bazzargh 2 days ago

That approximation is only used in the USA, Liberia, and Myanmar tho. In the rest of the world, we use the metric maritime approximation,

π * φ km = e nm

justinl33 2 days ago

historically, maritime navigation has always required much higher precision since a small error compounds into missing an island entirely. land-based measurements could afford to be fuzzier because you can course-correct using visible landmarks. this is also why maritime measurements standardized globally much earlier than land measurements.

tiffanyh 2 days ago

That was a super long post to just say “the ratio of mph/knots ≈ π/e … and it’s not very useful, but a cool coincidence.”

  • Philpax 2 days ago

    It's about the journey, not the destination.

    • tiffanyh 2 days ago

      There’s not much of a “journey” though … because both mile and knot are just arbitrary assigned measurements.

      ——-

      mile = 1,000 paces (as defined by Romans)

      knot = how many logs would pass by in 30 seconds.

      There’s no mathematical reason why their value is what it is.

      Unlike π and e that do.

      • ianburrell 2 days ago

        The nautical mile came first. It is one minute of longitude or latitude at equator.

        The speed was measured with knots at specific lengths.

cb321 2 days ago

Interesting to see xkcd's Randall Munroe's live tour linked!