Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

trajectoid

2024-12-04 View on smbc-comics.com → 1 revision
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trajectoid
Votey panel for trajectoid
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Explanation

This comic explains the real mathematical concept of "trajectoids" — a class of shapes that, when rolled on a surface, trace out a specific predefined path. The comic notes that some paths are forbidden (such as ones requiring too much curvature), but otherwise you can make an object of your choice that rolls along any arbitrary path.

The comic then takes a humorous turn in the final panels. The character explains "I like nothing existing in science that keeps writing the letter Z over and over" and offers an analogy: "It's like a ball, but science for different purposes." The visual shows a squiggly, absurd-looking 3D shape with an arrow indicating its rolling path.

The humor lies in the contrast between genuinely fascinating mathematics and the comedic anticlimax of how it might be used. Trajectoids are a real concept from a 2023 paper in Nature, where researchers showed you can design 3D shapes that will trace out any repeating path when rolled on a flat surface. The comic pokes fun at how pure mathematics can produce results that are intellectually thrilling but whose practical applications seem charmingly pointless — like designing a shape that endlessly writes the letter Z. The final panel's description of it as being "like a ball, but science for different purposes" is a wonderfully reductive way to describe a mathematically sophisticated object. SMBC frequently mines humor from the gap between the elegance of scientific ideas and their absurd or mundane real-world implications.

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