December Question – Man in the Mirror

It’s holiday season. After a full year’s work and study, we are all anxious for this well-deserved break. In addition to giving thanks, sending and receiving gifts, and participating in holiday activities, it is also time to look back at the past year and reflect.

This month’s question, is about reflection. We look in the mirror every day, and see our own image looking right back at us. However, something is a bit different. When I lift my right hand, the mirror image appears to lift his left hand. So left and right seem to be flipped. Yet, top and bottom are not flipped at all. If you think carefully about it, it should make absolutely no sense, because a mirror is a piece of glass that should treat left/right and top/bottom exactly the same way.

So why does a mirror image seem flipped in the left/right, but not the top/bottom direction? It’s a simple question, but not an easy question. Good luck and happy holidays.


Images provided by Classroom Clipart

One Reply to “December Question – Man in the Mirror”

  1. I encourage you to take some time to think about it carefully. You will likely find that all of the obvious explanations that come to mind are in fact, incorrect. When first presented with the problem, I found myself experimenting with a mirror, closing one eye, in various orientations, and imagining different scenarios without gravity, in outer space, to no avail.

    It is a difficult and counterintuitive question. I provided the first hint to this problem already: the mirror does not discriminate between left/right and top/bottom. Without divulging the answer completely, here is another big hint: the problem is with your perception – your brain is telling you what that reflected image is most likely to represent. We assume that what we see and perceive is veridical, yet this is a perfect case to challenge those assumptions.

    “The first principle is that you must not fool yourself – and you are the easiest person to fool” – Richard Feynman

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