Many of the most famous American animated films, particularly those from Warner Bros. and Metro-Goldwyn-Mayer studios, unconsciously developed a relatively consistent set of such "laws" which have become de rigueur in comic animation. They usually involve things behaving in accordance with how they appear to the cartoon characters, or what the characters expect, rather than how they objectively are. In one common example, when a cartoon character runs off a cliff, gravity has no effect until the character notices.
Specific reference to cartoon physics extends back at least to June 1980, when an article "O'Donnell's Laws of Cartoon Motion" appeared in Esquire. A version printed in V.18 No. 7 p. 12, 1994 by the Institute of Electrical and Electronics Engineers in its journal helped spread the word among the technical crowd, which has expanded and refined the idea. These laws are outlined on dozens of websites.
O'Donnell's examples include:
- Any body suspended in space will remain in space until made aware of its situation. Then the regular laws of gravity take over. This is why babies can defy gravity for elongated amounts of time. (The character walks off the edge of a cliff, remains suspended in midair, and doesn't fall until he looks down.) If this is referenced by a character in the cartoon as "Defying the law of gravity", it is often explained that the character(s) involved have "never studied law".
- Any body passing through solid matter (usually at high velocities) will leave a perforation conforming to its perimeter (the "silhouette of passage").
- Certain bodies can pass through solid walls painted to resemble tunnel entrances; others cannot. Corollary: Portable holes work.
- All principles of gravity are negated by fear (i.e., scaring someone causes him to jump impossibly high in the air).
- Any violent rearrangement of feline matter is impermanent. (In other words, cats heal fast and/or have an infinite number of lives.) Corollary: Cats can fit into unusually small spaces.
- Everything falls faster than an anvil. (A falling anvil will always land directly upon the character's head, regardless of the time gap between the body's and the anvil's respective drops.)
- Any vehicle on a path of travel is at a state of indeterminacy until an object enters a location in the path of travel. (Wolf looks both ways down the road, sees nothing, but gets run over by a bus as soon as he tries to cross.)
History of the idea
Warner Brothers Looney Tunes had numerous examples of their own cartoon physics (such as in the Wile E. Coyote and The Road Runner cartoons) or even acknowledged they ignore real world physics. In High Diving Hare (1948), Yosemite Sam cuts through a high diving board Bugs Bunny is standing on, the ladder and platform that Sam is on falls, leaving the cut plank suspended in mid-air. Bugs turns to the camera and cracks: "I know this defies the law of gravity, but, you see, I never studied law!"
More recently, it has been explicitly described by some cartoon characters, including Roger Rabbit, Bonkers D. Bobcat, and Yakko, Wakko, and Dot, who say that toons are allowed to bend or break natural laws for the purposes of comedy. Doing this is extremely tricky, so toons have a natural sense of comedic timing, giving them inherently funny properties.
In Who Framed Roger Rabbit, for example, Roger is unable to escape handcuffs for most of a sequence, doing so only to use both hands to hold the table still while Eddie Valiant attempts to saw the cuff off. When Eddie asks, exasperated, "Do you mean to tell me you could've taken your hand out of that cuff at any time?!" Roger responds: "Not at any time! Only when it was funny!" Several aspects of cartoon physics were discussed in the film's dialogue, and the concept was a minor plot theme.
In 1993, Stephen R. Gould, then a financial training consultant, writing in New Scientist, said that "... these seemingly nonsensical phenomena can be described by logical laws similar to those in our world. Nonsensical events are by no means limited to the Looniverse. Laws that govern our own Universe often seem contrary to common sense." This theme is described by Alan Cholodenko in his article, "The Nutty Universe of Animation".
In a Garfield animated short entitled "Secrets of the Animated Cartoon", the characters Orson and Wade give demonstrations of different laws of the cartoons and show humorous examples of them.
In 2012 O'Donnell's Laws of Cartoon Motion were used as the basis for a presentation and exhibition held at Stanley Picker Gallery, by Andy Holden titled 'Laws of Motion in a Cartoon Landscape' which explored ideas of cartoon physics in relation to art and the end of art history.
Cartoon physics is not limited to either cartoons or physics. For example, when a character recovers impossibly fast from a serious injury, the laws of biology rather than physics are being altered. Live-action shows and movies can also be subject to the laws of cartoon physics, explaining why, for example, The Three Stooges did not go blind from all the eye-poking, or the burglars in the Home Alone series survive life-threatening booby traps. In a review of one of the Home Alone films, film critic Roger Ebert noted that in the case of live-action productions, cartoon physics are not as effective at producing a comic effect, as the effects seem more realistic and thus audiences are more likely to wince at a stunt that looks painful than laugh:
Most of the live-action attempts to duplicate animation have failed, because when flesh-and-blood figures hit the pavement, we can almost hear the bones crunch, and it isn't funny.
Printed cartoons have their own family of cartoon physics "laws" and conventions.
- 12 basic principles of animation
- Acme Corporation
- Magic satchel
- Toon (role-playing game)
- In a neologism contest held by New Scientist, a winning entry coined the term "coyotus interruptus" for this phenomenon—a pun on coitus interruptus and Wile E. Coyote, who fell to his doom this way many times.
- O'Donnell's Laws of Cartoon Motion", Esquire, 6/80, reprinted in IEEE Institute, 10/94; V.18 #7 p.12. Copy on Web
-  Archived December 10, 2012, at Archive.is
- IMDB quotes from "Roger Rabbit"
- Stephen R. Gould, Looney Tuniverse: There is a crazy kind of physics at work in the world of cartoons (1993) New Scientist
- Alan Cholodenko, "The Nutty Universe of Animation, The “Discipline” of All “Disciplines”, And That’s Not All, Folks! Archived September 27, 2007, at the Wayback Machine." International Journal of Baudrillard Studies Volume 3, Number 1 (January 2006)
- Laws of Motion in a Cartoon Landscape on Vimeo
- Laws of Motion in a Cartoon Landscape | Stanley Picker Gallery
- Ebert, Roger (1992-11-20). "Home Alone 2: Lost in New York". rogerebert.com. Retrieved October 8, 2011.
- The Laws of Cartoon Motion adapted from An Elementary Education: An Easy Alternative to Actual Learning by Mark O'Donnell (ISBN 978-0-394-54430-4).
- Laws of Cartoon Thermodynamics from Roger Ebert's website.
- Acceleration Due to Gravity: Super Mario Brothers - a physicist's determination of the value of g used in Super Mario Bros.