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Science Forum

  1. 06 Oct '10 17:16
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.

    The mirror spins the image on the horizontal, but never the vertical.

    Is it because who ever made the first one did it wrong and
    we have all been copying him ever since?

    (I don't think I've posted in this Forum before...creepy...there is no chess)
  2. 06 Oct '10 17:18 / 1 edit
    Originally posted by greenpawn34
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.

    The mirror spins the image on the horizontal, but never the vertical.

    Is it because who ever made the first one did it wrong and
    we have all been copying him ever since?

    (I don't think I've posted in this Forum before...creepy...there is no chess)
    You think in terms of right-left. Think of the term west-east instead and it makes all sense.
    Put your mirror in the north, and put yourself south of it. Then you'll see your west ear to the west in the mirror, and your east ear to the east.
  3. 06 Oct '10 18:30
    Originally posted by greenpawn34
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.

    The mirror spins the image on the horizontal, but never the vertical.

    Is it because who ever made the first one did it wrong and
    we have all been copying him ever since?

    (I don't think I've posted in this Forum before...creepy...there is no chess)
    It is an illusion based on the fact that we are symmetrical left to right and we imagine ourselves in the person in the mirror by mentally rotating ourselves.

    However the image itself is not in any way 'reversed'. Each reflection is in the same place as the part it is reflecting. Your heads reflection is in the same place as is where your head is, your left hand is in the same place as where your left hand is etc. Its only when you mentally rotate yourself into your reflection that the apparent reversal is seen.
  4. Subscriber AThousandYoung
    Do ya think?
    06 Oct '10 18:31
    Originally posted by greenpawn34
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.

    The mirror spins the image on the horizontal, but never the vertical.

    Is it because who ever made the first one did it wrong and
    we have all been copying him ever since?

    (I don't think I've posted in this Forum before...creepy...there is no chess)
    It doesn't spin anything. It makes an image which is a chiral opposite to what is being reflected. That which is up is up. That which is north is north. That which is close to the mirror is close to the mirror surface.

    If you put a mirror directly above you, you will get an image that is reversed up and down but not front to back and therefore not right and left. It depends on what plane the mirror is in.
  5. Standard member wolfgang59
    Infidel
    06 Oct '10 18:43
    Originally posted by greenpawn34
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.

    The mirror spins the image on the horizontal, but never the vertical.

    Is it because who ever made the first one did it wrong and
    we have all been copying him ever since?

    (I don't think I've posted in this Forum before...creepy...there is no chess)
    twhitehead got it right ... its to do with our symmetry ... nothing to do with mirrors!


    Consider and intelligent 8 armed starfish with a single centralised eye.

    He would see the reflection reversed in 8 different planes of symmetry.
  6. 06 Oct '10 18:53 / 1 edit
    Thank you.

    It was just one of things that pops into to my head every now and then.
    It has all been solved. I can now sleep at nights.

    I'll have to come here more often.

    Can't leave without a joke or two to say thanks again.

    Is it bad luck to be superstitious?

    If you jog backwards do you actually gain weight?

    and how do you tell when you have run out of invisible ink?
  7. 06 Oct '10 20:44
    Originally posted by greenpawn34
    Thank you.

    It was just one of things that pops into to my head every now and then.
    It has all been solved. I can now sleep at nights.

    I'll have to come here more often.

    Can't leave without a joke or two to say thanks again.

    Is it bad luck to be superstitious?

    If you jog backwards do you actually gain weight?

    and how do you tell when you have run out of invisible ink?
    To answer your questions: yes, no and such a definition of ink is contradictory (an ink, by definition, leaves some kind of trace, otherwise it's useless as an ink).
  8. 06 Oct '10 23:03
    Originally posted by greenpawn34
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.

    The mirror spins the image on the horizontal, but never the vertical.

    Is it because who ever made the first one did it wrong and
    we have all been copying him ever since?

    (I don't think I've posted in this Forum before...creepy...there is no chess)
    some mirrors do spin the image on the vertical -- just look into the front side of a shiny spoon.
  9. 06 Oct '10 23:11
    Hey!

    You are correct. I am now back to square one.

    The spoon makers and the mirror makers want to get together
    and sort things out. One of them is doing things wrong.

    More sleepless nights....
  10. 07 Oct '10 02:56
    It's 4.00am and I've just woken up.

    I've been dreaming about an intelligent 8 armed
    starfish with a single centralised eye.
  11. 07 Oct '10 05:03
    Originally posted by KazetNagorra
    To answer your questions: yes, no and such a definition of ink is contradictory (an ink, by definition, leaves some kind of trace, otherwise it's useless as an ink).
    Invisible ink does leave a trace, it is just not a visible trace - until you heat it. Luckily, the ink is usually visibly while it is in the ink well, and visible while you write, it is only when it dries that it is no longer visible.
  12. 07 Oct '10 19:58
    Originally posted by greenpawn34
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.
    We don't. We see it back-to-front.

    No, that was a serious answer. Draw a 2-d picture of someone looking at a mirror, and the mirror image where he thinks he sees it, as someone would look at the whole scene from above. Something like this (iffy ASCII art follows):

    -v+
    -----------
    -^+

    The mirror image is mirrored in the mirror, not by it.

    Richard
  13. 08 Oct '10 15:18
    ??..could this have something to do with relativity?...
  14. 09 Oct '10 11:20
    Originally posted by highdraw
    ??..could this have something to do with relativity?...
    no
  15. 10 Oct '10 02:17
    Originally posted by greenpawn34
    What has always bugged me about mirrors is how come we always
    see the reflection as left to right and never upside down.

    The mirror spins the image on the horizontal, but never the vertical.

    Is it because who ever made the first one did it wrong and
    we have all been copying him ever since?

    (I don't think I've posted in this Forum before...creepy...there is no chess)
    the side of the mirror that is to the left of you is reflecting your LEFT arm, directly across from it.

    ditto for the side of the mirror that is to the right of you, and your right arm.