• xlash123@sh.itjust.works
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    28 days ago

    Low IQ: it’s not a straight line

    Medium IQ: it’s a geodesic on a sphere, so it is a straight line

    High IQ: it’s not a straight line

          • Wilzax@lemmy.world
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            28 days ago

            In actual reality there would be wind and water currents diverting any ship sailing that route from the depicted “line” anyway so the whole argument is pointless

            The only straight line paths in the universe are followed by electrostatically uncharged non-accelerating objects in free fall in a vacuum. Or massless particles.

  • ChaoticNeutralCzech@feddit.org
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    28 days ago

    It can get longer if sailing between Madagascar and the rest of Africa but Pakistan-Russia does not have the same ring to it, I guess.

    • affiliate@lemmy.world
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      28 days ago

      it’s a bit of a “spirit of the law vs letter of the law” kind of thing.

      technically speaking, you can’t have a straight line on a sphere. but, a very important property of straight lines is that they serve as the shortest paths between two points. (i.e., the shortest path between A and B is given by the line from A to B.) while it doesn’t make sense to talk about “straight lines” on a sphere, it does make sense to talk about “shortest paths” on a sphere, and that’s the “spirit of the law” approach.

      the “shortest paths” are called geodesics, and on the sphere, these correspond to the largest circles that can be drawn on the surface of the sphere. (e.g., the equator is a geodesic.)

      i’m not really sure if the line in question is a geodesic, though

      • itslilith@lemmy.blahaj.zone
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        28 days ago

        You are absolutely correct, but to add on to that even more:

        When we talk about space, we usually think about 3D euclidean space. That means that straight lines are the shortest way between two points, parallel lines stay the same distance forever, and a whole bunch of other nice features.

        Another way of thinking about objects like the earth is to think of them as 2D spherical manifolds. That means we concern ourself only to the surface of the earth, with no concept of going below the surface or flying up into the sky. In S2 (that’s what you call a 2D spherical manifold), and in spherical geometry in general, parallel straight lines will eventually cross, and further on loop back and form a closed loop. Sounds weird, right? Well, we do it all the time. Look at lines of Longitude, for example.

        We call the shortest line connecting two points in curved manifolds geodesics, as you said, and for all intents and purposes, they are straight. Remember, there is no concept of leaving the sphere, these two coordinates is all there is.

        What one can do, if one wants to, is embed any manifold into a higher-dimensional euclidean one. Geodesics in the embedded manifold are usually not straight in higher-dimensional euclidean space. Geodesics on a sphere, for example, look like great circles in 3D.

      • lightnsfw@reddthat.com
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        28 days ago

        Stop making up bullshit to justify it. It’s not a straight line so don’t say that it is. Words have meaning.

  • lugal@sopuli.xyz
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    28 days ago

    Globists will argue that on a globe this is a straight line. Seen these arguments before, don’t work on me

  • IninewCrow@lemmy.ca
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    28 days ago

    There was a conversation I read a while ago that showed how a sailboat could travel a straight line over water from Halifax, Nova Scotia in Canada, travel southeast and end up on the west coast of British Columbia.

    Basically sailing from the east coast of Canada to the west coast of Canada in a straight line.

  • taiyang@lemmy.world
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    28 days ago

    Would clarifying words have helped? “If you only sailed with forward force…” or “Following along the surface of the earth…” or… what?

    Obviously they mean that you don’t need to make any turns and that straight means an arc around the earth and not through the Earth, unless someone has a very different idea what sailing means…

    • LustyArgonianMana@lemmy.world
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      28 days ago

      Yes I think they mean it’s a continuous line, not a “straight” line. As in the line is uninterrupted (continuous). It’s also possible they mean the line qualifies as a nonlinear function since it also doesn’t double back over itself (A function is a relationship where each input value (X) will create only one output value (Y)).

      Math is hard. Describing lines like this is math - calculus actually due to the curve, and actually not just basic calculus but vector calculus because it involves an x,y, and z axis. Most laypeople will struggle to describe a line with the correct jargon.

  • thejoker954@lemmy.world
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    28 days ago

    I feel like this is related to the can’t measure the coast’ thing.

    Like if you zoom in enough you are always traveling in a straight line.

    • itslilith@lemmy.blahaj.zone
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      28 days ago

      You just discovered the field of calculus! If you look closely enough at any smooth function it looks locally linear, and the slope of that linear function is it’s derivative

      Not quite what’s happening here, here the problem is if you consider geodesics on a sphere to be straight. In special geometry they are, for all intents and purposes, but in higher euclidian geometry they form large circles

    • filcuk@lemmy.zip
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      28 days ago

      I don’t know… straight, I would assume, means that I could walk or drive a vehicle and not turn at all, ignoring any external influences like waves and currents in this case.

      • Tudsamfa@lemmy.world
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        28 days ago

        But your vehicle would itself “curve” “downwards” due to gravity, surely a straight line means that you can point a laser, or a hypothetical 0 mass particle beam, uninterrupted from your starting point to your destination.

        • Seeker of Carcosa@feddit.uk
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          28 days ago

          Depends on your frame of reference. When traversing the surface of a globe, your described concept of a straight line isn’t intuitive.

        • linkhidalgogato@lemmy.ml
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          28 days ago

          in ur every day life if u travel in a car without changing direction would u say that u went in a straight line or in an arc. Clearly u are just trying to be a pedantic cunt for no reason.

    • Varven@lemmy.worldOP
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      28 days ago

      Because going in that route would make it touch land which in the twitter post it says straight line without touching land

        • Bassman1805@lemmy.world
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          28 days ago

          Alaska, Canada, Russia, a few on the -stans.

          This is the longest straight-line all-water route on earth.

        • supamanc@lemmy.world
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          28 days ago

          India. You would have to set off somewhat perpendicular to the Indian coastline to be perfectly straight.

          • ironhydroxide@sh.itjust.works
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            28 days ago

            For some reason I don’t think this is true.

            A straight line connecting two things does not necessarily have to connect to said things perpendicular to their border.

            • supamanc@lemmy.world
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              28 days ago

              Yeah but, I’m talking about this particular case, not making a mathematical rule. You have to move away from the coast, and then cannot turn, so you have to head towards Africa. You can’t set off toward Australia. Although I hadn’t considered that you can just move the starting point. So, there’s that.

    • bstix@feddit.dk
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      28 days ago

      The picture was about sailing the longest direct line.

      It’s not the longest anyway, but that’s what it was about. Technically one could sail infinitely many times around Antarctica in a straight line.

      • ChaoticNeutralCzech@feddit.org
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        28 days ago

        around Antarctica in a straight line

        No, that’s not Earth’s great circle, you’ll be turning slightly. It only seems straight on most map projections because they want latitudes to be horizontal.

        • bstix@feddit.dk
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          28 days ago

          Well, I stand corrected. I guess we’ll need to wait for the ice on the North pole to melt before we can make a more stupid voyage.

        • lolcatnip@reddthat.com
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          28 days ago

          It would, however, seem like a straight line to whoever was on the boat, because they’d be traveling due west the whole time, and the course corrections they’d have to make to keep going west would look the same as course corrections needed to account for wind, ocean currents, etc.

          • ChaoticNeutralCzech@feddit.org
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            28 days ago

            I know but you need to be the right amount of pedantic. Too little and any sufficiently large curve seems straight, too much and you point out that there is no straight line on the surface of a sphere.