SYM·0019 · Lemniscate
Infinity
a notation with no stated reason
- Unicode
- U+221E infinity
- Meaning
- Unboundedness. In mathematics a limit notation, not a number — a distinction the popular career of the mark has entirely lost.
- History
- Introduced in print by John Wallis in De sectionibus conicis, 1655. Wallis simply used it, and left no explanation of why that shape. Every account of its origin is therefore reconstruction.
- Variants
- The lemniscate of Bernoulli is a different object that happens to share the outline; jewellery and tattoo forms drop the mathematics and keep the loop.
- Related
- ℵ aleph U+2135, Cantor’s notation for infinite cardinalities — the mark that does the work ∞ is popularly credited with; ♻ the other endless loop.
- Appears
- Mathematical typesetting, and — far more often — rings, pendants and forearms.
- Evolution
- Unexplained notation → emblem of eternity and devotion → the most-worn mathematical symbol in the world.
Sources · 3
- documented John Wallis, De sectionibus conicis, 1655 — the first appearance in print.
- documented Florian Cajori, A History of Mathematical Notations, 1928–29, on the subsequent adoption.
- traditional That the shape derives from the Roman numeral CIƆ for a thousand, or from omega. Both are long-standing conjectures about a silent source, offered as explanations far more confidently than the evidence allows.