Buttered toast phenomenon
The buttered toast phenomenon is an observation that buttered toast tends to land butter-side down after it falls. It is used an idiom representing pessimistic outlooks. Various people have attempted to determine whether there is an actual tendency for bread to fall in this fashion, with varying results.
The phenomenon is said[by whom?] to be an old proverb from "the north country". Written accounts can be traced to the mid-19th century. The phenomenon is often attributed to a parodic poem of James Payn from 1884:
I never had a slice of bread,
Particularly large and wide,
That did not fall upon the floor,
And always on the buttered side!
In the past, this has often been considered just a pessimistic belief. A 1991 study by the BBC's television series Q.E.D. found that when toast is tossed into the air, it lands butter-side down just one-half of the time (as would be predicted by chance). However, several scientific studies have found that when toast is dropped from a table (as opposed to being thrown in the air), it more often falls butter-side down. A study by Robert Matthews won the Ig Nobel Prize for physics in 1996.
When toast falls out of one's hand, it does so at an angle, by nature of it having slipped from its previous position, then the toast rotates. Given that tables are usually between two and six feet (0.7 to 1.83 meters), there is enough time for the toast to rotate about one-half of a turn, and thus lands upside down relative to its original position. Since the original position is usually butter-side up, the toast lands butter-side down. However, if the table is over 10 feet (3 meters) tall, the toast will rotate a full 360 degrees, and land butter-side up. Also, if the toast travels horizontally at over 3.6 miles per hour (1.6 m/s), the toast will not rotate enough to land butter-side down. In fact, the phenomenon is caused by fundamental physical constants.
The mass of butter added to toast (~4g) is small compared to the mass of the typical slice of toast (~35g), is spread thinly, and passes into the body of the toast. Its contribution to the total movement of inertia of the toast and rotational dynamics, thus its effect on the toast is negligible.— Roberts A J Matthews, Tumbling toast, Murphy's Law and the Fundamental Constants
The following findings are from Mythbusters:
- Period of rotation: The usual scenario for a falling piece of toast is that a non-rotating slice slides or careens off a horizontal surface, such as a plate or table, over a fairly straight lip, which serves as a momentary fulcrum. In this scenario, the leading edge (or corner) is subject to the downward acceleration of gravity—without a countering force from the horizontal surface—sooner than the trailing edge (or corner). The interval where the leading edge of the toast is accelerating downward faster than the trailing edge imparts angular momentum. Once the toast begins to fall freely, air resistance governs any further change in angular momentum, with the toast serving as a complex airfoil (extremely difficult to analyze, especially if the toast has large, irregular holes). For a short fall, the initial angular momentum will dominate. The period of rotation is the time it takes for the toast to complete a full 360 degree spin. The problem for toast, in the typical case, is that the floor interrupts its fall somewhere in between a 90 degree and 270 toast rotation—this will cause the toast to go from butter-side-up to butter-side-down. With a higher the release point, there is a greater the chance for it to rotate beyond 270 degrees and consequently land butter-side-up. An even higher release point could cause the toast to rotate more than once, and again land butter-side down, but this is no longer a short fall at low velocity, and turbulence in this case should not be neglected. (Frisbee toast would resist the fulcrum torque due to gyroscopic effects and probably not accord with this analysis.)
- Moment of inertia: At the moment a piece of toast begins flipping towards the kitchen floor, it has inertia—it doesn't want to stop flipping if it doesn't have to. Its moment of inertia is determined by the speed at which the toast is flipping, combined with the size and mass of the toast. Most breakfast toast is about the same size and mass, unless you're in Texas—home of the giant slices that carry the state name. But any way you slice it, the same rules apply. Add a little velocity to the spin as your breakfast goes sliding off your plate—give it a smack to add some inertia and see how it lands.
- Angular momentum: Just like a frisbee or a gyroscope, your toast gains stability when it spins. In fact, the faster it spins, the more stable it gets. This is angular momentum, or mass in motion around a single point, in action. Newton once claimed that a mass in motion likes to stay that way, and this is definitely true for toast. Once your toast is spinning, it wants to keep spinning—that is, until some other force acts on it, like the floor.
In popular culture
In the 2010 M. Night Shyamalan film Devil, a group of adults in an elevator become trapped by unknown forces. Slowly over the course of the film, people begin to die in the elevator as the power blinks on and off, pinning the people against each other and creating a false narrative that the others are murderers. In the film, supporting cast member and fictional security guard Ramirez, in his suspicion that there may be unholy forces at play, dropped a slice of toast with jelly on one side, and dropped it on the floor. The toast landed on the jelly-side, after which Ramirez coined the phrase "Jelly Side Down," and subsequently 'proved' that the devil was nearby. However, there is some dispute in the film about whether or not this did actually prove the devil was near.
This phenomenon was also demonstrated and parodied in the October 29, 2013 Nostalgia Critic review of Devil, (Reuploaded on July 23, 2016 by Channel Awesome on YouTube) in which actor Doug Walker plays a priest who uses multiple food items to determine whether or not the devil is near. After the other items show no sign of the devil, the priest tosses a piece of toast as the last test. The toast lands jelly side down which means the devil is near and the end of the world is imminent. Everybody in the church screams and panics as the priest repeatedly shouts, "Jelly side down!"
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- "Mythbusters Museum". Mythbusters Museum. Retrieved 2017-06-13.