I rewrote Portal from scratch and solved the Portal Paradox
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- Опубликовано: 22 янв 2023
- The Portal Paradox has been the subject of a lot of debate online, but now it has been implemented by rewriting Portal with moving portals.
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Not enough people have mentioned the god-tier move of making this video exactly how long it needed to be and that’s it. If any other creator covered this topic, this would’ve been a 14 min video at least. Bless you, sir. Subscribed.
One thing that sucks is he's wrong, but I do agree, 5 minute or less videos are the best 👌🏻
@@BalognamanforyaHow is he wrong though?
@nintardo2231 you can check my other comments to see the explanation, but here's a hint, it has to do with the conservation of energy 😉. This guys great at programming, but he's not so great at physics.
@@BalognamanforyaPortals already fundamentally break the conservation of energy regardless, so any further violations are a moot point.
@sharcc2511 no, they literally don't. Sure, if you look at it from a glance, it would seem like they do, but they don't.
Kinda cool that your de-make is now, at least in this particular regard, technically more advanced of a game than the actual original source version
The Wuffle house has found it’s new host
@@CBNST its* 🤓
@@CBNST The trebuchet is important!
@@kip258 me -> 💀
@@lod4246 Begone, BOT!
What would happen if you:
- Incrementally change how far down the moving portal moves, will the cube be "sucked" up and out the other portal?
- Both portals are moving in opposite directions, will the cube get the sum of the portals speed?
- Move the portals toward each other, having the object in the middle?
Just interjecting with my own thoughts:
1. Yes, the cube would be sucked up a bit. I think about it as a person that were standing and the orange portal slamming into me from the top. All the air above me has exited the blue portal at a high velocity, then comes my head, which has just entered another end of the world at a high velocity (this would be the same if the orange portal were stationary and I ran/fell head-first into it), so my head would definitely get tugged into the other end. Now if the portal stops midway, my head will retain the inertia and in the worst case, I'll be decapitated. Again, I think of it as jumping out of a moving train and the train immediately stopping to 0 when only my head is out of the door.
2. Logically, yes.
3. Depends entirely on how the atoms are recreated/phased on the other end. Ideally, they would either phase into each other or be in superposition. But logically, the atoms would layer/intertwine and you would end up with a fine Chell paste.
So the first question you had can be answered two ways, the previous commenter included velocity which is one of the ways to interpret it. I think you meant in a slower way as in how far would the portal need to go before it was sucked out. If the portals are both on a surface that faces the direction of gravity then it’s just when the center of gravity of the cube goes through that or would be “sucked” up and out. The second question is actually demonstrated in the video when he puts a portal through a surface and essentially it is the answer to your question. Its basically like if you were to drop a hula hoop over yourself, one side is moving (relatively) exactly at an opposite velocity of the other side. The third question is a bit harder to answer but I’d imagine it would be like trying to stuff the cube into a place with zero volume. In a real life scenario where we magically have portals to test this, I’d imagine that any object you put between the portals would make contact with itself and begin resisting whatever is pushing the portals together until it yields to the pressure.
This is the logical set of answers based on what the math is trying to simulate. What would actually happen in the N64 physics engine depends entirely on how James is simulating the "teleport."
1. Half the cube should appear on each portal face, at first. Gravitational forces on the Portal B side will immediately take effect on only the mass that is present on that side, and effect the whole cube as a calculation of the opposing forces on the other side, Portal A.
2. Yes, both logically, and according to the math.
3. It would look exactly the same as if there were no portals at all, and it was just two panels sandwiching the cube. Logically, the portals (or more accurately, the objects the portals are moving on) would either be forced to stop with the cube in the middle, or the opposing sides of the cube would crush the cube itself, depending on the force objects that the portals are painted on are exerting on the cube. It would be ultimately the cube crushing itself, but the force applied to the cube would be equal to the objects that the portal are moving on.
If we talk about just physic and not how he simulate the portal.
1. Think of it like the portal is grabing part of the box and throwing it like how you lift a box. So the answer is yes.
2. Since we are dealling with portal, we are dealing with relative position and velocity we have to take that into account. If you are talking opposite here as in from your POV in a room one go left and one go right with the direction facing the place they are heading. What would happen would be the velocity of the cube = the velocity of red portal + the velocity of blue portal. Imagine the slam experiment but the stationary one also moving forward. But opposite here mean how the portal is moved base on it orientation like one is going forward and one is going backwards then it will stay still like the hoola hoop example in the video.
3. The box will be destroy as it will try to exist in the same space. Imagine it more like slamming the middle box with 2 other box exactly the same down to the attom and the imperfection toward the middle one.
@@VarunGupta3009Yeah that phase/superposition answer doesn't really make sense, it's not like the portal instantly teleports an item into a different point in space, it lets the item "enter" that position from a specific direction, so the cube wouldn't have to phase into anything. The correct answer is what herewegoagain wrote: the cube would simply find itself in the middle of its own two sides crushing itself with the same force as the moving panels.
If you assume the portals to magically be unstoppable then sure, they would push until the cube disintegrates into atoms but you're just asking what would happen if you put the cube in an infinitely strong press.
I want to thank you.
1) giving the answer early, its why i stuck around for the rest of it, a sign of respect for a genuinely interesting video that gave a little more information and context to cement the findings presented
2) exactly how long it needed to be, tests, findings, results repeated tests with different settings and end. This earned a sub, if everything else on this channel is presented like this im going to be watching a lot
It always amazes me what games were possible on the old consoles if only someone had thought to make them at the time.
Has always been like this in all the aspects of technologies
think about now, what's possible
The Ocarina of Time devs made portals back in the day, but they weren't implemented.
game design is its own technology
a lot of new things are possible on old hardware, just because of how much more we know about stuff like 3D rendering and programming now! back then stuff like this was POSSIBLE, but probably would've never happened
“I could make you wait for it, but I value your time more than retention rate.” Mad respect for that.
I just told my friend about this project and his first question was if the ch_createairboat command will be in the de-make. 😂
Would be a sick easter egg if it also required the N64 keyboard to pull up the console!
@@VariaPrime the what now
I see no reason for this, unless he first made a de-make of half life 2 and was building his current project on top of it. But that would be... fuckin weird my dude
@@inanna8782 locale man has never heard of an Easter egg
@@inanna8782 How to make portal on N64:
Step one: Remake all of half-life 2
Step 2: Add portals
Step C: That's it. You win.
I always thought the portal paradox is what happens when you move one portal through the other.
I think there's a Veritasum video about it
I think you live under a rock 😂😂😂
Nothing happens. The one portal comes out the other, nbd
You tear the fabric of space-time and the universe implodes, only to create a super mass that explodes in a big bang that starts this whole reality all over again.
Its the momentum of the part of the cube that's already exited the portal that pulls the rest of the cube forward with it.
The explanation at 2:02 made the first experiment make SO MUCH MORE SENSE. Amazing video
Except his explanation makes no sense when you understand that momentum is conserved between portals. Think of it like a baseball in a car. If you remove air, a car driving over a baseball will not move the baseball. Because before the car drove over the baseball, its momentum was 0. Therefore, after it drives over the baseball, the momentum would be 0. In the first clip where the cube goes flying, the car drives over the baseball and stops, then causes the baseball to go flying in the opposite direction as fast as the car had been moving, having never touched the baseball. Somehow, the car imparted momentum to the baseball, having never touched it.
@@trmerc7635 Except that's not really how this works. Imagine it from the perspective of the exit portal. The moment the entrance portal touches the cube it starts coming out the other end. This happens regardless of whether it falls into the portal or if the portal moves towards it. Assuming the velocity of the cube falling is the same as the portal moving towards it the cube is coming up out of the other portal at the same speed in either situation. And this is where the momentum plays a role. The exit portal does not care how the cube is coming through, all that matters is how fast it's coming through. Momentum doesn't just stop as soon as it's come through and plop down, it's going to want to keep moving in the direction it was coming out of the portal at. If actually look at the exit portal you can see the cube come closer and come through the portal. From the exit portal's perspective the entrance portal may as well have been static and instead the platform the cube is on got pushed upwards. This is why relative velocity is key here. All that matters is the relative velocity of the cube compared to the portal.
@@RNeeko It really is how it works. Instead of a portal, imagine a car. If you throw a baseball at a moving car and it goes through the open windows, does the ball get faster or slower? No. Because the ball did not interact with a physical object to impart momentum. The portals are just points in space that are connected. So is a long tube. If you throw a ball through a tube that is moving, as long as the tube doesn't touch the ball, it doesn't affect the speed of the ball. For some reason, people seem to think because it is a wormhole and not a physical tube, it somehow changes the laws of physics.
@trmerc7635 the cube has to leave the exit portal with the same speed it has entered the portal... thus giving it momentum. Witch causes the box to accelerate upon exiting the stationary portal.
I think you are misunderstanding how the portals work in the game. The portals are not physical objects that can move and interact with other objects, they are just openings in space that connect two locations. The velocity of an object that passes through a portal is relative to the portal, not to any other reference frame. This means that if a portal is moving, it will affect the velocity of an object that exits the other portal, even if the object itself is stationary.
To illustrate this, let’s use your analogy of a baseball and a car. Imagine you have a car with two open windows on opposite sides, and a baseball that is resting on the ground. Now, suppose you drive the car over the baseball, so that one window is above the baseball and the other window is on the other side of the car. If you ignore air resistance and friction, what will happen to the baseball? Will it stay on the ground, or will it fly through the car?
The answer is that it depends on how you look at it. From the perspective of someone standing on the ground, the baseball will stay on the ground, because it has no horizontal velocity and nothing is pushing it. From the perspective of someone inside the car, however, the baseball will fly through the car, because it has a horizontal velocity equal to the speed of the car in the opposite direction. This is because motion is relative, and different observers can measure different velocities for the same object.
Now, imagine that instead of windows, you have portals on opposite sides of the car. The portals are connected, so that anything that enters one portal will exit the other with the same velocity, relative to the portal. What will happen to the baseball now? Will it stay on the ground, or will it fly through the portals?
The answer is that it will fly through the portals, regardless of how you look at it. This is because the portals are not physical objects that can move and interact with other objects, they are just openings in space that connect two locations. The velocity of an object that passes through a portal is relative to the portal, not to any other reference frame. This means that if a portal is moving, it will affect the velocity of an object that exits the other portal, even if the object itself is stationary.
To see why this is true, let’s look at what happens to the baseball from different perspectives. From the perspective of someone standing on the ground, the baseball will enter one portal with zero horizontal velocity and exit the other portal with a horizontal velocity equal to the speed of the car in the same direction. This is because when an object enters a portal, it inherits its velocity relative to the portal. Since from this perspective, the portal above the baseball is moving with the speed of the car in one direction, the baseball will exit the other portal with the same speed in the same direction.
From the perspective of someone inside the car, the baseball will enter one portal with a horizontal velocity equal to the speed of the car in the opposite direction and exit the other portal with zero horizontal velocity. This is because when an object exits a portal, it preserves its velocity relative to the portal. Since from this perspective, the portal below the baseball is moving with the speed of the car in the opposite direction, the baseball will enter the other portal with the same speed in the opposite direction.
As you can see, both perspectives agree on what happens to the baseball, even though they measure different velocities for the same object. This is because the portals are not physical objects that can move and interact with other objects, they are just openings in space that connect two locations. The velocity of an object that passes through a portal is relative to the portal, not to any other reference frame. This means that if a portal is moving, it will affect the velocity of an object that exits the other portal, even if the object itself is stationary.
Now tell us what happens when you smash two portals together with something in between them. 🤔
my shot in the dark is that the object would crash with its own edges
In "reality" I think the object would be crushed, and if the force moving the portals isn't enough to crush the object then the portals would just stop moving.
THIS is the question. Using the box as the example, I agree with the others - it would collide with itself. But what is hard to answer is if the portal act as a window, with no physical connection with the box, will it be able to meet the other portal and create infinite force? Surely that's impossible? But so are portals, probably...
In game world I'm sure the box would just go flying or teleport to a random coordinate, probably out of any feasible range and crash the game.
OP can you try this with a long pole, but the pole is on an angle, if at the right angle, surely the portals could meet since the pole would never collide with itself.
This is as fascinating as playing Portal was for the first time, thank you to all cause that's all I've ever wanted to feel again.
Edit: After thinking about it, it wouldn't be infinite force, but just a lot of force, or enough to collapse any object down to what I would assume to be a micro black hole? Too much mass in a certain space - which actually happens with stars etc... That seems reasonable if we allow portals to exist. I'm content with this theory.
@@EldeNova So.... The EASY answer to that paradox is to realize that the cube doesn't have infinite rigidity. If it can exert force on itself through the portals, then that means it's under compression. It will immediately begin to heat up. Depending on the material properties of the cube, it could crumble, crack, deform, or crush. If it crumbles, then parts of the cube will be expelled from between the portals. If it cracks, the parts of the cube will slip relative to each other, again possibly being expelled as a result. If it deforms, then mass will squeeze out the sides, again being expelled. And if it crushes, it'll get hotter. If the cube melts or vaporizes, see "deforms". If something somehow prevents the mass of the cube from escaping, then eventually you're going to trigger nuclear reactions and the mass will turn into energy, escaping from the trap. And yes: if somehow THAT'S prevented from happening, welcome to Black Hole City, population Cube, though the moment the portals move apart again it'll instantly vaporize via Hawking radiation and kill everyone around.
The COMPLICATED answer to that paradox is that you have to figure out where the energy to push the cube into itself comes from. The answer to that gets into some... pretty complicated physics. The short version is that moving the portals relative to each other must necessarily require the input of energy because it changes the geodesics of spacetime. (That is, there's potential energy bound up between the portals just like there's potential energy bound up in a ball at the top of a hill.) A realistic implementation of the physics would mean that a surface without a portal would be easier to move than a surface with a portal attached to it. And where does the energy to move the portal come from? From the piston attached to the surface, of course! So that means that trying to push a cube into itself would cause it to become harder to move the portal by AT LEAST as much as it would take to crush the cube if the portals weren't there. If the piston isn't strong enough to crush the cube, it'll stop moving.
Welcome to the Hydraulic Press Portal! Today we are going to crush... cubes.
If the object could fit side by side with itself, it would push itself out of the way and sit next to itself, and the portals would get closer and closer until the object couldn’t repeatedly push itself out of the way anymore.
once the object is balanced on itself or cannot fit anymore next to itself, then it would lay against itself and the side of the portal. The portals would be forced a certain distance apart but could be shifted together after overcoming friction to pass over the object infinitely.
To bring the portals together would compact the object, causing pieces to fall from between the portals.
If you smack the portals together really hard, I bet the air would begin nuclear fusion and blast the portals apart. This brings the question of what would be made if an atom fused with itself? Would nuclear fission be forced to take place if the portals were separated? Strange stuff.
Test idea: what happens when you halt the piston mid-way through the box?
If the box is being treated as a point (with a 3D hit box built around it), I imagine the box won't "jump" out of the exit portal until the entrance portal has crossed the box's reference point. If you treat the box as a bunch of infinitesimal boxes rigidly bound to each other, perhaps more interesting stuff can occur, like having only half as much momentum when it leaves, or being dragged by gravity due to half of the box being affected by it in different directions.
That's actually a great question. My guess is that he will simplify the problem and make the mass point like somewhere at the centre of the object rather than having it distributed. It sounds to me that having a distributed mass might be computationally a bit too much for a 64. But as you point out that would lead to some edge cases not behaving with the correct Physics while for the majority (where that simplification works well) he's got it spot on.
if the portal stopped halfway through the box you'd simply have half the momentum and so half(i cant remember physics its either this or a fourth) the velocity it would have had if the portal went all the way
Wouldn't the force be cancelled by the stopping of the portal piston?
While the engine would likely require changes to account for this, I also think it would logically exit at half the velocity:
If the matter inherits the relative velocity of the portals, and only half of it exits the portal, half of its matter inherits the velocity. The affected matter would continue to shoot forward and either pull the rest of the object along - and as the rest of the mass has no relative velocity, the object would equalize to about half velocity - or it would tear itself in half. This would be entirely based on the structural integrity of the object. If the bonds are strong (like a block of metal) they will stay as a whole object, but if they are extremely weak (like jello) it would be torn apart.
There is no momentum on the box as the box never moves, it is the universe that is moving ... Its a stationary box on a moving universe...
If the universe stops relatively to the box mid way the box will appear to stop...
That would mean interestingly that if the portal would stop at any time in the period the box is in the air after "Jumping" out it woul lose its aperent lateral velocity.
Now another way to look at it is... It's more of an information teletransportation. In that case every particle on the box gets deleted and recreated in its state including relative velocity vector. In this case the box would probably be shred apart as an instantaneous stoppage of the portal would produce an infinite acceleration capable of riping the box at the bond level that separate a moving particle from a non moving one..
First of all, appreciate the video length. Secondly - test your solution with the piston stopping half-way through the cube.
The way physics should work, the half that's already flying out of stationary portal should pull the still stationary half from the other end, losing a bit of energy. But would be interesting to see how it would actually work in the physics you coded.
it would depend on the vector of the exit portal and the speed of the piston. it would need to be enough force to pull the cube out of its state of rest and then overcome gravity. you could write this as a physics equation easily enough.
@@adultdeleted True. I was writing that assuming the rest of experiment is same (angles and the speed of the piston).
Would be interesting to play around with different setups, though. Like what if exit portal is stationary on the ceiling, i.e. facing same direction as the entrance. Then depending on combination of speed and what chunk of it goes through the portal the cube would either remain stationary or get pulled through... This could be a fun toy like 4D Toys.
Probably (in the engine) the cube shoots out if its center is through and stays in place if it's not
Logically, the entrance portal is rushing down and then stopping, so the cube should rush out partway but then suddenly stop when the entrance portal stops.
I think the trick is that portals only conserve momentum relative to the portals, not relative to the room. So if the cube is going through the portal a force on the portal to make it stop moving is equivalent to a force on the cube to make it stop as well. The same would be true if the entrance portal is stationary halfway down the cube but you start moving the exit portal around, it should drag the cube with it.
Typically objects in physics engines don't have mass density fields, but rather are point objects with discrete momenta. So it will either jump or not jump, but not half jump.
Funny thing about moving portals is that they are in portal 2 when you're using lasers to cut the neurotoxin tubes
And they are so frigging bugged
yeah they're also in the hydra DLC
They're not accelerating though. Earth is rotating at fixed speed so all portals are moving
@@pinwheelmotorbike Gravity is acceleration. So anything on earth IS accelerating as is everything else in the universe influence by gravity fields.
@Vaasref
I mean your conclusion is kinda right because relative to a fixed point in space earth is accelerating and so am I but saying gravity is acceleration is a gross oversimplification and the way you worded it implies that I am accelerating downwards regardless of the normal force from my chair right now… TLDR all motion is relative, including acceleration.
So, important question, what happens if you don't slam the entrance portal all the way down, but instead stop halfway through the cube?
in game, idk
Using real world physics, my guess is the top/front half of the cube will have velocity, because it's already through the portal, but the bottom/back half won't, so it's just about whether that velocity is enough to overcome the cube's inertia and pull the rest of it through. I'm not sure of the exact numbers, but it should definitely move at least a little... probably.
A good guess would be it goes half as far, but I suppose it'd need a test, to be sure.
@@Bluhbearyou are 100% correct. Let’s say the piston stops half way through the cube, it depends on how much the cube weighs obviously and how fast the piston is moving. Just like you said if the top half overcomes the inertia of the bottom half then the cube will go through.
If the piston stop 1/4th of the way at the top leaving the other 3/4th on the bottom, you’ll probably get the cube to do a little “hop” but not go all the way through the portal.
oh damn, thats a good point
I'm going to say that all of the replies explanations so far are wrong, though the results may be similar. Imagine not the orange portal moving, but the floor instead. What happens if you stop the cube halfway through the orange portal is almost exactly the same as if you move it all the way through (minus the bottom half of the cube still being in a different gravity zone for longer without being pushed, if you push it halfway through). So if you slam the floor with cube onto the orange portal, the speed is the same as when you slam the orange portal onto the floor as explained in the video, and if you stop the slamming halfway through the cube (minus the small correction as written) because the "slam" speed was the same. Ofcourse this correction is going to have a bigger and bigger effect as you go to an infinitesimal part of the cube.
@@woud3404I'll point out a small potential flaw in your logic; (but props! I wouldn't have thought this through all the way without reading your post) just that slamming the portal down from above and the floor (with cube) up from below aren't quite equivalent. When the portal is moving down the floor and cube are stationary with one another. When the floor moves the cube up it imparts momentum to it, which is all fine and well until the floor stops moving up, which from the point if view of the cube is like it accelerating downwards away from it.
If we look at the portal-stops-halfway-down case one would lead the to top half of the cube having velocity relative to portal, and converting that velocity to momentum upon exciting. This would impart half the momentum of a full portal drop, it would pop out the exit portal at half speed as the top half yanked the bottom half through. Maybe slightly more, actually. Between the portal starting to clip the top of the cube and it's final position the cube should start moving as portions of it pull 'upward' on the rest, causing the relative velocity to increase. This would make a great word problem for calculus students.
In the floor-stops-halfway-up case the cube would be entering the portal at the regular full speed, and as the floor stops gravity would act to deaccelerate it, but only the back half is still in a gravity-down zone, the front half is experiencing gravity as 45 degrees off from 'forward' (direction of travel). This would nearly cancel, impart some spin, and let the momentum carry the cube the rest of the way through at nearly full speed. Again, calculus for the exact answer.
portal 2 contains moving portals. you have to cut the lines to the neurotoxin and you do it using lasers through moving portals. it's the only implementation of moving portals in the series.
Well, theres also the in motion add-on
They're only enabled in that one room, far away from the player or any physics objects, because the developers were never able to get them to work properly. Moving portals in the Source engine are very buggy, and will fling things around that aren't even touching them.
True. This is achieved by changing the config settings when the map loads. You can always allow this using the command “ch_allowmobileportals 1”. However, portals cannot slam down on stationary objects, as the game hasn’t been coded to do so
Yeah, but they only move parallel to the portal, not forward and back.
you just gave me the biggest mindf**k of the day. cause until this time I just thought that the in game universe doesn't allow moving portals for some reason. now it all doesn't make sense
as some kind of physicists I strongly support this interpretation, the velocity of the cube relative to the portal should be what counts
It just depends on how you define the portal. After all it's a fantasy concept.
I would define it so it doesn't jump. Because in this version the portal would have to exert some kind of force on the cube to accelerate it, which sounds wrong to me. Also the laws of constant momentum would break down.
@@0ntimetaiment921 In order to understand the forces acting on the cube try changing your perspective slightly. Imagine you are standing on top of a moving cart going at an incredibly high speed (somehow not being blown off by the wind), and suddenly that cart comes to a stop. You would fly forward off the cart, right? That is essentially what is going on here, but the portal moving at the cube is turning the entire WORLD into that cart that you are standing on. Going through the orange portal means that you are "Suddenly not moving" relative to your previous speed so it flies "forward" relative to the blue portal. Another way to imagine it is to simply think about how it would appear in the blue portal should the orange portal envelope it quickly. Imagine the blue portal was on the ground and the orange portal enveloped the cube quickly. The cube would rise from the blue portal equally as quickly right? The cube would be quickly moving upwards and then come to a sudden stop with no momentum in the model you suggested.
@@0ntimetaiment921 Well since it's fantasy and everything goes, I'll say that whenever you go trough a portal you speed up to match earths rotation... because reasons😅
@@VaanOtacon Nicely explained. The model you describe definitely has some merit. But again: It's a fantasy concept, so it's a matter of taste. In your model the cube would still suddenly have energy in the form of movement energy which comes from nowhere. In the the cart example you gave, the person already has that energy since it is moving. With the portal the energy must somehow be transferred from the portal to the cube. But since the portal itself has no mass that makes no sense to me. Worse still: The force on the cube would have to be infinite, since is goes from not moving to moving instantly.
In my model (which is of cause also breaking physics) the portal does not interact with the cube. It is simply a doorway. The cube remains in its relative state to the world instead of the portal. So yes if the portal moves quickly over it, it simply appears in the other without momentum at all. It rubs you the wrong way, since you say "it moves but then suddenly stops". In my interpretation it would not move at all though. You would simply move the "doorway" around it.
Neither model is completely satisfying, since portals are inherently against the laws of physics. I guess it's a matter of personal experience and taste what put's you off more.
@@BxPanda7 Actually I once wrote a fantasy story with portals. And one day I woke up and realized exactly this problem.
And yeah. I just "solved" it by saying "it just works in this magical world, ok?".
And I'm not ashamed of that. It's either that or never ever writing fantasy stories at all.
EDIT: It's all about pushing the absurd to a point where it bothers people the least. Most people do not think about the fact, that earth rotates and the moved around the sun at absurd speeds.
Well, that's friggin cool. 😲
I'd also argue that in theory the orange portal should experience resistance when it hits the cube, such that it performs equivalent work to flinging the cube out of the blue portal. That conserves energy-though not momentum, because having portals facing different directions has already broken that permanently in this universe.
My position is that to properly use conservation laws through portals you must use the reference of the portal, in this case to conserve energy, velocity, relative to our reference, must remain constant at input and output (ignoring non conservative forces obviously) if we consider the portal as a system energy in must equal energy out… in any case energy is not conserved as potential energy can be increased with a portal eg perpetual motion machine using portal on floor and ceiling.
@@DracoTorment The object traversing the portals is ALWAYS the reference frame. Portals are only transformations of the vectors. If a person sat on the floor and the portal slammed down around them, they would feel acceleration and would fly out the exit. This is consistent with he person's interpretation; if they'd looked up, they would have observed the wall and ceiling careening toward them at speed, a sight consistent with them flying out the exit at speed. Further, we know the object's reference frame is the only view point we should examine because it is the object which possesses the momentum, velocity, and energy we are concerned with. The portals are just a boundary in space with an appropriate transformation that stitches space together at that boundary.
There ARE moving portal in Portal 2.
They're being used specifically in one scene in which you need to use a laser and a moving surface to cut through pipes.
Although I think I've heard there more of a hack and don't really work find with actual objects.
yeah, there is a command to enable them in any map, however he was talking about the original Portal, not Portal 2
those use hacks and mess up whenever theres an actual object
trouble is... those only move laterally, as soon as they rotate or extrude, portal's gone
All the portals are moving since earth and moon moove aswell
@@dopi3220 so true, god everyone’s dumb it’s like they don’t even consider the movement of the solar system relative to the Milky Way or the movement of the milky way relative to… ? on a daily basis lmao
Both examples shown feel so beautifully intuitive and natural. Love the work! Will there be a windows 98 port?
(let's start a chain of going to older and older versions)
Will there be a Windows 95 port?
@@tygical Will there be a Windows 3.1 port?
@@polorchen1592 will there be a Windows 2.0 port?
Why not DOS 3.3 with CGA, EGA, and VGA graphics options. Also don’t forget Roland MT-32, SoundBlaster, and pc speaker audio options?
A nes port??
So this is basically the same as the "shooting a cannonball from a moving car" experiment from Mythbusters.
Id love to see a video on "shooting the cube in to a portal where the exit is moving the same speed as the shot cube but in the other direction (maybe for when you imolement the bouncy pads (if you haven't done that already))
i like how you showed the results first. it really hooked me and made me want to see the rest of the video. super interesting !
So, lets say the portal lands on top of a human (really fast), but makes a sudden stop half way. Would then upper part of human (the part that has gone through the portal) be set in motion on other side of portal, and then pull lower part with it?
If speed of portal slamming down was fast enough, subject could be ripped in half. #Spagettification
Yeah, that is exactly what would happen.
@@james.lambert but would you get ripped in half though? If you think about it, the moment the first hair on your head enters the portal it's already pulling on your body. When your head is through, its already pulling your torso.
It's easier with "ticks" because you don't have to worry about individual atoms, but if you think about it an insanely fast portal might just rip you to shreds instead.
A portal stopping that fast might rip itself apart, too.
Yeah I always likened it to any changes in motion to a portal is like moving the entire universe on the other end of the portal. If you moved a portal (aka: accelerated a portal), you'd actually need to move/accelerate the whole universe along with it to match, unless the exit portal moved in a matching speed and direction to cancel it out. In "reality" you would be able to theoretically have a moving portal relative to its exit but it would have to continue moving in that direction and never change - absolutely no acceleration (no changes in direction or speed) would be possible as that would take infinite energy to do. Having the portal change direction or rotation would be akin to literally moving the entire universe on the other side of it. The reason is because of what you said, the person would get spaghettified if you went half way and then stopped. That's because the whole universe is suddenly 'stopping' (aka: instantly accelerating) on the other torso end of the portal relative to the other side of the portal that his legs are standing in.
Rotation of a portal is especially impossible; When you rotate a portal, the outer edges of the universe would be accelerating relative to your viewpoint at a rate of speed approaching infinity the further out you observe. If the universe is infinite then the rotation speed at the far corners of the universe also becomes infinite, and it would require not only infinite energy but also an infinite speed limit in the universe to move the whole universe on a swivel at infinite accelerations, as it must happen in order to conserve momentum between the two portals.
Also just to be technically correct, you can't have a moving portal anyway due to relativistic effects in spacetime. Spacetime is not uniform, so movements through it would not be a simple x universe moving relative to y universe, but rather you'd encounter shifting spacetime due to differing gravity at different points, and therefore even a totally uniform movement in one single direction relative to the exit portal would be varying all over the place, growing in differences the further out into the universe you look. For this same reason it would probably even disqualify a stationary portal just because of the immense energy required to reconcile the two reference frames - aka: the two 'universes' on either side of the portal.
Interestingly, the force between the two parts of the human would be directly caused by the portal's deceleration.
The next question would then be: What's the consequence of that?
Would a human/ an object that's halfway through a portal be able to hold the portal in place?
Would a heavy object sticking halfway through the portal increase the inertia of the object that the portal is attached to?
Would (as DeSinc conjectures) a moving portal have the inertia of the whole universe? I don't expect that: moving portals would not cause any effects, unless an object sticks through. But I would still not be 100% surprised if we figured out that portals that have objects sticking through would have infinite inertia while the object is sticking through; and in that case one _could_ argue that - since it's independent of the object - the cause isn't the object at all and all portals would have infinite inertia even when nothing is sticking through.
gosh, I remember this project when you were just testing out how much "depth" the N64 could render when looking at portals through a portal. this is amazing
haha I love that all of my favorite niche projects wouldn't exist if talented people like you didn't just do it for no particular reason but to satisfy your passions/obsessions. And the world is a better place for it.
Everything about this is awesome, I even love the included bloopers. And it's only a few minutes dang! Looks soooo good.
So if you throw a cube in a stationary portal while the other is travelling backwards at the same speed, you kill the momentum.
It looks very consistent to me.
No it wouldn't, the momentum would be kept. Rather, the distance traveled and trajectory would be altered.
@@Wild_Dice it's like jumping from the back of a vehicle at the same speed it is going forward
@@rogercruz1547 Yeah exactly, you inherit the *difference* of velocity (momentum and direction) between the portals.
@@rogercruz1547 exactly that!
I don't get it, the portal is just a link between 2 different places, it doesn't matter at which speed the portal is moving you remain unaffected by that, the only difference is that you get through the portal faster
valuing the viewers time and immediately grabbing my attention by briefly explaining its an N64 demake was such a good way to start the video to keep me hooked, well written and well done.
Isn't long form media also valuing the viewers time? I feel like my time was just wasted by a guy saying "my engine proves I'm right now complain in the comments"
@@pappi8338 To be honest, somebody could make a perfect video that has no loopholes in the explanation and somebody will still want to be the underdog and go "yeah, but" and get 1K likes.
So, are you expecting him to debate himself to save you the time of doing it?
He has an opinion and a logical argument to back that opinion, and he doesn’t hide the fact that he created an engine to do what cannot be done with the original engine, based on physics and relative motion.
Your argument is more of a “because I said” than anything in the video.
You instantly got me to subscribe by prioritizing my time before your retentionrate. Hats off. RUclips needs more creators like you.
Same.
So appreciative of you not baiting us with the answer, that I watched again months later after having forgotten the solution.
Personally I'm not very into physics but I understand GLaDOS saying that the portals do not affect momentum to mean that my momentum will never be affected by the portals. Otherwise the forces acting on different parts of me might be so different as I pass through a portal, that I might conceivable be torn apart by a portal falling fast enough, as each part that enters the portal suddenly accelerates into the portal.
Thing is, momentum is relative to your reference frame. If the portal is moving towards the cube, from the perspective of an observer moving with the portal, the portal is stationary and the cube is moving, so the cube has momentum.
Also in-game portals already change momentum. Momentum has magnitude and direction and the portals in the game change the direction no problem.
That's only true when the falling portal changes its speed quite a bit or suddenly stops.
it's actually the opposite interpretation that has this problem.
Say you have an orange portal that's stationary, and a blue portal travelling sideways at 1000 m/s. If you stick your head into the orange portal, this game dev's logic states that your head should poke out of the blue portal at 1000 m/s- you'd move along with it, so the most you'd feel is a strong wind whipping your hair.
However, if you don't think your body should inherit the momentum of a moving portal, then sticking your head out of the moving blue portal would cause your head to emerge at 0 m/s, as the portal flies away- (low-speed head goes in, low-speed head comes out-) snapping your neck clean off.
@@NotaWalrus1If you have a drone flying stationary and put an open window on the back of a truck and drive at the drone will it pass through and not move or will it suddenly ping off into outer space
@@Xtv1234I feel if you came out the back end you'd be perfectly fine and would just drop but if you came out the front end it would just blow you back in.
A lot of people's theories seem to forget air exists and is real and we aren't just surrounded by empty space void of atoms. The air would be going through too. You wouldn't just put your head through and have it suddenly be 100% different
"So... why am I demaking Portal for the Nintendo 64?"
BECAUSE IT'S FREAKING AWESOME!!!!!!!!!!!! I've been following that little project for a while now! Absolutely fantastic work!!!!!
"We do what we must because we can"
¯\_(ツ)_/¯
...why aren't YOU demaking Portal for the Nintendo 64?
Science isn't about why. It's about WHY NOT!!
i always thought of it as the total momentum of all three objects remaining consistent, so i figured the cube should stop, but admittedly i struggle to keep track of everything
I have the same idea. What happens to momentum here. The portal (or the object it is placed on) would decelerate giving it's momentum to the cube. But I cannot rationalize how that interaction would occur.
This was my thought too, but when I went to write out a comment about it explaining the math, I think I found the solution.
Newton's first law states that an object at rest stays at rest and an object in motion stays in motion, until acted on by an external force. But also, motion is relative. An external force acts on the platform to move it down towards the cube, so the cube is already in motion relative to the platform before it even enters the portal. When the cube goes through the portal, no additional external forces act upon it (aside from small ones like air resistance and gravity) so it retains the momentum relative to the portal.
This does seem completely illogical based on the laws of physics we know, but that's because our laws of physics don't allow for moving portals. If you imagine a similar situation in space, it might make more sense. If wormholes had no field of gravity, then an object entering a wormhole would come out the other side at the same speed it entered relative to the wormhole. It doesn't matter whether the wormhole or the object is moving, as motion is relative. No external force would have to act upon the object for it to retain its relative velocity.
@@mithrandireichner2667 The answer is basically that the cube doesn't actually accelerate and no additional momentum is required, so none is taken from the platform. The cube is already in motion relative to the portal as soon as the platform starts moving, it simply continues at the same relative velocity because no additional external forces act upon it to slow it down. It makes no sense with our current laws of physics, but, if wormholes area real (and traversable) our laws of physics are wrong anyway.
@@ayylith The way I see it, the system encapsulates the portals and the cubes. One side could argue that the *cube is moving* relative to the portals, but when discussing physics, or math, especially linear math, the discussion happens within systems. We could go on discussions about the properties of this system, but I'm going to ignore that for my comment. Assuming the system includes gravitation, that should logically include the exerting body of that gravitation. So the basis of this system is Earth, the cube and the portals. With both portals, gravitation is negative in both cases, so towards the basis ground of the system. This does not change regardless of any other factor. It is a fact, then, that the cube is resting relative to Earth and the portal is, in fact, the object that is moving. So it stands to reason to assume that the *portal is moving* relative to the cube.
So my interpretation of this problem more or less disregards the portals themselves as effect sources since the basis of the problem is the cube in resting position. The only thing that should really be affecting the cube is gravity, assuming the portals don't add, subtract, convert, transfer, etc in the process, and that itself is a question based in unrealized information of the *game's universe*, not ours.
@@mithrandireichner2667 From the cube's frame of reference the portal has velocity, but from the portal's frame of reference the cube has velocity. Relativity says whichever frame of reference you measure from the total energies involved are conserved (don't change over time), but that individual components of the system can measure different readings depending on the frame of reference you use. You can even use moving frames of reference such as the portal as long as you account for that movement.
We can simplify everything by measuring from the blue portal. And since when traveling through the portal the point in the middle of the orange portal is in the exact same place as the point in the middle of the blue portal (there is no spatial or time difference between them) We don't need to change to a different frame of reference, and therefore no adjustment is necessary (we'll call this point A).
The velocity of the box going into the portal, as measured from point A = the velocity of the box exiting the blue portal, as measured from Point A.
Thank you for respecting our time. just for that you got my like, subscribe, and loyalty to finish watching the video.
I am looking forward to your N64 Portal game. That sounds like lots of fun!!
Great job keep it up! We love your work!
Realistically wouldn’t a cube be stationary as if on a flat surface and only be affected by gravity, normal, and friction forces once out the other portal. I mean if you did that same thing but stopped halfway through the cube it would be odd for it to fly off the ground and gain speed from nowhere. Unless there are some unique portal physics I don’t know about. It’s a pretty cool video either way.
Portals aren't just doorways, but that completely redirect momentum for no cost. The only truth is that any velocity vector going in, is equal going out. To the Portals, an object moving towards the portal vs a portal moving towards an object looks exactly the same.
On the blue (exit) side, while the entrance side is halfway through, they see the Box emerging at speed. Once the entrance hits the ground, the box is still exiting at speed.
My theory is that a portal stopping half-way over a cube would cause it to partially fly off. Half the molecules of the cube would be stationary, half would be "moving", so the forces would balance out.
In-game, it would probably only matter if the object's origin or Center of Mass made it through the portal plane.
@@Appletank8 They redirect momentum but they don't create it. A portal is like a doorway, connecting two spaces in otherwise impossible ways
Portals do not thrust things out at specific velocities; they do to make the game work of course, but all they do is connect space
I do not see how he cube would gain any sort of momentum from a portal falling over it. The space through the orange portal is dictated by where the blue portal is. And even if that space is rapidly changing, there is no force causing the cube to move
@@100Darkspine technically going from a low portal to a high portal creates potential energy outta nowhere. that's why you can make perpetual motion out of a floor/ceiling pair.
Anyways, the only rule of portals is that if something enters the portal at speed, it will exit at speed. In order to exit a portal at all, you need some sort of velocity, otherwise nothing happens. From second 1 to second 2 of going through the blue portal, the box has a noticable change in position, therefore it now has a speed, Distance/time.
There is no way for the blue portal to tell the difference between the entire room moving at constant speed towards the portal, vs the portal moving at constant speed towards the box, so the results will be identical regardless.
@@100Darkspine
The portals are not creating the momentum. The cube already has momentum relative to the orange portal. Expecting it to stop once it leaves the blue portal is expecting its momentum to change for no reason.
“Moving portals aren’t implemented in portal”
That one random moving portal level in Portal 2: 👀
What level was this? I don't remember
@@LotharLivewhen you destroy the neurotoxin with lasers
Iirc, that’s a matter of just changing a single value to allow for it, but the logic required for the portal paradox isn’t implemented, as it was never intended to be used outside of that set piece.
So instead of either result happening, the box doesn’t go through. I may be wrong, this is just going off of what I remember.
@@MasterHyperionMC if the portal paradox was correct, moving a portal at a laser would accelerate the photons in a laser beyond c.
@@xelgodis80085 Ok? I feel like I’m the wrong person to say this to, given I didn’t actually express an opinion either way.
Honestly this makes the most sense, velocity being based off both the portals and the object
This video is absolutely correct in all regards.
The thing that people are missing about slamming down the portal that's blue on one side and orange on the other (the second experiment here) is that the orange and blue portals actually have the same velocities as each other, they're just also pointing in opposite directions. It's easier to think about the portals as having an in vs. out reference frame, rather than up vs. down or any other kind of reference frame.
If blue is stationary and orange moves toward the cube at 5 m/s, the cube will enter orange (in) at 5 m/s and exit (out) blue at 5 m/s. But in the experiment the "out" direction of blue is effectively moving at -5 m/s, not zero.
For another example, think about throwing a baseball. If you're on stationary ground and can throw a baseball at 20 mph, your throw makes it go 20 mph in whichever direction you threw. If you're on a train moving at 20 mph and throw it in the same direction as the train is moving, someone standing still will see a baseball moving at 40 mph. Conversely, if you throw it toward the back of the train (away from the direction of motion) a stationary observer would see the baseball stop and fall straight to the ground.
In all cases you have moved the ball in the same way relative to your own motion, but outside observers (us) see very different things.
To bring it back to the cube example, imagine instead that both portals are on vertical wall pieces, with the orange portal moving toward the cube which is sitting stationary on the ground. The blue portal is on a different section of wall and moving backward at the same speed that the orange portal is moving forward. Any motion conveyed by the orange portal running into the cube would be cancelled out by the backward motion of the blue portal.
The orange portal is essentially "throwing" the cube at 5 m/s, but it's on a moving train (the blue portal) and so it just stops and falls to the ground like the baseball.
What happens if you stop the moving orange portal while the cube is only halfway through? Would the momentum of the cube coming out the blue portal make it so the cube gets sucked inside the the orange portal and out the blue? If it doesn't go fully through, would it at least jump up a little?
I wanted to see this too!
I think that the cube would stop moving when the portal stopped moving, that's almost entirely based on my own intuition though
here's my hypothesis (at least in a real-world physics sense, no idea about his engine): in the instant the orange portal stops, half of the cube has had the momentum transferred to it, while the other half hasn't. therefore, the cube will only receive half of the momentum! the non-moving part gets pulled along by the moving part, and the moving part gets slowed down by the non-moving part. so, it'll still be launched, but only half as far!
I think it would still get launched, just not as far, like if you threw a ball, but stopped your hand halfway.
in-engine, it will probably either move or not depending on which side the origin position of the object stops at. in the real world or a physically accurate simulation, the momentum would be imparted in proportion to the weight of the object on either side of the portal
@@axollyon Agreed. For completeness though, if the cube could deform, the resulting tension would actually _stretch_ the cube.
Bro really just said that relative velocity is the same as conservation of velocity and then broke conservation of momentum. EPIC!
actually the conservation of momentum stays true because relative to the space outside of the exit portal the the cube is actually moving so as its coming out it gains momentum making it fly off
@@MommysGoodPuppy Couldn't you also say that the space relative to the exit portal is moving towards the cube? The global velocity of the cube is still 0 and relative motion only describes motion from a particular frame of reference
The interesting question isn't what happens when portals move linearly (because that's not a paradox), but rather what happens when they stop or change velocity.
To get an idea of how that could work, we can look at how reference frames work.
When a reference frame is accelerating, objects in that frame appear to accelerate in the other direction.
When a reference frame suddenly snaps to a different velocity, objects appear to receive an impulse.
Logically, you should therefore apply a force/impulse (relative to the portal's reference frame) to anything on that side.
For example, if the cube is being shoved through a moving portal and the portal stops, the portion that sticks out should keep going, while the part that stays behind should stop.
In reality, this would tear the two sides appart, but assuming it could survive, you would add up the momentum of the two parts to get the new momentum of the whole cube.
The more of it is sticking out, the faster it will fly away, since less of it is being held back.
I subbed because you did the most kind and generous thing a RUclipsr could do: the selfless act of getting right to the point.
The hula hoop analogy and your explanation for how it worked was solid and earned my subscription!
also "i value your time more than my retention rate"
simply based.
Absolutely. I got about halfway through the video, sure that the answer was A, and spent about 30 minutes thinking about it, looking it up, and reading the comments before I understood why B makes more sense. Then I resumed the video and he answered it in 30 seconds lol.
Except it's wrong. We've actually demonstrated this as false as we've created "white holes" for qubits that instantly communicated information over distances and didn't impart any extra energy when doing so.
All you're doing is taking the outside of a window and moving it somewhere else. Just as if you had stuck your hand through a window you would not get flung through it, the location of the exit is all that changes. If you drop a hula hoop over yourself you are not flung out the other side.
Not only does he lack a basic understanding of inertial frames of reference and light cones, but he's asserting that the universe has an inherent "orientation", or an up and down locked to one position in the universe. This is a very stupid idea postulated by flat earthers, and has been debunked at every turn.
@@xelgodis80085 lmao, it must suck to be so conceited you can’t finish a video before rage commenting. You literally just used the hula hoop example that the video proves is different from the Portal Paradox.
@Scottish Cheese except both he and you don't understand inertial frames of reference. If his model held true, light itself would be accelerated through a portal, which is stupid to say the least. It's a white hole, and the laws of thermodynamics are conclusive about the effects of a white hole, and have been demonstrated in real lab settings.
That you lack the fundamental knowledge to begin understanding *why* you're wrong isn't my problem. Grow up.
It's incredible what people can do, people would do such great lengths to make it possible, I love it every inch of it.
its crazy how when i notice a video is gonna wait til the end to show results i just skip, see the results then leave the video, but here seeing the results first made me wanna watch the entire thing and i would have watched a whole 20 minute video going more in depth about these physics and complications. amazing video with out using predatory tactics 10/10
You, sir get a instant like and subscribe for
a) not waiting with the result towards the end of the video
b) making the video as long, as it needs to be
c) seeming like a good youtuber overall
You could show a case where the blue portal isn't directly above the yellow but is still moving down to show the effect as well.
I would say the issue with this discussion is the difference between momentum and velocity. If you're basing your coding on velocity, then the cube should move at the same relative speed as the slamming portal, but if you're basing on momentum, as the orange portal can't impart any energy to the cube, the cube should just fall out, based on the possible position of the blue portal.
Agreed, and I feel that the velocity is also a bit of a red herring, since it assumes both sides of the portal are the same frame of reference, which I don't think is a simple answer.
My thoughts exactly. His setup violates conservation of momentum. I reasoned it out slightly differently though. If we assume that slamming the portal down on the cube launches it through the other portal, then there must be some force applied by the portal to the cube. If this force is proportional to the speed of the portal and points through the portal in the opposite direction of its motion, then the hula hoop example will actually launch the cube into the air!
@@1925683 not quite, as I could be reasoned that in the same way the orange (down) portal imparts energy to the cube, it could be argued that the blue (up) portal could rob it of the energy, and that addition/subtraction of energy could be based relative of the two portals position in space/ velocity/momentum.
@@1925683 even stationary portals violate conservation of momentum. if you throw a cube down into a portal and it shoots out horizontally from a portal on the wall then momentum wasn't conserved
the hula hoop example is fine because you still have the cancellation of the motion of the exit portal and the cube being pushed through
Nope. e=mc² applies in both scenarios. Speedy thing goes in, speedy thing goes out. It does not matter how the relative speed came about. In fact, the portal paradox is nothing more than people arguing against relativity.
It does not matter if it's the cube moving towards the portal or the entire planet being lifted up to the portal by a piston. The difference in speed remains the same. The only argument there is room for is whether the game is programmed with realistic physics or inconsistent and arbitrary ones. And in my opinion, any portal mechanic that doesn't impart momentum in such a scenario has sloppy programming if momentum is supposed to be preserved between portals.
Your explanation really makes sense!! Awesome video and project, thanks!
Subscribed entirely because my time was respected. 3 minute video for a 3 minute topic. Love it
I like to think of the portals in this game as doors
There is no delay whenever you teleport and you can see exactly what's on the other side with also 0 delay, so the portal isn't a physical object and more of a concept, a rip in the fabric of the space-time.
... If an open door comes at some object's direction at any speed it wouldn't be launched. the door's momentum wouldn't add up with the object's because they aren't even interacting.
Your "open door" idea is the same as the "holahoop" idea, but sideways, as shown the box did not move when it was hooped. The issue is one half of your door frame is moving while the other half is stationary, so spacetime shenanigans happen.
@@starburst98 "The issue is one half of your door frame is moving while the other half is stationary"
but in 3D space if you keep looking through the portals while they are moving they still act like a single stationary door, sure the FRAME is moving, but the portal (connection between both frames) isnt, the connection itself is static (in 3D space at least).
I think this movement would result into velocity in a 4th dimensional axis, but idk how it would translate into 3D movement
Correct! This is easily checked by placing two portals so that you can see yourself walking through.
Your explanation is spot on.
What this guy did, was to rewrite the Portal universe in a way that makes his hypothesis is the solution, essentially.
He didn't actually solve anything.
Portal 2 actually has _two_ examples of a portal on a moving surface. When we shoot a portal at the moon at the end of the game, it's easy to forget that the moon is actually moving substantially fast relative to the Earth. The moon portal is moving like 4000 km/h relative to the Earth portal, and yet when Chel and Wheatley enter it they aren't suddenly launched off the moon's surface at mach 3.5. The portals preserved their relative speed, as in this video.
Here’s the second example of a moving portal
ruclips.net/video/mCQiwhik8nc/видео.htmlsi=eNjSeNuZoeoGpVRC
@@ThePokeGod That's actually the one level in the entire game where they intentionally enabled the moving portals mechanic
Still: the movement is faked. It's just paralax, the moon does not actually move in engine
But that's an EXIT portal. The Entrance portal is "almost" stationary compared to Chell so there is no "speedy thing comes in" predicate. All checks.
surely they didn't actually model the relative orbital speeds of the Moon and Earth for that so that.
Portals are basically kinetic energy / potential energy translations. If you have a velocity difference between them, it translates onto the object passing through. An object passing through a portal higher than another is just an object going through an instantaneous PE adjustment in the form of space displacement . A moving portal is basically a KE translation, which necessarily involves a velocity difference between frames of reference.
This is the best reasoning I found so far, nicely said!
why do we imagine that a portal separates spaces and if the portal moves, then its space moves? It always seemed to me that the portal only teleports objects while maintaining their kinetic force, only in the case of the game Portal this force rotates at the angle of inclination of the portal itself
@@TheDEFCHER If you put the portal at a higher altitude, you already have a change in potential energy, and if you consider that velocity also varies according to how far away it is from the center of Earth's rotation (or when faced on a completely different orbital body like the moon), it will also necessarily need to have a change in velocity which also requires a change in kinetic energy.
When you go out of the moon portal, you do not get flung at the speed difference between the orbital speed of the moon and the velocity of rotation of the Earth, which is a difference of several hundred kilometers per second.
There's really no argument, just unwillingness to see that potal physics would just be too inconsistent otherwise.
I have a full watch and like after the highlight was right at the start. Neat video and the logic seems spot on for the tests.
My issue is that the hula hoop analogy is always how the portals work. They're just holes, the ends just happen to not physically connect. There's no reason for the energy of the portal to be conferred to the cube. Momentum is conserved between portals as well as the lack thereof. All of this with the caveat that I flunked out of high school. Regardless, loving the progress on the project, can't wait to see more!
I think if one portal moves, the other would have to move, too. The energy transfer from the portal to the cube seems to be a trick that gets around the space/occupation constraint on the other side.
Normally the entrance portal is static. This means forces acting on the cube have to push it through the portal. But if the portal moves, how is there going to be enough room on the other side, if the cube is not moving? I think the relativity trick is just a trick.
Or the portals are actually atom rematerializers.
@@user-zu1ix3yq2w I just assumed these things were like Loony Tunes holes.
Portals convey energy to what passes through them all the time. If you simply place a portal above another portal and pass an object through it, then it has just magically gained energy via passing through the portal. After all think about the times when you place a portal on the floor and ceiling of a room and fall infinitely. You continuously build up speed because the portals are in effect conveying energy to you by granting you more potential energy than should be possible.
Momentum is conserved through portals, but energy is not. Similarly if you go through a high portal to exit at a lower elevation, you will have effectively destroyed energy as well. Portals by their very nature allow you to create and destroy energy at will.
@@BlazeMakesGames In your example the energy isn't coming from the portals, it's coming from gravity. With nothing to slow an object down, gravity will cause it to accelerate through the portals until it's stopped. The energy is not magically gained. Momentum *is* energy, and is conserved through portals, but the portals themselves neither add nor take it away from the object.
Right when you talked about the "hula-hoop" analogy, it made sense. Everyone proposes the paradox when only taking in consideration the entrance portal, never the exit.
While they make a womehole while in tandem with one another they have their own unique positions in space, be it speed, or direction. Which does make a lot of sense.
My next portal paradox, is what if you do this across lateral direction, while moving?
So, imagine the portals are like the window of a car.
but, because the portals exist unconnected to two different inertial reference frames, then what occurs outside the blue portal, is not connected to what occurs outside the red portal.
So lets imagine you have a stationary red portal. And a moving blue portal.
If you stick your arm through the red portal then your scenario is best described like this.
Everything inside the car, is the red portal. The car is stationary and not moving.
Everything outside the blue portal is sticking out a car window. It is moving relative to the rest of the world. (Great - this explains that you will feel wind on your arm).
But what happens now, when the "blue portal" car stops. Well, in a normal car your entire body would feel a decelerating force and would struggle against it.
The parts of your body in "Red space" are in a stationary car, so those parts feel no decelerating force.
The parts of your arm in "Blue Space" now want to keep moving forward, while the blue portal entrance slows down. But, the tube of your arm in red space is connected physically to the tube of your arm outside the window in blue space.
So now, your arm in red space "Pulls" on your arm in blue space (in the direction of the deceleration the blue portal is undergoing). Your arm in blue space wants to keep going, but the blue portal is changing the acceleration, and applying that via the portal boundary.
Assuming the deceleration the blue portal is undergoing is low enough that it doesn't tear your arm off, you would decelerate your arm to the same relative velocity of the blue portal.
IE, in short, your arm in bluespace would "feel heavy" in the same way that your limbs feel heavy when you slow a car down. And your body (which is strapped in via seat belt or whatever) "pulls" your arms to the same relative velocity of the car. But in this instance, your body in redspace doesn't feel the deceleration, only the arm in bluespace does.
Haha thank you for clearing that up!
There's nothing applying force onto the cube itself...
Portals are basically wormholes... You're treating the ends of the portals as two separate entities, when they're one and the same.
If we're using the logic used for the angled portal, then it should have been shot out the top when it was in the hula-hoop orientation. Simply by adding rotation (180° rotation in the hula-hoop example), doesn't add velocity.
IF ANYTHING, what would occur if the portals were theoretically wide enough, is that you'd be stuck in a constant state of free-fall, until you gained enough momentum from the gravity and/or air pressure on the "stationary" end of the portal, to reach the edge of the portal.
Think of it like this. Assume you're floating in space. And both ends of the portal are 1km wide, and the orange end is moving at you at 100km/h. And the blue end is moving in the opposite direction at 100km/h as well. You'd be in a constant state of free-fall until you gained enough momentum to reach the edge of the portal. Remember, the portals are one and the same, the physical space between each end is arbitrary.
In this, the portals act like a small scale black-hole, requiring you to increase your momentum beyond that of the wormhole in order to escape. The wormhole isn't imparting momentum onto you.
@@notmyregret No, it isn't. But you already had momentum when you went in.
it always makes sense. its a easy physical behaviour. it was never paradox or a problem
Thanks for making this video. Editing and brevity 10/10
Your care for my time… this little convenience for the viewer, thank you and enjoy the sub. Excited to see more content 😎
I've always wanted to know for sure what would happen if a person/object was between two moving walls, both with portals on the surface, as they move towards the person/object from either side.
My belief is the person/object would make contact with itself on the sides facing the portals and then crush itself - though the physics are hard to imagine, because if the portals went perfectly over them/it, then in theory there'd be no resistance placed onto the walls to prevent them from fully closing and having the person/object perfectly pancake themselves imbetween.
Others believe you'd somehow stumble into some kind of imbetween portal space, though I believe this doesn't add up, because they're portals and not wormholes - there is no space between one portal and the other which one has to traverse to reach the other side.
Generally in a case like this, any theory that violates physics is probably wrong. Sometimes a theory makes no sense but the math all checks out, and it turns out to be true. The mystery then is figuring out why it works that way. In this case, I feel like pancaking something between the portals is probably wrong, as is the in-between space, as neither seems consistent with what we know about physics. A more logical outcome is for the object to exert a force that prevents the walls from closing completely. How is anyone's guess, but it probably depends on how exactly portals work in the first place. Or something else might happen, which would lead to new discoveries in physics.
@@Greywander87 Perhaps some kind of force would be exerted on the walls when the two portals reach the edge of the person/object they're simultaneously closing in on - but that would rely on the portals themselves being receptive to resistance, and them then also transferring resistances onto the surface they're on - imo that doesn't add up logically.
E.g. if you had a portal on one unstable and loose wall (say an office wall tile) which someone is primed to run and jump through, and a portal on another wall which is solid, and then you seal that portal off by placing another solid and immovable object infront of the portal the person would be exiting from, the person moving through the entrance portal would be meeting that object blocking the exit portal, exerting force on that - both the portals and the walls they're attached to encounter no resistance or force.
Imo this is why a person stood between two portals moving towards them would simply be pancaked by themselves by a force that encounters no resistance from said pancaking - it would in theory work with infinite mass but relative velocity.
I feel like, it'd be the same as imagining that your left and right are copies of you, being pushed towards you, then my right shoulder gets pressed against the right copies left and vice versa. They keep pushing more, with deadly force and all 3 of us (tho we're all just 1) are squashed
I think the most intuitive way to answer these questions is to convert the problem into an equivalent one where the portals do not exist. If you were to instead have two people stuck between what is essentially a hydraulic press, then yes, they would be pancaked.
This technique helps solve the subsequent question of whether the portals would need to exert additional force to pancake the person - they would, since the press would. This conclusion is supported by the requirement of energy conservation, as energy must be expended to deform an object.
@@the1necromancer I think you're overlooking the fact that the portals are the whole point of the thought experiment though - they don't obey any known laws of physics, hence why it's so interesting to speculate how a portal (as depicted in the game) would function in ways beyond what is demonstrated - it's more about intuiting the information about how the portals work that we already know - they're not wormholes, they're seemingly without a physical presence themselves, they're simply magical doorways which can be dynamically relocated.
The moving walls with the portals on their surface would provide the velocity at which something is pancaked between them, but they don't tangibly interact with anything except the surface they're placed on (they stay relative to it) - the surface doesn't experience any resistance or impact or any sort of force from an object passing through a portal on it - therefore we have to assume if two portals simultaneously moved across either side of a person meeting in the middle of them, that the person would be crushed by themselves in a manner where no resistance is experienced by the walls (unless part of the person sticks out beyond the surface of the portal.)
this is sick! glad this got in my recommended, this sort of project is right up my alley. looking forward to more.
VERY good explanation! Adding the hula hoop analogy really helped make this make sense for me.
He’s wrong. All the energy of the movement of the portal is absorbed by the ground. None of that energy is converted to the cube because the portal functions as a hole. The only scenario where ur logic makes sense is if you’re telling me the entrance to the portal has viscosity creating friction, which is never even remotely implied in any of the games. You use similar (but really not) experiments to justify your logic, when u should be using actual physics instead. Unless this video was purposely meant to be wrong to cause controversy and get engagement.
2:10 Yes! Exactly. Relativity says that your implementation is correct. Well done sir.
You had me the moment you told me you valued my time more than your retention. Subscription inbound
What I find weird about it is that it implies when you move a portal, you're effectively moving the entire world towards the opposite end
but that's how relative speed works, doesn't it?
yes it doesn't make sense, the object should maintain the velocity relative to the plane
this is a big issue people are trying to solve about "how would a real wormhole act"
as it is simply a tunnel from one point to another based on general assumptions and maths - and by that, moving the tunnel, if it were to serve for instantaneous traversal, would likely yield a similar result
and the way a portal's function is described is not entirely dissimilar from a wormhole, and in fact, people study the idea that maybe portals if achieved like this in real life would actually be wormhole technology.
@@KingOfRedPlays I'm a bit curious. What is more realistic, a portal that is simply a hole and has an exit somewhere else? Or an actual tunnel with a bit of length to it?
@@amitbar5691 I don't know... For the cube to shoot out like that, it must have made a pretty big impact. And I mean, the impact doesn't have a limited range, after all, or does it? It has to be the entire universe colliding with itself, unless there's a logical error in my thinking. Maybe this is actually realistic given we accept the idea of portals, but it seems to give portals a ton of power that goes beyond traversal which doesn't seem to fit the use case they've been assigned in-universe
Then I think it also gets even weirder... because if it works like this, then the entire gravitational force of the planet must have an effect through the portal onto itself, so frankly, I can't imagine that it could possibly physically work like the way he coded this
bro the texture of the paint on the wall and his skin as well as his shirt and arms are literally so similar that I thought there was a static filter applied to the entire video.
watching this was trippy as all hell.
Thank you for not making a 23 min video, talking about literally everything else before getting to your point. You’re a good dude
What bothers me about this problem and this solution is: what exactly gives the velocity to the cube?
From the cube's perspective, what pushes it away from the floor? Does it suddenly feel a force upwards and away from the portals? How does the Orange Portal transfer it's velocity to the cube if it never even touches it?
Say you place a portal on a ceiling and another on the floor and you drop a cube into it, allowing it to fall infinitely. As it passes through the portals it keeps picking up speed and if it wasn't for air resistance it would in fact pick up speed forever. Where is the energy coming from in that process? You might say gravity but no amount of height would allow you to fall at speeds reaching the speed of light within earth's gravitational field. No the portals themselves convey energy to objects that pass through them simply by their very nature of being able to transport objects to disparate points in spacetime.
But to give a more practical answer, the cube essentially pushes off of itself and the floor below it. Looking at purely the blue portal, what you would initially see in slow motion as the orange portal descends, is a small portion of the cube sticking out of the blue portal. Then a moment later more of the cube would be sticking out of the portal. But that would mean that the first portion of the cube would have to have moved out of the way in order for that to happen. Essentially the lower portion of the cube is pushing the higher portion forwards in order for it to exist the portal. And then the next portion does the same and so on and so on. By the time the cube fully exits, the entire cube is moving at the same velocity as the orange portal.
@@BlazeMakesGames No, it wouldn't keep picking up speed. The energy comes from gravity, that is a fact. You're in freefall, like jumping off a cliff, but you keep teleporting back up. The portals are doing absolutely nothing. The cube would reach terminal velocity and it would just keep falling at that same velocity. There is a limit to the speed. If we were in a vacuum, and you tossed a cube into portals that faced each other, the cube would keep the velocity you threw it at, because there are no other forces acting on it. If none moving portals did act on objects going into them, then everything would be shot out of stationary portals equal to the amount of force they exhibit. however, the portals do not interact in that way. They do not interact with objects going through them.
Portals are more like doorways. If a moving wall with an open doorway came towards you, and you go through, are you inheriting the wall's velocity? The difference here being the space on the other side, and how the forces on the other side interact with you, not the portal.
@@BlazeMakesGames By your definition, if you even touched a portal, it should suck you through it. On your gravity example, if you had infinite height, with a constant acceleration due to gravity, an object would speed up to its terminal velocity. This is what is happening in your example. This just can't happen outside of portals because A: get too far from earth and gravity decreases, and B: get too close, and the ground stops you.
The portals really just move one location in space to another, they don't pull objects through themselves (unless one is in space, sucking objects in because of the pressure difference).
@@ianwalsh3868 So portals work literally like doorways.
@@fantastikboom1094 Yes, that's my understanding.
I’m really torn on this, I may lose sleep over it, thanks for making it in N64 though, keep up the good work!
Probably the best way to think of this is that as the cube emerges out of the exit portal, it has to travel 1 cube width from just poking out of the exit portal to being fully out, and so relative to the exit portal it is moving at some speed, and therefore it has some momentum to keep moving
Love the idea, and love the fact you made a short video instead of making us lose our time :)
he still did. it was never a paradox or a porblem if you know physics. normaly you learned this in the 5th grade... but since people forget things, they think "it must be a paradox" if they initttially thinked wrong.
I actually appreciate you using the logic of conservation of momentum to solve the portal paradox. The portal moving over the cube at, say, 60mph, is no different from the cube moving into the portal at 60mph. This is very logically sound and I appreciate your approach
that's why it's not a paradox, it's solved by a fundamental law of physics lol
It is different, by the same logic a cube going 60mph not losing any speed from going through portal proves that portals have no mass, thus a portal colliding with a cube shouldn't increase its speed
I tried explaining this to my dad, he disagrees because the box didn't have energy to begin with. I told him to watch this video later, so hopefully I can win the argument through this video.
@@lasadaf5336 The portal is attached to a piston, which does have mass, therefore energy that can be passed to the cube.
@@lasadaf5336 Portals also create and destroy energy, so really they can behave however people want them to behave.
But you can also think of it that in order for the box to actually come out of the blue portal at all, each part of the box that comes out must be pushed out of the way by the next part of the box coming out behind it, and this will happen at the same speed that the orange portal moves over the box.
I guess it depends on how portals work. I always saw them literally as doorways or hula hoops so it would work the same way as literally just passing a cube through a hula hoop, meaning that the hoop has no effect on it at all?
Except for the part where you missed the point
@@DWal32be nice
@@DWal32says the guy who seems to have forgotten that the entire thing is a thought experiment and portals already break fundamental laws in physics, so OP’s interpretation is just as valid.
@@Scuuurbs says the guy who forgot that other fundamental laws of physics, i.e. gravity, still apply, thus this logic is flawed. Appling the same logic as the opening of a container to the openings of a wormhole is the only thing that makes sense.
You’re doing what to portal with N64?!! You can best believe you’re keeping me here for the whole video
Where does the energy to move the cube come from? Does the piston feel resistance as it transfers energy to the cube, so as to launch it?
Sounds right. reminds me of Tom Scott's video on that unconventional auger wherein the tube and its openings are spun, but the auger itself remains stationary yet still elevates grain.
Also when you think about it, on a cosmic scale, all velocity is relative.
The Wuffle house has found it’s new host
Just a nitpick, the physics of the rotating auger aren't the same as the physics of the stationary auger with rotating shaft, I believe the grains will move in distinguishable ways and have a different stress distribution. This is because in Newtonian mechanics rotating reference frames are non-inertial and so aren't related by such a simple transformation. Fictitious forces such as coriolis forces and centrifugal forces appear in them. Read about Mach's bucket experiment. In an idealized Newtonian (non-relativistic) universe, spinning the entire universe around a bucket won't cause the water to form a parabolic curve on its surface.
unless its light, that speed is absolute
But surely both the exit and the entrance to the portal are a part of the same object, so the second portal is moving towards the cube in your example even though it looks as if it is stationary.
I thought the same thing too.
Even though the two ‘portals’ are in separate areas of space relative to us.
But the portals occupy the same space-time area allowing them to be portals
The thing here is that while they are both moving at the same speed towards the cube, one of the portals is facing the other direction, so its velocity is technically reversed. The negative velocity and the positive velocity cancel each other out, so the cube remains neutral.
What you should do is run this with the blue portal on the floor. The block shouldn't jump out of the vlue portal if the math is correct.
@wolfofsummerbreeze if the blue portal is on the floor stationary, and the orange portal slams down, the cube will jump. It's the same as when it junks from the blue portal at an angle...
@@CastToFall because it treats the floor as a rising platform? I suppose...
subbed for n64 portal, because i need more n64 games.
also this format was phenomenal, the perfect paragraph to get the point across.
looking forward to see more!
Nice work! I liked that you expressed the solution mathematically. I always thought of it from a calculus perspective ie if you take infinitely many slices of the cube as it enters the portal those slices must maintain their linear distance from one anther. Therefore as the slices are entering the first portal they must exit the second portal with the same linear distance over time. This can also be expressed as velocity relative to the second portal. It also accounts for changes in speed ie acceleration
I like your approach. That was exactly my logic when I first thought about this paradox
I’d love to see how your game engine handles the orange and blue portals both moving but at different velocities, i.e. the orange portal moves down onto the box while the blue portal is elsewhere moving at a different velocity than the orange portal (and perhaps even at different angles to see what affect gravity plays). Particularly if the blue portal is moving in the same direction as the orange portal, how does the cube handle going from one to the other when they’re different speeds?
He did it already! the first experiment that is shown is exactly that. as you can see, the angle of the blue portal is not the same as the orange, and both move at different speeds, all that will happen is the speed of the cube will vary in the exit following the equation he proposed
While both portals were moving at different velocities, one portal was _not moving_ at all.
@@DWal32 Mathematically that is just a different speed though. Going by the equations shown in the video, only the relative velocity of the portal and object matters, so varying the speed of the blue portal only changes the resulting speed of the cube as it flies (or plops) out of the blue portal, maintaining the relative speed between the cube+portal system.
@@DWal32 In terms of the math involved that really isn't important. Combining the two velocities and changing their vector would work the same way, just with different magnitudes of velocity input and thus different magnitudes of velocity resulting.
the implementation already handles that because it uses the relative velocities of both portals so you can work out what that would do very easily
Great video, man. The first of yours I've seen. I like your non-sensationalist, calm approach to editing and content! Keep it up.
What kind of content do you watch that is sensationalist lol? You and I have two very different experiences on this platform
The fact that he had to make a nintendo 64 mod and a whole video about this is kind of hilarious. Great content. Perfect length.
No arguments from me. You are spot on. It's like being on a moving surface 10m long that goes at 10mph in one direction and you run along it at 10mph in the opposite direction. When you reach the end and the surface disappears beneath you there is no forward momentum. You will drop straight down because you will have been occupying the same lateral position in space at all times.
It's the same when you drop two back to back portals over a stationary object. It will enter the down facing portal at the same speed as it exits the upward facing portal. Both portals will also be moving downwards at the same speed as the object is travelling through the portals. The position of the object relative to the space outside the portals will remain the same. Exactly as if you dropped a hoola hoop over the object.
Super cool approach to this paradox! I see eye to eye with you
I sincerely hope you make this into a fully fleshed out game. Would love to play this on the 64!
Fun video! I love demakes so I'll be here!
What would be really interesting (but I don't think it could be feasibly implemented) would be the question of how much force does it need to move the portal. Because at least in my mind, that's where the energy for the cube movement comes from.
I've never even had N64, but I'm still impressed by this project. Keep up the amazing work! 👍
This is super impressive stuff, props my man.
Super late response, but I think the answer to this squarely sits on if you believe the space in between the portal can enact force onto the cube. For me, I see the portals as a mere translative motion across space, so I would say the only force on that cube as it leaves the blue portal is gravity. So I’d say it plops. But if you see the portal as a movement arm that pushes the portal out at the same velocity the arm moved onto it, then it’d launch as shown.
The box already has momentum relative to the orange portal. That momentum is carried through to the other side, which is why you see it launch out the blue portal.
@@APaleDotIt has momentum, but I believe that gravity acts against it, so it would result in a slight hop at most. After all, the acceleration that tbe box experiences should be equivalent to what would happen if you moves the tile that the box is on upwards at the same speed that the portal travels down and then suddenly stop. It would hop, but not as far as if it were launched at an angle.
@@darthplagueis13
The original question doesn't specify how fast the orange portal is moving. The implication is that if you answer 'A', the cube will **plop** out of the blue portal regardless of how fast the orange portal is moving.
I typically don't like or comment on videos, however I respect the fact the this guy got to the point and didn't drag out the video. I also find his solution to the moving portal questions to the best answer I've heard.
AWESOME VIDEO, PERFECT... short and stright to the point.
Another way to think about this, imagine if you are standing in front of the exit portal and looking through it. From your perspective, the cube is accelerating towards you at high speed. So it wouldn't make sense for it to suddenly stop when passjng through the portal and just flop out
The hula hoop example is really great
I'm curious now what would happen in the same test, but the ceiling portal doesn't slam all the way down, but instead like halfway down over the cube. Would the bottom half of the cube get 'sucked' up into the portal? And then the cube shoots out of the other portal anyaay, but at half velocity than the full slam down or something? Would be cool to also know why as well, if it does indeed work that way, or whichever way it works really.
I like it. If the rule is velocity is preserved between portals, if one portal is moving and the other is not that velocity needs to be preserved.
The only situation that I think might be weird is you do the reverse. Where you try go through the none moving portal to the moving one. You might not have enough speed to get through a stationary portal and may get shot backwards.
Not velocity: momentum.
@@darkcoeficient momentum=mass*velocity
We know that mass must be preserved through the portal in order for it to be a portal therefore velocity is the parameter we care about.
That's why his calculations don't consider the mass of the object at all, just their relative velocity. Not there relative momentum.
Suggestion/Question: In your version, could you remake the demonstration done in this video from a few years ago?
ruclips.net/video/0TZd95BCKMY/видео.html
A portal sandwich type scenario is both a common thought, and is also not an easy thing to intuit, and I am curious if you would yield similar results as they did. I'm also not sure if their method (from Portal 2 which does allow moving portals in one level) would work for testing the portal paradox, but would be interesting to see if you could implement it and compare your results from this video.
ruclips.net/video/zDAE9A_1NA4/видео.html This minutephysics video gives a satisfying answer to the portal sandwich situation.
i imagine it would prevent the portals from getting closer to each other than the height of the cube, as I would think weirdly the two opposite sides of the cube would be pressed against each other. would be cool see if this actually happens though
Yes!
Please crush yourself between two portals.
It would simply be an unstoppable force vs unmovable object paradox, I'd think.
@@DrowGM exactly this. It's all about normal forces and inertial reference frames.
3:16 started speaking Russian for a second Библиотека
2:35 I hadn't thought of that and completely changed my mind on how the paradox would go. Makes total sense with conservation of energy in a system.
he didn't solve that problem though. and he also didn't solve the problem of conservation of momentum.
I prefer to think about this as a conservation if momentum problem. The cube has no momentum because its not moving, when the portal passes over it it is now acted on by gravity in the new portal reference plane. This would cause it to plop or roll out of the portal, noting that the motion would start after the cube's center of mass is through the new portal. This also solves the problem of what happens if the moving portal stops part way, you just apply the balance of gravity that is acting on the sections in each portal and see what happens.
Yeah I was watching this wondering where the transfer of kinetic energy happens.
@@adrianpg4460 Your first example doesn't prove your point - in that example I am staying still and the door and room are moving relative to me, to someone in the room it appears that I am the one moving - that's from their reference plane. To an outside observer I am clearly staying still and the wall slams into me, I don't slam into the wall.
The portals connect two points on the same planet - they share a reference plane. So in the reference plane of the moving portal, sure I would be moving, but in the reference plane that the moving portal, the fixed portal, and I share (the earth) I am not moving, so I won't flung out of the second portal.
I contend that this is still a conservation of momentum problem because we all share the same intertial reference plane so energy must be conserved.
@@adrianpg4460 The real answer is that many smarter people have hashed this out online for years and there are good explanations for either behavior. The correct answer is whichever version the developer prefers for gameplay.
I love this change up in the structure of your content, and I am so happy to see your project come so far 😁
I think it is introducing some dire consequences. If "cube" has some more traction with the surface (glued, welded, etc), there is potential to tear objects apart.
Also, normally, objects are getting momentum in some natural ways based on their structure/joints, but if the portal is the thing that you are getting momentum from - momentum passing to some 2d slice of an object with is potentially can break it internally.
This would of course be true regardless if the weld/glue/bolts/fasteners by any other name were too weak. That by itself though wouldn't necessarily prove this unsound. Would just mean that if something was weak enough to be moved, it would be moved. Portals rarely care about fasteners anyway, see GLaDOS about all the cameras I knocked off her walls
The issue is not in the cube though. This comes from the portal suddenly stopping after it slammed down.
If the cube were on a pillar the portal could continue downwards, with no damage to the cube. Only when the portal stops moving you introduce an acceleration between the two frames, potentially causing a break in the pillar.
The real issue is thusly not relatively moving portals, but relatively *accelerating* ones
My argument for why the cube wouldn't shoot out of the portal is, no momentum is being transferred into the cube. My first introduction to this was with a moving train barreling towards the cube with a portal in the front. In this scenario, the portal is approaching the cube at high speeds, but that momentum belongs to the train. The train doesn't loose any momentum when it encounters the cube, so it cannot impart any momentum to the cube when it passes through the portal, therefore the cube maintains it's momentum, similar to how a falling object maintains it's momentum through portals.
I thought the same say until i looked at what happens to the parts of the cube that pass to the other side of the portal. as it exits, any part of the cube already through has to make way for the next so it would result in a force being applied and a reaction force onto where the cube is sitting. The paradox is that with the frame of reference of the first portal and the cube, the cube shouldn't have any momentum but from the frame of reference of the 2nd portal and the parts of the cube that pass through there must be momentum. people are arguing so much about the portal paradox because it is just that, a paradox that doesn't have an answer in this universe.
the cube not shooting out is just not possible. what would the alternative be? the cube turning into an infinitely thin square at the exit portal? and the momentum of the falling entrance portal just dissapears?
@@kannix386 Probably a boring answer, but I would imagine it would just come out the other side of the portal, then, slowly fall as gravity acts on it. I imagine the portal is like a door frame. If I dropped a door frame around you, you wouldn't go shooting out the other side.
@@Tismitch I think I get what you're saying. Like, if the cube has no momentum, then isn't it going to just end up all stuck in the same place on the other side?
That's not how I see it though. Think of a portal as a hula hoop with it's exit and entrance disjointed from one another. If you stand with this imaginary hula hoop around you, your torso will appear on one side of the hoop, while your legs appear on the other. Now, imagine someone drops this hula hoop down onto you. You now go through the hoop, and reappear on the other side. You do not fly up into the air, because the kinetic energy from the hula hoop falling was all absorbed by the ground, not you.
bro, a thing can't come out of something without moving.@@Petronio39
Thanks for the quick explanation.