/sci/ - Science & Math

a. the cube has no momentum

>>10460783
If the box is not point sized A is not possible. The front of the box will be coming out at the same velocity as it goes in, and hence when it's through it will take some kind of force to slow it down.

>>10460788
>what is frame of referece

>>10460788
Therefore it never exists the blue portal. Which it clearly does in A

>>10460789
this.

>>10460788
>a bug collides with a fast moving car
>instantly dies
wew such momentum that bug had miright?

>>10460783

>>10460801
what? if over half of the cube goes through the orange portal, which it will since the orange portal is on a movable press, then gravity will work on the cube and finish pulling it through and plop it down.

>>10460810
>being this retarded

>>10460826
>does not understand relativity

>>10460788
So? Portals as presented in Portal and Portal 2 already violate the law of conservation of momentum; if two portals are facing opposite directions, anything that goes through one and exits through the other has the sign on its direction (and therefore velocity, and therefore momentum) flipped.
Despite what GLaDOS may say, portals do not conserve momentum; they conserve speed. As it happens, speed is relative! The cube has speed relative to the orange portal, so that relative speed is conserved. It's B. That's it. The game does not care about whether it is physically possible or not because there would literally be no game if it did.

Also, you can't argue conservation of energy either, since portals violate that as well, and the game doesn't even pretend that they don't (there's literally an achievement for creating a perpetuum mobile by placing one portal on top of another and getting to terminal velocity with the free infinite potential energy).

>>10460814
>are people basing their "rules" on how some videogame says they work?

>Solve this puzzle using the rules given to you
NUH UH I DID MY OWN THING CAUSE MOMMY SAYS I'M UNIQUE!
Free thinkers need to be made to outwit a room full of bees.

>>10460814
>t. never encountered a 12th dim alien who can open up portals

>>10460841
interesting
is that the reason why the game can't allow moving portal to move ?

>>10460875
probably because it was too hard to program

>>10460875
What this anon said: >>10460878
There actually is a single scripted sequence in Portal 2 where you put a portal on a moving surface to cut some tubes with a laser, however, which sort of breaks any continuity there, unfortunately.
And, of course, it begs the question of what constitutes a "moving surface" anyway, since everything is moving all the time.

We already know that the angle a cube is shot at can be changed (and thus momentum is changed) when the angle of the exit portal is different. Why is it a stretch to say that the speed a cube is shot at can be changed when the speed of the exit portal is different? I feel like all the A arguments make this weird assumption that momentum must be conserved when I feel like the whole premise of portals is that that isn't the case

>>10460841
>Despite what GLaDOS may say
"Speedy thing goes in speedy thing comes out."

>>10460904
I think what throws people off is that portals create continuity and discontinuity at the same time. The cube's angle is changed, but if you look at it another way, it moved in a straight line. The cube changes its speed, but if you look at it another way, it keeps going at the same speed. In both of these cases, the former is what you would say if you were watching the cube go into the orange portal, and the latter is what you would say if you were to observe the cube by looking through the blue portal. In that sense, B is entirely consistent with the way portals are already known to behave. So portal physics is actually pretty intuitive. What you see is what you get. You just have to know where to look.

A and B are both possible.

If you put a portal in an object that can travel close to the speed of light for a long time, can you create a time portal?
>the portal, thus the space inside, experiences time dilation while moving at high speed

>>10460923
>Spectacular. You appear to understand how a portal affects forward momentum, or to be more precise, how it does not.
>Momentum, a function of mass and velocity, is conserved between portals. In layman's terms: speedy thing goes in, speedy thing comes out.

>>10460788
Pardon me but this is /sci/ not /v/ which means the other brainlets aren't here to help you.
Anyhow, the cube will exit the blue portal at the same rate it enters the orange one, hence B is the correct answer.

So to if a portal built on asteroid came flying by. We should be able to have an object standing still in front of it gain all the momentum of the gate?

>>10461031
So what, she left out the word relative before velocity.

>>10460783

B.

Even though the cube has no momentum, the force of the press hitting the flat piece of metal might cause the cube to fly upwards (and therefore diagonally) because of the sheer vibrational shockwave caused by the impact on the flat piece of metal.

Just as if I hit a wooden table with a hammer, coins on that table close to the hammer will jump a little in the air.

It all depends on how the 'floor' reacts to being struck, as it is on a thin podium I imagine a lot of vibration, and therefore for it to fly in the air.

If it were hitting a solid floor however, maybe concrete with metal on the top, there would be little to no vibration and A. is more likely.

>>10461057
It's not about relativity. If you enter a portal facing the opposite direction, the sign of your direction is flipped no matter what frame of reference you pick.

>>10461078
>>10461084
Yep and the blue portal is moving the same speed as the cube relative to the orange. So if the cube is moving at v towards orange and blue is moving towards orange at v, the speed that the cube exits is 0.

wouldnt the momentum of the space you re moving into affect the velocity. if cube takes potral and gets taken to into water or a solid or any possible place a portal could take you A does in fact exist

reminder: portals don't exist

learn GR brainlets. that is the physics of spacetime and causality

>>10461084
The frame of reference is the portal.

hmm

>>10460783
its always A u fuckign brainlets, stop trying to act smart ur all retarded, the piston portal will smack onto the fucking big ass metal floor and A will occur,

B only occurs if the portal piston keep going, but even then the cube will not fly but just over in the air for a much longer bit before falling down slowly

fucking baiting retards

>>10461245
Spoken like the brainlet depicted in your pic.
Velocity doesn't magically become zero once the cube is through.

>>10461272
yes, yes it does you aboslute retard

>>10461309
>yes, yes it does you aboslute retard
What force causes the cube to come to a stop?

>>10460783
A. because B. would have to somehow transfer energy which isn't happening

lol this retard said portals dont exist.

>>10461363
welcome to /v/ physics.
"muh portal physics reeeeee"

>>10461328
You can already get infinite energy from nowhere with portals just by putting one portal on top of another and jumping through.

>>10461319
The whole other world inside the portal u brainlet

>>10461319
and BTW the question is MISLEADING on purpose , because like I fuckign said, if likeo n the picture the portal slams onto the iron thing and stays there the cube will NOT fly anywhere, BUT if the portal would envelop it and KEEP FLYING DOWNWARDS then YES the cube would appear to fly a bit before arcing downwards in a drop

>>10461402
that's just gravity, the problem isn't about gravity

>>10460783
It would definitely be A, because the cube would still be sitting on the platform, just at a different angle. The momentum that the moving platform has will be absorbed by the cube's platform, not the cube itself.
If the portal were bigger, it's not like that velocity would magically transfer to the platform. All that would happen is that the support would keep going through the portal.

>>10460788
This is correct. No energy has been imparted to the constituent molecules of the cube. The universe has essentially shifted around it. It is now just in a different gravimetric environment and will slide down the incline.

>>10461043
Again, do you know what a reference frame is?

Also, how do I build muscle?

>>10461402
you have to supply energy by jumping in and then rely on the force of gravity. you aren't getting energy from nowhere you absolute retard, a force is acting on you.
>>10461363
the box isn't emerging, the portals are moving around the box. there isn't an "emerging motion" to start with.
Imagine the extreme case, where you have two portals back to back on a board. essentially a picture or door frame, but made of portals. Now imagine if someone climbs on a ladder and drops the "portal-frame" on you so that you would pass through it. would you suddenly fly out the other side? no, you would stay standing there because you weren't moving in the first place.
Now instead of having a "portal-frame" you've just moved the exit portal to another location, the same thing would happen.
how can you guys be this retarded?

>>10461710
>the box isn't emerging

What is relativity

>>10461716
Idk, you tell me anon?

>>10461718
You can't just ignore other reference frames

>>10461716
>I was merely pretending to be retarded
>ebintroll.png

>>10461710
>Now imagine if someone climbs on a ladder and drops the "portal-frame" on you so that you would pass through it. would you suddenly fly out the other side?
see >>10461265

>>10461436
>>10461710
>hurr durr gravity does all the work
What the everloving fuck is potential energy?
Forget that you're falling infinitely for a moment, since clearly that's tripping you up. The mere act of emerging at a higher elevation gives you potential energy. This is potential energy you got for free, because you didn't expend any kinetic energy to get to that height. CONSERVATION OF ENERGY IS VIOLATED.

>>10461710
>Imagine the extreme case, where you have two portals back to back on a board. essentially a picture or door frame, but made of portals. Now imagine if someone climbs on a ladder and drops the "portal-frame" on you so that you would pass through it. would you suddenly fly out the other side?
This is because you would add the momentia of the incoming portal, Xcos0 with 0 degrees defined as down, or simply X, and the outcoming portal, which is Xcos180 because the portal is facing up against its motion, or simply -X. The total momentum is 0.

More than a single cube, imagine the flow of air as each particle exits the blue portal.

>>10461419
>>10461430
Why tho? The cube has a velocity.

>>10461736
>Forget that you're falling infinitely for a moment, since clearly that's tripping you up. The mere act of emerging at a higher elevation gives you potential energy. This is potential energy you got for free, because you didn't expend any kinetic energy to get to that height. CONSERVATION OF ENERGY IS VIOLATED.
yea no shit, it seemed to me that >>10461402 was arguing that the portals somehow imparted energy to something, which they themselves don't.
>>10461740
>This is because you would add the momentia of the incoming portal, Xcos0 with 0 degrees defined as down, or simply X, and the outcoming portal, which is Xcos180 because the portal is facing up against its motion, or simply -X. The total momentum is 0.
is this why my hand doesn't rip off if I move a picture frame around it? because of the momentum of the frame?

>>10461767
>is this why my hand doesn't rip off if I move a picture frame around it? because of the momentum of the frame?
If its a picture frame with portals on either end, yes. Imagine the same experiment but you bisect the frame with your arm sticking through it and move each half of the frame away from each other. Suddenly the arm splits!

Eli, stop

>>10461078
B is the right answer but this explanation is retarded.

>>10460783
Actually, space is being bent around the cube, given the illusion of movement, when there is none.
therefore A.

>>10460783
Neither, with a slight change of A. You've got a gravitational field applied in two directions, one at the normal relative to the plate the block is sitting on and a second at the normal relative to the angled plate with the blue portal. The only way the block will move is if the torque experienced by the block as it "emerges" is enough to get it moving. Otherwise it will stay put because it's experiencing a surprising amount of static friction.

>>10460814
the most reddit image i'll see today

>>10462251
Ok hotshot
you fail at abstracting

>>10462017
Portals are just holes, man.

>>10460783
A, what the fuck

>>10461078
but the cube will already be through the portal by the time the press actually hits the pad

People who say it's A lack the ability to actually visualise what is happening and have no recourse but to fall back on simple rules they learnt in high school.

>>10462811
Technically the cube would be concurrently on top of the pad and through the portal for a little while before it falls off
>>10462833
>People who say it's X are dumb lol
Any yet, you offer no evidence.

>>10460783
Portals don't conserve momentum here is an explanation in Spanish you can subtitle.
https://www.youtube.com/watch?v=Tk_f2baL5wg

>>10463296
>Any yet, you offer no evidence.
I could accurately describe what actually happens or come up with half a dozen variations that show the contradictions that arise if we go with interpretation A, but if they can't (or refuse to) visualise it and instead cling to "hula hoops lol" and "muh momentum", what's the point? If they could work out for themselves what would happen if you stick your head out of the orange portal as it moves down, or if you stand really close to the blue portal, or if you put something on top of the cube, surely they would've done so by now. But instead they just unimaginatively keep repeating the same things.

>>10460783
B anyone who says otherwise is a plain retard

>>10463331
Way to avoid the question and divert back into ad hominem

>>10463369
I gave you three examples right there. I wonder why you didn't bother to visualise them? If my accurate observations feel like ad hominems to you then perhaps you should improve yourself.

>>10460783
its a, people saying b are contrarians, trolls, or retarded. or all of the above. the surface that the portal is on does not matter, the object passing the through the portal determines what happens.

>>10463382
That's the definition of an ad hominem: questioning the abilities of other people rather than proving your point directly
Asking us to argue your point for you is no different than admitting you have none

>>10463409
Frankly, if you lack the ability to see the answer, what can I do to make you see it? You refuse to cooperate. You don't have any arguments yourself. I'm literally just asking you to visualise something and you just say I'm asking you to argue your point. But if I say you refuse to visualise it's an ad hominem?

>>10463447
You aren't explaining which factors would lead to which outcome
It's a fictional utility, so visualising without any bounds could give multiple plausible answers.
If you answer B, you're saying the box gained an upward velocity. How is that?

>>10463472
Well, if you'd bothered to do what I've asked you several times already, you'd see that if, for example, you stuck your head through the portal, then even though you're standing still on one end, it's still going to slam down hard on the cube. Either that, or push you out as it moves. Either way, the inescapable conclusion is that portals can confer motion on objects. The former interpretation is more in line with how portals are known to work.

If you then look at the situation where you pull back your head so it's just on the other side of the portal, it's still going to slam into the cube, because the cube is going to come through it at speed.

Then if you extrapolate this to the situation where you're not standing in the way, nothing is going to stop the cube.

>>10463484
If you stick your head through a hole in the bottom of an elevator descending onto the cube, you'll also hit it. That doesn't mean that the cube is moving or has any energy. The portals here are identical in function to the hypothetical elevator, the only difference being the location and angle changes after the cube enters the 'elevator'. Just as it doesn't launch up into the elevator shaft, it also does not launch away from the exit portal.

>>10460783
Its a

B. Anyone that disagrees is an iq poster.

>>10463499
>If you stick your head through a hole in the bottom of an elevator descending onto the cube, you'll also hit it.
The implication here is that portals confer energy, considering you're holding your head still and yet it moves down.
>The portals here are identical in function to the hypothetical elevator, the only difference being the location and angle changes after the cube enters the 'elevator'
Well, yes, and that the inside of the 'elevator' is not moving at the same time that the outside is, which makes it rather unlike an elevator after all. You're not doing anything but rehashing the hula hoop argument here.

If you look at the blue portal then what you'll see happening is an elevator pushing the cube up towards the portal and suddenly stopping.

>>10463516
You're wrong to assume that two unmoving objects will not change in distance. Portals change the space between them, meaning neither the observer nor the box has momentum; it's an elevator that functions on distance rather than speed. Therefore, the only viable option is A.

>>10462788
you can't move holes while making the entrance static and the exit in movement

A if gravity exists.
B if it doesn't

If you can't measure properties of portal then assume that it is space with singularity, much like black holes,
portals don't contain information and are empty,
Black holes are similiar but they interact with dark matter/energy/vacuum and particles.
Portals do as well, however they have several unrealistic aspects to these processes

Portals by essence break laws of thermoregulation and perpetuality.
The two relatively realistic ways portals would work would be time travel and wormholes to other universes.
Time travel would consist of information travelling to another universe which exists fast forward after death of ours.
As the informations can pass faster than speed of light given that they never stop accelerating.
( >> information >>>)× infinity
This would create force stronger than gravity in theory,
,= unrealistic, unless we just watch processes happening in universes cyclicaly

Think of it as a black hole but with properties that accelerate you away from event horizon, in meanwhile hellofalot time passes ( so much that new universe starts)

If you would put portal on earth and measure time and another one on object near black hole you would have 2 different time readings assuming it wouldn't suck you out ( the black hole).

In the end maybe if true vacuum existed then there would be conditions for such endeavors.

T. high on meth.

>>10462466
how is a screenshot of a post on /sci/ considered “reddit”, pray tell

>>10460783
DISCONTINUOUS TRAJECTORIES IN PHASE SPACE CANNOT EXIST
SO STOP FUCKING MAKING THIS THREAD EVERY WEEK

>>10463712
Space is discrete though

>>10463733
no it’s not /v/tard, and don’t say “planck length” because that argument is retard-tier

>>10463557
You can this one. That's the only difference.

>>10463534
>You're wrong to assume that two unmoving objects will not change in distance.
It's literally moving, though. It's not just the portal reducing the distance as seen through the portal. You're hanging out of the portal and moving with it.
>it's an elevator that functions on distance rather than speed
Nonsense. It's literally the orange portal's speed that prompted the elevator analogy.

>>10460789
Is that velocity? Or is that points in 3D space becoming non-simply connected?

>>10463775
If the observer hangs out of the portal, that does not give velocity to the cube.
The orange portal can give no energy to the cube, which is why the elevator's speed is not relevant. It could be light speed or an inch per hour; the result is identical. The cube's distance from an observer next to the blue portal decreases without either having a velocity.

>>10461176
Best

>>10463808
>If the observer hangs out of the portal, that does not give velocity to the cube.
It gives velocity to the observer. I am establishing something here through this argument.
>The orange portal can give no energy to the cube
Then how does it give energy to the observer?
>The cube's distance from an observer next to the blue portal decreases without either having a velocity.
This is only partially true because the cube has potential velocity which is realised when it comes through the portal. The distance continues to decrease as the cube is moving through. It has movement.

>>10461176
I've been an A. fag all my life but for some reason this perfectly explained how the motion is relative to me.

>>10463844
The orange portal actually gives no energy to the observer, it just changes its position in space. It's the piston that changes the speed of the observer, which the cube is not connected to.
The cube only starts moving when it is already through the portal, and its velocity is downward and to the right if anything at all (because of potential friction). There is nothing in this equation to force the cube upward.

>>10463844
That's not true though. Imagine having a ball and plastic cup. The ball is on and table, and the plastic cup is being lowered over the ball to cover it up. From an observer inside the cup, the ball looks like its moving until the cup hits the table. The portal is the same situation with the exception that the space inside the "cup" is identical to the space somewhere near the ball on a different table through a nonsimple connection. An observer sitting on the different table would still see the ball appear to move the same way as they would if they were inside the cup, but this does not mean the ball is moving.

>>10463888
>There is nothing in this equation to force the cube upward.
You're trying to apply rules to deny observations, instead of deriving rules from observations. The cube comes through the portal. That is movement. The question is how do you deal with the fact that the cube moves?
>>10463896
>Hula hoop argument

>>10463921
The cube moves because the portal is able to change its position. That's what portals do, and have always done. There is nothing to suggest that going through a portal will give you more energy than you started with.

>>10463942
>The cube moves because the portal is able to change its position.
But you're not thinking about how it does this. Because a portal really is pretty much a hole. The cube isn't instantaneously transported. It goes through a hole, by degrees, until it is fully on the other side. Really, if A were true, then the cube would collide with itself and never make it through in the first place. If you accept that the cube comes out of the hole then you have to accept that it moved, physically moved, and if nothing is going to stop it it will keep going.

>>10463942
>There is nothing to suggest that going through a portal will give you more energy than you started with.
Confirmed for never actually playing the fucking game.

>>10463759
and that difference can cause things that wouldn't happen with normal holes.
Thank you.

>>10463977
The portal is both the start and end to the movement. The cube cannot keep going, because it never had a velocity.
>Really, if A were true, then the cube would collide with itself
I'm gonna need a source on that buddy

>>10463990
Yeah, such as launching things

>>10463921
>hula hoop argument
okay friend, let's put it in terms of what you clearly want to dismiss with handwaving: what happens if the top piston is replaced with just a thin parallel rectangular plate, falling at terminal velocity, with the orange portal on the bottom and the blue portal on top? What happens to the cube, and how is that different from a hula hoop falling over the cube? Be very explicit.

>>10463992
>The cube cannot keep going, because it never had a velocity.
This is obviously false because you WILL collide with the cube if you stand close enough to the blue portal even with interpretation A.
>I'm gonna need a source on that buddy
It's also obvious, isn't it? The first atom of cube moves through the portal and stops there. The second atom of cube moves through the portal and is now trying to move into the space occupied by the first atom. The two collide. And with the third, the fourth, and so on.

>>10464014
Under those circumstances it would function identically to a hula hoop. The relative velocity of the cube exiting the blue portal is identical to the velocity of the blue portal in the opposite direction.

>>10464017
If by 'collision' you mean maintaining structural integrity, you are correct. This is actually happening at all times to everything, and that is why the cube is able to go through the portal.

>>10464030
But you contradict yourself here because the plate isn't infinitesimally thin, if the plate is 1 inch thick then to a stationary observer the box will sit 1 inch higher than it started and therefore have apparently "moved", which is your justification for choosing B. Which is it?

>>10464060

>>10464095
Left hoop is infinitesimally thin, which is exactly the point I'm not making. A non-thin hoop 1 inch thick will cause the top section of the box to "hop" up by an inch. This gif is irrelevant.

>>10463704
because new friends like you should go back.

>>10464119
It does "hop", but since the exit portal is going downwards with the same velocity as the cube is emerging, it cancells out.
This is the argument B proposes, because if the exit portal is stationary, then nothing cancells the motion and the hop happens.

>>10460783
Considering the instantaneous teleportation of portals in portal, and the fact that the cube emerges depending on where it is within the portal, I'd say A is correct.
Sure, sure, objects with high velocity do come out of the opposite portal carrying that velocity, however movement of a portal does not transfer velocity to the object, especially considering the portal only transports, and doesn't collide.

>>10464145
That's nonsense then, that's a totally inadequate explanation for why the velocity "cancels out".