Portal 2's Most Broken Glitch

There are a lot of cool glitches in games - and they usually have some cool, but usually complicated explination that goes with them. However, there's one glitch in Portal 2, that just makes no sense...

Music used (in order):
Super Mario Odyssey OST - Steam Gardens
Quantum Conundrum OST - Spring Is In The Air
Ducktales (NES) - The Moon Theme

Videos referenced:
@MinutePhysics - "The Portal Paradox"
spidda - "Portal 2 | Propulsion Catch FIRST 24.70 (Former World Record)"

Thanks to baister09 for helping with the video creation process.

This video is not an actual speedrun world record, nor a speedrun tutorial. This video is a showcase of a speedrun strategy that goes in-depth to the various tricks, glitches and bugs that make the strategy possible.

[dabord]

"hey everyone, cave Johnson here. just wanted to let you know about something. DO. NOT. MAKE. CHAMBERS. WITH. MOVING. PORTALS. For some reason, the physics when it comes to going inside of a moving portal is extremely broken. Our scientists are still scratching their noggins about why this thing keeps on happening. If you ever see one of these, just let that anomaly of a wormhole alone and live a lot longer."

[Woot]

there's something really delightful about how this glitch is mostly only useful in post-wheatley-takeover chambers. it's as if he's so terrible at managing the facility, the very laws of the game break down

[tylerk]

I find it so endearing how so many speedrun categories have rules that are put in place because the glitch/skip "isn't fun"

[friedchickenUSA]

interesting. i didnt know moving portals were only a console command away. id always thought that moving surfaces were unable to support portals because their physics change every frame or something.

[Bingle]

I facepalmed incredibly hard when you explained that all you have to do is go to the main menu. As a programmer myself, it's such an understandable oversight, but so obvious once realized

[yyu]

it's not that the feature is incomplete or broken, its the fact that the physics around portals is simply bugged. you cannot have ropes through portals for instance. in portal 1 they do the security cameras in a very clever way; when it passes the portal, the cable is despawned and respawned afterwards. or teleported.
prop_portal always been buggy, especially in portal 2. that's why the paradox attempt didnt work, it might've worked if the cube was placed perfectly center in the portal, at best. in addition to that, certain surfaces may make portals respawn when transitioning between static and moving.
pretty great video as always through. kudos

[maxis_scott_engie_maximov_jr]

10:02 "You shoot a portal and you win"
He literally explained the entirety of Portal series within one sentence

[Fabelaz]

0:30 Ah yes, the chamber that I couldn't complete because I thought no moving portals was an actual game mechanic. I still feel betrayed.

[solarsyrup]

Since the moon is always orbiting the earth, doesn’t that make the end of portal 2 a moving portal?

[rd_ctrlr]

This is the real answer to the moving portal problem, obviously. As the portal approaches the cube, the cube is immediately shot backwards out of the way just before the portal contacts the ground

[thewhitetophat]

Msushi is almost verified, crazy progress, feels like yesterday when he was just 16k

[PloverTechOfficial]

Klooger said: “you shoot a portal and you win?” Yeah that’s the point of the game

[alexanderchippel]

I do really love how Wheatley just smashes two tests together and they always seem to have a solution.

[PortalPlayer]

"That sign can't stop me, because I can't read!"
Portals - 2011

[thechroniclegamer]

I think the speed boost is because of the velocity of the player, and since it reached over a certain number, it sets the velocity to around 15 (ish) launching you (it’s used in the cave Johnson level)

[nickoates]

1:08 this is the best displate ad - possibly the best youtube ad period - i've ever seen.

[AceLeach]

8:18 hey it's the triple laser test chamber guy

[demartian]

In the “portal paradox” the answer is B (in an ideal world where portals aren’t limited by the game’s programming).
If you think about the from the cube’s perspective, the portal moving towards the cube at a constant velocity is exactly the same as the cube moving towards the portal. We already know that momentum is conserved between stationary portals (“speedy thing goes in, speedy thing comes out”) so the same should be true of moving portals as well. And from the cube’s perspective, it had 0 momentum both before and after, but the entire world just dropped out from under it at the same speed as the portal was moving.
Think of it like stepping out of a moving train, but the train door is just the portals. From the perspective of the people on the train, you had no velocity before you stepped off, and no horizontal velocity after you stepped off, at least until you hit the ground. From the perspective of someone on the ground, you had the same velocity as the train both before and after you stepped off. From your own perspective, you had no velocity, and the entire world except for the train is moving around you.

EDIT: Now that I've thought about it a bit more, I will admit that it is a lot more complex than I initially suggested. If we say the blue portal is moving down and the orange portal is stationary (relative to the room), then from the perspective of someone looking through the blue portal, the entire universe is moving towards the cube, and then suddenly stops when the portal hits the platform. From the perspective of the someone looking through the orange portal, the entire universe (including the cube) is moving towards the portal and then suddenly stops. So now it depends on which end of the portal is moving relative to the universe, and because all movement is relative according to Einstein, that question is impossible to answer. Since objects can't accelerate or decelerate without some force acting on them, I think the best explanation is that, while a portal that was created while it was moving does not cause any problems, having a portal accelerate or decelerate relative to the other is what causes the paradox. Because acceleration requires force, accelerating one end of a portal would require the same amount of force as accelerating the entire universe (which is a lot). So if you shot the blue portal before the top platform started moving, then you just wouldn't be able to move it. And if you shot it while the platform was moving, then the portal would crush the platform beneath it and tunnel through the Earth until it came out the other side and continued into space forever.
Slightly unrelated, but this also made me question whether forces can be applied through portals. Like, if I placed a portal on the ceiling and then another one on the wall, and stood next to the one on the wall, would I fall through it due to the gravity from the other portal. If no, then that means the other fundamental forces (electromagnetism, and the weak and strong nuclear forces) shouldn't apply either, so walking through a portal will basically cause all the atoms in your body to fall apart.

0:53 its only a paradox when you dont understand how gravinertia works. That example doesnt show the exact angle of the portal. But it would probably just roll our the blue side distance depending on the speed of moving portal

[gummycubez]

The portal parodox doesn't take into account that when the portal comes down, more of the object will appear on the other side because of the fact that the portal is further down on the object. It wouldn't inherit the momentum of the object because it's not moving, even if it appears on the other end of the portal rapidly. There is no kinetic energy to transfer as the portal is technically not a physical object, however it will fall out of the other end of the portal due to gravity's effect on the box pulling it out and downwards from the sloped portal that it comes out from.