My 11-year-old son asked me last night if there was an East Pole or West Pole.
I told him he should be able to figure that out for himself; I asked him the leading question “what is the definition of East?”.
It didn’t go well. Then he asked if it would be different on Mars if Mars was “upside down” compared to the Earth. That didn’t go well either – severe conflict of mental models.
They don’t teach geography (or in this case perhaps astronomy) very clearly in school.
But then dictionaries have huge trouble with this, too.
Here are my definitions:
East: The direction in which the Earth (or any planet) spins.
West: The direction opposite to East.
North: The direction 90 degrees to the left of East.
South: The direction 90 degrees to the right of East.
Compare that with any dictionary you like.
#1 by Bob on 2014 June 30 - 21:54
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Now you need to define left and right. There are non-symmetrical things in physics that you could use, but they’re obviously not the basis of the original definition. My dictionary defines ‘left’ as ‘the side of a person or thing that is turned toward the west when the subject is facing north’, which isn’t helpful if we use your definitions of north and south.
#2 by Dave on 2014 June 30 - 22:16
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I don’t see how that definition of ‘left’ doesn’t work with the above. Seems OK to me.
Left and right – good question. It’s not so obvious (to me), but how about this:
Left: 90 degrees counterclockwise (from a given direction).
Right: 90 degrees clockwise (from a given direction).
I think there must be some more objective way, but, as I said, it isn’t so obvious how to do it without some referent (a human fist, cardinal directions, clockwise, etc.).
But North/South/East/West are horribly defined in the dictionaries I looked at online. And there’s no good reason for that.
#3 by Bob on 2014 July 1 - 16:22
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You define East as the direction the planet spins. North is 90 degrees left of that. The dictionary says that Left is the side that’s West when you’re facing North. So the dictionary needs North to be defined in order to define Left, and your definition needs Left defined in order to define North.
#4 by Dave on 2014 July 1 - 16:36
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Yes, but the dictionary definitions all have the same problem. My definitions are no worse (and arguably better).
Dictionaries always use other dictionary words in their definitions – nothing unusual about that.
(I googled a little – defining left and right without a referent seems to be almost impossible. The only known method was discovered by no less than Richard Feynman – and involves the beta decay of cobalt-60…)
#5 by Bob on 2014 July 4 - 18:10
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My favorite flubbed definition is one in my old dictionary: mother is defined as a woman who has given birth, while father is defined as a man who has conceived offspring. So I was a father before my wife was a mother.
#6 by Paolo on 2014 July 29 - 06:38
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you should be happy your son thought some and asked a question in the first place
you expect him to reason logically … that’s a learned skill
did you teach him how to think?
if you define the expectation , all you will get is something less than what you defined
teach fishing … dob’t worry about the rest … sooner or later he will be hungry
#7 by Clay on 2015 June 23 - 20:22
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Alternatively, your son asked about “Pole”, everyone knows that polar north is not at the same point that “north axis” of rotation is. The earths magnetic field does not run sideways… Thus no eastern or western polarized fields. Also, Pole is from the Latin term to PIVOT. so simply, the earth does not pivot on any lines of longitude, but at the intersection of all longitude. Lines of longitude define western and eastern hemispheres, so there is a prime meridian and the anti-meridian to separate the two at 0 degrees and 180degrees. If there was a pole, or pivot at any longitude there would be an oscillation of the earth, not a rotation. Great way to teach geography, and geometry, and magnetism all in one whack…. (I.e most people don’t know compasses go upside down in the wrong hemisphere.) Also, has to do with time…. http://www.dailytech.com/Lockheeds+F22+Raptor+Gets+Zapped+by+International+Date+Line/article6225.htm
#8 by Dave on 2015 June 26 - 16:04
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We we talking about the polar axis of rotation, not the magnetic pole. I’ll get into that with him when he’s a little older.