Comment by sorokod
7 years ago
Isn't "straight line" somewhat arbitrary? How about "the longest circle you could sail without hitting land" or some other reasonably smooth shape?
7 years ago
Isn't "straight line" somewhat arbitrary? How about "the longest circle you could sail without hitting land" or some other reasonably smooth shape?
I was just thinking this. If it is allow to sail over the same places more than once, they must be a route that is just a circle. Maybe along one of the southern parallels?
That's pedantic. Most people will realise that "straight line" means constant bearing.
From the maps they show, it’s pretty clearly a great circle (the obvious meaning for “straight line” on the surface of a sphere), not constant bearing.
Whoops, turns out I didn't actually understand what "constant bearing" meant. What I actually meant was "no rudder/steering" which is exactly what people would imagine as travelling in a straight line.
A constant bearing actually gives a Rhumb line: https://en.wikipedia.org/wiki/Rhumb_line
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Obvious perhaps, in a mathematically idealised system that's idealised according to axioms that are unstated ... a non-equitorial latitudinal line on a sphere is straight.
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What sort of constant bearing - magnetic bearings will vary along a map-based bearing. There's an arbitrary choice involved. We're probably not looking at changes in sea-level that put us off line - is a necessarily idealised system in which the question makes sense.
But, unless you are passing over a pole, a great circle doesn't use a constant bearing.
Life is arbitrary. Your question is equally interesting, except for the fact that you haven't offered up an answer to it.
Yes, "straight" is misguiding.