The answer is actually pretty simple.
If portals work through space time distortion, it's A.
If portals work through some sort of instant atomic assembler/disassembler, it's B.
The game never states how portals work, so it can be either of them.
>>7863410
>"science"
Its A, I'm pretty sure they mentioned something about space time in the game.
>>7863410
It's always B.
Energy is not conserved in Portal, and objects must always exit the portal at the same velocity relative to the portal that they entered.
Neither. Portals cannot be placed on moving objects.
>>7863569
False, portals are on moving objects in the portal 2.
HOWEVER
Stationary objects cannot enter portals.
>>7864395
>Stationary
There is an absolute frame of reference in Portal?
>>7864399
In the game yes, this whole thing has actually been tried in the game, the above portal surface would stop on top of the cube just like if it was any ordinary surface.
It has been tried in a different way though, some guy tried using the character instead of the cube, and jumped into the portal moving downwards.
Exited the other portal with only the momentum they gained from the jump.
>>7863410
We've been over this a million times. The answer is B.
>>7864731
I'm sorry you feel that way, but the only possible answer is still B. That's the eventual conclusion that every one of these threads arrives at.
>>7863410
You know I've always wondered how would momentum even be conserved? Say one atom thick part of the cube comes out of the other portal, but it's being held back by the rest. Then next second layer comes but it's being held back by the the rest, etc. I would assume that soon the cube would start breaking into little pieces as it comes out the portal, and those pieces went flying everywhere.
>>7864763
Why would it be held back? The cube enters orange and exits blue at the same rate. There's no stress on the cube.
>give me scientific expansion for something unscientific and impossible
>>7863410
https://www.youtube.com/watch?v=ASUUN0W4_JY
Lel this picture never ceases to get replies.
Where does the force on the box come from to have B occur? Please dont say relativity.
>>7864920
>Where does the force on the box come from to have B occur?
No force is necessary. It is already moving relative to the portal.
>>7863410
>the game never states how portals work
It did state they dont work on moving objects fagisimo.
>>7864927
>relative
',:^)
>>7864930
Is that a trigger word for you? If so, you're probably going to fail high school physics.
>>7864939
Trying way too hard m8erino.
There is no answer because the structure is a logical and physical impossibility. If you look into the orange portal, A is expected. If B happens, you think the cube was accelerated without force. If you are looking into the blue portal, B is expected. If A happens, you think the cube was decelerated without force.
Basically, this structure moves the entire universe relative to itself. If you could construct this, then you could construct an infinite energy creation machine.
>>7864986
>There is no answer because the structure is a logical and physical impossibility
It's a physical impossibilty but NOT a logical impossibilty. There is nothing inconsistent about option B.
>>7865005
Yes there is. If you are standing under the plinth holding the cube and look up into the orange portal, you would see the cube zooming off for no reason when it breaches the portal plane.
>>7865005
In the game, there is no relativity, each object is assigned it's own velocity.
All else equal, a is the answer
>>7864930
Don't ask for answers to physical questions and then reject a valid answer just because you don't like the word
>>7865036
An object can't have a constant velocity because the two vantage points see that differently. The object's velocity has to change once it breaches the portal plane from one of the universe's point of view.
>>7863493
Actually they just have to exit with the same speed, not velocity. The scalar stays the same but the vector is changed to whichever way the portal is facing
>>7865054
But the speed is different depending on where you stand.
>>7865036
>In the game, there is no relativity
Sure there is. Velocity is meaningless without the concept.
>>7865062
What?
>>7865130
https://en.wikipedia.org/wiki/Galilean_transformation#Galilean_transformations
>>7865130
If you look into the two different portals, you see the same object have two different speeds.
>>7865138
How is this related? All I said is that when you go through a portal, the magnitude of your speed relative to the entrance portal when you enter will be equal to the magnitude of your speed relative to the exit portal when you exit
>>7865042
You're using relativity wrong senpai. If you move unintentionally towards me with a cardboard box attached to your entire body, does that mean ill launch towards you?
Inb4 but thats not how portals werk waaah
>>7865249
>If you move unintentionally towards me with a cardboard box attached to your entire body, does that mean ill launch towards you?
What?
>>7865249
>If you move unintentionally towards me with a cardboard box attached to your entire body, does that mean ill launch towards you?
I don't know what my intentions or the cardboard box have to do with anything, but it is true that me moving towards you is the same as you moving towards me.
>>7865265
No it's not dipshit. Relativity only matter at speeds greater than 0.10*c
>>7865267
It seems like you're confusing "relativity" as in special and general relativity with "relativity" as in galilean relativity, which is part of classical physics. So, uh, yes it is, dipshit.
>>7865284
You keep bringing up this frame dependency but there's only one frame that matters, the cube.
You can test it out in portal 2 Co op.
Speed of object entering a portal is the same for all observers. Again, this is because the game assigns all values to each individual object.
The speed that you come out of a portal with is the speed the object was assigned before it went in.
You could argue that if portals could move, that the object inherits the portals speed when the object enters it, but there's no reason to believe that it would be coded that way
>>7865280
>portals work with classical physics
Lol engineer detected.
>>7864920
The portal. Even without moving portals, portals can change the momentum and energy of objects.
>>7864986
>If you could construct this, then you could construct an infinite energy creation machine.
I don't think so, you could just have the energy come from whatever mechanism creates the portal.
>>7865326
Conservation of energy is derived from isotropy of time.
Clearly portals fuck up spacetime and so that's not really a valid assumption to make.
>>7865028
In a matter transporter portal, that perspective isn't really real. It's just an illusion that appears when photons are transported across the portal.
In a GR wormhole portal, what you are seeing is gravitational tides.
>>7865340
>Conservation of energy is derived from isotropy of time.
Portals break isotropy of time if you don't consider them part of the system. If you consider the portal generator part of the system, turning on the portal 1 second later should create a portal 1 second later, and we have isotropy of time back. It's really no different from anything else that acts as a source or sink of energy; they all break isotropy of time when you consider them as separate from the system, but isotropy is restored when you consider the whole thing.
>>7865317
>>7865317
>>7865326
>>7865326
>>7865343
>>7865359
Literally none of this discussion is relevant.
If there was a hole instead of a portal, the only way the block moves is from the force of the two pistons hitting.
Considering the portal, it is literally just a spatial transformation from one coordinate system to another.
In any model of relativity, the physics are invariant. Therefore, a is the only option
>>7865372
In your model, if I dangle a ball from a string over the blue exit, and you're looking from beneath the yellow entrance, how do you explain the ball going from approaching you at high speeds to being at rest?
>>7865372
>Therefore, a is the only option
Please tell me you meant to say B.
>>7865404
>If you're standing in a road and a car is speeding towards you, how can you tell if the person driving is moving or not?
You don't. Motion is relative.
The question for you, who expects A, is why a person on the other side sees the ball accelerates but does not see the block accelerate.
>>7865404
>You're assuming that the rest of the universe on the other side of the portal is moving with the same speed of the portal. It's not
But it is. Look into the exit portal and you can see everything rushing towards you. You see the cube approaching at velocity V, enter at velocity V, and exit at velocity V. Why would it come to a stop once it's already through? At that point the portals are no longer even involved, it's just simple Newton's First Law.
>>7865418
Because the block is not dangling above a. Even though motion is relative, you can still recognize differences in frames that aren't yours.
>>7865435
Because the portal translates the object to a different coordinate in the same coordinate system.
Instead of resting in the hole in the piston, it rests in the spot the portal transforms it to.
There's no evidence from the game that the portal is anything more than thick window
>>7865459
>Because the block is not dangling
Does that mean your answer would be different if I gave it a slight nudge into the air before it passes through the portal?
You can't think of the two portals as two separate entities. it is in fact only One portal which connects one area of space to another. you can think of it like a hula-hoop that you grab the side of and swing up and down. the hula-hoop moves around but the space inside the hula-hoop doesn't change velocity. Theres no space-time travel or molecular discombobulating happening from one side of the portal to the other, it literally connects the space from one side to the other, the space the portal actually taking up is basically just more air in the room, evidenced by the fact you can stand half-way in one side and at the same time half-way in the other.
>>7865466
Yes. If you're driving in a car and wave your hand around, someone standing on the road can tell that your hand is moving independent from the frame of motion of the rest of the car, but if the car worked like portals, the resulting change in momentum from the collision would be solely from the difference between the frame of the car (blue portal) and the hand (dangling ball)
>>7865475
What if I told you the block wasn't actually touching the platform, but suspended from it by electrical repulsion forces?
What happens if someone on the blue side reaches through the portal and places his palm against the block before it passes through?
>>7863410
You ArE noT thINkinG With PORtals VeRy well.
>>7865501
Nothing interesting happens.
If you move through the blue portal and exit the orange, you'll either come out normally or re enter the orange because you're too slow
>>7865526
>re enter the orange because you're too slow
How would that work?
Say I'm on the blue portal side.
The orange portal is descending.
I stick my arm through the blue portal slowly, slower than the portal is descending.
You claim my arm is "too slow" and should re-enter.
How does that even work from my perspective?
>>7865582
there's no clear answer to how this would work, i have to admit that.
if you dropped the ball through the blue portal, and the speed it was moving before it went through the portal was slower than the speed of the orange piston, the ball would re enter the orange portal and come out of the blue portal with the same speed it went in + whatever speed it gained while falling before it was swallowed up again.
the problem with the hand, is that it is fixed to a reference frame and still is even after it enters a portal. my intuition tells me that just like the ball, your arm would be in the blue portal, and your hand would come out of the blue portal as well, if you moved your hand as fast or faster than the orange portal, it would move with the portal or "stretch" or even possibly rip your arm off, but i can't say anything about the nature of the hyperspace between the portals because it doesn't exist in game.
>>7865605
>if you dropped the ball through the blue portal, and the speed it was moving before it went through the portal was slower than the speed of the orange piston, the ball would re enter the orange portal and come out of the blue portal with the same speed it went in + whatever speed it gained while falling before it was swallowed up again.
You seem to think the ball will be momentarily ahead of the orange portal while at the same time being slower than the orange portal. This is inconsistent. How did the ball get to that position just beneath the orange portal other than by moving downward through the orange portal faster than the orange portal was moving downward?
>>7865622
because the orange portal doesn't change it's position at all from the time it enters the blue portal to the time that it exits the orange portal.
i.e. the ball moves instantaneously "between" the portals, which is consistent with the game physics
>>7865629
that was a little ambiguous,
what i meant is that regardless of the speed of an object, and the speed of the exit portal, an object passing through an exit portal will always be at least momentarily ahead of the exit.
This is because the object passes through the portals instantly, so the only time the object can re-enter the portal is some time after it originally exited it.
>>7865629
>the ball moves instantaneously
In the game, objects don't just pop into existence on the other side of the portal, they move through continuously. If you're looking at the ball from beneath the orange portal, you should see it move through the portal. It's not instantaneous. It has a speed, and from your perspective it has to be a speed greater than the orange portal's speed.
>>7865660
that only works if you assume figure b. is true.
what i've been talking about the whole time, is assuming a is true and then explaining the other effects of a. being true, and how it is consistent with game physics.
of course you'll see the object moving from one portal to the other. however, the instant that an object enters a portal, it is redrawn on the exit of the other portal. the only reason it's not instantaneous in game, is because your game is running at a certain fps and it takes time to draw the frames. but that is a systematic flaw that can be ruled out.
what we're talking about, is that if the orange portal is moving 5 m/s and a ball is moving 10 m/s when it enters the blue portal, it will exit the orange portal moving at 10 m/s and will be moving faster than the orange portal, and thus not re-enter it.
if the ball is moving 4 m/s, the ball will exit the orange portal moving 4 m/s and then re-enter the orange portal a fraction of a second later, and will fly out of the blue portal with a speed of 4 m/s
this is consistent with game physics. you can demonstrate this property by placing an entrance and an exit near each other on the floor. when you place an object in the portal, the object just kind of bobs up and down, but you never see the full object
i.e. the objects are never "half in half out" which suggests that portal travel is actually instant
>>7864759
How the fuck can it be B?
The box gains no energy from moving through a portal, and both A and B only show the box moving through the portal, so we have to assume that the platform the box was on does not pass through the portal.
From this information we narrow it down to which point of reference the momentum is conserved in. If it's the portal's point of reference (if its a molecular disassembler which it isn't) the box moves through it's entry point a Xm/s so it exits the exit portal at Xm/s.
If it works through spacetime distortion then the point of reference is the immediate surroundings in which case the box is moving at 0m/s, enters the portal at 0m/s and exits the portal at 0m/s.
Both are impossible since if its a molecular dissembler, how does it travel faster than light? It can and doesn't, it can't possibly exist.
The outcome for spatial distortion is far worse however, because now you have to deal with space-time "leakage". If you place one portal on the floor and another on the wall to your left, you now have an entire planet's mass in gravity on that wall to your left. The gravitational space-time distortion that is pulling us to the planet is now pulling us through that portal since that space time distortion is originating from both below you and that wall on your left.
>You sweat as you realize what you have done
>The orange portal hits the wall with the force of a thousand suns
>It's orangey center beckons and opens the gates of a new definition of pain
>Everything around you is slowly pulled towards the portal
>Things start to float between the midpoint of the of blue and orange portals
>The junk starts to pile up
> You run but you lose your footing
> Before you can even hit the floor you are hurled to this midpoint
>You fall into the pile of festering junk
>You feel the immense pressure on all sides as junk starts to pile up
>Has Science Gone Too Far?
Feel free to fix any of my shitty logic with valid points.
>>7865688
>i.e. the objects are never "half in half out"
Are you sure about that? Can you take a screenshot of an example demonstrating this?
>>7865750
>The box gains no energy from moving through a portal
False. Even without moving portals, boxes can gain gravitational potential energy. This happens in actual gameplay.
>>7865769
no it doesn't
it gains gravitational energy before entering a portal, and after exiting, but it doesn't gain any energy while it's moving "through" the portals
>>7865769
Adds no substance to the original post, the point still stands. That however does stand to prove that portals would violate the first law of thermodynamics.
>>7865777
No, what happens while falling is conversion of gravitational potential energy into kinetic energy. The change in total energy of the box happens when the box passes through the portal, increasing its gravitational potential energy.
>>7865784
A satellite can gain energy by slingshotting around Jupiter, does that mean Jupiter violates the laws of thermodynamics?
>>7865796
Sorry,
*space probe
Not exactly a satellite if we're not putting it into orbit.
>>7865757 again,
I don't have the game installed on my current computer, but here's a random Youtuber dragging an object through a portal, with the cube partially through. It doesn't disappear from one side and reappear on the other; you can see it the entire time it's passing through.
I don't think what you're saying in >>7865688 is how the game works at all.
Internally it might be the case that the game records only an object's center of mass or whatever, and that center of mass moves instantaneously, but I don't think that detail is supposed to ever be visible. If it were in some instance, I would consider it probably a glitch rather than intentional.
>>7865788
You didn't phrase this right, try again.
>>7865822
And here's one where it's visible from both sides, albeit not the clearest shot.
>>7865796
You need to pay attention in your HS physics class. Voyager 1 didn't gain energy willy nilly from no where by passing by jupiter, it actually slowed down jupiter by a fraction to increase it's own speed immensely; d(p)=mass*d(V). There is no violation of any laws here.
However, when you have a portal at the bottom of a ramp and a portal at the top of the track, guess what happens? The laws of thermodynamics break.
If you roll that ball down the ramp into the portal the ball speeds up and loses its gravitational (potential) energy but gains kinetic energy. The balls rolls into the portal and *Poof* it now has all the kinetic energy AND has gained gravitational (potential) energy from literally no where. Energy was just created from nothing. First law, broken.
>>7865851
The point, which you would have gotten immediately if you weren't assuming everyone was as brain damaged as you, is that there can be a transfer of energy from the portal to things passing through it. Unless you think that making portals would require no energy, which would be silly.
>>7865859
So the portal loses energy as things pass through it?
Are we talking about the same game here? What would make you assume that only a limited number of things can pass through the portal? This seems like a fill-all explanation, next you'll be telling me that the supernatural powers cause portals to exist.
>>7865892
Portals could have a huge amount of energy in them, larger than you'd ever expend in the course of the game. Or the energy could be transported from elsewhere (this would also explain portals only moving on stationary surfaces; the surfaces must be stationary relative to the generator rather than the gun, which could be only a controller). Am I making these explanations up? Of course. It's only to make the point that portals do not necessarily violate energy conservation. Unless they say somewhere in the game that "we're using this as an unlimited energy source," in which case the violation would be canon. But I don't think "devices may require energy to work" is as unreasonable a guess as "devices may work via supernatural powers."
So it seems like we're all agreed it's B and have staryed arguing about other shit, right?
>>7865910
>Unless they say somewhere in the game that "we're using this as an unlimited energy source," in which case the violation would be canon.
When I read this sentence, I realized that the problem is that you don't understand my argument. If your in high school, please finish your physics course before talking about physics, I would like to address your argument but their are so many basic things that I have to actually teach you first before you can even understand your own argument.
As of right now, in the code, there is no limit to how much material can pass through a portal and there is no time limit on portals so your argument just doesn't work.
>>7866032
no, the only person that's given any substantial argument is myself arguing for A.
there's literally no defense or argument in favor of B besides "muh frames of reference" which I addressed already.
>>7866076
So we're all agreed it's B except for this idiot, right?
>>7866113
no, i understand it perfectly well, i just said that there's no reason to assume that a moving portal effects the velocity of the object that moves through it.
>>7863410
look you fucking autists
because the game doesn't explicitly show/say how moving portals work you have to set reference frames to even try to understand how this works
setting it to the cube gives a stationary cube entering and a stationary cube exiting therefore it is A.
setting it to the orange portal gives the orange portal moving towards the cube at velocity 0 and the cube moving towards it at a velocity of -v
when the cube goes through the orange portal it comes out of the blue portal at speed v therefore it is B.
obviously there's a contradiction depending on which reference frame you set so it can be either as op stated
>>7866196
>setting reference frames
I don't think this guy understands relativity
>>7866231
lowest tier bait i have ever seen
>>7866234
nice bait, bro. I'm not taking it
>>7863410
Its fucking C
The box doesn't go through the portal because it can not travel past the ledge that the box is sitting on.
>>7866062
That's stupid, it's like saying rounding errors in the game means conservation of energy is violated. While strictly true, it's autistic.
It also doesn't matter because the portals can be powered remotely.
tl;dr: you're retarded
Thrusting a portal at a block would transfer the same amount of energy as thrusting a hoola hoop at it.
Can we at least agree that the energy of an object moving through portals is not conserved?
If there are 2 portals at different heights, an object moving from the lower to the higher portal will gain potential energy.
It is possible that this gain in energy of the object could somehow be compensated by the portals themselves such that energy is still conserved if you consider the system as a whole.
>>7866384
I don't see how anyone could deny that much.
>>7863410
You've got it backwards.
>>7866464
B is the type used in the game, and you can avoid things being cut in half simply by relaying forces from one side to another. That would certainly happen in a wormhole-type, and would probably have to be done in a matter-transfer type whether or not you preserve speed. Otherwise what happens if you dangle your hand into the thing? If the force holding your hand up doesn't transfer, it falls off!
A is ungodly complicated and would probably break things. For example, what do you do if two objects try to go through happens if two objects go through at different speeds? What if the "two objects" turn out to be the two forward arms of one rotating object?
>>7866464
>>7866486
Actually, never mind what I said about A. It's not complicated, it's just B with the added "feature" that once something is entirely through, you kill the momentum. Actually, that would still be moderately complicated and would still probably fuck up a lot by misjudging when objects were entirely through. But that wouldn't break most objects; it would feel like bumping into an unexpected wall.
Can portals exert forces on the surface they are on?
>OP's pic
> over 100 replies
every fucking time
>>7863410
https://www.youtube.com/watch?v=JHe-iU63nmE
blah blah blah
>>7866494
Why would momentum need to be killed?
Figure b. Actually violates galileo relativity
>>7867162
Idk how he coded this to work but you can clearly see that it most resembles a
>>7866616
In that scenario the cube would be smashing into itself from both sides. The portals wouldn't be exerting any force, but the cube would have to pancake out beyond the radios og the portal, and that would stop the pistons.
>>7867289
>Idk how he coded this to work
Poorly, clearly.
>>7867282
>Why would momentum need to be killed?
Because the box must leave the exit portal at the same rate it enters.
>Figure b. Actually violates galileo relativity
How so?
>>7866616
You don't even need moving portals for a situation like this. Put two portals on a wall and toss a rope through one. Then tug on both ends of the rope.
I don't know if the portal exerts a force on the wall/surface, though. I can see several possibilities:
(a) portals exert force on the surface they're on
(b) portals exert force on a remote location
(c) portals have so much mass that they don't accelerate visibly when you pull on them
(d) portals outright violate Newton's third law
The only possible option is A. Let's solve it.
Physics laws are the same for all observers in Universe (Relativity principle) so I can choose my favorite reference system to solve the problem. If I'm an observer on the portal, what I see is that I am not moving, and a box is coming towards me with velocity v.
Since, as every Portal player knows, the momentum is conserved when you go through a portal: that's why most people think B is the correct solution.
However, it should be noted that if your reference frame is the moving portal, then not only the box is moving, also the blue portal is moving at velocity v, the same as the box. And since the box and the portal are moving with the same velocity respect to me, then the relative velocity between them is 0 -and the correct answer is A.
The drawing is tricky, and that leads to the error in my opinion. Imagine that the box is not there, you only have the cylinder. As the platform "eats" the cylinder, it appears in the blue portal, but it has no velocity (if the orange portal suddenly stops you will have part of the cylinder coming out from the blue portal, but it will be static!) So the box cannot have any speed, as the cylinder. It simply will fall down from the platform since now it is inclined -and that's A.
>>7867434
>it appears in the blue portal, but it has no velocity
>>7867434
This was painful to read.
>>7867434
Momentum is not conserved, speed is. If two portals are placed upon the same wall and I enter one facing the wall, I come out facing away from the wall. If I had a velocity, my velocity has been reversed.
>>7865305
I believe this comes down to the fundamental question of whether we are asking if A or B occurs in the game or if this were to be implemented in real life.
If we're talking about the game, it's A. You don't even need to get into theory, you can test it. Now, unless we're assuming Portal 2 is a perfect simulator for reality, we can't assume this would hold true for reality.
But if we're talking about reality, well then this discussion becomes retarded.
Does a moving block exert a force on a stationary portal?
>>7867434
For starters, I am going to be speaking solely about the span of time in which some part of the cube is in traversing the plane of the portals (so not talking about before it enters the orange portal or after it exits the blue portal). Do not respond with statements about what the cube or the portals were doing before or after they came into contact.
Do you agree that if the cube is crossing the plane of the orange portal at 10 meters per second, it must be crossing the plane of the blue portal at 10 meters per second?
If not, at what speed does the cube cross (exit) the plane of the blue portal, if the cube crosses (enters) the plane of the orange portal at 10 meters per second? Zero? If the cube exits the portal at zero meters per second, does it truly exit the portal at all? Does it even begin to cross the plane? This would imply what actually happens in the game, where the orange portal hits the cube and stops.
Unless you are proposing that there is some higher-dimensional space in-between the portals, if you want to say that the cube exits the blue portal at all, you must assume that it does it with some non-zero speed. If this speed is non-zero, what is it? What if we try assuming that the speed at which it exits the portal is just enough to push it out of the portal and fall to the ground as it does in situation A. We will assume that 1 meter per second is sufficient to yield this result. Again, assuming the cube crossed the plane of the orange portal at 10 meters per second, and assuming the cube is 1 meter across. We will say [math] t_0 = 0 [/math] is the time at which the orange portal makes contact with the cube. We can comfortably say that the time at which half of the cube (0.5 meters) has crossed the plane of the orange portal is [eqn] t_half = 0.5 m / 10 (m/s) = 0.05 s [/eqn] Now, with the cube exiting the blue portal at 1 meter per second, I challenge you to find how much of the cube has exited the blue portal at [math] t = 0.05 [/math].
>>7867496
The game glitching out and the block stopping the surface isn't A.
The real question is how it would be implemented if you made a working game with moving portals and momentum. For that B is the only reasonable choice because otherwise you'd have glitches where the box went in one portal but didn't come out the other.
This should clear things up
IF the portals work the way I imagine; by bending space, they dont actually work in the scenario. basically portal "halves" moving reative to eachother is impossible
>haven't been on /sci/ since long time
>decide to check out
>see this thread
>119 replies
Hiroshimoot should just nuke this board. You guys never change.
>>7867557
I recognize that the the portal stopping upon contact with the block is not indicative of Valve programming these physics into the game, yes. I was simply commenting on the literal impossibility of scenario A if you try to argue it from any point other than arbitrary math being done by a computer program. If it comes out of the portal at all, it has to come out at the speed it came in.
B would be very easy to implement in a game. Portal 2 at no point accounts for the velocity of a portal. If it instead granted the cube the differential velocity between the cube and the portal it would work exactly like B. getObjectVelolocity(); would simply be replaced with getObjectVelocity() - getPortalVelocity();. However, in the game they went with the former and that results in scenario A, however only performed with the player character and not the cube.
The way the game actually works is that when an object comes into contact with the portal, it duplicates itself behind the other portal, and then the positioning of both objects are synchronized. In early versions of the first game this could be seen when the portal was placed on a thin wall.
>>7867640
You are correct.
Since the block isn't moving, it's a.
A block that perceives itself at rest in its frame can't be moving when it comes out the portal, relative to itself or it would violate galileo relativity.
It's just that simple
>>7867687
Everything is always at rest in its own frame...
>>7867699
not true
are you dumb or something?
>>7867861
Please just stop posting.
a.
Imagine the portal as a hole.
If the output of the portal were on the other side of the input, then it's equivalent to a simple hole. The block certainly would not shoot upward.
It doesn't matter if the hole has an output somewhere other than the other side of its input.
>>7867905
In a "simple hole" the block would exit the same speed it enters, therefore B.
>>7867911
Oh right, since the hole itself is moving. How daft.
Ok, then b is right.
>>7867911
Nice troll.
>>7867944
He's right you know.
>>7863410
A
a portal is like a door. instead of walking through a door to get from A to B. you walk through a portal (door) and get from A to C.
instead of running through a bedroom door, how about the bedroom door is coming towards you quickly. it envelops you and hits the wall behind you stopping abruptly. you are not going to be "propelled". you will remain standing.
probably wrong, but atleast im open to it. some of these B sayers are really trying to get the most out of their intro physics class
what if portals were invented and commercialized, wouldn't it be neat to select a location on some touch pad map, then open your front door to that location?
houses would be completely different. there would just be entire lots of only bathrooms(or any other room). you buy one from the lot and they give you a portal code for your portal at home.
efficient. plumbing problem? plumber goes to one place to fix them all.
im an idiot
How has nobody posted this yet?
>>7868004
>instead of running through a bedroom door, how about the bedroom door is coming towards you quickly.
Those two situations are physically the same.
If you run through into the door at speed X, you also exit at speed X, right? And once you are through, whatever the door does behind you doesn't matter, right?
>>7868025
sure, i was only trying to create an image similar to what the OP image depicts
door envelops me, crashes into wall behind me, do I fly forward relative to the doors velocity? no
>>7863410
people seem to be treating portals like magical objects rather than perspectives
>>7863410
Since you can see through portals before going through, it's space time distortion. A is the answer.
I'm so fucking sick of seeing this thread over the years and the countless fuckwits who claim though "scientific" reasoning that it's B.
IT'S FUCKING A! Portal (as explained in the game) conserve the momentum of the object passing through it.
GlaDOS says it best "Speedy thing goes in, speedy thing comes out"
NOW WITH THAT FUNDAMENTAL UNDERSTANDING OF HOW THEY WORK....The cube is not moving, it is merely sitting still on the platform. THE ONLY THING MOVING IS THE SURFACE WITH THE ORANGE PORTAL, THEREFORE when the orange portal passes over the cube the momentum of the cube [which is 0 because it's not fucking moving] is conserved. With that you get a result that is similar if not matching to A.
Now the rest of you B answering morons need to go back to school.
>>7863410
Just imagine the portal as a big hole that just ends up somewhere else instead of the other side. If you have a hole in the wall and throw something into it, it will leave the other side just as fast, but if you move the hole over top it doesn't move the object, so the velocity from the portal moving isn't conserved.
>>7868134
>>7868105
>>7868004
>>7868105
That's how I originally thought about it too, but problem with that, as noted in >>7867911 >>7867917, is that the other side of the hole is moving.
If the other side of the hole is moving, the object remains stationary. However, if the other side of the hole is not moving (as in the original situation), the block is propelled upward.
>>7868143
literally neither of those 2 posts you quote at the end answer a fucking thing.
People talking about this "other side of the hole" bullshit need to understand that the Orange Portal and the Blue Portal are not like 2 sides of a coin.
>>7868149
Why would the block be propelled? It sticks to the same momentum all along, that is to say 0 m/s. Look at case 2 in the picture. There is no reason for the cube to suddenly jump. Sure, it looks like it's moving while it passes through the portal, but it's actually not moving, its force of momentum is 0.
>>7868164
The cube is never moving, holy shit you dense autist
>>7868162
>>7865391
I don't really see how, in the experience you propose, the ball goes from high speed to rest. Before the ball enters the blue portal, it is going to a speed of X; and after is has passed through it, its speed becomes X+Y, where Y is the speed at which the yellow portal is moving towards the ground. What is there more to explain?
>>7868167
Yes, the cube is moving at 0 m/s. However, if there's a simple hole that is moving down over the cube, the cube is moving up *relative* to that hole (i.e. in the reference frame in which the hole is stationary). The key is that the other side of the hole is moving.
Now, in the original scenario, the other side of the hole is stationary. What does this crucial difference entail?
Think about it.
>>7868168
In the reference frame in which the hole is stationary, the cube is moving up. This is what is meant by "moving up relative to the hole".
Since we're speculating about portals working through space-time distortion, let's talk about how these portals would have to work if they were based on general relativity. Since the portals in game are used in gravitational fields, we can figure out what happens to accelerating portals (the orange portal which comes to a halt) through the equivalence principle.
The left-hand side with the portal accelerating upward is equivalent to having the portal fixed in a large downward gravitational field, with the platform launched upward in freefall so that it comes to a stop when it reaches the portal. In the game, we observe no leakage of gravity through the portals, so once the cube is partway through the portal, the part that's passed through will no longer be subject to the strong gravity that's slowing the platform beneath it down. Thus it will not come to a halt relative to the portal as the platform does, but will fly out of the portal with momentum.
>>7868182
The ball never enters the portal. I'm dangling it over the portal entrance from a string.
>>7868199
Then the ball stays immobile, but the space between the ball and me extends because of the change of position of the yellow portal. That's perfectly coherent with both A and real world physics.
>>7868194
To complete this: >>7868199
Incidentally, that's exactly why some celestial objets, in the real world, APPEAR to be moving at higher speeds that light (for example, the edge of the observable universe is more than 90 billion light-years away, while the universe is only 13,7 billion years old; the stars are not actually moving quicker than light, the space between them and us is just expanding)
(>>7868188)
In particular, note the following:
In the case where the hole is on the other side, the hole suddenly decelerates to 0 m/s at the last second. So the cube accelerates to the original speed of the hole *relative* to that (decelerating) reference frame.
If the other side of the hole were stationary, the cube still accelerates relative to it at the last second. Since the other side of the hole is now stationary, the cube suddenly accelerates to the original speed of the other side of the hole in our reference frame.
This is for what >>7868105 fails to account.
>>7868217
>>7868188
Shit, I erased my post by mistake. Well, at least you had the time to read it.
>>7868217
>>7868220
What exactly do you mean by "the hole is on the other side"? On the other side of what? As I understand the situation, there sure are two sides, but that's the hole that is separating them, so I don't see how the hole could change side (it's not on any side, or it is on both at the same time).
>>7868210
>stays immobile
Are you even paying attention? You are beneath the orange portal, so from your perspective, the ball starts out with downward motion from your perspective, then comes to a halt from your perspective.
It is not consistent with A and cannot be. Since the ball is on the same side of the portal as the cube, any effect you use to explain what happens to the ball must also apply to the cube.
If you want to go into what GR would say about all this, see >>7868194.
>>7868248
To make it even clearer, we can imagine that the guy on the blue side gives the string a tug to match the velocity of the block as it's coming out. From a person on the yellow side's perspective, the ball would be fixed before the portal came to a halt, and moving upward afterwards. They can easily explain this effect as being the result of whatever the portal does to the spacetime between them and the ball, but this effect should also apply to the cube.
>>7868228
I think that's a very good point, and that it furthermore illuminates a paradox for why the situation presented in OP is literally a physical impossibility.
Do the following thought experiment: it's like OP, except the cube is somehow suspended in the air, and the portal keeps moving down at, say, 5 m/s even after it passes over the cube.
Then in the situation of the simple hole, the cube does not "plop" on the other side: it moves upward at 5 m/s relative to the hole. Thus, in OP's situation where the other side of the hole is by contrast stationary, the cube shoots upward at the velocity of 5 m/s.
Now, the movement of the portal after it passes over the cube should not affect the cube. However, if the portal suddenly stops immediately after passing over the cube, then the cube "plops" on the other side.
Therefore acceleration of deceleration of the portal even after it passes over an object A continues to affect the acceleration of A, which seems a contradiction unless the portal somehow permanently entangles with anything that passes through it.
>>7863410
Portals aren't real.
So, none.
>>7866384
Smartest person in the thread.
It depends whether energy is conserved or not which in-turn depends on the properties of the portals.
>>7868285
Energy of objects moving through portals is not conserved. This is inarguable since you can do infinitely falling blocks in the game. Whether the energy change in the object is compensated by an energy change somewhere else is the only question, but it's not relevant to how objects passing through the portal behave.
>>7868282
Brainlet detected. If portals aren't real, then both. This is known as vacuous truth.
>>7868290
Fair enough. So it would then be B?
If you're having trouble understanding why it's B, imagine standing there looking into the blue portal. What do you see?
You see a piston with a cube on it speeding towards you, at speed V. When the cube is passed fully through the portal (still moving at speed V), THEN the piston stops. But the cube does not, because why would it? It's already moving and it's already through the portal, so the portal doesn't even matter anymore. It is literally just a Newton's First Law problem that you might see on the first day of freshman physics.
B
B
B
B
>>7863410
wasnt this fucking answered.
guy made test level, cube didnt work so he put himself there and jumped. and boom, the only movement was from the fucking jump
A
jesus
>>7868309
perspective changing
A
A
A
A
>>7868303
All it means is that the argument that B is wrong because it doesn't conserve energy is invalid.
But I would say B. People who get A get it because they think the cube should not accelerate as seen by someone on the orange side, and people who get B get it because they think the cube should not accelerate as seen by someone on the blue side. Since these principles can't both be true at once, we need a rule to decide which applies, and the most obvious rule is that objects without a force acting on them don't accelerate relative to observers on the same side of the portal.
>>7864731
>/sci is literally just a board full of outcast 12 year olds
And here you are, shitposting on a board full of 12 year olds. Your parents must be proud.
>>7863410
so if its B, at what point frame by frame does the cube start to move?
when the portal is halfway down the cube?
when it starts to move, isnt that an increase in velocity relative to the portal? wouldn't it start moving even faster now? exponentially every frame?
>>7868335
As seen from the blue side, the cube has always been moving.
>>7868310
I don't think we can take that behavior as canon due to how glitchy it was. If they make a Portal 3 including moving portals that you can interact with, they would certainly have to make code changes.
>>7863410
Unless the portal can create energy from nothing, it is A.
Alternatively, objects would have to resist entering the portal with force equivalent to their acceleration on the other side.
>>7868355
https://www.youtube.com/watch?v=P_bTsdmjgvs
>>7868324
Its not just the cube that is seen to accelerate, its the whole universe that would seem to accelerate, looking from the blue portal.
If you could see the blue portal and the cube, you would know that this isn't the case, the only conclusion you could make is that the orange portal is moving, and would expect a to be the outcome.
Since its not given you can actually see the cube, and since your observation doesn't effect the physics of the world, the only conclusion is that a is the result
Someone should post this on /lit/ and see what they come up with, since they are the smartest board on 4chan.
>>7863410
Imaging the opposite:
The descending portal slowly a approaches and eventually makes contact with cube. The cube breaches the other side at the exact rate it's being absorbed.
Now imagine halfway down the absorbing portal slams down. Will the cube accelerate and suddenly gain a velocity? No, the cube will just fully manifest itself faster than it was moments earlier.
However If you swith the moving parts of this puzzle and to drop the cube into the portal, 'b' is more than likely going to happen.
>>7868665
>the whole universe that would seem to accelerate, looking from the blue portal.
The whole universe on the opposite side of the portal is seen to accelerate. The cube is on the near side of the portal and should not be seen to accelerate. If you think otherwise, then please state your proposed rule for predicting the motion of the cube.
>>7868665
Also please remember that if you're looking from the orange side, you also see the whole universe on the opposite side seem to accelerate. So if you think the cube ought not to accelerate from the orange side's perspective, you need to explain why that's a valid assumption when everything else in the universe on the opposite side of the portal with the cube accelerates.
None of these arguments depend on whether you're looking at the cube. When we talk about observers, that's just shorthand for reference frames.
>>7863410
The actual answer is neither, since stationary objects cannot enter a portal:
https://youtu.be/S85nudR6D-Y?t=88
The question however is how is "stationary" defined - stationary relative to what?
>>7868839
>>7868848
I look into the orange portal, see everything moving towards me at speed of orange portal
I look into blue portal and see everything move towards me with the speed of the orange portal
I think we can agree on this.
My point was, what happens if I see myself looking at the orange portal through the blue portal or vice versa?
I would perceive that there is no motion occuring.
It doesn't matter if I actually see it or not, because as you pointed out, frame of reference is the only thing that matters.
Therefore, the block isn't moving no matter how you look at it, and the answer is a
>>7868915
>the block isn't moving no matter how you look at it
So the block here is passing out of the portal and at the same time has no velocity? This is what I'm hung up on.
>>7868915
>Therefore, the block isn't moving no matter how you look at it, and the answer is a
it's moving in all but a select few inertial reference frames desu
>>7868915
>I look into the orange portal, see everything moving towards me at speed of orange portal
>I look into blue portal and see everything move towards me with the speed of the orange portal
Before the portal comes to a halt, yes.
>My point was, what happens if I see myself looking at the orange portal through the blue portal or vice versa?
Sorry, this isn't very coherent. But if you meant that your line of sight goes down through the blue portal, out the orange portal, and then back to yourself, you would perceive the self you see as moving toward yourself, at least until the portal halts. That's not particularly relevant, though.
>the block isn't moving no matter how you look at it
False. Before the portal halts, the block is moving up and to the right from the point of view of someone on the blue side, and stationary from the orange PoV. After the portal halts, assuming its velocity in the blue PoV remains constant, it begins to move upward in the orange PoV.
Portals are whackadoodle bullshit.
Death to this thread.
>>7868974
So you agree that in all frames considered, everything is moving at the same speed.
Since that's the case, the whole system shares the same frame. I.e, there's no motion so it's a.
From the orange pov, the block is also moving up and to the right. You forgot that part
>>7869110
>So you agree that in all frames considered, everything is moving at the same speed.
No. That's obvious nonsense.
>From the orange pov, the block is also moving up and to the right.
Wrong.
>>7863410
In my opinion you would have to know the structural assembly of space itself and the mechanics of said assembly to really know what would happen when you reorganize it.
That said, it likely takes a very large amount of energy to reassemble space (even if its just cutting holes in it and patching them together). I think choice B is possible because the cube could draw energy from this reassembly process.
A better question is what happens when you force both a blue and its orange portal onto the same object from both sides.
In that case it is very likely that the machine reassembling space would have a tremendous (probably insurmountable) energy cost as it melts and compresses the object in an every decreasing volume of space. Much (probably most) of the superheated material would eject outward before the union of the portals is complete. If an atomic object (a photon, for instance) were to get trapped between them, thats where it gets really interesting, I'm sure.
blah blah blah jet fuel cant melt steel beems ay la mao im retard i know i know i just remembered this is /sci/ and some braniac will argue with anthing i say
>>7868344
that would be an illusion though.
>>7868335
each atomic layer would enter the cube one after another. each new layer that exits the blue one would have to push the other bit of the cube forward.
that would also mean that, say the cube is half in, it's half affected by gravity towards the platform and half effected by gravity towards the B-side floor without the normal force of the plattform however.
half of it would be moving out, while the other half would still be stationary on the plattform.
how would that even work? would the cube be distorted?
u could do fucking research on that if it wasn't a theoretical thought experiment.
>>7863410
You fuckers arent thinking in portals.
>>7869946
The part where the portal stops only exists to trick you. It cannot make a difference because it happens after the object is already through.
>>7869123
>agrees with me
>says it's nonsense
Please leave
>>7870056
What you said was nonsense, and no one has agreed with it except in your own mind.
The portal, the model. We do like up to your past, but never as effervescently. Do you not to up the box because over what? Put another way, to up the B on the edge of the manifold, we see that the rift of the portal be over like a baroque aperture.
Therefore, it's clearly option A. Over the end of the debate we have obtained. No more...
>>7870107
Take your pills, m'lady.
>>7863410
This is fucking easy when you think about what the observer on the blue end sees as the box is only halfway through the portal
It's moving at a high speed and will continue to do so when it's fully through the portal because physics
>>7870116
Its not that simple, because the physics should work out the same in all frames and it apparently doesn't
>>7870214
It IS that simple. There is nothing inconsistent there. If you think there is, you've misunderstood something important.
>>7870229
Please explain why then.
In all frames, everything is moving at the same speed. Prove me wrong
>>7870237
>In all frames, everything is moving at the same speed.
That's a nonsense sentence.
>>7870237
>In all frames, everything is moving at the same speed. Prove me wrong
The orange portal is moving downward in the rest frame of the platform beneath it. The platform is not moving in its own rest frame. Therefore the statement is false, and pretty fucking stupid.
Since movement is relative we can say that the orange portal and its platform stay still while everything else moves upwards.
Let's examine what happens with an object made up of two particles. Once a particle touches a portal it gets instantly teleported in front of the other portal, so a particle cannot be half in front of the orange portal and half in front of the blue portal. The first particle passes through the portal and maintains its absolute speed but changes its direction (we assume that the portal doesn't increase the speed of the particle).
When the second particle touches the orange portal the blue portal is now higher and the first particle traveled at the same speed diagonally so it did not advance vertically as much as much as the blue portal did. Hence the second particle is be higher than the first one, skewing the object.
Of course you can interpret things differently and get a different results, this is because portals get nonsensical when they move relative to each other.
>>7870281
I've been here the whole time; all you've been doing is posting non sequiturs which devolved to you repeating that nonsense line.
Do you have brain damage or something?
And it's not like you need context to know what you said is wrong, just an understanding of what basic words involving motion mean.
>>7870303
If nothing happens with a hula hoop, why would anything happen with a portal.
That's been my argument the whole time. I've staTed it in different ways because there seems to be some assumption that portals are magically different
the cube is 1 unit long
it would exit the blue portal at a rate of x units per second
it would thus have a velocity of x units per second out of the portal
it's b
>>7870790
you said the other side of the hole was moving.
what does that mean? that the blue portal is moving from the orange portal's frame of rest?
even if it was, it still wouldn't move the block unless you consider the force created when the two platforms smack each other.
>>7871861
The other side of the hole is moving in the case of the hula hoop. The other side of the hole is not moving in this problem.
