Portal: The Real World

So, on to a real post.

To be honest, if there was a single trigger that made me sign up here, it was Shamus Young’s blog. I realised I’d like my own space where I could just put up ideas and analyses, and if someone had the time, a discussion. This post is largely a response to his post about portals in the game ‘Portal’ and how they would work in real life so as not break the laws of physics (if that’s even a valid task at this point considering we’re talking about portals). The issue has already been discussed in detail in the comments there, and the game is several years old, but dammit, I’m going to have a go, too.

The first order of business is to decide what the portal is. For example, is it a pair of discs, that, on contact with matter anything with a relative velocity towards the opening, transports that matter whatever to the matching disc, and ejects it with a velocity relative to the second disc that is mirrored in it’s towards/away component? Terribly long question, I know. Or is it, simply, a hole, whose two sides happen to be quite far away? Note that I’m no longer specifically talking about Portal here, as that game says ‘screw it’ for purposes of fun. Which is good.

The problem, according to Shamus, is that if one opening is higher than the other, you could send an item through the lower one, have it emerge from the other, and have it interact with something on the way back down, say a water wheel, you could get free energy. Which is a big no-no. That energy has to come from somewhere. Now, a two-disc approach has the advantage that everything is relatively discrete, that is, when A happens, B happens, repeat. Any energy gained in moving from one to another can be paid by whatever is maintaining the discs, or the link between them. A hole, however, is more problematic. While it may take considerable energy opening the hole, does the hole stay open whatever? Does it need ‘closing’ or will it self-entrophise?

Gravity is the issue. The further away from an object (such as a planet) you are, the less it pulls on you, but the further you can fall towards it, gaining speed (mass is also an influence, but as long as the mass of the two objects is the same, they can be removed from the equation). As you fall, accelerating, you move faster, gaining kinetic energy. This comes from potential kinetic energy, which is lost as kinetic energy is gained. As you fall, you are also getting closer to the planet, giving you less room to accelerate further, so there is less potential energy.

A portal that gets something from down low, and puts it up high, has given it potential energy. That energy has to be paid for. However, that’s not the only issue. If the portals are not aligned in space, the object will also change direction. Newton’s laws state that an object cannot change speed or direction without external forces. Using force will expend energy, depending on the size of the force, and the amount of time it is applied (this is called the impulse). Also, objects of mass aren’t the only things going through these portals. Light is, too, and if photons/waves can pass through a portal, so can bosons (little particles that serve as messengers for forces). Assuming that gravity is a force (about which there is some debate), there is this point, up in the air, that has the same pull as the point low down. The portal above is going to start sucking the air in. Or is it? Air pressure below is greater, will it push through the hole, down the pressure gradient? Will these phenomena cancel out?

I have a partial solution to all this, but it’s getting late, I’ve been typing well over an hour, which is not what I want to spend on this blog, and I’m getting tired, so it won’t be as coherent as I’d want. I’ll post my solution next time, as it’s cruel to have you read all this and abandon it.

See you then,

Adam

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