Drop a Feather and a Hammer on the Moon

Science and philosophy reveal a reality that seldom conforms to our notions of common sense and conventional wisdom, and I like this, a lot. The universe is far more interesting than our parochial conceptions of what is obvious, always inviting us to dig a little deeper and look a little closer, for the truth is often elusive and counter intuitive.

Take the famous case of Galileo's thoughts on gravity. He argued, contra the Aristotelian model, that falling bodies of different weights (say, a feather and a hammer) should not fall at different speeds. Any differences, he thought, could be wholly attributed to air resistance slowing down the feather.

This may sound like the most ridiculous idea: of course a hammer would fall faster regardless of air resistance, it's heavier! Trying this experiment on the moon, however, where there is no air resistance, beautifully confirms Galileo's insight.

Of course, you don't have to go to the moon to prove this, or have access to a vacuum. To conduct your own experiment, you could simply place a feather on top of the flat surface of a book and drop the book to the ground. Go try it. What happened to the feather?
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