/sci/ - Science & Math

>>9685840
A. Portals conserve momentum of objects. Not the momentum of portals themselves.

>>9685840
Imagine the side of a house falling on Buster Keaton. All that happens is that he passes through the window. In this case once through the window he'd experience a different direction for gravitational pull. The house falling on him didn't transfer any momentum.
https://youtu.be/FN2SKWSOdGM?t=38

>>9685843
I mean, if you think about it as the momentum of the room around the box in relation to the box itself...

>>9685843
>>9685848
yeah I'm going with A too

>>9685843
Are you out of your mind? The particles in the box are emerging out of the blue portal at the speed of the yellow portal and the particles already there will just go "meh, I don't wanna go fast".

>>9685840
This thought experiment only serves to justify

>C. Portals can never experience relative motion

>>9685855
While the momentum of the steel might slam down on the platform and this create a "bounce" due to kinetic energy the momentum is lost for the entire oval that is the portal. Plus or minus a little bit of air pressure from the wind tunnel created by its falling.

>>9685868
This assumes the M.O of portals is to fuse with an eternally thin layer of existing matter and can't be pushed by a wall of matter. This layer would have to be so thin it was extra-dimensional in nature.

>>9685843
But this would imply that at half push and full momentum you could split someone in half.

>>9685878
Shit sorry. Meant for >>9685866

>>9685878
If you stopped halfway yeah, the particles already in motion would pull on the particles still at the other portal, maybe splitting them if the speed is high enough.

>>9685882
>The particals are already in motion.
There are no particals in motion. Portals act like holes. I am sure you could make a type of portal that does what you want. However these have been proven to merely conserve energy and phase it through itself. Portals are literally empty. Somehow.

>>9685840
either because portals don't conserve momentum

>>9685840
B, there's nothing stopping the box from continuing its motion after it emerges from the exit portal.

>>9685887
So the box just melts? If it stays rigid the particles would push on each other... even if it melted it would still get pushed through, the energy would just disperse more easily.

>>9685898
What does this even mean, so all the material that enters a portal gets smeared onto the portal like the event horizon of a black hole? There is no momentum conservation so how would anything get through?

>>9685902
From the blue portal frame, the blue portal is moving the same speed as the cube relative to the orange.

So it's a.

>>9686329
>From the blue portal frame, the blue portal is moving
what does that mean, you don't move in your own frame of reference, that's the whole point of it

>>9685843
>portals conserve momentum

>>9685840
B obviously. Use simple relativity and you will find it
is this board just for brainlets and high school drop outs?

>>9686403
People who think it's A are the same type of people who just memorize formulas and have zero intuitive understanding of anything.

>>9685840
It's B.

The box is moving inside orange at a speed equal to the movement of the hydraulic press.

Every now and then I post this on /v/ and spend the life of the thread arguing both sides of the argument with literally anybody who tries to give a definite answer for either, it's good fun

>>9686406
>>9686403
>>9686419
Those. /thread

>>9685840
https://link.springer.com/article/10.1007%2FBF02186206
the end of this paper has some part about
>TWITS looming on the horizon
that reminded me of twitter

I am appropriately sun burned today, but I wonder if they used the sunburn laser through the window :/

>>9685840
forgot pic

>>9686346
Yep. Therefore the speed of the cube relative to the blue portal is 0.

Just because you look through the blue portal and see the cube moving, doesn't mean the cube is moving relative to the blue.

>>9686484
sometimes they say you have to use an astrological alignment as a reference, which is a bit of geometric weirdness. This paper is really good about the relevant principles.
>https://link.springer.com/article/10.1007%2FBF02186206

>>9686484
the cube has to be moving to go through the portal, though. why shouldn't that motion continue?

>>9686472
>>9686474
>>9686488
what are you on about?

>>9685867
Well, you say that...

https://www.youtube.com/watch?v=mCQiwhik8nc

>>9686488
I wouldn't put too much stock in that paper. They ignore the fact that time is relative to the frame you're in. The math is ok, but the conclusion isnt.

Anyways, point is that from a 3rd frame, the blue and the cube are moving relative to the orange. Therefore, in every frame, the cube has 0 velocity relative to the blue.

>>9685898
Speedy thing goes in, Speedy thing comes out.

Is this some sort of elaborate troll? If the cube has no speed relative to the blue portal it would just get smeared across the portal because the instant it hits it, all the particles would stop.

>>9686502
A *portion* of the cube has 0 velocity in relation to the blue portal, the rest is moving in relation to it. And also, those parts are moving in relation to one another.

>>9686494
>what are you on about?
Newton's claim about there existing no absolute inertial frame. It leads to something called Mach's principle about the ultimate nature of reaction forces that would decide the outcome of OP's portal question. Therefore, OP should include the heavenly background in the specification of the initial condition. This paper "KILLING TIME" is really good, and relevant.
>https://link.springer.com/article/10.1007%2FBF02186206

>>9686502
>They ignore the fact that time is relative to the frame you're in
paper is about Mach's principle not being completely respected in general relativity even though it was problem in classical mechanics that predated relativity.

My personal view is that Mach's principle can be accounted for by using the momentum 4-vector of the whole universe to determine one special frame where the paradoxes alleviate. My book is kind of about that.

The General Relevance of the Modified Cosmological Model
MIRROR 1: http://vixra.org/abs/1712.0598
MIRROR 2: http://2occatl.net/1712.0598v2.pdf
MIRROR 3: https://drive.google.com/file/d/1sXrFZhMo9OjoauL0SgAvpSxD_8qaAYi0/view?usp=sharing

>>9686484
>Therefore the speed of the cube relative to the blue portal is 0.

The top face of the cube, the first bit to erncounter the orange portal. is at the blue portal right as the orange portal gets to it. A short interval of time later, it is one cube-width away from the blue portal. From the blue frame of reference, it is moving. From the orange, of course, it is not. Hence all the retardedness that is made possible by OP's post, and why the developers made it a "rule" that portals cannot move relative to each other, except twice in Portal 2 -- once in the link posted just above, and once when one is placed on the fucking Moon.

>>9686532
>the link posted just above,
wound up further above than I had anticipated.

>>9686499

>>9686531
aha, okay that seems interesting! but I won't believe it until I read it

>>9686528
Can you explain? I don't understand how part of the cube behaves differently from the rest of it

>>9685840
Imagine a large portal is racing towards you and you come out the other portal flying through the air. Makes no sense

>>9686626
Because it's silly made-up physics that doesn't real.

>>9686803
>Imagine a large portal is racing towards you Makes no sense

Simplified that for you.

>>9686813
You make no sense

>>9686814
you sense no make
me fuk fuk, ooga ooga

>>9686813

>>9686403
>>9686406
But momentum dude, the box has like, no momentum man

>>9686886
depends on your reference frame.
when falling to the earth you have no momentum because the earth is moving up towards you
change your reference frame to the portal and the box has momentum

>>9686403
everyone knows its b they are pretending to be retards

Imagine the same experiment but imagine the cube is sliced horizontally into a stack of very thin squares.

>>9686540
Hes a schizo.

Portals don't exist.

>>9685840
B

The frame of reference of the blue portal is what matters and from that perspective the press rushes up and propels the box through the portal

>>9685843
Then if we put portal in outer space or other planet you are going to fly with 400000km/h or whatever the speed of Earth is supposed to be

>>9685840
Depends on the plate "t" and the plate "s", if they are the exact same size, and the portals with exact place, the result is A

just imagine a plate wih a hole in it

if they are of diffrent sizes that's another shit to study

t.a genius

No one ITT has actually played the fucking game, it seems
Portals disappear if the surface they're placed on starts moving, so the whole question is pointless because portals don't work like that

>>9688901
Obviously in the experiment the entire room is moving except the portal. (which would be the same)

>>9685840
>>9685843

B, assuming the block is not teleported instantly as soon as it touches the portal, the top layer of atoms is going trough the portal first

This might not have momentum if portals conserve momentum but it will immediately gain momentum as soon as more of the block is pushed against it from the portal below

So the entire block (except the bottom layer of atoms) will gain the momentum of the portal slammed onto the block which will be more than enough the pull the bottom layer of atoms on the block with it, launching it into the air.

>>9688914
It would require one of the portals to have a different velocity than the other in any case.
There's a few parts in the game where that happens, like sabotaging the neurotoxin.
Regardless, this is a physics based thought experiment, not a real testable experiment for the game.

Won't the two plates hit each other and stop moving anyway, resulting in A.

>>9685840
neither because portals cant exist
if your werent a brainlet you would think about it for a few seconds and see how dumb the question is

>>9685848
Wow good analogy, this made it click for me anon.

So the general consensus is B, because from the perspective of the orange portal the block has momentum?

>>9690298
From the perspective of the blue portal the cube has momentum as it comes through.

In the first instance, the block is immobile (according to an immobile outside observer)(that's you)

In the B instance, the block has magically attained speed.

It's A you fucking idiots.

>>9690777
Portals are already magic to begin with

Jesus, this /v/eddit trash really shows howany newfags and underage retards we have. Consider a case where there is nothing to stop the orange portal, for example, suppose that the portal moves continuously to the left and the cube is there. If B is true that would mean that there is also no conservation of momentum, as the portal keeps moving and the net gain is that the block gains momentum. If A is true then the principle of relativite is wrong. So either one is incompatible with physics no matter how much you popsci loving redditors argue.

>>9690298
The general consensus is A because /sci/ is filled with brainlets.

>>9690794
>If B is true that would mean that there is also no conservation of momentum, as the portal keeps moving and the net gain is that the block gains momentum
Wrong. If you stand in front of the blue portal you'll see the block rushing up to meet the portal. From your perspective the block DOES have momentum. That's relativity. Frame of reference matters and from the frame of reference outside the portal what you see is the block being pushed to the portal and through it by a piston.

>>9690799
Yes you fuckig retatd but an observer outside watching both sees that the portal and the blocl keep moving.

>>9685840 why has no one tried this shit out in portal yet?

>>9690804
https://www.youtube.com/watch?v=JHe-iU63nmE

>>9685840
A

>>9686898
>when falling to earth you have no momentum
Can you explain this to me or this just a retarded shitpost?

>>9685840
If it was B, the block wouldn't remain intact because it doesn't all go through at once.

Think about it: what would happen if you made the portal move fast and then stop when it was halfway over the block? Would the block just he sucked up inside of it?

>>9692252
>what would happen if you made the portal move fast and then stop when it was halfway over the block? Would the block just he sucked up inside of it?
Yes.

>>9692287
Bullshit.

All right, imagine this: you're in a hurry to catch a train, but you get up to the platform just in time to see it pull out of the station. But, luckily for you, there's a portal on a nearby wall, and, looking through, you can determine that its counterpart was placed on the wall inside one of the wagons of the train that just left. What happens if you step through?

>A) You break your legs and hurtle down the aisle because you just stepped onto a speeding train
>B) You casually stroll onto the train as if walking into another room, or as if you were already on the train and moving from wagon to wagon.

I think you'll find your answer to this question must be the same as to the OP's

>>9692463
Trick question! Due to the quantum link the very act of motion is made trivial due to the way portals transfer momentum. The act of entering a portal in motion will immediatly bring any item placed inside up to speed since it too is moving, however this motion is not discernable to outside observers due to the frequency of the forces at work. Similar to how helicopter blades are not visible in certain places to the naked eye when in motion.

>>9692497

>>9692453
Just because you don't like the result doesn't mean it's bullshit. Like how you can lift a magnet with a piece of copper if you move fast enough.

>>9692509
Lifting a magnet with a piece of copper if you move it fast enough doesn't break one of the most fundamental laws of physics.

>>9692556
Portals break the fundamental laws of physics by merely existing, B is what prevents them from being broken even more

>>9692558
It breaks conservation of energy just by existing, but that doesn't mean it should also break conservation of momentum.

>>9692562
Right, which is why the cube, after moving through the portal, keeps moving.

>>9686231
>thing enters the portal going in the x direction in a frame of reference
>thing enters the other portal in the y direction in the SAME frame of reference

linear momentum isn't conserved. the real laws of physics don't apply to these portals. That means anything can happen.

>>9692574
It doesn't move through the cube. The cube doesn't move until it's through the portal and gravity acts on it.

Take a keyring and slide it over something without touching the thing. The thing it passes over doesn't move. That's what's happening here.

>>9692583
>The cube doesn't move until it's through the portal
That's a contradiction.
>That's what's happening here.
It obviously isn't because you can't move one side of the ring without moving the other.

/v/ is making fun of us again guys

>>>/v/414162574
OP being a faggot as usual

A
if you drop a hoola hoop on yourself, you dont fucking fly. you look like a dipshit retard instead

>>9685840

To anynone feeling confident about either of the answers, consider the following variations and check if your reasoning still holds.
>1. The cube is attached to the platform
>2. The orange portal platform is moving at slow speed.
>3. The final position of the orange portal platform is half a cube's length above the other platform (i.e. only half of the cube goes through the portal)

b.
the reason is simple.
think of it like this, for it to transfer from one part to the next, the part on the other side of the portal must push the next part out. now given that we now know that the parts push on each other to transfer from point a to b, we can conclude that the faster they are forced to push on each other, the higher the speed it leaves at will be.

if they did not push on each other than the matter would just pile up on itself out of the entrance of the second portal, which is impossible.

The portal isn't a object, its just a shortcut in spacetime. Instead of being squished the box takes a shortcut in spacetime instead.
The portal doesn't move, the piston or whatever moves, so the box never gains any momentum and will go with a.

>>9693711
B

>1. The cube is attached to the platform
Assuming the platform and connection is solid and attached to the ground, the acceleration experienced by the cube upwards from the starting reference frame is unlikely to break the connection

>2. The orange portal platform is moving at slow speed.
The cube will have a lower final speed in reference to the orange entrance

>3. The final position of the orange portal platform is half a cube's length above the other platform (i.e. only half of the cube goes through the portal)
Only half of the cube will experience the acceleration when the portal stops, having to accelerate the lower "stationary" half with its existing velocity, so the speed will be halved

>>9688364
>just imagine a plate wih a hole in it
two sides of a hole don't have different relative velocities or rotations

>>9693685
You leave the hoop interface with the same momentum relative to its exit as you entered with relative to its entrance. The same is true for portals, except now it's possible for the entrance and exit to be in relative motion, which is why portals and hula hoops aren't the same fucking thing.

>>9690799
>From your perspective the block DOES have momentum.
But that perception is flawed. Because it would be more accurate to say that you would be the one falling towards the block. And if you fell on the block it wouldn't all of a sudden start flying. Even with relativity.

>>9693737
This. The "hula hoop" meme is the most brainlet argument ever.

Here's another thought experiment - instead of a cube, imagine a 100m tall pillar and you standing on top of it. The orange portal falls down onto you and the pillar. Do you expect to suddenly stop moving once the orange portal reaches the bottom of the pillar?

If the block doesn't have momentum in the reference frame of someone on the blue side, then it also doesn't have any kinetic energy.

As such, I ask: what happens if I put my hand right in front of the portal as the cube is rapidly emerging? Will it hurt? With "no" kinetic energy, it shouldn't be able to collide, let alone injure me, but I just put myself in the path of a heavy metal object. Does pass through me? Does it just stop without an impact, and if so, what happens to the kinetic energy of the falling platform on the other side? If it does have the kinetic energy to cause an impact, where does it magically vanish to a second later?

>>9693742
>it would be more accurate to say that you would be the one falling towards the block
Only from the perspective of the block, but that perception is no less flawed. Unless, of course, you were to step through the portal before it reaches the cube. Then you will immediately find yourself falling at the speed of the piston. If you did not (because muh momentum) then you'd get trapped "between" the portals, which isn't actually a thing.

>>9693750
Yes. Furthermore, let's say the pillar is one kilometers tall, so that the orange portal takes a while to reach the bottom of the pillar (at 10 m/s speed, 100 seconds). In this time, I jump off the pillar and brake using air resistance and friction. I then stand still and wait for the pillar to finish emerging.

When the orange portal hits the ground the pillar is standing on and stops moving, the pillar also stops moving. In other words, its velocity changes by 10m/s in the direction of the blue portal's tangent vector. Because I also came through the same portal system, the same change of velocity is applied to me. I get smashed diagonally into the ground at 10 m/s, and badly injured.

>>>/v/414164106

is this the first time /sci/ gets baited with this meme?

>>9693770
> Then you will immediately find yourself falling at the speed of the piston. If you did not (because muh momentum) then you'd get trapped "between" the portals, which isn't actually a thing.

This conclusion is even more obvious if you consider only sticking an arm through. I'm stationary on my side of the portal, but my arm on the other side is falling with the portal platform - stationary in the portal's frame of reference, just as I'm stationary in my side of the portal's frame of reference, but still clearly about to break my wrist when it hits the platform.

>>9693786
>Because I also came through the same portal system, the same change of velocity is applied to me.
No, that makes no sense. You're not somehow magically connected to the portal just because you came through it.

>>9690871
Just piping in to say he answered your question already in his post, but you don't understand the concepts in question (Frame of reference) or you wouldn't have asked that question in the first place.

>>9686422
The fuck is that?

>>9693853
a 5 dimensional rubiks cube

this should help you visualize the problem better and make a decision

>>9688308
Too bad nobody ever put a portal on another planet

Imagine that the blue portal is placed on the top of the moving platform (with the orange portal on the bottom). Which is equivalent to just having a hole in the platform.

>>9694008
what does this have to do with the original scenario?

>>9694020
does it make a difference whether the blue portal is on top of the orange or to the side?

>>9694018
You changed it, motherfucker

>>9694024
obviously

>>9694024
Yes, because when it's to the side the portals are moving relative to each other.

>>9694024
What makes a difference is how the portals move relative to each other.

>>9694024
imagine that you're standing next to the blue portal in >>9694008 , the moment the platform stops you'd get pushed down because of your momentum. this wouldn't happen in the original scenario.

>>9688901
You need to use moving portals in portal 2 to complete the game, though.

>>9686499
They tell you in the commentary that those portals aren't the same ones used in the game. They are a glorified cutscene.

instead of the portal approaching the box imagine the box approaching the portal at the same rate. If your answer changes, you're wrong.

>>9685840
It's a relative paradox. From the box's frame of reference, it has no momentum. From the blue portal's frame of reference, the box and the entire universe around it has momentum.

>>9694142
Okay? That's about the details of the game's programming - moving portals are complicated so when they were needed for a setpiece, they were hacked in rather than created as a fully-integrated system. In the game's universe as opposed to its code, however, a portal is a portal and portals are perfectly capable of being in relative motion.

>>9685843
The box has momentum relative to the portal though.

>>9693871
give up already, A-fags are mostly bait and irredeemable brainlets with no intuition for physics

Do people really think it's B?

>>9685866
>hoola hoop analogies your argument

>>9685843
Momentum is a vector, and by going through a portal in any direction other than forward you change your momentum vector's direction. Saying portals conserve momentum is naive and wrong. The momentum's direction changes within regular setups, and this question at hand is a good example for when momentum's size gets changed by passing through a portal.

>>9685848
>>9685858
>>9693700
>>any hoola hoop Afag
This analogy is flawed, as looking through the window/hoop you see a static world. The exit side moves at the same speed as the entrance side, which means they both move as one. The portals in question move differently from one another. If you stand in the cube's position and look at the world through the orange portal, you would see the world through the blue portal, meaning a room that is "glued" to the moving platform. While the room is stationary relative to the moving platform, it's not stationary relative to you. When you (or a box) emerge through the blue portal, you'll see the room rushing towards you at the speed of the orange portal, and since you get measured/observed from within the room, you are the one rushing out of the portal.

Relativity is the key, and B is the correct answer.

>>9694243
>Relativity is the key
Relativity is meaningless when it comes to portals which is why B is impossible.

>>9694008
it would still come out moving relative to the exit, Afag

>>9694252
portals are impossible too, nigger

>>9694252
Relativity is everything when it comes to portals. Your exiting of the portals is exactly how it looks to you when you look through the portals' joined surface. Say you face north in a room where you have two portals on the same wall facing south. There's a compass rose drawn on the floor in front of the blue portal as you are looking into the orange portal, and one drawn under your feet. You look down, you are facing north. You look into the orange portal and through the blue portal you see you're facing south. You step through the portals and you are now facing south.
You exit a portal based on how it looks like when you look into the portal. If you look through the portal and see you're facing south, you'll exit facing south. If you look through the portal and see a room rushing towards you, you'll exit the portals with the room rushing at you, i.e you moving at high velocity.
Relativity comes into play by the exit's space relative to the entering object.

>>9685840
The answer is neither. Its the average of both

>>9685840
Can’t someone just fucking try this in Garry’s mod?

>>9694300
gmod doesn't natively support portal physics, besides the Portal games' engine doesn't natively support moving portals
any in-game or in-engine test would have to occur in modded environments and couldn't really be taken as proof

>>9694235
/thread

>>9694300

>>9694346
nice

>>9694346
Yes, but what about real life?

>>9694275
relativity doesn't apply to this case because there is no consistency between reference frames.
linear momentum isn't conserved in this situation

>>9685840
Since we're no longer dealing with euclidean space I'm going to assume classical mechanics no longer applies, but according to classical mechanics the answer is going to be B.

>>9685843
momentum is relative.

>>9694386
way to contradict yourself, buddy

>>9685843
This.
You're not getting sucked into the portal, it's not an event horizon you dumb niggers.

>>9694393
what do you mean, partner?

>>9694235
it's long so it's correct

>>9694329
but portal 2 has moving portals....

>>9694400
>classical mechanics no longer applies, but according to classical mechanics...

you're right in that classical mechanics doesn't apply. appealing to it for your supposition is completely fallacious

>>9694421
Neither answer is correct I just stated which one would probably be correct in-game, or in a world where portals still mean classical mechanics is correct.

>>9694427
>or in a world where portals still mean classical mechanics is correct.
this is completely nonsensical.
a trivial inspection shows that linear momentum isn't conserved, so classical mechanics cannot be correct.

have you even taken a mechanics course?

>>9685843
Don't listen to them anon. Per the game Portal itself, momentum is conserved. There is no other force acting on the object and we do not know how portals work other than the new data and information given by the game. Therefore it must be A.

>>9694443
wrong

>>9694409
true, but only in a controlled environment where the portals aren't interactable and there are no physics objects going through them, since they weren't coded to handle those situations

>>9685840
Coming from being a classically trained musician to a physicist i find these discussions particularly amusing.
In music I noticed most musicians who over estimate their talent and greatness would 'musically masturbate' by playing annoying things that never seemed to go anywhere but just harped on odeas that they were especially prideful of, or which they believed showcased their talent. In reality the trained ear wanted them to shut up because their playing was annoying and not as good and creative as they thought.

In this thread we see physicists masturbating by arguing about the semantics of things which only even exist in their imagination. This isn't science, it is science fiction, and I bet my year's salary that not one of you seriously discussing the semantics of 'portals' would name the jew - your fantastical extrapolations are based on his fallacies.

Good day

>>9694438
What's wrong? I said classical mechanics don't apply, but it makes much more sense for the difference of velocity of the two portals to be transferred to the cube in-game intuitively, as that would seem "correct" from the view of the cube.

just mailed an emergency notice to the /sci/ jannies about a particularly terrible post

>>9694464
just mailed my fist to your face

>>9694463
velocity has direction. no reference frame you pick has the velocity of the portals and cube as consistent. as soon as the cube enters one portal and exits the other, a universal change in velocity takes place.

that is to say, it doesn't move in the same direction for any [math] \frac{d}{dt} [/math] any reference frame during time the cube is in the portals, or for any time before and after the cube is in the portals

>>9690809
there you go guys problem solved

>>9694476
i'm waiting in anticipation

>>9694477
From the frame of reference of the cube the velocity stays the same through portals. I should've said speed though

>>9694494
No it doesn't. it goes from 0 relative to portal B, to in the +y-z direction, or it goes from the +z direction relative to portal A to the +z direction and simultaneously the +z-y direction, where z is up, and y is to the right

>>9694505
The portal is moving closer and closer towards the top of the cube. Let's call this face the front face.

According to B, the cube is now launched in the direction of the front face. The portal has gone from moving in front of the front face, to behind. Intuitively this makes the most sense. Relative to the cube, the portals maintain constant velocity; relative to the portals, the cube has passed through a 'hoop'.

>>9694520
that frame of reference is discontinuous

>>9685840
Since the cube is stationary, when the portal comes down, no matter the speed, the cube will also appear stationary on the other portal. Since the cube dosn't experience any change in pressure and momentum (assuming it all happens in an instant and negatng the fact that the platform would shake), it is not able to be catapulted away. The only relevant force here would be the gravitational force pulling the cube down (neglecting frictional force) after it appears on the other side, which is why answer A is correct.

>>9694458
>muh juice

>>9694535
>falling for such obvious bait

What Bfags don't realize is that the portal doesn't teleport. It's just a hole.

>>9694542
>falling for my pretending to fall for bait bait

>>9694546
>green texting your current situation to me

>>9694545
No, that's exactly what makes B work

>>9694531
but the cube isn't stationary when its emerging from the blue portal. if it was stationary, it wouldn't need to change its velocity once its on the other side.

>>9694569
IT'S A FUCKING HOLE YOU RETARD. NOTHING SPECIAL EXPECT FOR THE FACT THAT IT RIPS TROUGH SPACE. THERE IS NOTHING FILLING OUT THE HOLE. IF I LET A HULLA HOOP FALL ON YOU YOU DON'T GET LAUNCHED AWAY.
ITS
JUST
A
HOLE

>>9694580

>>9694588
I don't see an argument there. Try and refute the hulla hoop theory

>>9694554
>he fell for it again

>>9694598
it's a discontinuous coordinate transformation that doesn't conserve momentum

>>9694598
The two sides of a hula hoop can't move independently.

>>9694580
>>9694598
Portals break the laws of physics, you cannot apply them accurately to this problem.

Example:
a: I place one portal on the floor, and another on the ceiling, I then place an apple in between the portals. What would you estimate that the potential energy of that apple is?
b: Instead of an apple I pour a bucket of water into the lower portal, I then place a water turbine in the middle, how much energy can I extract from this closed system?

>>9694613
That doesn't make the allegory less true

>>9694616
>Let's strawman him guys that'll work
The hulla hoop still makes for a good allegory

>>9694611
How hard is it for you to understand that only the press is moving?

>>9694598
you shouldn't be so silly as to not understand this

>>9694450
Prove that I'm wrong. I'll be waiting for a paper with a timestamp.

>>9694617
No, that's precisely what makes it the least true it could possibly be.

>>9694621
Except it isn't.
The hula hoop idiocy assumes that the laws of physics work like normally.
They don't, if they did then the portals wouldn't work at all.
You can't just shout strawman and dismiss the argument.

>>9694624
So if the other end of the portal was on the other side of the press it wouldn't launch?

>>9694629
you said "momentum is conserved." this isn't true.

>>9694631
Okay, then explain B to me without using the laws of physics

>>9694623
this is a false premise

>>9694637
peak brainlet. neither case is true because physics doesn't apply to this situation

>>9694637
They only break conservation of energy.
How about you explain this post without using the laws of physics.

>>9694642
So what is true then?

>>9694647
anything you feel like is as true (and as false) as anything else

>>9694632
Yes.

>>9694632
yes, in that case it would be essentially like a hulla-hoop

I just hope you all realise that the question is too vague to give an answer to. It's like asking "what happens when an immovable object meets an unstoppable force?"

>>9694654
>>9694655
But now, because they are at different points in space, even if the whole premise of a portal is that it connects two points in space seamlessly, for some reason the cube launches, right?

>>9694664
they pass through each other

>>9694666
No, it's because they don't move at the same rate. Relative location is irrelevant. Relative speed is the deciding factor.

>>9685840
anons, thats a boring question, try this one:

>>9694671
Why don't you fags understand that the blue portal is technically right on the other side?

>>9694677
because that's a conclusion that could only be made by a microcephalic smoothbrain

>>9694681
Based "I have no arguments" poster

>>9694684
you replied to the wrong person

>>9694686
Based "you replied to the wrong person" poster

got two lazy, low IQ replies in a row

>>9694695
Congrats on being the third

A

getting*

>>9694677
That's not even relevant because again it's not relative location that matters. Although maybe it does help if you realise that, while the blue portal is "technically" right on the other side, it also isn't, simultaneously.

>>9694676
A)
the rod would just float since it's being supported by itself

B)
this one breaks physics and is a good reason for why portals aren't freely allowed to be placed in moving surfaces. but for the sake or a discussion, here's what could happen
the surface with the orange portal would simply not move down as to not break reality (unlikely), or
the rod would break since both of it's ends are being forced into one another and the orange portal has no resistance stopping it's movement (in this case, no matter how much force the rod could sustain, it would necessarily be destroyed from the very beggining of the portal's movement until it became as thin as the distance between the two surfaces)

C)
I might be remembering this wrong, but in the games, when you shoot a portal that has an object inside it, the part of that object is relocated to the portal's new location
it's impossible to determine which parts of the rod are outside of one or the other portal, so I'd assume that the rod would break instantly wherever the universe determined as the most reasonable place to separate the object from itself, either in it's point of least resistance, or some other more abstract reason

these are all simply my opinions

>>9694729
So because it isn't, the cube spicks out, right?

>>9694743
Indirectly, yes, because I was hoping that you would realise that just as the portal is in two places at once, it is also moving and not moving at the same time, and that is the reason the cube moves.

>>9694632
IMO even if the two portals were literally a hula hoop the cube would *still* hop even if slightly because there is still a transition between the two frames of reference. Not even bringing any trembling ground into the equation. xy1 is still pushing the box into xy2.

>>9694632
IMO even if the two portals were literally a hula hoop the cube would *still* hop even if slightly because there is still a transition between the two frames of reference. Not even bringing any trembling ground into the equation. xyz1 is still pushing the box into xyz2, in relative terms.

>>9694747
Why?

>>9694752
Because you can't be stationary and exit a stationary portal.

Essentially, the portals existing in two places relative to themselves entails that everything else exists in two places relative to itself. You need only think of shitty MSPaint comics of people fucking themselves in the ass through a portal to see that. Your ass is both behind you and in front of you.

So when one of the portals starts moving, that means everything is moving relative to itself as well as the portals. The cube is moving and not moving. Specifically, it depends on which side of the portal you're on. When it comes out the blue side, it's on the side where it was moving.

>>9694759
that means the other portal is moving relative to the first one, just like the cube is.
both of the relative motions cancel out and the cube just flops out of the portal

but that's just a shitpost, there is no continuous coordinate transformation going from one reference frame to another. since the transformation is discontinuous, what happens is a matter of opinion, not mathematical or physical fact

>>9694768
>that means the other portal is moving relative to the first one, just like the cube is.
Yes, that's what I said
>both of the relative motions cancel out and the cube just flops out of the portal
No, that's retarded.
>since the transformation is discontinuous
Why would it be?

>>9694776
they're discontinuous b/c portals are two dimensional and one sided. it's possible to construct a closed contour inside the portals that cannot be mapped smoothly to a closed contour outside the portals, for example tying a rope to it's tail going through the portal is not the same as tying a rope to its tail outside the portal.
you would have to untie the rope to take it out of the portals. this is analogous to breaking a contour integral around a singular point in the complex plane

>>9694795
Ya lost me

>>9694867
just focus on the rope analogy.

if you can stretch rubber band along some path in space, and then move that rubber band to another place in space, those two paths have a continuous transformation between them
if you have to cut the rubberband to stretch it from one path to another, there does not exist a continuous transformation between the two paths.
that is to say, the transformation is discontinuous.

>>9685840
In order to accelerate the box you need to apply a force to it. No force is applied, and therefore it will not accelerate.

All A posts are bait

>>9695668
>referting to newtons first law whilest completely ignoring newtons second law

Either option breaks real life physics you reddit fucks

>>9695668
All B posts are bait

>insert pic of reference frame being on cube instead of orange portal here

>>9695668
The cube has momentum in this example.
Those two are not equivalent.

>>9686406
retard, is half of the box going to start moving when the other half is static? youre the one that sounds like you failed physics 1

>>9685840
its A dont be dumb

Why is it that in all arguments for B the people considering these Galilean transformations neglect the transformation of the sloped plane?

If you are considering the orange portal's perspective, the blue portal is moving at speed v, thus, the box is moving with speed v after it goes through the orange portal, which would be stationary relative to the blue portal, hence A.

Your reference frame choice shouldn't change the outcome, just simplify the math/scenario.

>>9695911
>>9695911
>>9695911
>>9695911

This
Solved forever never post again

>>9695913
posted this quite a few times and it doesn't stop this thread from being posted nor does it stop the thread

>>9695926
Maybe it will enlighten one person so I won't have to post it next time. I'm putting this question on my physics exam next time to see if anyone can actually apply basic concepts for themselves.

>>9695928
you know this is a contradiction right. the fact you can get two very different outcomes with just a reference frame shift proves that and also shows why it doesn't follow real life physics so why would you put this on a physics exam if it's not applicable

>>9695937
You only get different outcomes by neglecting physics and taking partial transforms. It is more a question about challenging assumptions and seeing different arguments. Done all the time with student A and student B "arguments" this is no different.

>>9695939
aight then don't be surprised when students arbitrarily pick one frame and ignore the other

>>9695956
I won't be, I'm used to students not doing well on my exams, but brings up discussions afterwards

>>9695926
Seems like it stopped the thread

>>9695939
No, from the perspective of the cube the portal, but also all the universe seen through it is moving that is, if you consider the scenario were the orange portal keeps moving the momentum of the system will change as the block gains velocity. It's not just violation of momentum, the problem arises from considering that a block can simultaneously see an object at rest and moving which obviously is a discrepancy. That is of you assume inertial frames. A resolution could be that they are and not, and actually the portals interact with what goes through them and that the portals have a finite life to not violate conservation of energy obviously (we already knlw it can "lift") objects agaisnt gravity). But if they interact A is also a possibility. It's a retarded problem.

>>9685840
https://www.youtube.com/watch?v=S85nudR6D-Y

>>9695961
just wait a bit dawg
the best you can do is hope to enlighten one person by replying to them with the knowledge of reference frames as
>>9695928
said

>>9695964
When does the block gain a velocity? In the orange portal's frame, the block has a velocity v beforehand and a velocity v afterwards. Transforming this back to the "lab" frame, the block is still stationary and the orange portal is moving at v downward as it always has been.

>>9695968
Consider the orange portal horizontal and moving to the left. The cube to the left of it and the blue portal horizontal but pointing to the right and stationary. If you ignore the you can see through the portal in the lab frame after the orange portal passes through the block, answer b would say that the block must keep moving and the total momentum changed since now both the orange portal and the block are moving. Now, you can say but the "universe is moving", which is nonsense, by itself, but the point is thay of you had anoth block next to the blue one you could possibly observe that tthe block is simultaneously at rest and moving, trusting relativity blindly woth portals. This shouldn't cause a fuss, as the thing is literally transporting matter instantaneously from one point to another, so there musy be an interaction. You can see this as you put a portal in at a higher level, and another in the floor and you can magically gain potential energy. This interaction, however, can be whatever because actual portal dynamics are not a real thing and so for all you know it can be A. Please spare your class from this retarded internet memes.

Also, I'm not fucking saying it's A, but that either interpretation is not consistent, or can be shown through "physics".

>>9695986

1. Please proofread, typos are usually a sign of trolls or laziness/apathy.

2. I think you've been missing the point that the velocity of the block does not change. In the "lab" frame it is 0 before and 0 after and in the orange portal's frame it is v before and v after. The only time it goes from 0 to v is when you do the transformation from the "lab" frame to the orange portal's frame.

3. I've been saying it is A this whole time and correcting the misuse of Galilean transformations (which people use to arrive at B) also consistently results in A.

4. I'm not saying that portals are physically possible or they are not, as programmed, violating aspects of physics, but they are at least self consistent and preserve enough to allow for intelligent discussions.

>>9694379
Your reference frame should be the joined plane of the two portals. Your velocity going into the plane is your velocity going out of it. You need to take the room as the frame of reference, shift to the joined plane, then shift to the exit room. And relative motion is part of that changing-frame-of-reference process.
The easiest way to do it is looking into the exit portal before/while an object goes through it. If the entrance portal is moving towards the cube, looking into the exit portal would yield the following view: a room moving towards you, with a cube heading towards the portal's hole. Like watching the video feed of a falling camera. The magic of the portal is that it applies the momentum and energy to an object that passes through it as if its image was there all along, the way it was seen. In the previous post's north/south example, if there's someone observing the blue portal as you walk through the orange, he'll just see you walking southwards before you pass through, despite you originally walking north, because if the portal orientation. The portal doesn't care you walked north, it only "knows" you went into it. Same goes for portals at different heights: it doesn't matter you entered a portal at some low altitude, because looking at the exit portal it looks like you were always walking at a higher altitude, and when you pass through, the portals make it so.
When the portal is moving towards a stationary object, it doesn't matter who was moving, because relative to the entrance portal, relative to the portals' shared plane, the object is the one moving. The observer at the exit sees a box moving towards him, along with the entire room. When the object goes through the portal's surface, it gains its "observed" physical properties, and goes out with the same relative velocity as seen in case B.
This theory is consistent with any and every phenomenon observed in any of the two Portal games.

>>9694621
It's only good when the two portals are on either side of the same moving surface, back to back. It's not good for when they are on surfaces far away, on the same surface facing one way, or on surfaces at an angle. All of which are regular-case portals as seen in the first game. Walking through a standing hula hoop will not place you several meters ahead, as it won't make you face a different direction. You can't separate the "in" from the "out" of a hula hoop, which is the core of the portals, meaning it's not a good analogy.

>>9694637
Placing two portals anywhere, throw/push something into one portal and look at its motion from the other. However it looks like before going into the portal, it'll be after going out of the portal. Looks fast moving towards you? It'll look fast going out.

>>9695997
1. Fuck off to reddit with your formating

A is not correct because as you say, there is a sudden movement (discontinuous) of the block. How on earth doesn't that imply inertia? So in A scenerio there is still an underlying mechanism which cannot be speculated alone from this, but that the blue portal act's on the block by bringing it to rest. The ring analogy everyone is talking about is stupid as here you have two connected objects, but one in motion and one at rest respect each other which is the crux of the problem.

>>9696039
I suppose I want to clarify that neither A or B are correct because you are giving to little information in an unreasonable scenerio in classical physic or even in relativity (wormholes aren't portals).

>>9695911
>the box is moving with speed v after it goes through the orange portal,
Yes
>which would be stationary relative to the blue portal, hence A.
No, that's retarded

>>9695911
This isn't going to stop debate because it is based on the assumption:
>If you are considering the orange portal's perspective, the blue portal is moving at speed v
If I don't accept that, then everything else falls apart. Trying to prove that would also require more than is possible with fake physics. Even if I do go along with this assumption, there are still several problems:
First, what happens to the matter that should be displaced by the cube? You have a cube that just entered a room without moving. Since the cube isn't moving, it should not be able to push the air out of the way.
Next, at what point does the cube disconnect from the portal? My assumption would be that the portal has no effect on anything that is not inside the plane of the portal. You seem to be suggesting that the cube as a whole maintains some connection with the portal. If the orange portal did not hit the platform and could keep moving around, would that continue to affect the cube even when it is on the blue side?

>>9695894
>use the reference frame of the block
What massive force stops the entire world from moving around the block?

>>9696486
idk m8 why don't you link me the wiki of the physics of this video game. you sure seem to know a lot about something that isn't real

>>9696513
The physics is the same as real life except you have a gun that can create doors.

>>9696616
except the whole infinite energy thing. you apparently missed the point in my original point. the cube never gained a velocity in its reference frame

>>9696638
That is true, it is more correct to say that it already had a velocity.

>>9696644
are you intentionally being dumb

>>9696649
I'm being intentionally correct. The cube doesn't experience its movement as acceleration. It will just find itself to already be in motion as it comes out of the portal, as if it had been all along.

>>9696657
are you not aware of what you are saying. the cube goes from still to instantaneous velocity from literally nowhere. take an undergrad relativity class god damn

>>9696644
From the cube's reference frame the entire world on the other side of the portal has velocity relative to it.

>>9696660
Two frames of reference.
>>9696667
But the cube is not a portal and will thus behave simply like a cube.

>>9695998
Good post, A brainelts take note.

Same result if yellow portal is moving instead. What's your choice?

>>9685840
apparently, using the word fucking and calling others 'retard' makes someone right!

There is not enough information, therefore the correct answer can be either or neither; and established by observation of an experiment

Source: actual research scientist

>>9696830
I don't understand whats going on in this picture

>>9685840
If anything it's inverse b

answer is obviously A. imagine if it wasnt a portal but just a hole. box wouldnt go anywhere

>>9696908
>dur dur portals are holes

>>9696916
where is it stated what a portal is or its properties?

>>9696931
I don't know, try the game "Portal"?

>>9696934
so in that game it is most definitely behaving like A

>in which /sci/ spends literal days arguing over a meme made in ms paint

>>9685840
B. portals conserve momentum. Just as the portal moves relative to the box, so does the box relatilve to the portal. When the blue, satationary portal becomes the reference point, the box is launched because the box was, as far as the blue portal is concerned, hurtling towards orange out of blue. The box isn't going to just stop because motion is relative. Force an RL circuit by adding a second source after charging; the current will stay a continuous function. Momentum works the same exact way.

Take a physics course, gents.

>>9686528
>the cube has 0 velocity relative to the blue portal even though the entrance orange portal is fucking moving space as far as relative motion is concerned
buhRAINlet

>>9686528
Oh wait, second reply was me forgetting which side you were arguing for because I missed a word. Sorry.

BOTH ANSWERS LEAD TO CONTRADICTIONS OR PURE SPECULATION WITHOUT MORE KNOWLEDGE ON HOW THE FUCKING PORTALS WORK.

>>9685840
Answer has to be B. A feels better but if they were to try and implement this even in a game space, it will lead to a bunch of fucked up physics unless you use B logic.

>>9685840

>>9697191
>hurr durr the box sticks to a surface with large incline
I'd post a dumb peepee to show you what I think you look like, but I'm currently mobileposting. please accept my apologies.

>>9697191
>the velocity of the portal is lost when it comes into contact with the wall
Can you make the simple mental exercise of imagining it without the wall, an just letting the orange portal move?

>>9697207
There's a surface in the original picture

>>9697191
If top is true, then the answer is B. Relative motion of object and portal.

>>9697213
could someone tell me why portals don't function like hula hoops?
>the orange portal makes contact with the surface around the box
>the box just appears on the other side from the blue portal at the same rate that the yellow portal did when it was moving towards the surface the box was on. The velocity of the orange portal, however was lost when it made contact with the surface around the box.
>i'm thinking of it in the was of swatting a fly on a wall with a tennis racket but somehow the fly managed to perfectly avoid any part of the net
>since the tennis racket stops when it hits the wall the fly on the other side doesn't seem to be moving away from the racket once it hits the wall

or maybe there's something I just don't get about portal physics

>>9697211
No shit, the point is that if you really think that because there is a wall, all the physics should change?
>>9697242
>Or maybe there's something I just don't get about portal physics
Don't feel bad, no one really gets it as there is no such thing. Basically you have the means of having jump discontinuities on the trajectory of a particle. That basically means an infinite force applied at just one event. Curiously, that is how classical elastic collision is modeled fir rigid objects, but that is because the time it takes to bounce is really small so it's an approximation. Here, it is not. Besides, if you have a forces and interactions, you can't use simple arguments as consecetion od momemtum or galilean invariance.

>>9697289
If there wasn't a wall the orange portal would keep on moving beyond the box taking along with it air molecules into the portal.

this would result in the blue portal ejecting the box along with the air giving the result the same appearance as the first instance
>now picture the additional air isn't there and the orange portal stops where the box ends
>yes, the wall/ surface does make a difference

>>9697298
What the fuck are you talking about? The wall puts an extra constriction that has nothing to do with the invariance over frames.
>>9697191
This retarded picture shows that A is incompatible with galilean relativity.

>>9697311
whilst a woman is on top & doing reverse cowgirl
Does
>A The penis stay where it is in relation to the vagina
>B The penis gets propelled deeper into the vagina due to the velocity of the vagina

>>9685840
A.

>>9697242
A hula hoop doen't work because you can't put a hula hoop over top of something without moving it. Additionally, if you have something moving through a stationary hula hoop, the hula hoop will not be able to interact with it in any way. If you apply the hula hoop comparison to the blue portal you would get answer B.

Depends on the portal used. As the question is purely theoretic then both answers are plausible. However, portals don't exist so you're arguing over a shitty drawing.

>>9697341
I like you thinking anon, if only highschool science was taught this way I might not be such a brainlet now.

>>9695998
tl;dr "what you see is what you get". It's the most intuitive shit ever.

>>9697191
This isn't even actually explaining anything. "It's A because I imagine it to be A, it's not even that hard if you visualize it"

>>9697341
t. virgin

>>9697341
It's not a fucking hoop becae the otange pprtal moves in relationship to tge blue one.

>>9685848
so the people who answer B
are they treating the area on either side of the portal as more than just two rooms stitched together by a door frame?

since portals do not seem to be a real construct I guess whether you think A or B depends on whether you see portals as a window frame/door frame or whether you see them as <something else>

>>9697741
B here. They are window frames, just window frames where both sides can move in relation to each other. Essentially, it's a different window depending on which side you're on.

>>9697676
Did you even read anything you retard

>>9697099
>portals conserve momentum.
this is not true

>>9685843
its clearly B. although the box itself experiences no change in momentum the speed at which the portal envelops the box imparts an apparant momentum to the room, from the frame of reference of the box.
The box cant emerge from the portal traveling at X km/h relative to the room and then just stop, momentum must be conserved.
and speaking of energy being conserved, this implies that the portal encounters resistance as it envelops the cube proportional to the square of the speed at which the cube is enveloped * the mass of the cube

>>9698709
the frame of reference of the box isn't glued to the box, it's anywhere in space that's moving at the same velocity as the box, so the blue portal is also in the frame of reference of the box.

the box being stationary at one point in its frame, and moving in another means the spatial transformation between the two locations is not continuous and therefore not physical.

>>9698694
Yes
>Results in the box appearing at the same rate that the yellow portal fell on it
Self-evident.
>There is no sideways velocity
Unfounded assumption that is merely a restatement of A.
>The box is still touching the wall and the yellow portal did not touch the wall
Irrelevant observations.
>Additionally the blue portal is not moving away from the box
It would be if we assumed B rather than A.
>The velocity of the yellow portal is lost when it comes into contact with the wall
Another irrelevant observation. By this time, the portal has passed the cube entirely.

The only thing there to suggest that it's A is "it's A" in different words.

If momentum wasn't a factor, it wouldn't pass through at all.

So the question is actually - what type of portal are you using?

Portal x will carry the momentum

Portal y will crush/kill/atomize/squish/vaporize you

So is it portal x or y?

/thread

>>9698929
incoherent and nonphysical ramblings

>>9685840
Depends on the operation of the portal