This animation depicts how light, sound and gravity appear to diminish as they travel through space. A different version of this animation was originally created by Beau Janzen in 1993 as part of a NASA distance learning series on physics. The purpose was to demonstrate how laser light, which is essentially a one-dimensional beam, is able to maintain its brightness over long distances while regular light appears to dim.
In 2002 when Janzen was invited to speak at the International Workshop on Visualization and Mathematics, he completely recreated The Inverse Square Law to demonstrate topics in his lecture.
The revised version not only features more sophisticated animation, but also takes the concepts much further. The inverse square law is now applied to gravity and is used to explain the effects of the sun and moon on the Earth's tides.
Not Just "What", But "Why"
The equations involved in calculating the tidal effects from a heavenly body give a perfect example of the power of animation to communicate abstract information. As Janzen explains:
“Students are told that the tides on Earth are caused by the gravitational pull of the moon and sun. They then might read that the sun’s mass is over 27 million times greater than the moon’s mass. Even calculating for the weakening of gravitational pull over distance, the pull we feel from the sun is still over 200 times greater than the pull we feel from the moon. This may seem a bit puzzling since the tides on Earth are pulled twice as much by the moon than the sun.
“When a student asks why this is so, the typical answer is for an instructor to plop the quantifying equation in their lap. This is obviously not a very satisfying explanation and relies on the student to make a blind leap of faith that the equation ‘just works’. If the confused student asks for further explanation as to why it works, the typical response is ‘Just look at the equation. See, it works.’
“The Inverse Square Law presents the 'why'. Only at the very end when the viewer sees how the gravity is working on the oceans, is an equation put together to quantify what they now understand.”
The Inverse Square Law is now available in a DVD compilation of Zipheron short films in our on-line store.
Honors and Awards:
-Aurora Gold Award, 2002
-featured in Visualization and Mathematics III,
Hege and Polthier, eds., Springer 2003
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