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It Just Is

James Shaw
I wonder how much of what we 'know' has ever been properly explained? Our teachers repeat what they have been taught and our text books are re-writes of earlier text books. Perhaps that is the way to pass exams, don't think about what is missing, just repeat what was taught and so it goes on.


Lately I have been looking through some of my old 'how it works' books from my childhood, encyclopedias, atlases and 'online' to see what they say about the Earth's seasons. At least they all agree! It is all down to the tilt of the Earth's axis, the northern hemisphere points towards the Sun in the summer and away from the Sun in winter. Simple! We don't need to know anything more.


A simple experiment: Take a dinner plate and place an apple near the rim with its stalk pointing slightly towards the centre, a model of the tilted Earth. Now slowly and carefully twist the plate on top of a table so as not to disturb the apple until the plate has turned through 180 degrees. Now which way is the apple pointing? Do you still understand the seasons or did you have a book/teacher that really explained it? Perhaps you are a heretic and thought for yourself? Andy Millar raised some of these issues in "You don't need practical skills to be an engineer", 'knowing' how to do something can stop new thinking.


Have a virtual mug of coffee and think about it!
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    James,

    I only mentioned the gyroscope analogy as being a simple corollary that most people can relate to, rather than something "I believe". To quote Andy, "it is a bit more complicated than that"! Even a gyroscope will change its direction of axis if there is a force applied, though not necessarily in the direction of that force.

    The reason the axis of the earth remains pointing in the same direction is that there is no major force trying to make it change its direction. However there are forces acting on it and the direction of the axis is actually moving, a feature called the precession of  the equinoxes (see https://www.britannica.com/science/precession-of-the-equinoxes) which causes the direction of the axis of rotation of the earth to wobble with a frequency of once every 25,722 years (give or take a few months...). This means that the signs of the zodiac and their horoscope months no longer align with the constellations which matched when they were first recorded. The vernal equinox, originally when the sun entered the constellation of Aries, has now moved through Pisces and is now in Aquarius, though I suspect that most people who try to explain the seasons haven't a clue about this yet are still happy to talk/sing about "The dawning of the Age of Aquarius"!

    There are many explanations which are over-simplified just to make them approachable to the target audience. I still remember my first week at University where we were told that initially we had learned from our parents, then our primary school teachers explained why our parents were wrong and gave us a different explanation. Then our secondary school teachers explained that our primary school teachers were wrong and gave us yet another explanation, and now we were at University where our lecturers would explain why our secondary school teachers were wrong....

    From this I would suggest it is always a good idea to challenge accepted wisdom/explanations, but not necessarily to throw them out (otherwise how do people learn if they don't have the underpinning knowledge to understand the full concept).

    Regards,

    Alasdair
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  • 0
    James,

    I only mentioned the gyroscope analogy as being a simple corollary that most people can relate to, rather than something "I believe". To quote Andy, "it is a bit more complicated than that"! Even a gyroscope will change its direction of axis if there is a force applied, though not necessarily in the direction of that force.

    The reason the axis of the earth remains pointing in the same direction is that there is no major force trying to make it change its direction. However there are forces acting on it and the direction of the axis is actually moving, a feature called the precession of  the equinoxes (see https://www.britannica.com/science/precession-of-the-equinoxes) which causes the direction of the axis of rotation of the earth to wobble with a frequency of once every 25,722 years (give or take a few months...). This means that the signs of the zodiac and their horoscope months no longer align with the constellations which matched when they were first recorded. The vernal equinox, originally when the sun entered the constellation of Aries, has now moved through Pisces and is now in Aquarius, though I suspect that most people who try to explain the seasons haven't a clue about this yet are still happy to talk/sing about "The dawning of the Age of Aquarius"!

    There are many explanations which are over-simplified just to make them approachable to the target audience. I still remember my first week at University where we were told that initially we had learned from our parents, then our primary school teachers explained why our parents were wrong and gave us a different explanation. Then our secondary school teachers explained that our primary school teachers were wrong and gave us yet another explanation, and now we were at University where our lecturers would explain why our secondary school teachers were wrong....

    From this I would suggest it is always a good idea to challenge accepted wisdom/explanations, but not necessarily to throw them out (otherwise how do people learn if they don't have the underpinning knowledge to understand the full concept).

    Regards,

    Alasdair
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