Schrödinger's cat is a seemingly paradoxical thought experiment devised by Erwin Schrödinger that attempts to illustrate the incompleteness of the theory of quantum mechanics when going from subatomic to macroscopic systems.

The original formulation of Schrödinger's catEdit

In 1935, Schrödinger published an essay describing the conceptual problems in quantum mechanics. A brief paragraph in this essay described the cat paradox:

One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following diabolical device (which must be secured against direct interference by the cat): in a Geiger counter there is a tiny bit of radioactive substance, so small that perhaps in the course of one hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer which shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The first atomic decay would have poisoned it. The Psi function for the entire system would express this by having in it the living and the dead cat (pardon the expression) mixed or smeared out in equal parts.[1]

Adaptations in science fictionEdit


It was not long before science-fiction writers picked up this evocative concept, often using it in a humorous vein. Several have taken the thought experiment a step further, pointing out or extra complications which might arise should the experiment actually be performed.

For example, in his novel American Gods, Neil Gaiman has a character observe, "if they don't ever open the box to feed it'll eventually just be two different kinds of dead." Likewise, Terry Pratchett's Lords and Ladies adds the issue of a third possible state, in the case of Greebo, "Bloody Furious." Douglas Adams describes an attempt to enact the experiment in Dirk Gently's Holistic Detective Agency. By using clairvoyance to see inside the box, it was found that the cat was neither alive nor dead, but missing, and Dirk's services were employed in order to recover it.

In "Schrödinger's Cat-Sitter" by F. Gwynplaine MacIntyre (published in Analog magazine, July/August 2001), a time-traveler named Smedley Faversham visits the past to interview Erwin Schrödinger but gets tricked into taking care of Schrödinger's wife's cat while she is away and Schrödinger is visiting Max Planck. In attempting to take care of the cat, Faversham inadvertently locks it in a cabinet with a Geiger counter, a vial of acid, and a hammer, unintentionally enacting Schrödinger's thought experiment, but with results that remain as uncertain as in the original case.

Yet another example of the cat in popular fiction is the cat Quark, from Jeff Noon's book "Automated Alice". In it, Alice has the question "Am I real, or am I fake?" which is much like "Is it alive, or is it dead?" Near the end of the book, Alice encounters a cat named Quark, who is invisible, and got that way by being locked in a box and having a strange substance poured in, mixing it with a chameleon. The cat was both influenced by the Cheshire Cat, and Schrödinger's Cat, the Cheshire Cat and the Alice books being similar to the experiment already.

The American science-fiction writer and psychologist Robert Anton Wilson wrote the novel Schrödinger's Cat trilogy as the spiritual sequel to The Illuminatus! Trilogy. The storyline of this novel interweaves many characters who live in parallel universes. Each part of the novel is numbered as "Part One"

In Dan Simmons' books Endymion and The Rise of Endymion, one of the main protagonists is sentenced to death by being locked in a larger version of a Schrödinger's cat-box, so that random chance, rather than any single person, is responsible for his eventual death.

In FlatterlandEdit

On a somewhat more serious level, Ian Stewart's novel Flatterland, (a sequel to Flatland) attempts to explain many concepts in modern mathematics and physics through the device of having a young female Flatlander explore other parts of the "Mathiverse." Schrödinger's Cat is just one of the many strange Mathiverse denizens she and her guide meet; the cat is still uncertain whether it is alive or dead, long after it left the box. Her guide, the Space Hopper, reassures the Cat with a modern view of quantum decoherence. Ursula K. Le Guin wrote a story entitled "Schrödinger's Cat" in 1974 (reprinted in The Compass Rose, published in 1982), which also deals with decoherence. Greg Egan's novel Quarantine, billed as "a story of quantum catastrophe," features an alternative solution to the paradox: in Egan's version of quantum mechanics, the wave function does not collapse naturally. Only certain living things—human beings among them—collapse the wave function of things they observe. Humans are therefore highly dangerous to other lifeforms which require the full diversity of uncollapsed wavefunctions to survive.

In QuarantineEdit

As Egan notes, Schrödinger's hypothetical cat is one of the most familiar illustrations of quantum-mechanical oddities. In Quarantine, a physicist asks the narrator, an ex-cop and private investigator, if he has ever heard of "the quantum measurement problem." The narrator is naturally confused, but when asked if he's heard of Schrödinger's cat, he replies, "Of course."

File:Schrodinger cat in box.jpg

Animals other than catsEdit

Fiction writers have confined other animals besides cats in such contraptions. Dan Simmons's novel Endymion begins with hero Raul Endymion sentenced to death by imprisonment in a Schrödinger box.

In the fortieth-anniversary Doctor Who audio drama "Zagreus" (2003), the Doctor is locked in a lead-lined box also containing cyanide in an effort to explain his situation of being neither dead nor alive. Afterwards, the Doctor does mention that he has met Schrödinger's Cat.

Kosuke Fujishima's manga series Ah! My Goddess featured a play on Schrödinger's Cat. During one storyline, a storage room was expanded to infinite proportions and the main characters encountered a Schrodinger's Whale, a rare species with the ability to travel through space-time in a five-dimensional quantum state.

In the eroge (Japanese erotic game) Itsuka Todoku Anosora ni, made by Lump of Sugar, the setting is the main city of Koumeishi. In one story line, a main heroine, Konome, explains the story of Schrödinger's cat. Later, one can see that Koumeishi itself is the same as the situation of Schrödinger's cat: locked in space unable for anyone to come in, or leave, but the people inside are given all their basic needs. They still live in their city with some understanding of the outside world, but are unable to question their existence, or are unable to gain intention to leave. Thus Koumeishi exists as part of Tokyo, but at the same time, not a part of Tokyo.

Schrödinger's Cat used in television seriesEdit

In Bones Edit

In an episode entitled "The Pain in the Heart", Dr. Jack Hodgins said to Dr. Zack Addy that a crime scene is like Schrödinger's Cat. Aired 5/19/08 The lab was a crime scene, they could not disturb the scene, nor could they solve the crime without entering the lab.

In The Big Bang Theory Edit

In the episode "The Tangerine Factor" which aired 05/19/08, Leonard's attempt to arrange a date with Penny results in both Penny and Leonard seeking Sheldon's advice. Sheldon advises Penny that “just like Schrödinger's cat being alive or dead at same time” her date with Leonard currently has both “good and bad” probabilistic outcomes. The only way to find out is to “open the box”, in other words collapse the wave-function of an uncertain date into a specific outcome. Penny misunderstands Sheldon's argument and interprets his advice as general encouragement to go on the date. Apparently, a long session of Sheldon trying to get his point across to Penny ensues with Sheldon reciting Schrödinger's cat definition every time. Later Sheldon mentions Schrödinger's cat to Leonard who instantly gets the implied wave-function collapse as “brilliant”. (As previously established in the series when Leonard attempts to ask Leslie out “success of the whole date is determined by chemistry of good-bye kiss at the very end”.) At the appointed hour, when Leonard comes by to pick up Penny, she is clearly even more uncomfortable and concerned about going out on a date which may ruin their friendship. Leonard mentions Schrödinger's cat to Penny to which she replies she heard “far too much about Schrödinger's cat”. Leonard interprets that as sign of approval and passionately kisses Penny. Probability functions collapses into a clear determined outcome: Penny enjoys the kiss and clearly has no more fears and concerns about going out with Leonard. Recognizing her own chemistry with Leonard, Penny finally understands Schrödinger's cat analogy by mentioning "the cat is alive".

In CSI: Crime Scene Investigation Edit

In an episode entitled "The Theory of Everything", the dead elderly couple had a gravestone for a cat named Schrödinger Martin. This is a reference to the theme of the episode, which is that everyone in the cases are connected by String Theory.

In Numb3rs Edit

While Don is burdened by the possibility of him wrongly sending an innocent man to jail based on flawed evidence, his brother Charlie and Physics professor Larry remark that the evidence "proving Don right and wrong at the same time" is the "old paradox of Schrödinger's cat". Don's father then asks if that's "that Persian that keeps hiding out in [his] garage". (Episode first aired 1 April 2005)

In FuturamaEdit

A montage of some of Professor Farnsworth's achievements includes Schrödinger's Kit Kat Club. Episode 2ACV10 - "A Clone of my Own"

In HellsingEdit

A nazi character in the popular manga Hellsing by Kouta Hirano resembles a young boy with cat ears named Schrödinger who can be at several places at once.

In House M.D.Edit

In an episode entitled "The Right Stuff", while talking about the appearance of Alison Cameron (supposedly in Arizona), Doctor Wilson remarks, "...since she's not a dead cat, she can't be in two places at once."

The central character Gregory House replies, "Physics joke: don't hear enough of those."

In Six Feet UnderEdit

In an episode entitled "A Perfect Circle", the character Nate has a vision of watching a made-up television show that discusses the theory in brief.

In Sliders Edit

Quinn has a pet cat named Schrödinger.

In Stargate SG-1Edit

Samantha Carter gives a pet cat named Schrödinger to an alien.

In Yu-Gi-Oh! GXEdit

Dr. Eisenstein uses a card known as "Schrödinger's Cat"

In West WingEdit

In Season 7 Ellie Bartlet gets married at the White House. The name of the band playing the reception is Schrodinger's Cats.

In Video GamesEdit

In Digital_Devil_SagaEdit

A game produced by Atlus, there is a enigmatic cat-like creature revealed to have some connection to God, whom the main character can see throughout the games.

In Wild Arms 3Edit

The character of Shady the Cat, owned by a Maya Schrödinger, is based on Schrödinger's cat, and is claustrophobic as a result of the "experiment."

In NethackEdit

One of the monsters encountered in this text based game was called 'Quantum Mechanic', and often carried a chest. Opening the chest, it would (sometimes) contain the corpse of Schrodinger's cat


  1. E. Schrödinger, Die gegenwärtige Situation in der Quantenmechanik, Naturwissenschaftern. 23: pp. 807-812; 823-823, 844-849. (1935). English translation: John D. Trimmer, Proceedings of the American Philosophical Society 124, pp. 323-38 (1980), reprinted in Quantum Theory and Measurement, p. 152 (1983).

External linksEdit