Why mirror reverses

And when you point east, your reflection also points east. So much for the false idea that mirrors reverse left and right. Similarly, if you point south, the reflection points north. Another way to think about it is that mirrors reverse front and back. Text looks reversed to us in mirrors because of this back-to-front reversal. In a reflection, the backside of the text is facing you, instead of the usual front side. Text seen this way—from behind and through the glass—looks reversed in exactly the same way that writing in a mirror looks re versed see photo below.

Your experiment with the transparency makes the situation perfectly, ahem, clear. You can try doing this mirror experiment without a mirror—working instead with two people standing face to face.

Here's another way to think of it, widely popularized by physicist Richard Feynman see the interview response featured here. Stand in front of a mirror, and note which direction you're facing. For the sake of this thought experiment, let's assume you're facing North. Point due East with your right hand, and your reflection points East as well. Point due west with your left hand, and your reflection gestures in the same direction.

That's because these directions both lie along a plane parallel with the mirror. Similarly, point up or down and your reflection will follow suit, motioning in the same direction. But deviate from that parallel plane even a little and thinks go wonky. Remember: your image has been reversed along the axis perpendicular to the mirror.

Try pointing directly at the mirror, such that your fingertip is now directed due North. This is again the basic in-out reversal. But wait, my right hand is the image's left hand. Both I and my image face East the explanation of facing opposite direction is not working and the in-out operation is done with the top-bottom reversal Sorry Mr.

Geoff Steel, the image's head is towards cardinal down, the super Scientific American article is fine but that is not the proper reason, see, in the SIDE case, when a Pormpuraaw wonder girl moves her South hand Southward her helpless image moves her North hand Northward, even in heavenly Australia.

And, well, Physics is not any cause, it is an effort to understand the 'cause'. So what is only left is really that mental process. Our brain tries to place our head downwards facing the same direction and sort out what is right-left. You don't believe? But for TOP, brain is not used to do this. Now you understand that there is a process. The process is the reason.

We our brain place s our head first. Still not convinced? Lie horizontally in front of a mirror. Your right hand is upwards say , your image's right hand is downwards. See, top-bottom with mirror is reversed, but with you it is still left-right reversal.

Your brain placed your head horizontally first. Pratap K. Saha, Kolkata, India You guys are making it too complicated. The text reverses left-to-right because when you turn the paper towards the mirror, YOU'VE reversed the writing left-to-right.

Then you just see a mirror image of it. Try writing on a transparency, and hold it up so you can read it correctly.

Then hold it in front of the mirror. If that's all scientists did, we wouldn't get anywhere. Adam Gulyas, Edmonton Canada Close one eye. Look at wall with two windows, but one is actually a mirror. If light bounces off everything in reverse angle, then we should experience mirror image like camera obscura. But, only one parallax results, not total. Brain should not be able to know difference in mirror and window. It is a mirror image or what you see if you were looking from the mirror but still gazing forward.

No, wait. If you look at a mountain in a lake it is upsidedown. But not left to right. If we assumed that people would get to the back side by going head first over the top, I would be answering a different question. That question would be: Why do mirrors reverse up and down? There is something that mirrors do flip. They flip front and back. Just imagine that you were Obi-Wan and you walked forward a bit to where the image would be. Your right hand would be on the right side still.

However, your back would be facing towards where the mirror was, not your front. So, mirrors flip front and back. I guess I should state the full question: Why do mirrors reverse left and right, but they don't reverse up and down?