Talk:Antipodal point

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 Field: Geometry


Historical aspect[edit]

Moved from the article:

One has to also consider the aspect of what antipodes means, which is literally "under one's feet", back when the Earth was flat. This caused great consternation in the church at the time because there was the issue of whether Christ had saved these people, as well. This is very explored in the brilliant Umberto Eco's Island of the Day Before as well as in Rennaissance Encyclopedias.

Please edit / integrate me.

I think this is pretty well covered in antipodes. — Johan the Ghost seance 21:45, 25 January 2006 (UTC)

How to find[edit]

I think someone should post how to find the anitpodal point of a location without using a globe.

I hope this works...![edit]

If you were to take the lattitude and swap North for South or vice versa, then take the Longitude from 180 and swap East for West or vice versa, that would work.

The Lattitude and Longitude of where I live (Whitehaven, Cumbria, England) is about 54.5° North, 3.5° West; so the opposite point would be 54.5° South, (180-3.5=)176.5° East, which is about half way in the ocean between New Zealand and the Antarctic, and it's probably isn't surprising that there's nothing good on the other side of the world to me given that about 70% of the Earth's surface is water!

Alternatively you could use Google Earth, put it on measure mode, select the starting point, go to roughly where you think the Antipodal Point to it is, and move the mouse around it and as you circle round the Antipodal Point the measuring line will itself go around the world like a skipping rope.

Back-formation from Greek[edit]

I've edited away text concerning the singular form antipode arising from the "mistaken belief" that antipodes is the plural of antipode. At best, this is badly put. If you back-form antipodes (plural) to antipode (singular) without knowing that it's the Greek plural of antipous, you are not asserting that the Greek singular is also antipode, you are simply following the normal pattern of English plural forms. Believing that the English singular of antipodes is antipode is perfectly correct. It clearly is, and etymology be damned.

There is a school of thought that holds that any usage that does not strictly follow some historically-based argument is incorrect. E.g., decimate must always be used to mean "reduce by one-tenth" and not, as it is nearly universally used, to mean "severely reduce." The problem with this is that any attempt to base this on a consistent general rule such as "words must always be used in senses they had when they first appeared in the language" results in practically all usage being "incorrect."

In any case, to be really sticky the Greek words should be in Greek letters. I'll leave that to someone who knows Greek. -Dmh 19:39, 6 January 2006 (UTC)

The belief that that singular form was already in conventional use was indeed mistaken at the time when the form originated in that way. Perhaps it was not explained clearly enough and could be misunderstood, so it's badly put, but not incorrect if the intended meaning is followed. Michael Hardy 00:21, 7 January 2006 (UTC)
I'm not sure I follow that. My main point is that we're only guessing what was in the minds of the first people to use "antipode" as a singular in English, but we can say for sure what the Greek singular is. -Dmh 18:15, 11 January 2006 (UTC)
Hang on a second. From what I can make out (and again, I don't know Greek), "antipodes" means "under/opposite the feet". It seems more like an modifier than a noun, and the entry for antipodes seems to bear this out. If that's right, then the putative singular "antipous" would just be a different (and probably unused) modifier, meaning "under/opposite the foot". The entry on antipodes also states, plausibly, that the word shifted in meaning when it came from Greek to Latin, from "under/opposite the feet" to "person with feet opposite". It's not clear to me whether it was considered singular or plural in Latin, but by the time it comes to English it's clearly plural, setting the stage for the back-formation. All this drift in form and meaning is quite normal; characterizing any particular usage as a mistake borne of ignorance considerably distorts the picture. -Dmh 21:29, 12 January 2006 (UTC)

Midsummer is Midwinter at Antipodal Point?[edit]

The arcticle says that if it's Midsummer at one point it must be Midwinter at it's Antipodal point, but what if the original point is on the equator? (which would mean the Antipodal Point is on the equator, too)

In fact I didn't think they had Summer and Winter between the tropics? Should that bit be scrapped as it's from the POV of someone who isn't in the tropics, not to mention that it's true for any points outside the tropics on the opposite hemisphere to one another, if it's Midwinter in Oslo it's Midsummer in Cape Town, even if they're not even close to being anti-podal.

Since it's never summer or winter at the equator, the statement that if it's summer at one point, then it's winter at the antipodal point is vacuously true, i.e. (roughly speaking) true but uninformative. Also, since it did not say "only if", I see no need to delete the comment. Michael Hardy 23:53, 22 January 2006 (UTC)

See antipodes for geographical usage[edit]

Following the merger discussions at Talk:Antipodes, this article is now about the mathematical aspect of antipodal points (as it always was to a large extent). Antipodes is about the geographical aspect. — Johan the Ghost seance 21:43, 25 January 2006 (UTC)

Colloquial of Diametrically opposed/Polar opposites?[edit]

Hey, would you guys kill me if I added a little section about the colloquial usage of the terms Diametrically opposed and Polar opposites? I swear if I could find a better place I wouldn't ask. Ewlyahoocom 12:57, 6 April 2006 (UTC)

I categorically state that there will be no contract for your assassination — at least not from me.  ;-) However, it doesn't really seem to be particularly related to the subject. In fact, I'm inclined to suggest that since you're really just explaining the meanings of words, you should be putting them in Wiktionary. Diametrically opposed isn't really a subject for an encyclopedia article. — Johan the Ghost seance 11:56, 7 April 2006 (UTC)
Yeah, you're probably right. I ran across a few links to the non-existent Polar opposite and went looking for a good place to redirect them to. Mathlete links to this page via "...those who do well in math team tend to be diametrically opposite to real athletes..." and it seemed as good a place as any. (Oh, and just so you don't think I'm some random kook, I got here by disambiguating links to Pole/Polar.) Ewlyahoocom 15:13, 7 April 2006 (UTC)