When you look in a mirror, your reflection looks like another person standing facing you. If that person raised their right hand, it appears on the left side of your view. This makes us say mirrors flip left and right. But mirrors do not flip up and down because gravity pulls everything down, so we know which way is up.
The Secret Twist
A mirror actually flips things front to back. Imagine if you walked through a glass wall into a room that was a perfect copy of yours. Your front would become the back of your twin. That twin has their left hand on the same side as yours, but because they are facing you, we call it the other side.
Why Not Up and Down?
The mirror does not care about up or down. If you lie down on the floor and look at a vertical mirror, your reflection still looks upright. We only think of left and right because humans have two eyes side by side and a face that is wider than it is tall. We are used to turning people around vertically (like walking) rather than flipping them upside down.
Mirrors don't swap sides; they reverse depth.
Examples
- If you stand sideways to a mirror, your reflection also stands sideways without flipping left or right.
- Holding a ball in your right hand makes it look like it is in the left hand of your reflection.
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See also
- Why Do We See Mirages on Hot Roads?
- Why Do We See Colors When It's Actually Black and White?
- Why does the moon appear larger on the horizon than overhead?
- Why Do Mirrors Make You Look Backward?
- How Does Those Aren't Mountains Those Are Waves Work?