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Explain xkcd: It's 'cause you're dumb.
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This well-known effect has of course been replicated in countless experiments.
Title text: This well-known effect has of course been replicated in countless experiments.


Ambox notice.png This explanation may be incomplete or incorrect: New page

BDLPSWDKS is an acronym for Bernoulli Doppler Leidenfrost Peltzman Sapir Whorf Dunning Kruger Stroop, as explained in the comic.

The effect mentioned appears to be a mashup of seven scientific principles from different scientific fields, with elements from each principle appearing in the resulting description of the effect:

Bernoulli's principle in fluid dynamics (also mentioned in 803: Airfoil) states that an increase in the speed of a fluid with certain properties occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy, often incorrectly used to explain how an airplane lifts off the ground. This is referenced by the firetruck lifting off.

The Doppler effect in physics refers to the change in a wave's frequency for an observer moving relative to its source. The effect can be observed from the siren sounding in an approaching vehicle. This is referenced by the firetruck moving towards the observer and making noise.

The Leidenfrost effect refers to how liquid will produce an insulating vapor layer when in near contact with an extremely hot surface, causing it to hover over said surface. This is referenced by the firetruck hovering on a layer of superheated gas.

The Peltzman effect refers to how regulations intended to increase safety are ineffective or counterproductive. This is likely referenced by the observer responding to a dangerous situation more slowly if the language he is warned in has a word describing the object he's in danger from ("firefighter") than if the language didn't.

The Sapir–Whorf hypothesis states that a person's world view and cognitive processes are affected by the structure of the language the person speaks. This is referenced by how the observer reacts differently depending on the tonality of the language in which the warning is uttered.

The Dunning–Kruger effect refers to unskilled people mistakenly perceive themselves as more skilled than they really are, while skilled people underestimate their own abilities. This is referenced by how observers react differently when they erroneously perceive themselves to be fluent in a language.

The Stroop effect refers to the phenomenon in which it is easier to name the color of the ink in which a word is written when the word refers to the same color as the ink than when the word refers to a different color. If we assume the firetruck is red, this suggests that the driver shouting RED would get a faster response than the driver shouting GREEN.

Usually, for an effect to be considered real, the scientific method requires the effect to be replicated by different experimenters in different times and places. It is hard to imagine several scientists in different parts of the world creating the setup to replicate this effect; however the title text mentions it has been done countless times.

Furthermore, the opportunity of publishing this comic strip may (or may not) be related to the recently issued sequels of franchises such as `Mad Max` and `Carmageddon`, where it's not unusual to find heavy wheeled vehicles trampling pedestrians for the lulz.


Ponytail stands next to a screen displaying a firetruck hurtling toward Cueball on what appears to be a layer of gas.
Ponytail: The Bernoulli-Doppler-Leidenfrost-Peltzman-Sapir-Whorf-Dunning-Kruger-Stroop Effect states that if a speeding fire truck lifts off and hurtles towards you on a layer of superheated gas, you'll dive out of the way faster if the driver screams "RED!" in a non-tonal language that has a word for "firefighter" than if they scream "GREEN!" in a tonal language with no word for "firefighter" which you think you're fluent in but aren't.

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