3 ms·

What about letters?

• RichardCA 6y ago
  You mean like, why do the people who paint markings onto an ambulance have to do it reversed? Yeah that's a good question. If I'm sitting in my car and looking at an ambulance in the rear-view mirror, it's not the mirror itself that reverses the lettering, and that's the key thing to understand. The only thing the mirror is doing is reversing the Z-axis. So the question becomes, why does a Z-axis reversal cause me to perceive that the X-axis is getting reversed? If I turn around to look at the ambulance, I just took my head through a 180 degree rotation around the Y-axis. Then (and only then) does the image get reversed on the X-axis. If you could imagine being behind the ambulance, and it were made of some imaginary transparent material, you would still see the lettering as not reversed. The key is to be precise when you use words to describe an optical phenomenon. A mirror reflects, and that's all it does.