Timeline for Why are mirror images flipped horizontally but not vertically?
Current License: CC BY-SA 3.0
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| Nov 20, 2018 at 22:09 | comment | added | Keith Thompson | @industry7: Sure -- but you're also looking at the other side of it. The transformation can be seen in (at least) two ways: (1) A reflection on a vertical plane combined with a rotation about a vertical axis, or (2) a single reflection about the plane of the mirror. You could also see it as (3) a reflection on a horizontal plane combined with a rotation about a horizontal axis. We tend to choose (1) because it's more physically plausible. | |
| Nov 20, 2018 at 19:06 | comment | added | industry7 | I'm not sure if I really made my point. Just forget about the fact that humans are symmetrical for a second, and think about something that is inherently asymetrical. For example, hold some text in front of a mirror. It will be flipped horizontally, but not vertically. And this is not a matter of perception, an objective electronic device would register the text is indeed backwards. | |
| Nov 17, 2018 at 22:03 | comment | added | Keith Thompson | @industry7: It appears flipped horizontally to us. If we weren't bilaterally symmetric, we might think of it differently. To us, a left-to-right reversal seems natural, even though it's not physically plausible, because the result of the reversal still looks natural. To an intelligent being without that kind of symmetry, a left-to-right reversal might not seem any more natural than a front-to-back reversal. | |
| Jan 13, 2017 at 18:17 | comment | added | industry7 | "If we weren't bilaterally symmetric, we might see it differently." If you hold something asymmetric in front of a mirror, like let's say some text, it still appears flipped horizontally. So that doesn't really explain it. | |
| Nov 8, 2014 at 0:40 | history | edited | Keith Thompson | CC BY-SA 3.0 |
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| Oct 12, 2011 at 19:11 | history | answered | Keith Thompson | CC BY-SA 3.0 |