Post by MikeO on Jan 10, 2010 15:49:17 GMT -5
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Why do mirrors SEEM to reverse left and right, .BUT not up and down?
How does a common mirror, in the common configuration, reverse left and right, and not up and down?
It would seem that the mirror doesn't have the wherewithal to discriminate between horizontal and vertical.
The image of yourself in your bathroom mirror has its heart on the wrong side, yet it's not upside down. Why?
If, in a mirror, we watch a tennis match between two right-handed players we will see two left-handed players,
yet they will not be playing upside down. Why the asymmetry?
***
In 1969 I was a Physics major in college, and I loved the science very much. One day, while taking a break from my studies and half watching a re-run of “Leave It To Beaver” on TV, an eventful challenge was presented to me. I have never forgotten this, and it has deeply affected my life. In this old TV sitcom (even THEN it was old!) I first heard this mirror riddle which has defied clear and complete explanation for centuries.
This chance viewing of a serious paradox in a comic presentation was a very long time ago, and my memory of many of its surrounding details has dimmed and distorted. This in itself is a fascinating subject, that human memory is far from immune to alteration. However, the heart of the matter presented on the TV show is still very clear. I’d love to verify the small details someday, and get a peek at the competition between accurate memories and confabulated distortions.
I’ve never again seen this TV episode, but that may change soon as more and more such material is becoming available via the Internet. When I do again see that show, it will be a unique opportunity to compare my 40 year old memories (including any distortions) with the original presentation. Before that happens, I want to document the details of my probably inaccurate memories.
Here’s the best of what I can recall. The Beaver and Wally were brushing their hair, standing side-by-side in front of the same mirror. Beaver turns to his brother and casually asks, “Hey, Wally. Why does a mirror reverse left and right, but not up and down?”
As all the Physics student circuits in my brain awoke with a start, Wally looked in the mirror with a quizzical face, then turned to the Beaver and said nothing.
He then looks back in the mirror with greater perplexity, and then turns to the Beaver again, this time with a scowl on his face. “Shut up, Beaver. We’re going to be late for school,” he commands, resuming his hair brushing, determined to brush off Beaver’s perplexing riddle as well.
By this time I was fully awake and poised to hear the answer, but there was none. The issue was dropped by the Beaver and Wally, and so was my jaw.
Mentally I was cranking away answers, thinking this question could very well someday end up on an Optics exam. But I did not like the few pseudo answers that were forthcoming; I was stumped!
Through the commercial, I thought hard on the problem, but stayed glued to the TV set in case it came up again. It DID come up again! But again, it wasn’t answered, just posed for the comic effect. A third time it came up, and again, the puzzlement it caused was milked for the comic effect, but the Physics of any answer was absent.
I don’t think it was the Beaver who asked the question its second and third times. It dimly seems that Ward Cleaver, the Beaver’s father, was involved in the later incidents. It was passed on from Beaver to Wally and then to Ward. It was contagious. I too caught the curiosity with which this mirror question seems packed.
The years past, I tinkered with the problem from time to time, and gradually found the answer.
Why do mirrors SEEM to reverse left and right, .BUT not up and down?
How does a common mirror, in the common configuration, reverse left and right, and not up and down?
It would seem that the mirror doesn't have the wherewithal to discriminate between horizontal and vertical.
The image of yourself in your bathroom mirror has its heart on the wrong side, yet it's not upside down. Why?
If, in a mirror, we watch a tennis match between two right-handed players we will see two left-handed players,
yet they will not be playing upside down. Why the asymmetry?
***
In 1969 I was a Physics major in college, and I loved the science very much. One day, while taking a break from my studies and half watching a re-run of “Leave It To Beaver” on TV, an eventful challenge was presented to me. I have never forgotten this, and it has deeply affected my life. In this old TV sitcom (even THEN it was old!) I first heard this mirror riddle which has defied clear and complete explanation for centuries.
This chance viewing of a serious paradox in a comic presentation was a very long time ago, and my memory of many of its surrounding details has dimmed and distorted. This in itself is a fascinating subject, that human memory is far from immune to alteration. However, the heart of the matter presented on the TV show is still very clear. I’d love to verify the small details someday, and get a peek at the competition between accurate memories and confabulated distortions.
I’ve never again seen this TV episode, but that may change soon as more and more such material is becoming available via the Internet. When I do again see that show, it will be a unique opportunity to compare my 40 year old memories (including any distortions) with the original presentation. Before that happens, I want to document the details of my probably inaccurate memories.
Here’s the best of what I can recall. The Beaver and Wally were brushing their hair, standing side-by-side in front of the same mirror. Beaver turns to his brother and casually asks, “Hey, Wally. Why does a mirror reverse left and right, but not up and down?”
As all the Physics student circuits in my brain awoke with a start, Wally looked in the mirror with a quizzical face, then turned to the Beaver and said nothing.
He then looks back in the mirror with greater perplexity, and then turns to the Beaver again, this time with a scowl on his face. “Shut up, Beaver. We’re going to be late for school,” he commands, resuming his hair brushing, determined to brush off Beaver’s perplexing riddle as well.
By this time I was fully awake and poised to hear the answer, but there was none. The issue was dropped by the Beaver and Wally, and so was my jaw.
Mentally I was cranking away answers, thinking this question could very well someday end up on an Optics exam. But I did not like the few pseudo answers that were forthcoming; I was stumped!
Through the commercial, I thought hard on the problem, but stayed glued to the TV set in case it came up again. It DID come up again! But again, it wasn’t answered, just posed for the comic effect. A third time it came up, and again, the puzzlement it caused was milked for the comic effect, but the Physics of any answer was absent.
I don’t think it was the Beaver who asked the question its second and third times. It dimly seems that Ward Cleaver, the Beaver’s father, was involved in the later incidents. It was passed on from Beaver to Wally and then to Ward. It was contagious. I too caught the curiosity with which this mirror question seems packed.
The years past, I tinkered with the problem from time to time, and gradually found the answer.