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A comment on Why Do Mirrors Flip Things Horizontally but Not Vertically? Here's the Physics. Parent comment

Re:Why Do Mirrors Flip Things Horizontally but Not Verticall... by quietbritishjim on Wednesday October 07, 2020 @12:00PM (#24709516)
> The words “up” and “down” are absolute, but the words “left” and “right” are relative to you.

I disagree. In this sort of conversation, "up" refers to the direction from your feet to your head, not away from the ground. If you do a handstand and hold your piece of paper up to the mirror then you'll still find it flipped left-to-right but not top-to-bottom if you turn it the instinctive way, and still find it flipped top-to-bottom but not left-to-right if you turn it vertically.

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Re:Why Do Mirrors Flip Things Horizontally but Not Verticall... by kelnos on Wednesday October 07, 2020 @01:50PM (#24710769)
> In this sort of conversation, "up" refers to the direction from your feet to your head, not away from the ground.

I disagree. To me, "up" is opposite the direction of gravity. If I were doing a handstand on the ground and someone told me to look up, I'd look toward my feet.

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Re:Why Do Mirrors Flip Things Horizontally but Not Verticall... by yeellow on Wednesday October 07, 2020 @12:34PM (#24709922)
And what if you stand on a mirror?
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Re:Why Do Mirrors Flip Things Horizontally but Not Verticall... by quietbritishjim on Wednesday October 07, 2020 @01:51PM (#24710776)
I'm not sure if you're joking but that doesn't change what our perception of up and down are.
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Re:Why Do Mirrors Flip Things Horizontally but Not Verticall... by yeellow on Wednesday October 07, 2020 @02:26PM (#24711131)
I am not joking. When you stand on the mirror the direction from your feet to your head is different than for the guy in the mirror. It shows that the mirror changes only one axe, orthogonal to its surface. It does not rotate anything nor change up/down or left/right. So when I look at the mirror en face only the direction of y axis is changed, x and z is not affected.
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Re:Why Do Mirrors Flip Things Horizontally but Not Verticall... by quietbritishjim on Wednesday October 07, 2020 @10:04PM (#24714890)
I agree, and that doesn't contradict what I said in my original comment. I think we are just getting tangled in semantics rather than fundamentally disagreeing on anything.
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