• stupidcasey@lemmy.world
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    14 days ago

    This isn’t actually surprising, like in a vacuum it is but when you conceder that each point on earth has a full 360 degrees of points that means a line can be drawn to every possible point on earth unless something happens to be in the way, the Earth’s surface is 70% water so you only have a 30% chance of hitting something that is already low but it gets much much lower since we know this is cherry picked as the most exaggerated example you only need one instance on the entire earth of a point that can reach around it out of all the infinite points.

    • ilinamorato@lemmy.world
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      14 days ago

      30% wouldn’t be a lot if the land were all even-sized islands, but it’s all in big chunks; most of which is in a pair of unbroken masses that runs from more or less the North Pole to the Drake Passage. There aren’t any straight lines from the British Isles to Hawaii or to Indonesia, or even to Australia if I’m doing the geography correctly; nor are there any straight lines from Madagascar to Greenland, or from Iceland to anywhere in the Pacific, at least by liquid water.

      Add in the fact that we’re not used to seeing the roundness of the Earth from any perspective other than along the equator and split on the date line, and it’s really just something that puts two things into a category together that don’t seem like they should be connected.

      It’s like the fact that Mercury is (on average) the closest planet to Venus, but also to Earth, Jupiter, even Neptune. Ok, yes, that shouldn’t be a surprise, because it’s the closest to the sun and the sun is always in the middle; but it’s not the way we usually look at the Solar System, and also we know that Neptune is so far away from Mercury that it’s mind-boggling that Mercury could ever be the closest planet to it. It’s very unintuitive based on our usual perspective and existing understanding.

  • lemmyknow@lemmy.today
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    14 days ago

    Straight line? That looks hella curved, innit? Can’t fool us with a globe. A flat map, maybe. But not a globe. Despite it being a 2D representation of a globe

  • pyre@lemmy.world
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    14 days ago

    in case there are others like me who have to see what it looks like on a Mercator projection map:

    • x0x7@lemmy.world
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      13 days ago

      Wow. I can’t believe my perspective of the world is that distorted. It makes me want to only look at it in 3D. If we’ve all mainly looked at Mercator projections our whole lives our sense of where everything is relative to everything else and what direction is completely off.

      People complain about the proportional sizing of Mercator but the sense of direction it gives us is completely broken. I think the average person knows it’s off and people think there is an error factor to consider that a really straight like might be a little squiggly. But nope. This made me realize the Mercator gives pretty much zero accurate sense of direction if real distance is involved.

      • Cethin@lemmy.zip
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        13 days ago

        Short distances are fine, and obviously directly east/west are fine. Directly north/south is also pretty alright, but, as you move further from the equator, any east or west movement is covering less distance, and vice versa.

      • Morlark@feddit.uk
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        12 days ago

        People complain about the proportional sizing of Mercator but the sense of direction it gives us is completely broken.

        With respect, this is silly. People complain about the proportional sizing of the Mercator projection because disproportionate sizing is literally the only problem with the Mercator projection.

        The sense of direction being off has got literally nothing to do with Mercator. That’s an inherent drawback of trying to project a three dimensional globe onto a 2D image. Literally every single projection has this exact problem, in one form or another. It is considered ot be an acceptable trade-off for not having to work with globes all the time.

        Stop looking for yet more baseless reasons to bash the Mercator projection, which is a perfectly reasonable and acceptable projection to use within its intended usecase (which this specific example literally is).

  • spicy pancake@lemmy.zip
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    14 days ago


    Comms Officer: Sirs, we still have quite a bit of time to change course.

    Red: But we’re going straight.

    Purple: Yeah. Turning’s no fun. Why is this happening? Make it not happen.

      • zebidiah@lemmy.ca
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        14 days ago

        Don’t make fun of flat earthers, their ideology is spreading all over the globe!

    • deltapi@lemmy.world
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      14 days ago

      Well, yeah…if you want a line that is straight in 3 dimensions then any point on earth at sea level to any other point earth at sea level will require you to go below the surface of the planet.

  • Sundray@lemmus.org
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    14 days ago

    I got this far on the Wikipedia and gave up:

    On a curved surface, the concept of straight lines is replaced by a more general concept of geodesics, curves which are locally straight with respect to the surface. Geodesics on the sphere are great circles, circles whose center coincides with the center of the sphere.

    • Kobibi@sh.itjust.works
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      14 days ago

      I went down a rabbit hole about globes and maps recently

      Basically, to find the shortest distant between two places on a globe (a ‘straight’ line), imagine a hoop or circle round the earth that cuts it exactly in half, and rotate it until it passes through both places (still cutting it exactly in half)

      That’s a great circle.

      There are 2d map projections that are built around this, but they only work when one of the locations is at the center of the map. So it could show the shortest distance from, say, London to anywhere with a straight line, but it wouldn’t work for a route not including London

      • merc@sh.itjust.works
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        13 days ago

        Another way to think about it is with elastic bands.

        Imagine getting a globe and putting a pin in each place. One pin in the UK, and one in New Zealand. Now put an elastic band between those two pins so that it’s tight. The elastic will be as short as possible, which is as straight a line as possible. But, since the globe is curved the elastic has to curve with it. So, that’s your straight line on a curved surface.

        If you wrap the elastic around the other side of the globe (you might need a bigger elastic), you can find the other half of the circle. It’s the place where the elastic is at its tightest, but also where its evenly balanced between slipping to either side. For example, say you have a pin in California and another one in Japan. Both Japan and California are at about 30-40degrees north latitude. But, if you put an elastic starting in Japan and then going around the earth at 30 degrees north through China, Turkey, Spain, etc. when you let go the elastic will slip to the north until there’s no tension anymore. To keep it from slipping you have to balance the tension so it doesn’t slip to the north and doesn’t slip to the south, so it’s going flat around the whole globe. That makes the long half of the great circle.

        • tux7350@lemmy.world
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          14 days ago

          Another way to say it, if you cut a sphere in half and both sides are equal, its a great circle. All lines of longitude and the equator are great circles.

  • Nanook@lemmy.zip
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    14 days ago

    Even better, imho, you can sail in a direct line from OG Zeeland (Netherlands) to New Zealand.

          • MojoMcJojo@lemmy.world
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            14 days ago

            “This, then, was the Drake Passage, the most dreaded bit of ocean on the globe—and rightly so. Here nature has been given a proving ground on which to demonstrate what she can do if left alone.” -Lansing

            Below 40 degrees south there is no law; below 50 degrees south there is no God -sailing proverb