While playing Portal 2 I encountered several drawings on the walls:

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Something about someone getting shot, companion cubes, people choking on poisonous gas and Chell doing nasty things to GLaDOS.

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Something about Schrödinger’s cat (?) and mathematics that don’t make any sense to me.

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“The bell invites, hear the turret, for it is knell. That summons to heaven or to hell.” Apparently this is a Macbeth quote:

"I go, and it is done; the bell invites me. Hear it not, Duncan, for it is a knell That summons thee to heaven or to hell."

How it relates to the game however is a mystery to me. So does anyone know what the story behind them is and what they mean?

  • 8
    That math actually looks like physics to me. I see formulas for radiation and the like.
    – user56
    Commented Apr 24, 2011 at 17:17
  • Any idea what it might be about?
    – Ivo Flipse
    Commented Apr 24, 2011 at 17:18
  • 5
    Not really. Although, Valve has always put random formulas in its games. Half-Life, Portal, even Team Fortress 2.
    – user56
    Commented Apr 24, 2011 at 17:35
  • 7
    The math on the left in the second picture is relativity related, while the top right look like QM Commented Apr 24, 2011 at 23:48

8 Answers 8


The drawings on the walls were done by the Rat Man (real name Doug Rattmann), a schizophrenic former employee of Aperture Science. He was convinced GLaDOS would continue to try to kill Aperture employees if switched on, and so took precautions when GLaDOS was 'fixed' and reactivated, thereby surviving GlaDOS flooding the Enrichment Centre with a deadly neurotoxin. He manipulated the order GlaDOS chose test subjects to put Chell first, as Aperture/GlaDOS had identified her as being abnormally tenacious and thus unsuitable for testing (hence the bell curve); his hope was that she'd be more capable of frustrating GlaDOS than he was.

The images you see around the portal gun are a retelling of the events in Portal; Aperture turns GlaDOS on; GlaDOS floods the Enrichment Centre with a deadly neurotoxin; Chell resists GLaDOS's cakey temptation and destroys her, and is put into suspended animation.

Most of his handiwork is from after his pills ran out. Not all of it is logical.

Edit: also, see acmshar's answer for the significance of the equations the Rat Man's scrawled on the walls.

  • 5
    Guess I should ask who on earth this Rat Man is then ;-)
    – Ivo Flipse
    Commented Apr 24, 2011 at 16:19
  • but whats with the moon abowe the portal gun and the tenacity graph?
    – user9368
    Commented May 7, 2011 at 8:33
  • 1
    @kacsa The tenacity graph, also seen in the comic, explains that Chell is so extremely tenacious as to be originally excluded from testing; she was "hacked in" anyway.. As for the moon, it's a foreshadowing of... things to come.
    – badp
    Commented May 7, 2011 at 10:46

Merus' answer is great for covering the reason for the writing (and especially for the third image). I want to clarify what some of the equations are in the second image.

From left, the first equation (starting with t, and including the equation below it starting with gamma) is referencing Time Dilation (Special relativity).

The equation above that is Schrodinger's Equation for a Single Particle in a Potential Well.

The bottom right equations are Maxwell's Laws

The right hand equation is a wave-particle's momentum

The bottom left equation is the time independent Schrodinger equation.

  • 12
    I wish I could give you rep for being able to identify those. Awesome job. Commented Apr 25, 2011 at 6:04
  • 2
    +1 I was just about to post this same thing, before I saw this answer... with the caveat that the equation in the lower-left is again the time-independent version of the Schrödinger-equation (notice there is no t...). They just replaced the potential energy with c^2/v, which I think is just nonsense because the units aren't correct. I also have a few other nitpicks, I'll fix them up if that's alright with you. Commented Apr 25, 2011 at 23:24
  • I have no problem with edits. I've changed it to the time independent version.
    – acmshar
    Commented Apr 25, 2011 at 23:47

They're drawings/"instructions" by the "Rat-man", left for Chell when she wakes up.

The full comic is available at http://www.thinkwithportals.com/comic/

  • 5
    The comic is also viewable from within Portal 2, in the Extras section (at least in the PC version).
    – sjohnston
    Commented Apr 24, 2011 at 17:16
  • 2
    @sjo, does that just open up a webpage in the Steam overlay to the above URL?
    – Nick T
    Commented Apr 24, 2011 at 17:28
  • Probably.
    – sjohnston
    Commented Apr 24, 2011 at 17:42
  • 2
    Yes, it does.
    – user56
    Commented Apr 24, 2011 at 21:13

Spoiler: There's also some neat foreshadowing in that

every one of those drawings has the moon in it!

  • 1
    Portal 3! On the moon!
    – Jack G
    Commented Jul 6, 2020 at 0:17

The first picture seems to be a historic account of the deadly neurotoxin, Chell's victory over GLaDOS, and the tortured test subjects/Aperture employees.

The equations in the second one are, according to my friend, the Schrodinger equation and the position momentum uncertainty principle... whatever the heck that is. He says Valve seems to like to throw random equations into their games without much context.

The third picture is this: http://www.thinkwithportals.com/comic/?l=en#27

Presumably they're all drawn up by Rattmann in his panicked and nearly schizophrenic state.


Here's some background relating to the Schrödinger's Cat drawing:

A cat, along with a flask containing a poison and a radioactive source, is placed in a sealed box shielded against environmentally induced quantum decoherence. If an internal Geiger counter detects radiation, the flask is shattered, releasing the poison that kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when we look in the box, we see the cat either alive or dead, not both alive and dead

  • What sort of pills was Schrodinger poping? That seems awfully morbid and over complicated. Poison is a horrible way to die and senseless killing of any animal (even for science) is animal cruelty. Why not just have an LED diode attached to the Geiger counter that tuns on when the Geiger counter detects radiation?
    – Jack G
    Commented Jul 6, 2020 at 0:20

The first pictures surrounding the portal gun represent the events in Portal, such as the reactivation of GLaDOS, the flooding of the facility with neurotoxin, and Chell killing GLaDOS.

The pictures with the cat represent the Schrödinger’s Cat experiment, which says that the cat left in a box will be both dead and alive until opened. This is talked about when Ratman puts Chell into an indefinite sleep where she would be both alive and dead until someone opens the chamber.

Finally, the last pictures are the graph shown on Chell's record, showing that she has amazing tenacity she she would never give up. This was why Ratman chose her, as Chell would be the one to actually challenge GLaDOS. The quote, "The bell invites, hear the turret, for it is knell. That summons to heaven or to hell," is a quote from MacBeth.

Also, for those of you who don't know who Ratman is, he is a surviving scientist from GLaDOS' attack as he predicted that she would kill everyone. He has schizophrenia, causing him to scribble on the walls in such a vivid pattern.

  • 1
    Note that the original quote from Macbeth lacks the reference to turrets. "I go, and it is done; the bell invites me. / Hear it not, Duncan, for it is a knell / That summons thee to heaven or to hell."
    – sjohnston
    Commented May 13, 2011 at 2:21

The poem actually is an alteration of the quote from MacBeth "I go, and it is done; the bell invites me. Hear it not, Duncan, for it is a knell That summons thee to heaven or to hell."

  • I have actually just seen that this was under the picture all along
    – HeyJesus
    Commented Jul 13, 2016 at 21:30

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