IS *LITERALLY* IN MOTION

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>>8974537
Okay, so where does the momentum come from?

I mean, a rule with portals is that they don't respect conservation of energy in such a way that if you send it back, the opposite effect occurs (i.e., gain potential energy going to a higher elevation and negate potential energy going to a lower elevation). If you were to push the object back through the portal, what would happen? Surely, the piston wouldn't start to lift back upward as you pushed the object against the floor on the other side. You would just be pushing the object against the floor.

It's A

Box has no relative inertia and the portal doesn't impart inertia to it

>>8974561
What force causes the cube to slow down once it's come out the orange side?

>>8974271
portal 2 is not canon

>>8974581
It's glued to the platform obviously

>>8974581
portals only have one side, the box is not moving

>>8974593
>portals only have one side
?

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>>8974252

>>8974537
That's not oranges frame of reference. That's blues frame of reference.

From oranges frame of reference the cube is not moving

>>8974581
It was never moving, so it can't slow down. The portal is like a hula hoop

>>8974593
>>8974637
If it's not moving, how does the top of the cube change from being flush with the inclined plane to being above the inclined plane? Any point on the cube has to change positions from the orange portal in order to get above the orange portal.

>>8974666
It changes when it moves relative to the blue. But since it is not moving relative to orange, as soon as the entire cube is covered by the blue, its motion relative to the blue no longer matters

>>8974252
Here is a hint for those who dont know the answer:
If you changed the weight of the piston, but the velocity was kept constant, would the cube's velocity change coming out of portal B?
If you changed the velocity of the piston, what effect would it have on the cube as it passes through the portal?

Consider kinetic forces.
>>8974537
The movement is velocity based, not acceleration based until you consider the phonetic movements of a solid

>>8974256
These are objectively the dumbest responses in these threads.

>>8974252
B, because it's tested before.

>>8974252
gr8 b8 m8

>>8974773
What?

>>8974561
>Okay, so where does the momentum come from?
The portal is moving the entire universe, including the cube. Like bruh it's so simple how can this be more simple. If you were on the other side of the orange portal, the things that you would see looking THROUGH that portal would be moving toward you.

>Surely, the piston wouldn't start to lift back upward as you pushed the object against the floor on the other side.
Of course it would, brainlet. Pushing an object through one side of a portal makes it come out at the same speed. So there would be a force separating the cube from the surface of the blue portal.

>>8974635
Worst bait I've ever seen.

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People tell me what happens in this scenario.

BTFO

>>8974752
>If you changed the weight of the piston, but the velocity was kept constant, would the cube's velocity change coming out of portal B?
No.

>If you changed the velocity of the piston, what effect would it have on the cube as it passes through the portal?
The cube would exit the orange portal at exactly the velocity of the platform.

>>8974783
>The portal is moving the entire universe, including the cube.
That just makes your position worse. Where does the kinetic energy of an ENTIRE UNIVERSE go when the portal stops?

>>8974791
>Where does the kinetic energy of an ENTIRE UNIVERSE go when the portal stops?

It disappears. Portals do not conserve energy, this is a very, very, very well know fact.

When you pass an object from a portal at a higher height to a lower height, where does the potential kinetic energy go? It disappears. The only reason you can make perpetual motion machines with portals is precisely because they do not conserve energy.

Imagine the piston stops midway on the cube.

If A is right, the cube will be sticking halfway out of the blue portal.

If B is right, the cube will shoot out of the portal, just as if the piston came fully down upon it.

In fact, if B is correct, if even a single atom of the cube touches the portal, the rest of the cube will be sucked through.

Seeing as we do not see this type of behavior in the Portal games, we must conclude A.

>>8974796
I see what you're saying and it makes sense. Minor point though, what you're referring to is called "gravitational potential energy". There's no such thing as "potential kinetic energy".

>>8974799
>this question AGAIN

If the piston stops half way through, it comes out at HALF SPEED.

Simple mathematical proof:

Let's say the speed of the piston is v, and the mass of the cube is m. Now let's calculate the momentum relative to the surface of the portal.

The portion on the blue half is moving at speed 0, with mass m/2.

The portion on the other side is moving at speed v, with mass m/2.

We know that portals conserve momentum. So we know that the final speed "x" multiplied by the total mass "m" must equal the total sum of momentum

x*m = 0*(m/2) + v*(m/2)

x*m= v*m*(1/2)

x = v*(1/2)

x = v/2

Half the speed, mathematically proven.

>>8974821
>>8974799

It's the same as if a sticky ball of mass m/2 moving at speed v runs into a stationary ball of the same size. They stick together, and continue on moving as one large object with mass m and speed v/2.

>>8974821
Wrong.

You can't just do the calculation when mass = m/2.

The cube is accumulating mass, and therefore momentum as it comes out the exit portal.

So the cube would come out at full speed even if a single atom went through the portal.

>>8974821
Wrong wrong wrong. The instance the cube begins to exit the second portal, it is already at maximum velocity! And unless some force acts to slow it down, it will continue at maximum velocity.

meaning >>8974830
is right

>>8974830
>Wrong
No you

>You can't just do the calculation when mass = m/2.
Yes I can

>The cube is accumulating mass
No it is not. If the portal has stopped, the cube is not accumulating mass.

I can also do the same calculation for the piston starting out fast, decelerating and coming to a slow stop as it passes the cube. This would involve calculus and I could do this for you if you want!

In fact doing the calculus would be fun, I'd be willing to do it if people want to see...

>>8974836
see>>8974833

What is slowing the cube down to half speed? Nothing, therefore it will continue at maximum velocity.

>>8974833
>And unless some force acts to slow it down
The tension force from the other side of the cube.

If the cube was made of sand or something it would just rip apart in two. But since they are connected, the moving part of the cube has to pull the non-moving part, slowing it down.

>>8974837
>What is slowing the cube down to half speed?
Tension.

>>8974840
Under this interpretation, the cube would be accelerating out of the exit portal. Because the portion exerting a tension force is constantly decreasing. But this is not the case. The cube does not accelerate out of the exit portal, it exits with constant velocity.

CS majors pls stop trying to do physics

>>8974842
>Under this interpretation, the cube would be accelerating out of the exit portal.

Ok, what situation are you talking about?

Are you talking about the situation where the portal passes through the cube without stopping or....what?

>Because the portion exerting a tension force is constantly decreasing
If you are talking about after the piston stops, no. The portion is the same... Why would it change? It is always the upper half and exactly the upper half.

>CS majors pls stop trying to do physics
Your memes won't help you know.

>>8974851
Jesus you are dull....

Ok so you claim that if the piston stops halfway, the cube will exit with 1/2 velocity.

This means that when the pistol is at 1/4 down the cube, the cube will be exiting with 1/4 speed. At 3/8 way down the cube, it will be exiting with 3/8 total speed... and so on...

This means that observing the cube from the exit portal, one will see the cube accelerating out. Starting slow and gaining speed.

This however is not possible. The cube is always exiting with constant velocity. Precisely the downwards velocity fo the piston to be exact.

>>8974857
>This means that observing the cube from the exit portal, one will see the cube accelerating out.
>thinking wit portals iz hard xD

You would not see the cube accelerating out. If you were looking into the orange portal, you would see the cube approaching you at exactly the speed v, and it will continue at that speed.

Now if the piston where to stop, the bottom half of the cube would start accelerating at a rate that you can calculate by how fast the piston is stopping. If the piston stopped instantly (which is not possible) the BOTTOM half of the cube will accelerate an infinite amount for a zero length of time. Only because you are saying that the piston decelerates an infinite amount in 0 time.

When you actually bring the piston to a decelerated stop, this problem disappears. It involves calculus but I can do because I'm actually educated.

I think he wants to see the calculus. I'll derive the formula for you now, but only because you asked so nicely.

Real life portals when?

>>8974311
The box is at all times at rest on the surface. Portals can be thought of as doors between two points in space rather than contiguous rooms. If you throw a ball through a door it retains it's energy in the other room. Same with portals. HOWEVER, if you move a door over an object at rest, the object will remain at rest. The correct interpretation of OP's picture is that, in fact, space is moving relative to the box. the correct answer is a.

there is in fact a sequence from Portal that demonstrates this. After escaping, there is a puzzle that involves casting a portal on the roof and riding a pillar into it, which point the pillar stops. Although your velocity relative to the portal is non-zero, when the pillar comes to a stop on the other side, you don't fly off of it.

>>8974666
The inclined plane is in motion, dipshit.

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>>8974895
>Portals can be thought of as doors between two points in space rather than contiguous rooms.

If you want to use the old "door" analogy thing, Please see this image for the correct interpretation.

It's not just like moving a door. It's moving a door, AND ALSO MOVING THE ENTIRE REALITY BEHIND THAT DOOR TOO. See image.

>inb4 what if the portal stops
I have an image for this, too.

>>8974252
newton's 1st law only applies to objects who's net force is zero. The box is affected by gravity, therefore the first law does not apply.

>>8974287
This is true. Portals can't exist.
>>8974289
>>8974471
>>8974577
Imagine if you were the cube. The situation from your perspective is the orange portal comes toward you at say 10 m/s. Now consider falling into a stationary orange portal at 10 m/s.

From your perspective as the cube, these two situations are identical, you can't tell the difference between them. So the same thing must happen in each(first postulate of special relativity). Since when you fall into the portal, you fly out of the other with the same speed. The same thing must happen when the portal is pushed towards you.

>>8974898
And if the portal is placed on an accelerating surface then that "ENTIRE REALITY" would feel an acceleration?

What about if you placed it one a rotating surfaced, would that entire reality get tilted on its head?

>>8974252
The answer is neither because if you account for shockwave feed back it will bounce a little due to its attatchment to the floor.
Assuming the portal will work on a flat surface while smoothing is not an issue it will not catch on the edges and then slide down the portal as per figure A

Try slamming your fist down on a table to see the coins jump and jangle.

>>8974287
You are quite literally retarded.
>>Non-trivial space time
>Can't apply standard conservation rules
That doesn't mean a god damn thing. Given any portal situation, we can calculate what is going to happen next. We have perfect predictive ability with portals, and this fact stays true.

It still operates within it's own rules. Sure you can build a perpetual motion machine, but given the exact height of the two portals, the amount of water your are using and properties of the turbine you can always predict exactly how much energy it will produce. The math doesn't explode or anything, every still works out.

And since we can predict the unique outcome of any situation, we should be able to find the unique outcome of this situation in the OP.

>>8974898
Great picture, it proves my point. If you stop the train, the box stops too. Same with this problem.

If you think about portals, energy is conserved relative to the entry environment THROUGH the portal, and then forces from the new environment immediately begin to act on the object. Standard kinematics can be applied with portals if each portal jump is aligned with the last and the forces of each environment are applied.

>>8974901
>inertial reference frames don't exist
Tell us more about how you never even took a high school physics class.

>>8974902
>And if the portal is placed on an accelerating surface then that "ENTIRE REALITY" would feel an acceleration?
Yep!

>What about if you placed it one a rotating surfaced, would that entire reality get tilted on its head?
Yep!

Of course you would never be able to tell unless things from one side of the portal interact with things on the other side of the portal, and the point where the portals meet.

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>>8974909
>If you stop the train

You've activated my trap card.

If you suddenly stopped the orange portal with respect to the blue portal, using the door analogy your situation would look like this.

>>8974902
It's pretty clear forces don't propagate through portals. If you cast one portal on the ceiling and a second on the wall next to you, you don't fall through. Yet, the ceiling is immediately next to you.

>>8974916
Except you're a retard, and improperly modeled the problem.

the blue and orange portals cannot move relative to each other because they are the same point in space. So, when you stop the blue portal, you stop the motion of the orange portal, and the space that exists around it, relative to an observer from the blue side.

>>8974922
>the blue and orange portals cannot move relative to each other
Yes they can. The actual SURFACE is the same point in space, but as you can clearly see in the pic here: >>8974561 the piston is moving relative to the triangle. I do trust you have working eyes.

>>8974925
Yep, but unlike you I have more than a second grade critical thinking capacity and recognize the distance from blue to range through the portal is zero, and that the orange portal approaches the cube and then stops, and the cube, at no point, attains any kinetic until it's mass is exposed to the gravity of the orange side and it accelerates off the platform.

This problem can be solved very trivially by examining the forces acting on the cube. You have blue side's gravity, the normal force of the platform, and orange side's gravity. The box remains at equilibrium until it is acted on by a force.

As a final reminder for your /v/ sized brain, the space around the orange portal is in motion relative to the cube THROUGH the portal.

>>8974929
Let me see.. how would I put this...

At the time that the piston is passing over the cube, at that time what is the speed that the cube is exiting the exit portal?

You can say the speed it zero, or else the cube would either

1) never emerge from the portal

2) it was already on the other side of the portal resting there

So the speed cannot be zero.

The cube is exiting the portal at speed v. And unless it is acted on by some outside force, it will continue to move at speed v.

>>8974934
*You can't say the speed is zero

Portals are essentially holes in space. So it's just like having a platform with a hole. The hole being there won't impart any additional momentum. So A occurs.

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>>8974256

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>>8974710
>as soon as the last atom of the cube passed through the portal, the cube, which was once moving at a certain speed will immediate stop

An object in motion will stay in motion unless acted on by an outside force. What force would cause the cube to suddenly stop in mid air?

Assume no gravity, as this does not change the fundamental question.

See pic

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>>8974942
>>8974946
Well these problems have a *fairly* simple solution, which would be to require force to push the portal based on what is moving through it.

Of course maintaining any significant speed would require a tremendous amount of force, as the change in velocity is almost instantaneous. And the box in my mind is getting sucked into the portal as you push and it accelerates. Interesting problem.

>>8974944
People who say there is no answer are willingly refusing to think abstractly.

If you take a pole and stick it along the first green arrow, it would behave like it is standing still.

If you take another pole and stick it where the second green arrow is (threw the portal) that pole will behave like the red box is moving. It all depends on where you are. If you know where you are, you can always say, for certain, what will happen next.

No contradictions.

Of course you could blast me the fuck out of you find a situation where this leads to a contradiction/ non-predictable situation.

>actually trying to argue conservation of energy
*cough* perpetual motion machines *cough*

>>8974955
As I'm thinking about it, I believe it could work fine, as long as portals have some thickness. This seems reasonable, there's already limitations on allowable surface.

In game, object was affected by gravity depending on which side of the portal the center of the mass of our object was.
Easily observable by making a portal on a wall and ceiling and sticking the box halfway through.

a) suppose the piston was stopped an inch before half of the box (regardless if it stopped instantaneously or gradually):
Scenario A) the box would remain stuck almost halfway through blue, dead center.
Scenario B) the box would be pulled from blue by the part of the box that passed orange.

b) suppose the piston was stopped an inch behind half of the box (regardless if it stopped instantaneously or gradually):
Scenario A) the box would slide down the blue and possibly fall out due to gravity.
Scenario B) same as b-B.

Now, suppose case B is correct and the piston moves and decelerates in such a way that:
1) for a brief duration t as box enters orange the pulling force on the blue side P is greater than gravity on orange side G;
2) after time t, P < G and eventually P reaches 0;
3) box's center of mass, taking all pulling forces into account, NEVER crosses portal threshold.
Such scenario is well-defined.

From the pov of blue, box would jump a bit out of the portal and then return to being stuck dead center.
From the pov of orange, box would jump a bit into the portal and then go back into original position (suppose perfectly even gravity).

But if the box is pulled (by itself, huh), then it's actually accelerating, and momentum is preserved.
Hence the thing that makes the box "fly out speedily" in case B is the momentum accumulated over the time by the box pulling on itself.

So the requirement for scenario B to make sense, is for the passing through orange to cause object to pull on itself.
And if that's the case then the speed at which box makes it out of the blue portal is not constant (assuming constant piston speed) but accelerating.

So still inconclusive, unless you assume that it preserves piston velocity then there's your contradiction.

>>8974964
I don't even know why the fuck you're talking about gravity, it has literally zero effect on the problem. Assume no gravity.

>Hence the thing that makes the box "fly out speedily" in case B is the momentum accumulated over the time by the box pulling on itself.
Totally wrong. In the vanilla problem, the box is not pulling on itself. In the vanilla problem, the box is already IN motion from the very beginning, and simply stays in motion.

>there's your contradiction.
How do you figure that? Please explain with zero gravity since gravity does not actually affect the problem.

>>8974974
The gravity is important because it's an observable game fact that distinguishes to which space does the object in question belong.
So, which instance of physic forces are applied to the object (we are dealing with two sets of those).

And, as observed, it belongs to the space whose gravity affects it. The transition point being the center of its mass.

The box is not in motion the way we normally define motion, it's in motion in one space (instance of observable universe), while not being in motion in another space.
Pov refers to which space we're referring to at that time.

And the only contradiction is if we both assume B is correct *and* box flies out with the piston's velocity.
Because if we assume B then the movement is accelerated, not constant.
Short proof: orange moves over part of box => part of box accelerates => part of box pulls box => box moves in the opposite direction as orange => more box passes orange in next instant of time.
Hence accelerated, not constant.

>>8974274
Get fucked: https://youtu.be/Ajf7hahKKXo?t=1m5s

>>8974983
>orange moves over part of box => part of box accelerates

Ok now I see the fault.

First: What is acceleration?

It means it goes from one velocity to another. A change in velocity. But there is no change in velocity here.

As the cube is exiting the portal, it exits at speed v. On that side of the portal, it was always at speed v, and thus the velocity has not changed.

In fact, on BOTH sides of the portal, if you look at the cube's speed relative to the surface of the portal, you will see that one one side it is moving as speed v, and on the other side it is also moving at speed v.
The speed never changes from 0 to v, the speed is always at v from the very beginning.

>b-b-but the exit portal is not moving relative to the cube!
That's only if you draw a path from the exit portal straight to the cube without the path passing through the portal. The cube does not take this path, however. If you draw the path through the portal (the actual way that the cube goes in the problem), you will see that on that path, the exit portal is indeed moving at speed v relative to the cube.

Your logic just uses the path that the cube doesn't take, and that is why you get the wrong answer. You feel like all paths should be equal, but this is neither necessary nor accurate. It's not necessary because cubes can only take one path.

>>8974252
it's a.
>inertia
clearly bait. what is the box's state before it enters the portal/literally just a hole? however fast the hole is moving doesn't affect the object it passes over, though in this case there's the change in the gravity.

>>8974996
>there is no change in velocity here
The way I see it, there is.

In one space the part of box that's going through orange is having its velocity set to v, up from zero. (thus in this space, it will pull the box)
In the other space the very same part has its velocity set to zero, down from v. (thus in this space, it will not pull the box)

Imagine someone removes blue (without loss of generality, placing another blue where it instantly disappears) while box is almost halfway through. Box gets crushed.
Imagine someone removes blue while box is over halfway through. Box gets pulled from blue by that part of it, that was already out of blue.


Magical laws of portals somehow nullify all forces of both spaces that would make the box go crazy and keep it together instead, so from both perspectives the transition is smooth as if the portal was not there (just a plain hole in single instance of universe).
The way I see it portals are interweaving two instances of same universe, and the only "weird" physics happen in-between. But! We know for a fact that portals do it in such a way that maintains seamlessness, even in case one portal disappears midway.

I'll think on it more, now I gotta go.

>>8974908
No dumbass you need a consistent set of rules to get make a prediction. Notice how everyone here is just using Newtonian physics to try and answer the question, conservation laws come from conserved Noether currents. In non-trivial space times these currents need not exist, the classic example is in GR where there is no global conservation of energy. To summarise:
>You're applying Newtonian physics to something that is manifestly non-Newtonian.
There is literally no way to answer this question.

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What would happen here? My guess is that the stick would keep moving with the portal.

>>8974581
Cube doesnt move space does reeeeeeee

>>8974271
>literally not canon
>relevant
(((HMMMMMMMM)))

Kys you fucking mongoloid

>>8974946
Again, the cube was never moving with respect to the orange, so it shouldn't move at all.

>>8974252
The mistake you're making is that you're thinking about this as though the orange portal being dropped onto the pedestal is the same as the pedestal being rammed against the orange portal. If the speed-lines were underneath the bottom pedestal as opposed to the top one, then it'd be B.

It's a lot easier to visualize if you face the blue portal straight up instead of sideways.. If I drop an orange portal on top of a cube, is the cube just going to get some sort of "speed boost" and shoot upwards out the blue? Go drop a hula hoop around a box and see what happens. What experiences the change is the orange portal, not the box.

>>8974252
Your matter exits the blue portal at the same rate it enters the orange portal, so I imagine if you're rapidly being ejected through the blue portal than B would be the likely scenario.
Staring into the blue portal, it would appear that the cube is moving toward the orange and not the other way around.

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>>8974252
>>8975274
-better yet, imagine a scenario where we have the blue portal facing upwards, and the orange portal only rushes halfway down the length of the box and then abruptly stops. toes the top half of the box fly up, while the bottom half stays put or something? Not really, no. You'd get a tiny hop at most, since the top half of the box will briefly be moving quickly on the lefthand side as it "grows" out the top of the blue portal. It wouldn't be enough to actually pull the bottom up though unless this were super fast. Though I guess theoretically if the orange platform were moving insanely fast and stopped immediately when it hit the stoppers, you could rip the box in half.

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Here you go, best I can do.
It proves that B can't be the case, but it's still inconclusive whether A must be the case.

The key here is observing that portals are designed so that they relay matter between them as if they were holes to other places.
Obviously passing through a hole under normal circumstances doesn't make the box accelerate - it preserves its momentum.

For B to be true, the box would need to emerge out of blue with initial velocity being that of piston.
So at some point during transition, some force had to be given to the box, suppose (without loss of generality) that it happens midway.
Then the moment orange passes half of box, the box is "sucked up" into the piston and out the blue.

This is inconsistent with what either orange-reality observer AND blue-reality observer expects if portals were replaced by holes.
Orange expects box to stay put throughout the whole ordeal as no forces are exerted on it.
Blue expects his room to keep approaching the box at constant speed, and, after crossing the threshold, for the box to start falling (due to it now being subject to blue gravity).

Assuming option B however:
Orange sees box sucked up the piston at middle-box threshold, inconsistent with what they'd expect.
Blue sees his room approach the box, and then after threshold is crossed the box continues approaching him at the room's pace (how are these related?).

Any issues with this logic?

>>8975302
>Any issues with this logic?
more with the initial assumption , but I'm just playing devils advocate here

Between t 1 - 4 on the lefthand side, all of the parts of the box which are through the portal are moving with respect to the blue portal (by virtue of the fact that they're moving with respect to the orange portal). You're moving at some speed V through the portal. Look at >>8975297 but imagine the box is a hamburger. First, the top bun goes through. Then, from underneath, the burger comes up. If you're standing on flat ground and suddenly the floor beneath you raises (presumebaly at a high speed) what happens? You hop upwards. If you replace the burger with something gooey like a shmore, you might even pull the bottom up (although it would also be pulling you down, which I think evens everything out, hence why I think either the box breaks in half or stays still, depending on the properties of the box and how fast the portal was dropped down).

Yeah, the initial assumption is crap. It's essentially "portals break physics to maintain a certain goal, no matter what", and we use the thing they maintain as substance for proof.
It sucks, but it's what we're given (by virtue of game's explanation of how portals are supposed to operate).

I also get your point. What you are saying is just one of the ways portals could be breaking physics to do what they are supposed to do, my example is just another way.
Of course, at this point it's speculation, however it's not the B some people were suggesting here for sure.
It could be some weird variant of B, but the box most *certainly* doesn't preserve piston's velocity. That just observably doesn't make sense.

File: thishere.jpg (65KB, 1272x450px) Image search: [Google]

65KB, 1272x450px

>>8974252

>>8974281
you are rarted

Do objects travel through the portal continuously or as a whole?
In other words, is the object physically on the orange side until the entirety of the object has finished passing through the portal?

>>8975393
According to in-game mechanics it travels as a whole the moment center of mass goes through.
But feel free to assume otherwise.

>>8974799
/thread

>>8974875
>t. CS major

>>8975356
I thought of a slightly easier way to think about it: let the portal envelop the whole pedestal the box was on. The pedestal, box and all, comes out the portal at the speed which the orange portal is moving down, then when the orange portal stops, the whole pedestal stops. Obviously the box flies upwards, right? Now play through the scenario again, and again, and again, with less and less of the pedestal coming through until only the box comes through. Does the box suddenly lose the ability to jump upwards?

>>8974252
Guys, stop posting it really isn't answerable. You can see that by considering the momentum of the block as measured from the frame of the orange portal, and from a frame at rest in the lab. The momentum of the block clearly doesn't transform between the frames. Portals lead to solutions that are no longer Galilean invariant.

But in game portals do conserve momentum, so what's going on? Simple, the devs broke relativity by insisting the lab frame be (in some way) privileged. Sure you could create a load of ad hoc assumptions about the nature of portals to argue for one of them. But then there's nothing stopping someone else from creating another set of rules that can be used for the other side. There is no answer. Stop posting it.

>>8974252
Assume the thickness of the portal to be the thickness of the higgs field boson.
The effects are brought about via some kind of undiscovered force exploit using advanced quantum mechanics.
Now assume the piston slowly descends upon the object and the portal expresses 0 friction on the top area and friction remains nominal on the bottom.

The circular nature of the piston will cause a reverbration in a near perfect circle if the speed of the piston is too great.

This will vibrate the atoms of the table in a vacuum and also creat air pressure on the descent.

The portal is topical and therefore the only force that will be present is the reverb of the speed of the collision of the piston...

Ergo it is neither A or B.

It is C. It will bounce a little.

>>8975233
>the cube was never moving with respect to the orange
Look at how fast as fuck that pink box is moving. Look at it. That pink box is moving fast as FUCK boi.

>>8975461
Create air pressure in a non vacuum***

and vibrate the table in a normal vacuum****

>>8975446
Yeah, I do get it. You can read what I wrote some time ago.
Essentially what you're calling "jumping" I called being "pulled through", but it's the same principle:
>>8974964

>>8975449
>Guys, stop posting it really isn't answerable

You are too stupid to understand it.

>Portals lead to solutions that are no longer Galilean invariant.

Not if you use paths.

>Sure you could create a load of ad hoc assumptions

This shows you have no fundemental understanding of the argument. These aren't ad hoc assumptions, they are the logical conclusion, the ONLY logic conclusion, based off of the only law of portals that be know: "Momentum is conserved between portals"

Extrapolating for that will reveal one, unique, logical answer.

>But then there's nothing stopping someone else from creating another set of rules that can be used for the other side.

Actually any other rule you come up with that does not logically follow from the laws of portals would be provably wrong. You draw the path that the cube takes, and this works for any situation ever. Drawing the path that the cube does not take is just some arbitrary nonsense that came out of nowhere, and can be proven wrong with other examples.

>>8975477
>Hurr durr
If something isn't Galilean invariant then it's not classically correct. There's nothing else to it.
>laws of portals
I'm out.

>>8975480
It IS Galilean invariant when you use paths.

>>laws of portals
Glados says in the game "Momentum, as a function of mass and velocity, is conserved between portals". That is the only law we need to prove paths.

>>8975483
>It IS Galilean invariant when you use paths.
It quite clearly isn't. But go ahead, I'm looking forward to your """"proof""".
>is conserved between portals
But not conserved between frames.

>>8975496
>But go ahead, I'm looking forward to your """"proof""".
Ok I'm working on it right now, will post when I finish

>>8975302
A quite obviously cant be the case, which has been proven and explaind many times ITT and in he thread a months or so ago.

So if your assuption is true (which is arguable) it must be inconclusive then.

Its either B or inconclusive

Galilean relativity; this situation is equivalent to the portal standing still and box hurtling towards it. Intuitive case for B.

>>8974252
There is no scientific way to determine this. What the fuck is the physics behind a portal? The portal is the only thing making a connection with the box, so any force derived from the moving platform is absorbed into the platform which olds the box. What force from the moving portal is exerted on the box? That's the question; the one which has no answer as this is an imaginary concept.

>>8975612
While that should be true, the way the game is coded means that's not the case.

>>8975477
>"Momentum is conserved between portals"
Why make that assumption? Might as well assume the fairies are real while your at it, and that the faires exist between portals, transfering objects between them.

>>8975634
if it wasnt, either the cubes mass or its velocity would have to change, which is both clearly not happening in the game

>>8975634
GLaDOS:

"Momentum, a function of mass and velocity, is conserved between portals. In layman's terms, speedy thing goes in, speedy thing comes out."

And no, she's not wrong.

>Might as well assume the fairies are real while your at it, and that the faires exist between portals

That would be circular logic, but it wouldn't affect the results at all. Just like how in math you can add an infinite number of axioms without running into inconsistencies. But there is no reason to enter the circle of logic in the fairy example. There is, however, a reason to make conservation of momentum an axiom of portal math, and that's because it's what works in the game and GLaDOS said it.

>>8975629
I am working on this right now as we speak.

>>8975644
Why would "it have" to change? We still don't know anything about the physics behind these portals. It could be that it only matters what the object is doing. Whatever velocity, mass, and volume the object has going into the portal are the same it will have exiting the portal, no matter the portals apparent velocity in space. Who's to say it behaves like matter; might be some sort of anti-matter bs.

>>8975649
The momentum conservation is in reference to the object passing through the portal, not the portal itself. I don't think it implies that the portals share this; that one portals apparent velocity is somehow conserved in the other. The portals have no assumed mass as far as I can tell, so their apparent velocity is the only thing to consider. Are they matter? Can they be affected by our laws governing matter?

>>8974799
>if even a single atom of the cube touches the portal, the rest of the cube will be sucked through
retard alert

Lets do it autisms!!

The cube was not accelerating when it came in contact with the portal.
The portal is A hole. When you take a wooden cube and slam a piece of cardboard with a hole on a platform where the cube stands, even if the platform shakes the cube only ends up shaking slightly however still ending up on the other side of the hole.

>>A portal is a "hole" connecting two points of space time seamlessly.

However if you were to accelerate the platform with the cube upwards rather than moving the hole, when the platform is no longer able to move, due to the already accelerated cube, some of the force from the elevating platform with be transferred.

>>8975671
>The momentum conservation is in reference to the object passing through the portal, not the portal itself.

News flash: An object moving relative to a portal is the exact same thing as a portal moving relative to an object.

If an portal is moving toward an object, then from the portal's point of view the object has momentum and the portal is the one that is standing still.

the thought exercise should tell you that the very idea of a portal is the problem, not the reference frames or the physics. The Idea of a portal is a story that can't be verified, so the story has no use.

>>8975683
We are creating a new type of math. Portal Math.

It has happened countless times in history that we discover useful things from people just playing seemingly meaningless games with math.

/d/ here, we solved this problem a long time ago. Portals just connect two points in spacetime such that they are adjacent and physics operates normally across them. Therefore moving the portal itself is irrelevant as you're just moving the space it is connected to rather than exerting any sort of effect upon matter traversing the portal.

Therefore the answer is A and you may resume jizzing on your own face without worrying about sudden unintended acceleration.

>>8975680
>god is a brainlet
i knew it!

>>8975690
That violates the principle of relativity.

>>8975690
That's still wrong because the cube would still have a velocity vector in the new space as it goes through the portal

>>8975682
It still doesn't magically give that object momentum. Why should it exit the other portal with "relatively gained" momentum?

>>8975690
>>8975695
and it also violates conservation of momentum

>>8975695
we're all about violating things, but relativity didn't complain.

>>8975698
Imagine a new portal for every nanometer the portal moves, it's basically like that. In the silly way you imagine it, every piece of matter would be explosively ripped to shreds by the minute relative differences in velocity at the atomic level. Not that some of us wouldn't fap to that, but it wouldn't be a practical physics for portals.

>>8975705
portals have no momentum, remember they're connected spacetime, which doesn't have momentum as a property. Space holds matter, it isn't matter such that it can violate laws of physics.

>>8975706
>>8975708
What the fuck are you cunts talking about?

>>8975708
I meant the outcome, scenario A. Premises that lead to scenario A imply that conservation of momentum can be violated

>>8975700
>Why should it exit the other portal with "relatively gained" momentum?

Because you are asking about what momentum it exits with RELATIVE to the surface of the portal.

Momentum relative to the surface of the portal in = Momentum relative to the surface of the portal out

>>8975706
>>8975708
If what you are saying is true, then something falling into a portal on the ground connected to a portal on a wall would come out and fall straight down, instead of being launched sideways.

>>8975371
EXACTLY

/thread

>>8974289
>Schmucks

JUDAISM INTENSIFIES

>>8975371
>>8975757
I'm sorry but that image just proves it's B.

An object moving relative to a portal is the exact same thing as a portal moving relative to an object.

It's called relativity.

>>8975719
They really don't. Stop thinking of the portal as a thing, it's not. It's just connected spacetime that you might not intuitively think is connected. There's nothing actually there to give a crap about momentum.

It'd be easier to explain if one side of the portal had a strong gravitational differential rather than a weak or non-existent one. Suppose the portal's endpoint is actually on the surface of Jupiter. Then mass would be affected through the connected spacetime and fly upwards into the portal (assuming the initial portal descending on the test object is in a location of substantially lower gravity such as on earth). But even though that imparted momentum would be conserved across the portal, that wouldn't cause the test object to go flying given that the same gravity that pulled it upward is also now pulling it down.

So the answer is really A given that the initial question doesn't specify a gravitational difference across the merged spacetime, so there's nothing to impart motion onto the test object.

Thus, when I thrust my dick through the portal, momentum is conserved and A is still the correct answer.

>>8974996
You're wrong though. A frame is a frame. It doesn't matter how it gets from one to the other. If the orange portal was big enough, you'd also see the ground, the platform, the cube,the orange portal, everything moving towards the orange portal at the same velocity,

>>8975944
You're using Galilean transformations, which require a flat, unbroken spacetime.

You have to use a Sterling Transformation in this case, and when you do all Sterling reference frames are equally valid and obey newton's laws of motion.

>>8974787

it just pops out with twice the speed you stupid pig

>>8975971
Thanks for proving (B).

>>8974252
Moving portals violates the conservation of energy

Imagine a doorframe gets dropped on you. Do you come shooting out of the doorframe or have you passed through it and are still standing in place? Even if the other side of the door frame led to a different location?

>>8975989
Portals are not doorframes

>>8975999
So you're saying that portals exert force on things that go through it? How come that literally never happened in the game?

>>8976001
Can a doorframe displace you in space and orientation?

>>8975988
Still portals violate the conservation of energy. Doesn't mean the universe explodes, just means we can make free energy (in a predictable way, mind you).

>>8975989
See this image:
>>8974898

>>8976003
yes, you travel through the doorway

>>8976006
>empty doorframe moves towards me
>I am in the same place relative to the rest of the room before and after I pass through it

>portal moves towards me
>After I pass through it I am in a different place and possibly orientation relative to the rest of the room

>>8976003
The only difference between a portal and a door frame is that the portal connects different locations. You're attacking the example instead of the actual question. The box is completely stationary, it's continues to be stationary when the hole falls on it, the hole is moving onto the box, the box never moves. There is no outside force acting on the box, the only thing that touches it is the completely stationary floor and the air. It isn't even on different floor when it comes out of the portal because the base of the box is still in the portal when it comes out. The only force is from the sides of the piston banging on the floor and gravity making it slide down the ramp.

>>8976022
It doesn't completely connect two locations though.
For example: gravity does not transfer through portals.

>>8976025
I'm not sure what you mean specifically there, but even if the connection isn't absolute there are zero instances of portals adding additional force to an object that passes through it, that's pure fan fiction.

>>8976032
Because portals never move in the game. However, that portals CAN move is an axiom of this whole scenario.

>>8976037
>>8974993
Fucking brainlet fanfiction authors shouldn't be allowed on this board.

>>8976039
see
>>8974590

>>8976045
Give me a source brainlet. I'm getting bored of you.

File: Sterling Relativity.png (32KB, 631x261px) Image search: [Google]

32KB, 631x261px

I have solved this problem, anyone who thinks that the answer is "xD there is no answer!" or
"A" is dead wrong.

Please review this paper I just published on Portal Math:

http://journalofsci.weebly.com/home/sterling-relativity-and-sterling-transformations-in-portal-math

This should convince every last one of you.

>>8975629
>>8975302
>>8975007
>>8975012
>>8974983
>>8974942
Read what I just wrote.

>>8976111
Fuck me, are you for real or is this just an elaborate troll? You don't even define your """""""""""""""""""""""""""transformation""""""""""""""""""""""""""". I don't think I've ever said this unironically, but this time I mean it: kill yourself.

Velocity isn't conserved. The energy is transferred to the table and because of inertial properties of the block, it will just plop over.

>>8976142
>Velocity isn't conserved

Prove it.

Do this.

Take a piece of paper, and cut a circular hole out of the middle of the paper.

Take an M&M candy or something else and place it on a table.

Place the piece of paper over the thing so that it goes through the hole.

Observe your findings. Did the small thing fly straight into the air, or did it remain on the desk?

>>8976178
Now demonstrate that a portal is equivalent to a hole in a piece of paper.

>>8976178
In your example, the bottom plane of the paper is not moving relative to the top

It would be like taking a piece of paper, putting one portal on one side and another portal right on the other side. And then moving the paper on top of the M&M.

When you compare this to the question in the OP, the exit portal in your example is moving at negative v speed compared to the situation in the OP. Negative v cancels out with v, so the M&m does not move.

But even in that example, the M&M is still moving at speed v with respect to the exit portal / top of the paper.

>>8976111
This is correct. "Sterling Relativity" is truly the only thing that makes sense with portals.

>>8976178
It bounced

I used a penny

>>8976168
The law of the conservation of momentum.

>>8976230
*falls between two portals to gain infinite speed*

>>8976230
Are you going to explain your position or not?

The law of the conservation of momentum proves that velocity IS conserved.

None of you are properly addressing the partial piston descent issue.

>>8976265
You mean this right here?

>>8974821

Firstly it must be defined what it is the portal does. The portals

A. Connect two previously non-3-adjacent points in space.

B. Do so without any 3-space between the connected areas from the reference frame of objects moving through the portal.

The conjunction of A & B lead to an hypothesis that the local 4-space is morphed to make the portal areas 4-adjacent, while 3-space is sustained globally.

Under this hypothesis, a transformation of a portal's 3-position would simultaneously alter local 4-space continuously.

The portal, as it stands, is in 3-space no different from a normal hole in an object. Therefore, conservation of momentum is conserved assuming the previous statements are correct.

>>8976315
Can you draw a picture of that this 4 space would look like?

Just reduce the area the portals are in to 2d and show me the 3D equivalent.

>>8976274
You need to integrate momentum over time.

>>8976274
This can't be right because it means the cube accelerates out of the exit portal.

The cube must exit the portal at precisely the speed of the piston.

>>8976383
In that example, we were supposing that the piston comes to an immediate stop.

If we calculate it decelerating to a stop, then yes we would need calculus. This is the next problem I'm working on. I'll publish when I solve it.

The last paper I just published also has to do with portal math. You might be interested:

http://journalofsci.weebly.com/home/sterling-relativity-and-sterling-transformations-in-portal-math

>>8974944
this is flawed. this is stupidly flawed.

moving the blue portal towards the cube does not mean the cube is moving closer to you through the portal. the cube is stationary.

what is changing is your perspective of the cube... your 'lens' your are viewing the cube through is moving, not the cube

imagine staring through a cardboard tube at something. then imagine moving the cardboard tube closer to the object while still staring through the tube. The object is not moving, all that is changing is your perspective of the object

>>8974944
You are using Galilean Transformations.

With portals, space is not flat and unbroken so you have to use Sterling Transformations.

>>8976111
First part is explained fine, the second part is garbage - work on it.

>>8976315
Imo this is the right approach.

>>8976330
Extra dimension is just instances of same universe (exactly the same, only transformed relative to each other), in our cases the size of new axis is 2 (because we have two instances).

Imagine that there's an invisible copy of the world you are in right now, that is an exact copy. You are there, box is there, piston is there etc.
Now superimpose that copy on top of real world, transforming it so portals of each universe are adjacent. We are looking at similarity transformation, preserving distances.
This is the *only* place where universes cross - there is no other way of affecting fourth dimension than by passing through the portal.

The moment an object goes through some portal, the copy-reality becomes their "real" reality, and vice versa.

Of course, this is just one of the ways one could understand the magic behind portals. Doesn't conclusively mean that this is the case.
But if we assume that it is, then:
a) space is flat and unbroken, just 4-dimensional, Galilean transformation still apply;
b) option B of original question cannot be the case (idea of proof: box gains acceleration by sole fact of going through portal, portals don't impose forces on the box, contradiction)

File: 1 or 2.png (21KB, 1271x531px) Image search: [Google]

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1 or 2?

>>8974944
>the cube does not move, AND moves towards you at the same time
The cube does not move. Looking through the portal, it looks like it's moving, but that is irrelevant. The light from the cube is literally going a different path through the portal. It's like saying the portal is closer to you when you are looking through a telescope.

Its actually quite simple:
-The cube is not moving before going through the portal
-It is moving after going through
-While it's going through, the part that has gone through is moving, the other part isn't

The cube is in motion after going through the portal and is obviously not going to suddenly stop for no reason. So B is the correct answer.

>>8977251
>It's like saying the portal is closer to you when you are looking through a telescope.
No it's not.
A portal reduces the actual distance between you and the cube.

>>8974944
where is the pic with the potato coming out of the orange portal

>>8977157
2

>>8974252
Friend had an interesting proposition. Obviously not supported by the game's physics but would allow portals to conserve energy: essentially, any gravitational potential energy that an object would gain by being pushed through a portal would have to be compensated for by the object going through the portal encountering resistance. IE if it gains say 98J of gravitational potential energy due to the height difference between the portals, then it would require 98J of energy to push it through. Similarly, an object losing potential energy would be sucked through upon contact with the portal, gaining kinetic energy to compensate for the lost potential energy.

The reason why this can be discussed endlessly
without coming to a conclusion is because there is no definitive answer if you don't make some assumptions about how the portal works.

You have to decide if an object will go back to the relative velocity it had before entering the portal when it has passed through the Portal. Or you have to decide that it will keep its relative velocity to the orange portal(and the universe as its exiting) after it has passed through. It can't keep its momentum with both at the same time, so you have to make arbitrary assumptions not based on any physics or the problem shown about the portal workings.

Stopping and starting the motion of the cube requires the same energy, so in that respect, both A and B are the same, they both break Newtonian physics because there is nothing that interacts with the cube when it either starts or stops moving.

Anyone that disagrees with this hasn't thought about the problem enough.

For the people saying there are no forces acting on the box so it does not accelerate, you are right. The object has a constant speed v relative to the portal. For the object to pass through the portal at all, which it does in both case a and b, it must be moving relative to the portal. So now if you consider forces acting on it once it is on the other side of the portal you get gravity as the only force acting on it causing velocity in the x direction to remain constant and the cube will accelerate downward with its initial velocity being upward. Based on my reasoning i would say B

>>8977397

That's not arbitrary. That's how GLaDOS herself says it works. "Momentum, as a function of velocity and mass, is conserved"

>It can't keep its momentum with both at the same time
The "paradox" you are referring to has been solved. Read this:

http://journalofsci.weebly.com/home/sterling-relativity-and-sterling-transformations-in-portal-math

>>8977157
1

put the blue portal on the other side of the cart. It's no different from drilling a hole through the cart and shooting an object through. Provided it doesn't graze the inner walls, nothing happens.

>>8974281
the object does not move but the portal does. The 2nd portal is stationary so the object just plops out.

>>8977749
You only consider one reference frame. But all reference frames must agree on causality. When you chose your frame. You are saying it is a special reference frame, so you are assigning arbitrary rules.

File: QuickMemo+_2017-06-16-00-06-29.png (135KB, 1440x2392px) Image search: [Google]

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What would happen to the cube in this case? Would it smash itself?

>>8977775
..... Did you even read the paper?

Do you seriously not understand Sterling Transformations?

>>8977793
Cube would smash itself and ooze out the sides

>>8977793
when the cube touches itself top/bottom the pistons cant move any further unless theyre powerful enough to crush the cube

>>8974837
The rest of the cube that has yet to accelerate. If the orange portal is going fast enough or the cube is weak enough it would be ripped apart by tidal forces

>>8977806
Why not?
The cube is not touching the pistons in any way

>>8977814
without any force acting on it the cube cannot be crushed

>>8977814
The pistons are touching spacetime and spacetime is touching the cube

>>8977796
I read it, look at how you are getting your cube velocity, you are choosing the orange portal/piston relative velocity and carrying it through the portal. But the Cube has a relative velocity with everything in the universe. You are not considering any of those. Your solution only works for a portal with that special property.

Think about it some more and come back, I'll be sleeping now.

>>8977754
1 would violate newtons third law

>>8977825
But that just proves that portals can impart force on objects, meaning the answer to OP is B

>>8977835
>But the Cube has a relative velocity with everything in the universe. You are not considering any of those.

You can do the same exact thing from any point in the universe, even if you start with the table that the cube is sitting on, even if you start with the area outside the blue portal.

Yes, we already know that Galilean Transformations don't work, this is not a proof of anything besides the fact that the space is not flat and unbroken when you have portals.

Not surprising that people are having a hard time wrapping their brain around Sterling Relativity. You have to follow the math.

>>8974252
The box isn't moving; this is like opening a door beside the box and expecting it to go flying out of it because the door was lower onto the box.
Are you retarded?

>>8977854
>The box isn't moving

bruh look at this gif:
>>8974946

Look at the right side. You honestly believe that's not moving? Bro look at the orange portal... bro you can literally the see the box moving. Like bruh open your eyes. That box is moving fast as fuck.

>>8974265
Mothafucking engineers

The box has no momentum ffs

>>8977849
I'd love to see your example of how it works when you measure the velocity relative to the table then. Or better yet, what happens when you stop the piston half way through. Your paper shold go over more examples if all these actually work(they dont, whithout phantom energy apering or disappearing.)

>>8977969
There is no such thing as absolute momentum.

Things can only "not have momentum" in relation to OTHER THINGS.

>>8974252
portals probably already break those laws though, just moving from one place to another is enough to change the potential energy

>>8974252
Portals don't make any sense because there are at least two answers for every question like this. It's literally a waste of time to even consider.

It's A

>>8975680
Your retarded cardboard with a hole in it (or the more popular hula hoop analogy) has one glaring problem with it. If you slam cardboard with a hole in it (or a hula hoop) over an object the exit hole of said cardboard/hula hoop is moving. If the exit hole were stationary, which is impossible without portals, it would be B. Its exiting a STATIONARY hole with the same apparent velocity that it went into the blue portal with. Its gains its energy from a slight resistance against the moving piston due to the weight of the cube acting against gravity while exiting in the orange portals "stationary" reference frame. This is how it would work in real life, end of discussion. It may work differently in game, but thats up to the creators discretion, not necessarily the laws of physics.

>>8977849
You're wrong, but for the right reasons.
While the cube does have a velocity relative to the orange portal, so does the blue portal. Therefore, from the orange portal frame, the relative velocity of the cube and the blue portal is 0, and therefore by conservation of momentum, the answer is A.

>>8978983
>from the orange portal frame, relative velocity of the cube and the blue portal is 0

Youre trolling right? Please tell me you are trolling. I refuse to believe anyone can be this retarded and still be able to operate a computer. Who ties your shoes for you in the morning?

File: 9000+ h.png (9KB, 974x299px) Image search: [Google]

9KB, 974x299px

Okay brainlets, lets bring some general relativity into this shit.

But lets start simpler, see my amazing drawing.
You have 2 cars "a" and "b" both traveling at the same velocity down the highway. Their relative velocity Is 0.

Car "b" suddenly fucks off through a portal and has now changes its direction. Car b still has the same momentum, but their relative speed has increased. Fucking portal magic.

>but anon, in the problem, car "b" velocity would have to increase along the its starting direction too.
Okay calm you tits for a second. This is where GR comes in.

If we instead imagine the road as its path through SpaceTime (i.e. 4D du, du du DUU~) The change in direction is instead an analog to a change along its time axis. Its momentum HAS now changed, but the car(cube) will not experience any acceleration, its sound strange maybe depending on how good your intuition for GR is, but this isn't anything that strange in the world of GR, Falling objects do this exact same thing everyday because of a curve in spacetime, we call it gravity.

>but anon, what happens if the portal stops before the cube has gone all the way through. bwaaa
Oh Jesus common. If we go back to the car example, this would be comparable to the two half's of the car getting sent though different portals in different directions. They would then experience the change in velocity as a force pulling itself apart.
>bullshit
Nah man, this also happens everyday close to backhole event horizons as objects pastaficate. The top part of the object will be on a slower path through spacetime than the lower. Now fuck off!

>So is it solved then?
Fuck no, I'm making assumptions about how portals work, in order to make it work.

>>8979135
The Orange Portal sees the cube moving at v, but it also sees the blue portal moving at v, so the velocity of the cube relative to the blue portal is 0.

>>8979354
Now im sure youre trolling. Anyone whos stupid enough to say those things unironically would have forgotten how to breathe at some point and died before finishing that post.

>>8974289
Depends on the speed of the platform. If its 30km/h the box would exit the second portal at the same speed right?

>>8974252
>>8974281
>>8974901
>>8974537
>hurr durr i dun understand what inertia nor reference frames are
Nice try morons. The answer is B. kys brainlets.

>>8977840
no it doesnt retard. the box isnt launching from the cart, its being teleported infront of it.

>>8975073
This

>>8974252
momentum cannot be conserved in any frame of reference for this situation
it is inherently unphysical

>>8979979
>momentum cannot be conserved in any frame of reference

It is if you use a sterling transformation instead of a Galilean transformation.

Galilean transformations only work in a flat, unbroken space. This is not the case with portals.

Every time I see this thread posted there are more and more brainlets claiming the answer is A.

A good reminder of the average intelligence of this board.

>Autism speaks: the thread
Jesus /sci/, haven't been on this board for a week and this happens.

At least maybe some of you are enjoying discussing it I guess.

This is funny.. A whole bunch of idiots using physics jargon to prove each other wrong.

"A portal moves the entire universe with it"

"Only an idiot would say the answer is A, kill yourself.."

I'd bet my left nut 90% of you trolls has never taken the time to read a fucking paper and understand how you can help people understand the point you are trying to make.

Clearly, the confusion here is given by our multiple interpretations of what a portal is.

Be smart, faggots. Before you explain the behavior of a solid going through a "portal", first describe what a "portal" or at least think about a interesting analogy to clarify your conjectures.

Don't be an idiot, please. Also, there is zero scientific evidence on the existence of portals. Life is not a game, faggot.

File: when your waifu's mangaka kills himself.jpg (35KB, 599x463px) Image search: [Google]

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>>8980189
Somebody fucking said it
/thread

>>8980189
way to ruin the fun

>>8974993
such an overrated game

maybe antichamber ruined it for me to be fair, portal 2 was piss easy after that

>>8974787
If the direction of the orange portal's velocity is the same as the cube reduce the speed of the cube by the speed of the orange piston.

Unless the velocity of the orange portal is deterministic of spatial velocity the following given is reason (this is purely speculation as we dont know how the portals function exactly):
As matter of the cube enters the blue portal it does not carry the orange portal's velocity and thus will move back into the orange portal repelling the matter of the cube at the speed of the moving platform. Because the platform is at a angle we can say that only the projected velocity is changed and the horizontal velocity is kept constant.
If the cube carries the velocity of the orange portal then the net velocity is added.

>>8974917
Not exactly, if you consider forces as particles it can still hold that gravitrons can pass through the portal but only those passing through the portal will act upon the environment, which wouldnt be very much.

That said, if you stand at the center of the two portals, one below one above, the size of the portal would increase that reversed gravity. Similarly, the closer the two portals the more reversed the gravity of feel.

But maybe you are right, obviously atomic forces the cause pressure propagate as we see with the moon sequence, but Im not sure about others.

>>8976129
Sterling vs Galilean? Look it up, he states them multiple times. Its not like some mathematical niche in spatial representation, these are popular and commonly regarded transformations.

>>8977841
In that the cube is applying force unto itself, sure

>>8974913
and how come nothing in that reality slides due to this acceleration?

>>8975774
portals do not have mass nor momentum

the cube does

therefore only when the cube has momentum, can the cube continue having momentum on the other side of the portal

>>8977793
cube is traveling infinitesimally fast and at least partially explodes into energy when the two collide

or goes even further as to cumulatively gain mass and destroy itself in a black hole

can someone try this in game? also it's a

>>8981593
i don't think it's supported by the game engine. the one case where you have a moving portal, it moves sideways and you can't enter it, it's only for the laser. if you can hack the game to test OP's scenario i don't think it will give a meaningful result, not necessarily what the game designers would have intended.

File: Velocity is not conserved through a portal.png (4KB, 659x283px) Image search: [Google]

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If B is true, then explain how the cube could even travel through the orange portal in pic related.

>>8981681
Explain how it couldn't?

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tfw u kno it B

>>8981686
Exactly! Reference frames don't cause changes in momentum.

>>8981681
It falls through then comes right back

Eventually it reaches an equilibrium of either being stationary or hovering in the inbetween portal space, like when you drop something in a portal in game.

>>8981681
It would just come out of the orange portal falling at V
are you dumb?

>>8981703
How can it come through if the other reference is moving? Does it shoot out at 3V?

>>8981719
>Does it shoot out at 3V?
If the portal was on the other side it would...

>>8981726
What?

>>8981727
Look at the picture again
The cube comes out of the orange portal moving downwards at V.
If the orange portal were facing the other direction it would come out moving downwards at 3V

Momentum is a vector lol

>>8981873
yes it is, it has a direction

>>8974252
We're talking about Portal physics which are completely arbitrary in the game right? So why hasn't anybody tried to make a mod which replicates this exact experiment in the game to see what would actually happen instead of arguing like idiots using Newtonian physics, which may not even apply in this case?

If you can have half of the object sticking out on both sides, than the answer is A


If the portal sucks the object as soon it's touched, then it's B

>>8982069
B happens, I think they already tried

>>8982089
> B happens, I think they already tried
Well then what are we arguing about?

>but the designers didn't think about this situation
The designers are just supposed to make the levels in which the mechanics of the game are used. Everybody on Portal's development team agreed to use an arbitrary set of rules upon which they built the game. Whether or not they thought about this situation doesn't matter here, just like they didn't think about every shortcut in a level.

https://www.youtube.com/watch?v=S85nudR6D-Y
>Uploaded on May 20, 2011

>>8982264
>portal 2 came out 6 years ago
holy shit

>stand up a pencil on a table
>make a ring with your thumb and pointer finger
>quickly move it down over the pencil
>watch the pencil jump into the air with equal speed to your hand

Actually, this doesn't happen.

Scenario A is correct.

>>8982588
A portal is not equivalent to a ring

>>8983395
>I DECIDE WHAT LAWS OF PHYSICS THIS MADE UP SCENARIO FULFILLS WAAAAAAAAAAAAAAAAAAAAH
kill yourself

If you drop a hula hoop over a ball it doesn't fly into the air.

>>8983417
already been demonstrated in this thread

>>8983420
If you throw a ball into a hula hoop it doesn't teleport either

>>8983428
if the blue portal was facing directly upward it would be exactly the same as just dropping a hula hoop over the cube.

>>8983426
>this thread
you're a fucking retard if you didn't prove both ways inconsistent within 5 minutes of seeing the first of these threads years ago on whenever you first saw it

>>8983453
That's not the case in this scenario though

>>8983466
having the blue portal slightly tilted doesn't make a difference in the ball's momentum

>>8983468
think about what you just said for a second

>>8983470
I accidentally said ball instead of cube?

>>8975274
>'the mistake you are making is general relativity'
my fucking sides

>>8980239
The point wasn't it being easy, it was about it being fun.

>HURR SLAMMING EMPTY SPACE INTO SOMETHING GIVES IT VELOCITY

What are the governing rules that make a "portal" impossible in practice? Are there any mathematics or theoretical physics based in "wormholes" that make them possible?

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>>8974252
The object would come out the blue portal at the speed the yellow portal is traveling, as soon as the piston head meets the object stand the object will slide off the surface out of the blue portal.

The object is relocated(not moved) but it has no energy imparted on it thus it can't fly out.
Space around the object is moved and the object itself is not moved.

A is the only reasonable answer.

>>8982264
Why are you still arguing? Here is the solution
You get stuck between if you stay still
If you move you actually gain momentum and it becomes B

>>8983928
no one cares about what actually happens in game

http://www.strawpoll.me/13229119

Here, I will build an alternative interpretation of how portals work.

Lets say that a portal works by cloning all electromagnetic phenomena which comes though it. Meaning, if a photon touches it portal, it is cloned at the out output portal. Same goes for matter.

Under this interpretation of portal mechanics, A would be correct. Each new layer of cube atoms being cloned would have just enough energy to push the cube up slightly to make room for themselves.

>>8983933
no one cares about the nonsensical troll question

>>8983908
it's moving relative to the blue portal

>>8984006
No, the space the cube occupies is moved.

>>8984027
what do you even mean

did you fail high school physics

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The real question is what happens when portal stops with the cube halfway through

>>8984033
no im so smart you cant keep up

the question is utter nonsense

from the same frame of reference (the room/world where the portals are), the box cannot simultaneously have a momentum (it moves through the stationary blue portal) and not have it (it's stationary on the platform)

>>8984060
Stop assuming physics apply to the Portal universe

>>8984068
if you want to know what happens in the game engine, see
https://www.youtube.com/watch?v=JHe-iU63nmE

if you want an "in-universe" explanation, only the game developer could give you a definitive answer

>>8984060
if you're gonna go for this kind of reasoning, why not just go straight for "the box cannot simultaneously exist in two different points in space as the portal moves over it"?

it has no momentum however you look at it. the portal is moving, not the platform or the box. the only time the box would actually move is after it's been transferred to the angled platform. at this point the cube would either slide, roll off, or stay motionless on the angled platform, depending on the cube's (and to an extent the platform's) physical properties.

>>8984757
you haven't played the game have you

>>8984774
you'll have to do better than that, friendo.

>>8984865
>the only time the box would actually move is after it's been transferred to the angled platform
you fucking dumb shit, that's not how the portals in the game work, when the box is halfway through it's stationary relative to the platform it's sitting on, moving relative to the orange portal, and moving relative to the blue portal

>>8984882
>stationary relative to the platform it's sitting on
exactly. both the platform and the cube are stationary. and since there isn't any matter transferring any kind of momentum to anything, it will remain stationary. until, of course, it passes through the portal, at which point gravity happens.
>moving relative to the orange portal, and moving relative to the blue portal
means literally fucking nothing. portals aren't matter. they don't even "move", they just transport shit from one spot to another, that's it. game engine mechanics or "why portals don't/can't exist" has nothing to do with the question at hand.

>>8974252
A: Provides push from nowhere; it isn't obvious in that case, but when you analyze the mechanics further it's clear.
B: That would mean that the portal somehow increased the objects velocity, but that would cause different points of the object to have different velocities as it travels through the portal, and that isn't possible.

>>8985099
With B, every part of the cube stays in the same relative position to every other part. It only has different velocities because it exists in two frames of reference at the same time. Even before it crosses the portal threshold you could say that it is stationary from one point of view, and moving at the speed of the orange portal from another.

>>8984984
Imagine a stationary portal leading to an exit portal that moves sideways. You stick your arm through, taking care not to touch the sides. What happens to your arm? Does it remain "stationary"? What does that look like?

>>8974944
This is such a cop-out. As if portals are at all plausible in the first place, as long as they don't move. As if you don't have the problem of the cube existing in two places at once with stationary portals already.

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The cube does not move because of any momentum of the orange portal. If it moves at all it would similar to scenario A. because as the portal envelopes the cube part of the cube will experience the gravity from the reference of the blue portal, applying a torque because of the cube's position. There is a chance that the cube will not move if the angle is not steep enough.

If the cube does manage to complete go through the orange portal it is possible that it will slide down the slope of the blue portal pane.

>>8974252
>this thread got over 300 replies
Sad. /sci/ should take an IQ test.

>>8986106
IQ tests are bogus

almost everyone on /sci/ gets 130-145 on those mensa online tests

>>8986108
/sci/ is self-selected for intelligence though, and further so for the people who want to brag about their results

>>8986116
if you have the time, you can try this, even though i know pretty much nothing about you i won't be surprised if you get a very high result
http://test.mensa.no/

i'm inclined to believe that i'm highly intelligent but i also think that it's way too common for people to get 130+ IQ scores on this test

>>8986106
Let's hear your answer then along with your IQ

Portal 1 made it very clear that momentum is conserved when a collision with a portal occurs.

I made an illustration of this. Neither A nor B occur. The only thing that happens is the normal and weight change directions as soon as the center of mass passes the portal. This rapid change causes the box to sort of flop over onto the face closest to the ground.

>>8986132
>i also think that it's way too common for people to get 130+ IQ scores on this test
or rather, that the test is far too easy. anyone who isn't literally retarded can figure out most or all of the patterns if they just try. the main reason why you would get a "low" (still 110-130) score would be if you ran out of time and had to guess/rush some of the answers.

Are there no mods for either portal game that would allow this to be tested?

>>8987157
https://www.youtube.com/watch?v=JHe-iU63nmE