8 ms·

Why is there land at all at the south pole? Can't just be coincidence.

by platz 4y ago

jameshart 4y ago
But there’s none at the North Pole. One pattern that is curiously consistent is that broadly land tends to be antipodal to ocean (and not just because there’s more ocean in general - there’s a genuine statistical skew) - so having land at one pole and none at the other matches that overall pattern. (https://www.geodatos.net/en/antipodes https://www.geodatos.net/en/antipodes) Basically a surprisingly large proportion of antipodal pairs have land at one end and water at the other (although water-water is also common). In other words it would certainly be more surprising to have land at both poles; and we should be unsurprised if we find land at neither or land at one and not the other. So by that measure the poles are fairly typical of other antipodes.
- SketchySeaBeast 4y ago
  To me that really looks like pattern matching where there isn't actually any (though I'd like to know more details around the "statistical skew")- saying that there's a lot of antipodal land-water or water-water pairs only makes sense considering the vast majority of the planet is water. Regardless, it's just an interesting snapshot in time considering continental drift.
  - jameshart 4y ago
    30% of the surface is land. But only 15% of land has land antipodal to it, which certainly initially feels like less than you would expect by random chance. It’s easy to fall into some counterintuitive fallacies reasoning about this though because we’re considering a spherical surface pairwise and you might be tempted to say ‘ah, but we’re counting the antipodal land twice so that probably accounts for the 15%/30% thing’ - but I don’t think that follows; that 15% with land antipodal to it can be thought of as two sets of 7.5% of the land, which are antipodal to one another - the ‘double counting’ doesn’t work that way to eliminate the anomaly.
    - SketchySeaBeast 4y ago
      Just for curiosities sake I fell down the rabbit hole and ran the numbers (please someone correct me if I'm wrong on this - it's been a loooooong time since I did statistics). This is all assuming some sort of even distribution of land/water, so the numbers don't reflect real world continental distribution, but I don't know how to account for that. We have a 30% chance of picking a random point on Earth and getting land. Because earth is so big and these theoretical points are so small I'm going to assume that one point of land existing doesn't effect the odds of another piece of land existing. So that's two antipodal points, each with a 30% chance of being land. Putting that into a probability calculator (again, long time since statistics) that gives us odds of both point A & B being land as 9%. If we flip that around and go with the 30% land and 70% water odds we end up with a chance of 21%. It seems like there's actually MORE land that's antipodal to other land than we'd expect statistically? I must have some bad math here.
      - jameshart 4y ago
        (Edit - I misread my own math here) Not sure where 21% comes from - if 3/10 of points are on land, 9/100 antipode-pairs should be land-land, and that means 9/100 / 30/100 = 9/30 = 30% of land should have land opposite it, and conversely 70% should have water? But the true numbers are 15%/85% - on the actual earth, land is more likely to have ocean opposite it than random chance would suggest. Analyzing whether items sufficiently far from the ‘expected’ random distribution as to be statistically significant is a rather different exercise though.
        deleted 4y ago
        [deleted]
      - addaon 4y ago
        > We have a 30% chance of picking a random point on Earth and getting land. Because earth is so big and these theoretical points are so small I'm going to assume that one point of land existing doesn't effect the odds of another piece of land existing. This is the issue. A large contributor of the "point antipodal to land is water" anomaly is the typical size of land masses. If, for example, the average size of land masses was 30% of earth's area, then we'd have a single large land mass (Pangaea style), and all antipodal points would be water. The approximation of independence here doesn't reflect reality. Eurasia alone is more than 10% of the land area of Earth.
- mFixman 4y ago
  Is antipodal land a physical property of Earth's continents, or is it mathematical fact of distribution on spheres? If we distribute chunks of land randomly on a sphere we would expect roughly the same amount of land on any randomly-chosen hemisphere. But what can we say about the average amount of land in the hemisphere with the most land? My intuition says that in an Earth-like sphere, with 29% land and 71% water, there's a high chance of there existing a hemisphere with almost all of the land. I have no idea how to prove this empirically, but it seems like a really nice maths problem.
  - jameshart 4y ago
    It also depends on how strongly clustered the land tends to be - if the land is all going to be continuous then presumably there are more distributions of that land that are weighted towards a single hemisphere. Suspect there’s something to do with the fractal dimension of the coastlines as well. Agreed - sounds like a rich vein of math.
  - s1artibartfast 4y ago
    My understanding is that it is a physical property, arising from the fact that crustal basically all crustal growth occurs in ocean floors . The locations of the continents spend the vast majority of the time either approaching a clustered state, or leaving it. Because the thick continents with land are a minority of the surface [2], They only briefly pass through a period of even dispersal when passing from one clustered state to another. >My intuition says that in an Earth-like sphere, with 29% land and 71% water, there's a high chance of there existing a hemisphere with almost all of the land Can you explain more? If you have 7 or so plates with land, why would you expect them to have a high chance of being in the same hemisphere? The math is the same as flipping a coin 7 times. Flip the first and see which side it lands on, then flip the remaining 6 and see how many match the same hemisphere. What am I missing? https://www.youtube.com/watch?v=gQqQhZp4uG8 https://www.youtube.com/watch?v=gQqQhZp4uG8 https://www.imperial.ac.uk/news/199334/scientists-find-link-between-tectonic-plate/ https://www.imperial.ac.uk/news/199334/scientists-find-link-...
    - mFixman 4y ago
- gorgoiler 4y ago
  The North Pole isn’t far off being land. A lot of the Arctic Sea is only slightly underwater. https://commons.m.wikimedia.org/wiki/File:IBCAO_betamap.jpg https://commons.m.wikimedia.org/wiki/File:IBCAO_betamap.jpg
NKosmatos 4y ago
Well, land is heavier than water so it drops to the bottom of the earth (South Pole) whereas there is nothing at the top of the earth (North Pole), just water and ice. (Joking obviously, I’m not a flat/hollow-earther or anything similar)

Why is there land at all at the south pole? Can't just be coincidence.

by platz 4y ago

Why is there land at all at the south pole? Can't just be coincidence.

But there’s none at the North Pole. One pattern that is curiously consistent is that broadly land tends to be antipodal to ocean (and not just because there’s more ocean in general - there’s a genuine statistical skew) - so having land at one pole and none at the other matches that overall pattern. (https://www.geodatos.net/en/antipodes https://www.geodatos.net/en/antipodes) Basically a surprisingly large proportion of antipodal pairs have land at one end and water at the other (although water-water is also common). In other words it would certainly be more surprising to have land at both poles; and we should be unsurprised if we find land at neither or land at one and not the other. So by that measure the poles are fairly typical of other antipodes.

SketchySeaBeast 4y ago
To me that really looks like pattern matching where there isn't actually any (though I'd like to know more details around the "statistical skew")- saying that there's a lot of antipodal land-water or water-water pairs only makes sense considering the vast majority of the planet is water. Regardless, it's just an interesting snapshot in time considering continental drift.
- jameshart 4y ago
  30% of the surface is land. But only 15% of land has land antipodal to it, which certainly initially feels like less than you would expect by random chance. It’s easy to fall into some counterintuitive fallacies reasoning about this though because we’re considering a spherical surface pairwise and you might be tempted to say ‘ah, but we’re counting the antipodal land twice so that probably accounts for the 15%/30% thing’ - but I don’t think that follows; that 15% with land antipodal to it can be thought of as two sets of 7.5% of the land, which are antipodal to one another - the ‘double counting’ doesn’t work that way to eliminate the anomaly.
  - SketchySeaBeast 4y ago
    Just for curiosities sake I fell down the rabbit hole and ran the numbers (please someone correct me if I'm wrong on this - it's been a loooooong time since I did statistics). This is all assuming some sort of even distribution of land/water, so the numbers don't reflect real world continental distribution, but I don't know how to account for that. We have a 30% chance of picking a random point on Earth and getting land. Because earth is so big and these theoretical points are so small I'm going to assume that one point of land existing doesn't effect the odds of another piece of land existing. So that's two antipodal points, each with a 30% chance of being land. Putting that into a probability calculator (again, long time since statistics) that gives us odds of both point A & B being land as 9%. If we flip that around and go with the 30% land and 70% water odds we end up with a chance of 21%. It seems like there's actually MORE land that's antipodal to other land than we'd expect statistically? I must have some bad math here.
    - jameshart 4y ago
      (Edit - I misread my own math here) Not sure where 21% comes from - if 3/10 of points are on land, 9/100 antipode-pairs should be land-land, and that means 9/100 / 30/100 = 9/30 = 30% of land should have land opposite it, and conversely 70% should have water? But the true numbers are 15%/85% - on the actual earth, land is more likely to have ocean opposite it than random chance would suggest. Analyzing whether items sufficiently far from the ‘expected’ random distribution as to be statistically significant is a rather different exercise though.
      - deleted 4y ago
        [deleted]
    - addaon 4y ago
      > We have a 30% chance of picking a random point on Earth and getting land. Because earth is so big and these theoretical points are so small I'm going to assume that one point of land existing doesn't effect the odds of another piece of land existing. This is the issue. A large contributor of the "point antipodal to land is water" anomaly is the typical size of land masses. If, for example, the average size of land masses was 30% of earth's area, then we'd have a single large land mass (Pangaea style), and all antipodal points would be water. The approximation of independence here doesn't reflect reality. Eurasia alone is more than 10% of the land area of Earth.
mFixman 4y ago
Is antipodal land a physical property of Earth's continents, or is it mathematical fact of distribution on spheres? If we distribute chunks of land randomly on a sphere we would expect roughly the same amount of land on any randomly-chosen hemisphere. But what can we say about the average amount of land in the hemisphere with the most land? My intuition says that in an Earth-like sphere, with 29% land and 71% water, there's a high chance of there existing a hemisphere with almost all of the land. I have no idea how to prove this empirically, but it seems like a really nice maths problem.
- jameshart 4y ago
  It also depends on how strongly clustered the land tends to be - if the land is all going to be continuous then presumably there are more distributions of that land that are weighted towards a single hemisphere. Suspect there’s something to do with the fractal dimension of the coastlines as well. Agreed - sounds like a rich vein of math.
- s1artibartfast 4y ago
  My understanding is that it is a physical property, arising from the fact that crustal basically all crustal growth occurs in ocean floors . The locations of the continents spend the vast majority of the time either approaching a clustered state, or leaving it. Because the thick continents with land are a minority of the surface [2], They only briefly pass through a period of even dispersal when passing from one clustered state to another. >My intuition says that in an Earth-like sphere, with 29% land and 71% water, there's a high chance of there existing a hemisphere with almost all of the land Can you explain more? If you have 7 or so plates with land, why would you expect them to have a high chance of being in the same hemisphere? The math is the same as flipping a coin 7 times. Flip the first and see which side it lands on, then flip the remaining 6 and see how many match the same hemisphere. What am I missing? https://www.youtube.com/watch?v=gQqQhZp4uG8 https://www.youtube.com/watch?v=gQqQhZp4uG8 https://www.imperial.ac.uk/news/199334/scientists-find-link-between-tectonic-plate/ https://www.imperial.ac.uk/news/199334/scientists-find-link-...
  - mFixman 4y ago
gorgoiler 4y ago
The North Pole isn’t far off being land. A lot of the Arctic Sea is only slightly underwater. https://commons.m.wikimedia.org/wiki/File:IBCAO_betamap.jpg https://commons.m.wikimedia.org/wiki/File:IBCAO_betamap.jpg

NKosmatos 4y ago

Well, land is heavier than water so it drops to the bottom of the earth (South Pole) whereas there is nothing at the top of the earth (North Pole), just water and ice. (Joking obviously, I’m not a flat/hollow-earther or anything similar)