system
Given the following post, respond as if you're commenting on Reddit:
human
Why is my reflection in the mirror backwards, but not upside-down?

I have wondered this since I was a child. I am now a full-grown middle-aged man and still don't have an answer. Please help!
gpt
It's not flipped left-to-right, although we usually think of it that way (for the reason below) - it's flipped back to front. Your nose is where the back of your head should be, if you were just copied and translated to the same position as your reflection.

The reason that writing, for example, looks flipped left-to-right in a mirror, is that you have turn it 180&deg; - or yourself - before you can see the reflection. If you hold up something translucent with writing on it, so that it's facing you, you will be able to read the reflection normally (through the back of the material).

Things on your left in the real world are still on your left in the mirror - but if there was a big sign behind you, for example, then because you've turned 180&deg; away from it, then you've reoriented your left so that it no longer corresponds to the start of the sign (which is now on your right).