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Overview
Futility Closet is a collection of entertaining curiosities in history, literature, language, art, philosophy, and mathematics, designed to help you waste time as enjoyably as possible. The database contains more than 12,000 items, and more are added each day.
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Polchinski's Paradox
Image: Wikimedia Commons In 1990, physicist Joseph Polchinski described a puzzling situation: Suppose a billiard ball were sent through a traversable wormhole into the past, where it knocked its earlier self off course, away from the wormhole. This is a v
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Tile Swap
You're tiling a floor with 41 and 22 tiles when you accidentally break one. A tile of the other shape is available. Show that it's not possible to cover the floor by rearranging the tiles. SelectClick for Answer Color the tiles as shown. Now every 41 tile
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Level Best
"To give an accurate and exhaustive account of that period would need a far less brilliant pen than mine." - Max Beerbohm "These foolish remarks show a want of knowledge that must be the result of years of study." - Oscar Wilde
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Black and White
Alexey Khanyan devised this "no-brainer" in 2008. Black is in check. His only legal response is to interpose one of his knights, which then checks White, who must capture the knight, and so on. The whole ensuing 22-ply bloodbath unfolds mechanically, alwa
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Postal Inspector
In 1897, to help inaugurate New York City's new pneumatic mail system, officials sent a live black cat in a canister from the Produce Exchange Post Office on Bowling Green to the General Post Office on Park Row, a distance of 3,750 feet. "How it could liv
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Nothing Doing
Recess, County Galway, Ireland: Image: Wikimedia Commons Aspelt, Luxembourg: Image: Wikimedia Commons Bechyne, Czech Republic: Image: Wikimedia Commons ("In this house, no important person was born, lived, and most importantly did not die, and that is why
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Friendly Numbers
The divisors of 30 are 1, 2, 3, 5, 6, 10, 15, and 30. Add those up and divide the sum by 30 itself and you get 12/5. The divisors of 140 are 1, 2, 4, 5, 7, 10, 14, 20, 28, 35, 70, and 140. Add those up and divide the sum by 140 and you also get 12/5. This
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In a Word
intendiment n. intention or purpose auspicate v. to begin an undertaking mercation n. the act of purchasing something Alnaschar n. a person given to unrealistic dreams, expectations, or plans In the summer of 1967, the Beatles briefly considered buying a
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The Sylvester-Gallai Theorem
Every finite set of points in the Euclidean plane that is not collinear has a line that passes through exactly two of the points. This proof is by Michigan State University mathematician Leroy Milton Kelly. Consider a set S of points that aren't all colli
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Ernst's Paradox
MIT undergraduate Michael Ernst pointed out this problem to philosopher George Boolos during a course on paradox and infinity. An expression is a finite sequence of symbols. When expression β is appended to expression α, the symbols of α are written in or
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