2014 The Bad Science Show - Melbourne School Shows & School Incursions
Walking On Glass With Bare Feet (Magical Thinking)
"Any suitably advanced technology is indistinguishable from magic."
Arthur C. Clarke
*This resource is intended for use after viewing The Bad Science Show. Students should be reminded of the portion of the show the lesson relates to.
Purpose
To learn what "magical thinking" is and how people can mistakenly attribute extraordinary phenomena to magical causes. Students should also learn the role of surface area and pressure in mystical stunts such as walking on broken glass and laying on a bed of nails.
Introduction
Often when presented with a phenomena or experience that is beyond their understanding, people will mistakenly attribute the phenomena to an powerful unseen force.
"I can not understand how early Egyptians built the pyramids...therefore they must have been built by Aliens."
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"I can not understand how that tarot reader knew so much about me...therefore she must by psychic."
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"I do not understand how that vase fell off the shelf...therefore it must have been a ghost."
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"I do not understand how humankind went to the moon...therefore it it was a hoax."
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In The Bad Science Show, Nicholas walked on broken glass with bare feet. This stunt is often performed by Fakirs who claim that, because they can walk on the shards without being cut, they must have superhuman abilities.
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In reality, the stunt relies on pressure. Specifically, that pressure equals force divided by area. The greater the area, the lower the pressure. A single shard of glass has a small area that should cause enough pressure to puncture the skin. However, the amount of pressure can be lowered by
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a) Using thicker glass with thicker edges.
b) Standing on the flat sides of the glasses rather than the sharp edges.
c) Using many pieces of glass instead of one.
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This same principle also applies to the bed of nails.
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Discussions
1) What would be the "magical" explanation for these simple questions?
a) Why do objects fall down when you drop them?
b) Why do we see rainbows after it rains?
c) Why do black swans only exist in Australia?
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2) What would be your reaction be if you believed a magical explanation but were then presented with the truth? Would you instantly change your mind? Or would you argue?
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3) What would you say if someone presented you with a magician explanation to a scientific phenomena?
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4) How is magical thinking useful?
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Activities
Activity 1
Recreate Nicholas' walking on broken glass experiment with raw eggs. Take two cartons of eggs and place them shoulder width apart. Have the students stand on the eggs without breaking them. You can either instruct them on the best method (make sure the tops of the eggs are all at the same then carefully step on to them while holding on to a chair for balance) or you can let them experiment with the best method.
What is the smallest number of eggs they can stand on without breaking them?
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What would a 'magical' explanation of being able to stand on eggs be?
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Activity 2
Read My Year of Magical Thinking and identify all of the examples of magical thinking? Have you ever believed any of these examples?
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