https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=Ictlogist 2026-05-31T21:25:00Z User contributions MediaWiki 1.30.0 https://www.explainxkcd.com/wiki/index.php?title=3177:_Chessboard_Alignment&diff=400889 2025-12-06T06:49:59Z

<p>Ictlogist: </p> <hr /> <div>{{comic<br /> | number = 3177<br /> | date = December 5, 2025<br /> | title = Chessboard Alignment<br /> | image = chessboard_alignment_2x.png<br /> | imagesize = 397x289px<br /> | noexpand = true<br /> | titletext = Luckily, the range is limited by the fact that the square boundary lines follow great circles.<br /> }}<br /> <br /> ==Explanation==<br /> {{incomplete|This page was created BY AN ALIGNED BISHOP. Don't remove this notice too soon.}}<br /> &lt;p&gt;The comic shows an overhead view of three chess boards side by side, with two players facing each other across most of the boards. Yellow squares (used to show the available or actual movement of a given piece) have been marked leading from the starting position of the middle board's right bishop (F1) to the upper-right. The path continues beyond the edge of the middle board, across four columns of empty space or unseen table, and ends in the top left corner (A8) of the right board. The right board has only one rook (black rectangle) while the other two boards each have two, so it is implied that the bishop has captured the rook. The text below jokingly claims that if you align chess boards exactly, pieces can cross the boundary like this. This is not legal in normal chess {{citation needed}}, but fits into Randall's long history of comics about unusual chess rules or boards.&lt;/p&gt;<br /> &lt;p&gt;The title text refers to the fact that chess boards are normally placed approximately level (parallel to the surface of the Earth). A perfect line of chessboards placed end to end on the surface of an Earth-sized sphere (or on perfectly placed tables on that sphere) would form a &quot;great circle&quot; - the longest possible path around that sphere. While nearby boards would appear to be in the same plane, the curvature of the earth would cause boards more distant than 3.57 meters away to be in planes so different that the squares would be more than a micrometer off from the ideal straight lines leading off the board. It is thus implied that each infinite-range piece's valid path is a straight line of virtual squares that eventually leads into space. Otherwise, the alleged rule would allow chess moves between boards that were kilometers (or even whole countries) apart in any vertical line. If following the great circle along the ground was considered a straight line, then it would also be possible for each side's rooks and queen to capture their counterparts in the other color's back row, just by moving backwards around the planet. This does not rule out motion to another board on another celestial body or spaceship, though delivery of a chess piece across this distance would be impractical. This is thus the second comic in a week about [[3174:_Bridge_Clearance|distances extending past typical boundaries]].&lt;/p&gt;<br /> <br /> ==Transcript==<br /> {{incomplete transcript|Don't remove this notice too soon.}}<br /> <br /> It doesn't happen often because it requires micrometer precision, but if two chess boards are '''''perfectly''''' aligned, it's actually legal to move pieces between them.<br /> <br /> {{comic discussion}}&lt;noinclude&gt;<br /> [[Category:Chess]]</div>

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