# Why do mirrors flip horizontally (but not vertically)? | Summary and Q&A

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February 9, 2015
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Physics Girl
Why do mirrors flip horizontally (but not vertically)?

## TL;DR

Mirrors appear to flip things horizontally due to the way we present objects to them, but they actually flip them in the z-direction.

## Key Insights

• ð Mirrors reflect objects as they are presented.
• ðĪŠ The flip in the mirror is actually in the z-direction, not horizontally or vertically.
• ðŠĐ Our perception of mirror reflections is influenced by our daily experiences and bodily symmetry.
• ðŽ Objects can be horizontally and vertically flipped depending on how they are presented to the mirror.
• ðŠĐ Mirrors accurately depict the orientation of objects, but our interpretation of the reflection may differ due to our experiences.
• ð§âðĶž Mirrors can be used to recreate a person's image by flipping it through itself in the z-direction.
• ðĻ The way we present objects to the mirror determines the perceived orientation in the reflection.

## Transcript

Have you ever wondered why mirrors appear to flip things horizontally but not vertically? For example, this piece of paper that says food, now says doof in the mirror. With backwards letters, of course, but they're still right side up. How would the mirror know the x direction from the y direction? Another example, if I raise my right hand, the mir... Read More

### Q: Why do mirrors appear to flip things horizontally?

Mirrors seem to flip things horizontally because they reflect objects as they are presented. If we turn an object away from us, the mirror will reflect it in a horizontally flipped manner.

### Q: How does the mirror actually flip the image?

The mirror flips the image in the z-direction. It recreates the object's orientation by flipping it front to back, which can be seen with the example of a left-handed glove turning into a right-handed glove.

### Q: Why do we perceive mirror reflections as a normal-looking person facing us?

Our perception is influenced by our left and right symmetry. Since most people have left and right symmetry, our mirror reflections appear as normal-looking individuals facing us.

### Q: Can mirrors also flip things vertically?

Mirrors can also flip things vertically if the object is turned away from the observer in that direction. The mirror reflects the object in a vertically flipped orientation.

## Summary & Key Takeaways

• Mirrors reflect objects as they are presented, so if an object is turned away from the observer, the mirror will appear to flip it horizontally.

• The direction of the flip is actually in the z-direction, not horizontally or vertically.

• Our perception of mirror reflections is influenced by our daily experiences and the symmetry of our bodies.