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What does the land under Antarctica’s ice sheet look like?

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Re: What does the land under Antarctica’s ice sheet look like?

#51

Post by treeman79 »

mFixman wrote: post #40
s1artibartfast wrote: post #39

Earlier quoted context omitted.

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 clus…

> The math is the same as flipping a coin 7 times [...] I'm not saying that a particular hemisphere has a high change of having most of the land; I'm saying that there will be a hemisphere that has this chance. 29% of Earth is land and 80% of this land is in the land hemisphere, so this problem would be the equivalent of rolling a D48 14 times and placing the dice on a table so that any 11 of the rolled numbers are v…

Take it account dice rolling in a small fixed area where they tend to get stuck together?

Re: What does the land under Antarctica’s ice sheet look like?

#52

Post by [deleted] »

jameshart wrote: post #48
SketchySeaBeast wrote: post #35

Earlier quoted context omitted.

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 l…

(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…

[deleted]

Re: What does the land under Antarctica’s ice sheet look like?

#53

Post by schrodinger »

usrusr wrote: post #37
idoh wrote: post #36

Time to demote Antarctica to an archipelago? (And join Pluto on the geographic name B-team)

I believe that the term you were looking for was toponymy, avoids the awkwardness of "geography, but off-earth": and join Pluto on the toponymic B-team.

How long have you been waiting to find a use for that word? :)

Re: What does the land under Antarctica’s ice sheet look like?

#54

Post by mFixman »

s1artibartfast wrote: post #49
mFixman wrote: post #45

Earlier quoted context omitted.

Your example is not the same for two reasons: 1. You are assuming there always are 7 continents and each of them contains 1% of all space on the Earth's surface. I assume there are 14 continents with 2% of the Earth's surface each, which is still incorrect but it's closer to reality. 2. I'm not defining hemisphere however I want: I'm using the canonical definition of hemisphere, but choosing any hemisphere for me dic…

Thats interesting. A few questions: 1)When you say you are using the canonical definition of hemisphere, do you mean North and South? Or are you talking about East and West as well? 2) Out of curiosity, why 14 continents? If you are using North and South as pre-defined hemispheres, ignoring East and West, I do think it can be reduced down to a coin flip if you want to prove that plates are unlikely to almost all be i…

The Northern, Southern, Eastern, and Western Hemispheres are just four of the infinite hemispheres of a sphere.

By "canonical definition of hemisphere" I'm talking about the surface of any half-sphere that covers half of the Earth; the "joke" in my proof is that you can choose any one.

For any two continents there's always a hemisphere that contains both of them (assuming you don't worry about the semicircle in the border of the hemisphere). If you put three equidistant continents with the maximum possible distance between them (so that they form an equilateral triangle whose centre is the centre of the sphere) then you can't do anything about it.

Think it like shining a light from some point in space that lights 80% of the land in Earth.

Re: What does the land under Antarctica’s ice sheet look like?

#56

Post by PopAlongKid »

Tepix wrote: post #13

Are there any interesting sci-fi novels or games that take place in the (far) future in Antarctica with humanity being forced away from the equator by the increasing temperatures?

Yes, A World Out Of Time by Larry Niven.

"Almost all remaining life on Earth has adapted to live in Antarctica. Elsewhere life is extinct except for some evidence of biological activity in the Himalayan mountains."

https://en.wikipedia.org/wiki/A_World_Out_of_Time

Re: What does the land under Antarctica’s ice sheet look like?

#57

Post by rgarciah »

Tepix wrote: post #13

Are there any interesting sci-fi novels or games that take place in the (far) future in Antarctica with humanity being forced away from the equator by the increasing temperatures?

"Antarctica" by Kim Stanley Robinson. Near future, but excellent prose and narrative.

Re: What does the land under Antarctica’s ice sheet look like?

#58

Post by vl »

jameshart wrote: post #32
SketchySeaBeast wrote: post #26

Earlier quoted context omitted.

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.

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% th…

If you look at the Pacific Ocean from "top" (i.e. get a globe and rotate it), you'll see that it effectively covers almost entire hemisphere. So there is no surprise that most of the land has no antipodal land. The more interesting question is why initial continent, Pangea existed as such instead of the bunch of the smaller continents, which would seem more logical and likely.

EDIT: also, do we know if there were no other continents that submerged?

Re: What does the land under Antarctica’s ice sheet look like?

#59

Post by s1artibartfast »

mFixman wrote: post #54
s1artibartfast wrote: post #49

Earlier quoted context omitted.

Thats interesting. A few questions: 1)When you say you are using the canonical definition of hemisphere, do you mean North and South? Or are you talking about East and West as well? 2) Out of curiosity, why 14 continents? If you are using North and South as pre-defined hemispheres, ignoring East and West, I do think it can be reduced down to a coin flip if you want to prove that plates are unlikely to almost all be i…

The Northern, Southern, Eastern, and Western Hemispheres are just four of the infinite hemispheres of a sphere. By "canonical definition of hemisphere" I'm talking about the surface of any half-sphere that covers half of the Earth; the "joke" in my proof is that you can choose any one. For any two continents there's always a hemisphere that contains both of them (assuming you don't worry about the semicircle in the b…

I see, that joke went over my head.

That is what I initially meant by having "freedom to define hemispheres however you want", eg set arbitrary centers.

That certainly makes it a more interesting problem and increases the chances substantially.

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