A Portal to Physics: Conserving Laws

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[Note: This piece was originally going to be called “The Physics of Portal, ” but I’ve decided that that would be inappropriate.  If you’ve played or completed a Portal game, you know how the game works.  In no way am I trying to teach you how to play.  This post is for the curious.  If you’re genuinely interested in physics and love Portal, why not learn about physics and read about Portal at the same time?]

The wonderful thing about Portal is that even though the player is given several physics-defying tools, Valve tries very hard to make sure that the basic principles of Newtonian mechanics are followed wherever possible.  In this feature, we briefly examine a few topics in physics that pertain to what will be one of this year’s most beloved video games, Portal 2.

The Portal:  Neither Here Nor There

We clearly don’t have the technology to create a portal gun.  Even if we did, it would be a more primitive form of teleportation.  Theoretical physicist Michio Kaku believes that in the future, we will be able to teleport water molecules to the moon as scientists have already been able to teleport atoms of simple elements from one place to another.  Unfortunately, this type of teleportation requires destroying the original copy of something, sending information about this object’s make-up somewhere else, and re-building it from scratch.  This would be very sketchy for humans considering the number of cells (and within them, atoms) that make up a human body.

The teleportation technology in Portal lies way beyond our means (for now) and is deeply embedded in the realm of science fiction.  When you think about how you’ve interacted with portals in the game, you have to appreciate how the folks at Valve give Isaac Newton a nod in their attempt to stay true to classical mechanics — that is, once you get by that first big “hump,” the portals themselves.

The conservation of mass is one of physics’ most fundamental rules.  Matter can neither be created nor destroyed.  We see this in the game as Chell is free to jump through portals and transport cubes from one place to another.  Whatever goes into one portal comes out the other.

More importantly, not only do portals conserve mass, they also conserve life!  Now, it’s possible that some of you are thinking that the portal gun just creates wormholes, but this isn’t the case.

If you were to sit in on an upper-level, undergraduate lecture about wormholes and general relativity, there’s a good chance that a lot of the discussion would revolve around the Einstein-Rosen bridge (also known as the Schwarzchild wormhole).  In short, this type of wormhole is a bridge between two points in the space-time continuum:  a black hole at the “entrance” and a white hole at the “exit.”  These singularities suck up and spit out matter and radiation, respectively.  Space-time is so warped at the mouths of both singularities that there would be no way to survive being stretched out like that.  And even if you did survive, you probably wouldn’t survive on the way out.  God wouldn’t be able to protect Chell near the event horizon (read: point of no return) of a black hole.  Even assuming that prayers travel at the speed of light, God would not hear Chell’s cries since photons can’t even escape the pull of a black hole.

So, no.  The portal gun does not create wormholes.  Would we be able to harness Aperture Science’s technology and create their kind of portal?  Maybe someday.

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Author: Ryan Gan

Ryan is Managing Editor and Reviews Editor of SideQuesting. In 2004, he began writing about his video gaming experiences in a blog at 1Up. He began writing for SideQuesting upon its inception in the Spring of 2009. Ryan is an educator by day and writes critically about games by night.

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  • Excellently written, Ryan!

  • matias echevria

    great article. it´s a great point of view on portal 2, different from what has already been said about it.

  • Isaac

    I was expecting something better to be honest. It built up but never really went anywhere. Yes. We know how Portal works, but you should have gone into theories about what the portal gun does rather than just say “LOL SNOT A WORMHOLE BRO”.


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  • Dude, this is incredible.

  • Gevth

    What about energy conservation? If you were on ground level, and put a portal 4 stories high, wouldn’t it change the potential energy of whatever went into it, without changing other energies, like kinetic?

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  • alltheparts

    tl;dr version:
    Speedy thing goes in. Speedy thing comes out.

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  • Wow, I wish normal Physics was this fun. Great article!

  • cobyrne


    As mentioned in a comment above, the law of conservation of energy apparently does not apply in the portal universe. Referring to the “flinging” example from the article; when entering a low portal and exiting from a portal above, kinetic energy is maintained and potential energy is added. This is impossible, unless that potential energy is coming from somewhere.

    In Portal 1, as part of the story, you are required to destroy a companion cube to continue. There is no convincing reason why the companion cube should be destroyed other than as part of GladOS’s ongoing mind game. But what if there was another reason. What if the Aperture Science developed a way to generate energy that involved the “companion” cube. This would explain the quantity of cubes being moved around the facility, as well as the need for their destruction.

  • zach

    Any movement at all through a portal (in any direction) breaks the law of conservation of energy. The object passing through the portal is “disappearing” from all of the fields that surround it (ever particle in the object is being acted upon by gravitic, electromagnetic and nuclear fields “emanating” from every other particle in the universe). When an object “ports” (moves from one point to another without crossing the intervening space), it’s potential energy due to all of these fields changes; that energy (the net change is microscopic) is just either lost or created from nothing.

    The portals also appear to violate the light-speed ceiling (you can never place portals far enough apart to actually test this in-game).

  • Billy D williams

    This was not a well written. What’s more, it’s dealing with a middle school level understanding physics that everyone should already have. I mean what sort of research did you do for this piece exactly? None would be my guess.

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  • Maybe. But I like to think that it’s better written than the sentence that you lead off with in your comment.

    I’m not going to get into what I think I know about physics, but I do know a few things. For example, I know physics isn’t offered in middle school. Secondly, I didn’t write this piece for people who have degrees in physics. I wrote it for people who don’t know that much about physics, were curious about it, and enjoyed playing Portal.

    Could I have written something more complicated? Probably. Know why I didn’t? I didn’t because 1) I’m not a pompous douchebag and 2) not everyone has a physics degree and wouldn’t be able to follow.

    If you want big, fancy words, go open up a dictionary.

  • Wesley Johnson

    I can’t believe Billy D Williams spoke to you like that after you were nice enough to pay to get your picture made with him. Whatajerk!?

  • Billy D, Billy D, all of America is dying to know …

    How’s that dick taste?

  • Henryhbk

    Why does this teleportation violate the speed of light? If your warp space your relative velocity is the same as you have only travelled say 1m in your warped space, while those places may be 10 meters apart to all other observers. The snail crawling across the piece of paper takes 10 minutes. Fold the opposite edges so that the paper forms a loop with the edges next to each other. Now the snail can get edge to edge in 1 minute. the snail still crawls the same speed, but gets to his destination 10x faster.

    A portal is a door essentially which means it is a warp between places rather than star trek style teleportation.

  • jimmy


    What about in the end of Portal 2 when you shoot a portal on the moon from the earth and immediately end up on its surface?

  • QuantumBunnii

    I agree with Billy. Notwithstanding the fact that this is based around elementary physics (that, in any case, was already explained to you by Glados: ‘speedy things go in, speedy things go out’), you also seem to completely ignore *their own* explanation for the prospects behind the Portal gun. In the game, they refer to it as a “Quantum Tunneling Device”. I’m going to have to assume this passed over your head; otherwise, you’d have acknowledged that Quantum Tunneling is a real-life quantum teleportation phenomena. This, I believe, is what this article (or anything akin to it) should have been written on.
    Virtually every game follows fundamental newtonian physics. This article was dissapointing.

  • Ryan Gan

    Yes. I don’t remember it being referred to as a Quantum Tunneling Device, but you’re probably correct. If I did, I probably would have thought about discussing tunneling. I’m sorry for disappointing you.

  • sth128

    Portals may conserve momentum, but it certainly does not conserve energy. By virtue of its ability to violate the first law of thermodynamics, its existence in reality (in the future or any other time) is extremely unlikely.

    Consider this: place one portal on the floor and one on the ceiling, then drop an object through it. You will now have given said object free potential energy. In essence, you have created a perpetual motion construct in which you can harvest free energy.

    To put forth an example of the above idea, if you placed a water wheel at the edge of the floor portal, then run water through the portal, you now have an infinite waterfall. Connect the waterwheel to a generator turbine and you can basically draw power from it forever until the Earth gets disintegrated by the Sun.

    Come to think of it, maybe that’s what they’re using to power Aperture… That would explain why there’s so much water around.

  • I’ve noticed the use of physics with a lot of Valve games. They incorporate it really well.

    Thanks for the write up!

  • Tony

    In 1963, New Zealand mathematician Roy Kerr proposed the first realistic theory for a rotating black hole. The concept hinges on neutron stars, which are massive collapsed stars the size of Manhattan but with the mass of Earth’s sun Kerr postulated that if dying stars collapsed into a rotating ring of neutron stars, their centrifugal force would prevent them from turning into a singularity. Since the black hole wouldn’t have a singularity, Kerr believed it would be safe to enter without fear of the infinite gravitational force at its center.

    Maybe the portal is a Mini-Kerr Ring? Food for Thought;)