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Thread: Why is North up?

  1. #61
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    Quote Originally Posted by Noclevername View Post
    You said in post #33, up and down are never relative. I was just responding to what you said.

    Sorry if my clarification was unclear.
    I realize that, and it was clear. What I’m saying is that you were not responding to what I was trying to point out, but just nitpicking my lack of precision in writing. I thought it should be clear from the context that I meant relative in the sense I had defined it in the previous paragraph, I.e. relative to body position. And you are right that I left it out but I just thought it should have been clear what I meant.

    Perhaps I need to be clearer. What I meant to say is:

    Of course, north, south, east, west, up, down are all relative to the local reference. But, unlike East, west, north, and south, we do not have words that change when your body position changes. Well, Grant pointed out that we actually do, but they are not commonly used. Is that clear enough now?
    As above, so below

  2. #62
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    Quote Originally Posted by Jens View Post
    What I’m saying is that you were not responding to what I was trying to point out, but just nitpicking my lack of precision in writing.
    Precision in communication is one of my neurological issues.

    Of course, north, south, east, west, up, down are all relative to the local reference. But, unlike East, west, north, and south, we do not have words that change when your body position changes. Well, Grant pointed out that we actually do, but they are not commonly used. Is that clear enough now?
    Yes, thank you.
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  3. #63
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    Quote Originally Posted by Ken G View Post
    But your point is well taken that even in human cultures that have long lived at very high latitudes, one might imagine less of an interest in the 24 hour span we ourselves are so obsessed with!
    There's a recent study about that. https://www.cell.com/current-biology...822(19)31194-7
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  4. #64
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    Quote Originally Posted by Jens View Post
    I think I understand what you mean, and I don’t disagree with your characterization. I just meant to say that although there is a difference in how we map the world regarding NS and EW, on a local level, so for example when making a town map, they are basically equivalent.

    I think it’s interesting to consider a planet with no rotation. Not only would there not be a reason to put the North Pole in any specific location, but there would perhaps not be an idea of poles. So you could map it so that latitude and longitude are similar, and that you could travel north forever just like you can keep going west forever.


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    If you have a nonrotating planet and make longitude into a latitude-like measurement, then you have to pick an EXTRA arbitrary point (in addition to the single arbitrary point if you pick a pole and keep longitude as running through this point). I can’t see how that would be a better/ less arbitrary mapping system? But it is a really interesting idea.
    I wonder if adopting such a system would have any other ramification? Would navigating by compass be much more difficult?

    Presumably a compass pointing north is the reason why latitude is different qualitatively to longitude?

    I know magnetic north wanders ....what would our mapping system be like if the north magnetic pole was at a point on the equator or some other random point?

    How fast could magnetic north flip? What would happen to modern life if it did? Or perhaps it would just throw off bird/shark migrations? Presumably it wouldn’t affect gps navigation systems?
    "It's only a model....?" :-)
    https://www.youtube.com/watch?v=m3dZl3yfGpc

  5. #65
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    Quote Originally Posted by plant View Post
    If you have a nonrotating planet and make longitude into a latitude-like measurement, then you have to pick an EXTRA arbitrary point (in addition to the single arbitrary point if you pick a pole and keep longitude as running through this point). I can’t see how that would be a better/ less arbitrary mapping system? But it is a really interesting idea.
    I wonder if adopting such a system would have any other ramification? Would navigating by compass be much more difficult?

    Presumably a compass pointing north is the reason why latitude is different qualitatively to longitude?
    Yeah, that's a good question, and I don't think it is because of the compass per se, but perhaps because the earth rotates around that axis. So they are like the points of a spinning ball that don't move. And I think that on a non-spinning world, you could make a system where you would sort of have north/south poles and east/west poles, and the latitude lines would intersect the east/west poles just like the longitude lines intersect the north/south poles. And then you could define north as moving in a certain direction, so south would just be going opposite to north. I think it would work but I'm not sure.

    The problem with the magnetic navigation is that the earth's magnetic field is created by the rotation of the iron core, so I think that on a non-rotating planet you would not have a magnetic field, and so compasses wouldn't work. I think.
    As above, so below

  6. #66
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    Quote Originally Posted by Noclevername View Post
    It seems we have two separate ways that the 24 hour cycle can manifest, one is evolutionary and controlled by genes, and for that, looking at simple species with rapid adaptations might be a good way to go. The other is cultural evolution, and that requires intelligent species like humans. It would also be interesting to look at the cultural norms (calendars, routines, art, etc.) of human tribes that live at high latitude and have a history of isolation from low-latitude cultures (if any like that still exist). For example, in a culture like that, does the indigenous word for a repeating routine carry a direct connection with the 24 sun cycle, or is that cycle not important enough to constrain that so tightly? In our own culture, "day" is either a 24 hour period, or just the sunlit fraction of that period, so even for us it is not clear that it's a 24 hour period, but the ambiguity doesn't bother us because the distinction from one day to the next is small, and our routine is going to be built around 24 hours either way. It seems natural that as long as there is an internal biological 24 hour clock, the daily routine will always be built around it, but are there any cultures where that internal clock has drifted enough that the culture was able to embrace a different approach to the "daily routine"? (Personally, I feel like if I had no need to coordinate with a 24 hour day/night cycle, my clock would drift a lot-- I would resist going to bed, and also resist waking up, causing up to a 1 hour shift every day-- that's pretty much what happens to me any time I get decoupled from what others are doing!).
    Last edited by Ken G; 2019-Nov-03 at 02:55 PM.

  7. #67
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    Quote Originally Posted by Jens View Post
    And I think that on a non-spinning world, you could make a system where you would sort of have north/south poles and east/west poles, and the latitude lines would intersect the east/west poles just like the longitude lines intersect the north/south poles.
    Actually, two poles is problematic. Your lines of reference are not perpendicular, and you will have a tough time defining unique locations (see two locations in diagram 2)



    What you need is a point - and a meridian to establish an angle.

    I wish I could remember what book it was in that I read recently. I recall what they did was use a major landmark as a reference (you know, like Olympus Mons major). You need one other reference point (maybe the next largest landmark but cannot be antipodal) to define a meridian. (Alternately, in the case of a one-face body - use high-noon and landmark.)



    Now, your (arbitrary) grid is defined as distance-from-landmark (by) radial-angle-from-meridian. (see diagram 1)
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    Last edited by DaveC426913; 2019-Nov-04 at 04:59 PM.

  8. #68
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    Quote Originally Posted by plant View Post
    If we lived on a planet that was 'tidally locked' (is that the correct term?) or rotated very slowly... would that have affected our mapping system? I assume we wouldn't need to preference the north/south pole as an origin
    Quote Originally Posted by plant View Post
    My point is without rotation of the Earth, there should be no reason not to put ‘north pole’ at (for example) Grenwich?
    There wouldn't be a natural north & south, so there'd be no reason to invent/imagine such a thing. There would be a natural pole-like axis to orient along, with the directions defined as "toward the sun" and "away from the sun", but those are not north & south.

    * * *

    Way back when I was still doing medical X-ray stuff, I ran into the strangest orientation system I've ever encountered, while I was using a C-arm in an OR during surgery. (A C-arm is an X-ray machine with a big letter C... on an arm... where the X-ray emitter and receiver are at the two ends of the C and the arm makes it possible to arrange them in a variety of angles relative to the patient in all 3 dimensions.) One of the surgeons told me to move the C-arm "north" for the next picture. I looked around to try to find what was in the room that I could use to figure out which way was north, found nothing, tried recalling the turns in the hospital's hallways to get there from the exits, figured out that that would mean moving from the patient's right thigh to his right and X-raying nothing but air, thought about the room again not in terms of real directions but to try to find anything they could have been thinking of as a central/focal point of the room that they might think looked prominent enough to be called "north" for some reason, looked back at the surgeon in confusion, and finally got the answer. He had meant "proximal" (toward the middle of the patient's body; "up" when standing), and knew he was in a room where everybody knew the word "proximal", but he had nevertheless replaced it with something harder to understand.

  9. #69
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    Quote Originally Posted by DaveC426913 View Post
    Actually, two poles is problematic. Your lines of reference are not perpendicular, and you will have a tough time defining unique locations (see two locations in diagram 2)
    Thanks. That was really interesting and educational. I hadn't realize that you would run into problems with mapping points.

    And what about the other way of doing it, where none of the lines are perpendicular, so like this? Would that be a problem as well?
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    As above, so below

  10. #70
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    I'm just writing this because I never got any feedback from anyone about the last question I had.
    As above, so below

  11. #71
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    Apologies, I hadn't seen your response. (Not the first time I've grumbled that - unlike most other fora - CQ does not have a "New Posts Alert" feature.)

    Anyway, I think you'll see that the same problem arises.

    The arrow points to a meridian of the "North" pole, that also runs through the "West" pole.


    Say that meridian is defined to be the "0 degrees West" meridian on the North (red) coordinate system. Say it's defined as the "90 degrees North" meridian on the West (blue) coordinate system. (You can pick any numbers you want, it doesn't matter.)

    The coordinates "0 degrees West, 90 degrees North" does not specify a point - it is the same coords for all points on that great circle - or at least that quadrant.

    That's not the only problem, it just happens to be the worst case.

    If you want more detail, I can draw up a more detailed sketch.
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    Last edited by DaveC426913; 2019-Dec-03 at 09:01 AM.

  12. #72
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    Quote Originally Posted by DaveC426913 View Post
    I hadn't seen your response. Not the first time I've grumbled that - unlike most other fora - CQ does not have a "New Posts Alert" feature.
    Actually it does. On the reply with quote screen there is an option to subscribe to the thread. See below.


    _20191203_083809.JPG

  13. #73
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    Quote Originally Posted by headrush View Post
    Actually it does. On the reply with quote screen there is an option to subscribe to the thread. See below.


    _20191203_083809.JPG
    Yeah, I'm auto-subscribed to all threads I respond to.

    But all that does is show it inline. One must still go through all the threads in the list to find the little icon.

    And it doesn't show new posts. Jens sent another message - which is indistinguishable from a thread I'm already subscribed to.

    Other fora have a central alert in the main menu bar.

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