5 ms·
> in a straight line along the Earth’s surface. This already seems suspect, given that the earth's surface is curved. A true straight line from the starting p
by a_e_k 2y ago
> in a straight line along the Earth’s surface.
This already seems suspect, given that the earth's surface is curved. A true straight line from the starting point would take us off into space.
So this feels like it's all just quibbling about different curved lines and which is closest to some definition of straight.
- runjake 2y agoFrom the article: > To be pedantic, by ‘straight line’ here I really mean ‘geodesic’ — the > generalisation of ‘straight line’ for curved surfaces and space as well > as ‘flat’, Euclidian spaces. > A geodesic is just the shortest path between two points in a surface. If > you’re placed on a surface and continually walk “forward”, by definition > you will trace out a geodesic. > Some people replying to my original tweet pointed out that a straight > line from the original point and direction would take you into space."
- 12_throw_away 2y agoThis is not correct, not even technically correct. Look up the term "geodesic".
- shadowgovt 2y agoWe need a word like "geodesic" precisely because "a straight line on a sphere" is an ambiguous concept.
- dylan604 2y agoMan, talking about missing the point even pedantically. Good job on impressing me with that
- elwell 2y agoIs not pedantry the aim of this article?
- dylan604 2y agoAt least the article gets it right though
- wang_li 2y agoThe article doesn’t though. East is a path parallel to the equator on a spheroid. East of Seattle is a circle around the globe at a particular latitude. Facing the thing 1mm east of Seattle is a different heading than facing the thing 5000km east of Seattle. As has already been said as soon as you “go”, if you aren’t turning some infinitesimal amount you aren’t going east. It’s only a surprising result when misleading people by arguing that east is a particular heading.
- dylan604 2y agoBut it just said in a straight line to the east. It gave you a cardinal direction to start. From there forward, you go in a straight line. It gets tricky if you suggest that you can only travel along a great circle in the direction of the rotation along that axis. Since the axis is actually tilted, this is the result you get from traveling along that great circle.
- cush 2y agoThe issue people have is with "straight". It's ambiguous. And the simplest, most intuitive interpretation of "straight" in the context of someone directing you to travel East, is to continue travelling East. It's like handing someone a compass pointing East, then saying "walk in a straight line", and expecting them to slowly travel in a wandering arc. It's insane.
- dylan604 2y agoMaybe so, but that's not how geometry works. If geometry worked by my interpretation, then I would have skated through that class with an even higher grade than I got by following the rules. Also, the GGGGP that I replied to started by trying to walking a tangential line to a sphere resulting in a space walk. That's like THC induced levels of strained thinking of the subject.
- elwell 2y ago> A true straight line from the starting point would take us off into space. How do you know? "Straight" relative to what? The expanding universe? Would continuous adjustments need to be made to account for the displacement due to that expansion? Does this then assume some 'outer' universe / reference container?
- wongarsu 2y agoObviously he meant a geodesic though spacetime, assuming constant speed. Of course your speed does become relevant, but as long as it's positive, "space" seems broadly correct. At least if we ignore the first 10km or so of your journey. A true straight line (geodesic) from the starting point would take us straight into a tree, hill or building. At that point the journey would end since humans can't phase through solid objects. You never reach another country.
- xixixao 2y agoA true straight line from the starting point would take us into the Earth, because space is curved in its proximity.
- seadan83 2y agoStraight line of travel means you do not turn left or right. Different from heading continuously east. In the former, walking straight on the curved surface creates a curved path. In the latter, the compass needle will shift a bit as you travel, so you will be turning a bit to stay on the due easterly course. To your point, this a straight line relative to the traveller while staying on the surface of the globe (which is the premise).
- silisili 2y agoI feel sorry for the first cop who gives you a field sobriety test.
- deleted 2y ago[deleted]