Go east from Seattle
Ambiguity of “Go east” vs “straight line”
- Central dispute: does “face east, then go in a straight line along Earth’s surface” mean “keep going east (constant compass bearing / latitude)” or “don’t turn left or right (a geodesic / great circle)”?
- Many readers felt their intuitive interpretation was “maintain an easterly heading,” which leads to France (or Canada first, if you account for Canada before the Atlantic).
- Others argue the text clearly means: start facing east, then go straight without turning, which results in a great-circle path hitting Australia.
Geodesics, straightness, and pedantry
- Several comments note that “straight line on a sphere” is inherently ambiguous; hence the need for the term “geodesic.”
- Some challenge the article’s explanation of geodesics or claim it misuses the concept; others defend it as correct spherical geometry.
- There’s back‑and‑forth over reference frames: straight in 3D Euclidean space (tangent line into space) vs straight on the 2D Earth surface (great circle).
- A subthread argues that there are no truly straight lines on Earth’s surface, so any answer is an approximation.
Title, image, and perceived trickery
- Many are irritated that the original title (“Go east from Seattle”) and the illustrative arrow strongly suggested “travel east,” making the actual answer feel like a “gotcha.”
- The author updated the title and added caveats about the image after criticism; some say this resolves the issue, others still find the puzzle unfair or “wordplay more than geometry.”
Navigation and projections
- Navigators historically used constant-latitude (rhumb) lines; great-circle routes require more sophisticated navigation.
- Some argue a reasonable “most obvious” interpretation should mirror that practical tradition.
- Others propose alternative framings (e.g., ideal paper airplane launched east) to make the intended great-circle idea clearer.
- One commenter advocates two-point equidistant map projections for visualizing great-circle routes.
Side discussions
- Latitude surprises: how far north Seattle is relative to Europe, and climate effects (Gulf Stream/AMOC).
- A few playful variants: “go south from Detroit” (reaching Canada), longest straight sailing route, and classic physics/geometry puzzles.