2014-10-31
Explanation
The Joke
A couple is in bed together. One partner says, "Nope. Elbow in the ear isn't sexy." The other (wearing glasses, clearly a theoretical physicist) enthusiastically responds, "I've got a solution! The sexy is just bound up in a dimension so small that it can't be detected." The caption below reads: "Never have sex with a theoretical physicist."
The Humor
The comic parodies how theoretical physicists use the concept of extra compactified dimensions (from string theory) to explain away problems. In string theory, there are proposed extra spatial dimensions that are "curled up" so small that they cannot be observed or measured. The physicist in the comic applies this same logic to an awkward sexual encounter: rather than admitting that an elbow in the ear is simply not sexy, they argue that the sexiness exists but is hidden in an undetectable dimension. The joke is that this is exactly the kind of unfalsifiable reasoning that critics level at string theory -- if something cannot be detected, claiming it exists in a hidden dimension is not really an explanation. The caption's advice to "never have sex with a theoretical physicist" suggests they will always find a theoretical framework to avoid admitting failure.
References
The joke references string theory and the concept of compactified extra dimensions. String theory proposes up to 10 or 11 spatial dimensions, with the extras "compactified" at scales too small to observe. This has been a point of criticism from physicists like Lee Smolin and Peter Woit, who argue that string theory's untestability makes it more philosophy than science.