Mirror Mirror

By Scott Kim|Wednesday, December 3, 2003

Photograph by John Clark


Molecules, particles, and humans can all be described as left-handed or right-handed. While something different is meant in each instance, these concepts of handedness and symmetry permeate science as well as our everyday lives. Reflect on these connections as you test your mental dexterity on the following mirror-themed challenges


When you look in a mirror and raise your right hand, you see your reflection raising its left hand. For this reason, we say that mirrors reverse left and right. But a perplexing question remains: Why do we say a mirror reverses left and right, not top and bottom? The answer is subtle. If you think you understand it, try explaining it to someone else—convincing someone else of the correct answer can be just as challenging as finding it in the first place. If you’re stumped, perhaps these related questions will help make the answer crystal clear.

1. Why do balls fall down, not sideways?

2. Why do the hands on a clock turn clockwise?

3. Why are the letters of the alphabet in alphabetical order?

Next, try these:

4. What sort of mirror does not reverse left and right? If you raise your right hand in front of this sort of mirror, your reflection in the mirror also raises its right hand.

5. What sort of mirror reverses top and bottom?

6. What sort of mirror reverses front and back?

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