45: Schrodinger

Explain xkcd: It's 'cause you're dumb.
Revision as of 19:40, 29 April 2015 by Kynde (talk | contribs) (Transcript details. More on LiveJournal)
Jump to: navigation, search
There was no alt-text until you moused over
Title text: There was no alt-text until you moused over


Schrödinger's cat is a famous thought experiment proposed by Erwin Schrödinger to question the Copenhagen interpretation of quantum mechanics.

Under the Copenhagen interpretation, any particle is described by a wave function that allows one to calculate the probability that it is any given state. A radioactive nucleus with a half-life of one hour, for instance, would have a wave-function that would split, showing two distinct states (decayed, undecayed) that change over time until some "observation" forced the wave-function into one state or another (called "collapsing the wave-function"). Before the wave-function is collapsed, it is incorrect to say that the atom has decayed or has not decayed; it is in a "superposition" of states, effectively half-decayed and half-undecayed.

Schrödinger thought this was absurd, and devised the Schrödinger's cat thought experiment to show this. The experiment goes as follows: Put a cat in a box, he said, with a device triggered by the decay of an atom with a half-life of one hour that would release a poisonous gas if triggered. Then, after waiting an hour, the Copenhagen interpretation would say that the atom is in a superposition of decayed and undecayed states, and thus, by extension, the cat would be in a superposition of alive and dead states. Only when the box is opened would the wave-function for the cat collapse into either alive or dead states. Since it is absurd for a cat to be both alive and dead, it is absurd for an atom to be both decayed and undecayed. Yet that's what quantum mechanics implies.

Black Hat and Cueball are likening the last panel to the box with the cat: until you read it, it is in a mixed state (a superposition) of both funny and unfunny, and its wave-function won't collapse until you read it.

The punchline is that the last panel simply says "Shit.", which indeed either applies to the fact that the panel is not funny (and thus the author thinks "Shit. It wasn't funny") or else the reader may be amused by the fact that the build-up of the first three panels leads to the punchline like "shit." Unlike absolute values like the death of a cat or the decay of a nucleus, the humour of the comic is subjective and, in fact, could be both funny and unfunny at the same time (to different readers).

The title text, which Randall here calls the alt-text, is more akin to the actual problem, suggesting that it did not exist until it was caused to be observed by the mouse over.


[Black Hat and Cueball are standing next to each other. Above them the text is written in a box with shades around it.]
Schrödinger's Comic
[Black Hat and Cueball are still standing next to each other, but Cueball has lifted his arms above his head. The text is again written in a box with shades around it.]
The last panel of this comic is both funny and not funny at the same time.
[Black Hat and Cueball are still standing next to each other, Cueball arms are down again. The text is again written in a box with shades around it.]
Until you read it, there's no way to tell which it will end up being.
[Black Hat and Cueball are still standing next to each other. Cueball has become smaller and smaller through the three frames after the first. Quite clearly here in the last panel. The text is again written in a box with shades around it.]


  • This was the 42nd comic originally posted to LiveJournal.
  • There had been a break of almost a month between this and the previous comic.
    • This time was probably used to prepare the launch of the new xkcd site.
  • Original title: "Drawing: Schrodinger"
    • For the first time in eight comics, and only the second time since after the first day on LiveJournal, is the weekday not part of the title on LiveJournal.
    • But apart from in the very next comic, the extra word "Drawing" was still added to the title for this and the four comics after the next, in spite of the simultaneous release on xkcd.
  • There were no original Randall quote for this comic.
  • This was the first comic to be posted simultaneous (i.e. on the same day) on both LiveJournal and the new xkcd site.
  • This comic was thus one of the last 11 comics posted on LiveJournal.
  • The Schrödinger equation was enhanced by Paul Dirac only three years later in 1928: Dirac equation. It did combine the Schrödinger world with Einstein, e.g. relativity.
  • Black Hat's hat is beginning to shorten from its top-hat look, although its height varies between panels. (As does Cueballs height compared to Black Hat.)

comment.png add a comment! ⋅ comment.png add a topic (use sparingly)! ⋅ Icons-mini-action refresh blue.gif refresh comments!


There were no comments until you scrolled down. 20:21, 1 December 2014 (UTC)

There were two comments before you scrolled down. 12:02, 17 October 2015 (UTC)

...shit...--TheTimeBandit (talk) 21:20, 30 October 2017 (UTC)