Was GLaDOS Wrong About Science? - Momentum & Physics in Portal - Extra Credits

portals a triumph in fact we're making a note here huge success it's hard to overstate our satisfaction but aperture science while they do what they must because they can might not be espousing proper physics lessons to all of us no matter what glado said but there's no use crying over some possible mistakes and we should keep on trying to make science less opaque so our analysis will be done with a physics lesson we hope is fun for the people who ever wondered if portal's rules of momentum and energy could ever hold up in real life we promise there's cake at the end [Music] to help us think with portals please welcome back this week's writer astrophysicist and star trek science consultant erin mcdonald thanks aaron portal while a phenomenal game tends to make physicists go a little crazy what with its quantum tunneling selectively destructive material emancipation grills or well everything about the hard light bridge but one thing that might make real world sense is its use of momentum and energy to

solve muscles but does it so we thought it would be fun to explore these specific principles and learn more about them through the lens of our favorite puzzle shooter we first have to discuss the concept of momentum momentum is the property of an object in this case humans cubes turrets etc that combines the mass and the velocity of that object and if you want to change an object's momentum you're first going to have to overcome its inertia which is basically a fancier term for newton's first law of motion an object in motion stays in motion and an object at rest stays at rest so really inertia is the resistance an object has to changes in its momentum specifically changes to its velocity therefore the amount of zappy grabby power technical term that your portal gun uses when it picks up a cube is determined by that cube's inertia how much it doesn't want to move now i know glados would appreciate this next question what do we mean by move well that's where we have to define an inertial reference frame aka an area where an object that doesn't have any forces acting on it

doesn't change its speed but since the earth is rotating at a constant speed and we know that portal takes place on earth we can say that within the walls of the aperture science lab we can use a standard inertial reference frame so as far as testing is concerned we define this inertial reference frame when we walk into each test chamber and as such momentum must be conserved because momentum just can't be created or destroyed and it has to be changed or transferred from one form to another this principle is called conservation of momentum which leads us nicely into conservation of energy the physics law that aperture seems to toy around more with than our own sanity it's a law similar to conservation of momentum in that it states energy in a system cannot be created or destroyed but only transferred or changed states so with all that in mind the tldr is when you walk into an aperture science test chamber that room is your closed system and the total momentum and energy in it is fixed when a cube is dropped from a dispenser it doesn't really seem any different than a cube sitting on the

ground creating a portal on the ceiling and one on the floor under it causing said cube to fall through and pop out from the ceiling because i mean that's how gravity works right but this is where the conservation of energy is important for both potential energy energy an object has due to its position relative to other objects usually height and kinetic energy the energy an object has due to its motion when a cube is sitting in a dispenser it was being held at a height giving it potential energy and then when it drops we get that energy transferred to kinetic energy as the speed increases and the distance above the floor decreases before hitting the ground but when a cube sits on the floor of a chamber according to our inertial reference frame we defined the chamber itself its height is zero therefore it has no potential or kinetic energy even though the down direction gravity pulls doesn't change in the test chamber with the ability to build a portal underneath the cube sitting on the ground again height equaling zero and a twin portal on the ceiling you've immediately created energy out of nothing because now the cube has

potential energy which in our current understanding of physics is impossible also when you're on the top of a platform and you make a portal in the floor that will carry your momentum or kinetic energy once you pass through it to whatever twin portal you've made regardless of where it is that instantaneous change in direction while still maintaining your speed as well as the creation or destruction of energy based on your height off the ground breaks all of the laws if we're just treating portals as simple holes to jump through and in that way portal just doesn't violate the laws of conservation of energy it obliterates them like a poor companion cube lost in an incinerator so sad so there you have it while portal's incredibly fun gameplay relies on our intuition for how momentum and energy work in order to solve its puzzles it actually ends up violating those exact physics laws and of course this doesn't make the game any less enjoyable to play through or explore it's just fun to call out glados for trying to have her sciency cake and eating it too or um you know we could be wrong and uh your science

and tests are perfect on my signal we run look a bird but we did just break the rules again legendary patron roll call ahmed ziad turk alicia bramble casey muestia dominic valenciana gunner clovis kyle murgatroyd and o reels one thank you so much [Applause] [Music] you