Why do mirrors flip the image horizontally and not vertically

The mirroring process is not at all as easy as it might seem. Have you ever wondered why we see the word reflected in the mirror inverted in the horizontal and not the vertical plane? For example, a sign with the word "Hello" in the mirror will read as "TvirP", while all the letters will be reflected only horizontally. What's the matter here?

And why, if you raise your right hand up, then its "left" mirror image will also rush up and not down. How does the mirror distinguish the X direction from the Y direction?

In fact, the rotation of the image in the mirror has nothing to do with the mirror itself. It's all about us, as we flip objects horizontally.

If the sign with the inscription "Hello" is turned vertically and brought back to the mirror, then we will see the inverted word "Hello", but already turned in the right direction. The reality is that the mirror does not flip objects horizontally or vertically. In fact, it flips them along the Z-axis according to this graph of 3D space.

The whole problem is that it is difficult for us to visualize the Z direction, since we are used to seeing objects in relation to horizontal and vertical axes. In addition, we ourselves, having horizontally symmetrical bodies, do not notice the catch when we look in the mirror.

In the video presented, the physicist shows how the mirror image “works” with a glove on her left hand, which she removes and turns it inside out. This is a real mirror image.