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Science brain teasers require understanding of the physical or biological world and the laws that govern it.


Puzzle ID:#107
Fun:** (1.98)
Difficulty:** (1.97)
Submitted By:offsky**




Why does a mirror appear to invert the left-right directions, but not up-down?

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Oct 06, 2001

I do not care for the " problem" or the proposed solution. Mirrors do not do anything at all but reflect a direct image. Wordplay like "inverted" image has no establishment in a simple and easily understood concept. Randy Eatmon
Nov 12, 2002

I agree with Randy. Mirrors do not invert anything. They just reflex light back. The trick is in making people think that mirrors invert left and right when in fact they do not.
May 11, 2003

actually, if the mirror inverted left and right, it wouldn't show up backwards at all.
------- mirror
\ /
\ /
\ /
/\ inverted
/ \
/ \
/ \
-------- you

it would be like shaking somebody's right hand, with your right hand. they cross over in the middle.
Jun 08, 2003

i agree, too easy and mirrors don't actually invert, they reflect.
Oct 18, 2004

I agree.
Jan 31, 2005

It all depends on the shape of the mirror. You are assuming (and fair enough too) that the mirror was flat.
What happens if it's a curved mirror? Consider if you will, a spoon... (if you believe that there is one )
Mar 30, 2005

I agree with everyone else on this one, and i don't think it was very good...........and i am not sorry, u just need to try harder......
Apr 20, 2005

May 31, 2005

I agree, there is no spoon.
Jul 27, 2005

Hey dolphin person, if they didn't try hard, where is your perfect teaser? Oh yeah, you don't have one, so don't tell somebody they didn't try

Good one though, easy
Oct 12, 2005

I don't get it, front to back??? ok but they reflect light rays don't they
Nov 28, 2005

Jan 24, 2006

well what do ya know, I learn something new here each day and thats KOOL
Feb 18, 2006

Don't listen to what anyone else says, this is a cute teaser and I learned something new today!
Mar 23, 2006

Mirrors DO invert left and right. If they didn't, why would anyone think they did? (They do invert front and back as well.) For example, write a word on a piece of paper and hold it up to the mirror. The word will be reversed. The reason mirrors invert left and right, but not top and bottom, is because left and right are subjective, while top and bottom are not. If I'm facing you, my right will be your left, and my left will be your right. However, as long as we're both in roughly the same location (because of curvature of the earth), my top and your top will be the same, and my bottom and your bottom will be the same.
Mar 23, 2006

bigswaff, quit whining. This is called the "Comments" section, not the "Worship" section. We have a right to complain. dolphin was not being rude, simply pointing out that she did not like the teaser. That way, offsky will know how to make a better teaser next time. If offsky doesn't like criticism, he/she should not post teasers here, or not read the comments.
Mar 23, 2006

Considering that the teaser asked why the mirror "appears" to invert, the answer does not answer the question.the answer is because eyes are to the left and right of each other. appearances are deceiving
Mar 24, 2006

kinda easy...
Aug 07, 2006

What if you're a vampire? Then you don't have a reflection at all.
Nov 12, 2006

Reasonably easy one. Reflection is the key, for mirror images. You are tricking and/or teasing your eyes and mind with the logic behind a mirror. Great teaser!
Feb 17, 2007

but i still dont get it!!!!!!!!!!! and no im not a blonde and not a little kid im 13 and still dont get it!!!!!!!!!!!!!!!!!errrrrrr
May 05, 2007

Jul 10, 2008

echo above post...What???
Aug 12, 2008

Fantastic teaser.

Nobody's answered the implied question yet, "Why does a mirror appear to invert left-right?"

Answer #1: Because we tend to look at ourselves, we are very symmetrical, and we imagine a kind of "twin" standing in front of us.
Answer #2: If we look at inverted lettering, we usually just call it "backwards" without specifying the type of inversion.

It has nothing to do with having two eyes. Close one eye and see if that makes a difference.

Here's how to prove that mirrors DO invert front-to-back, exactly as offsky said.

[DOWN is the way gravity is pulling, and UP is the opposite. FRONT is toward the mirror and BACK is away from it. LEFT and RIGHT you can figure out yourself.]

1) Get a piece of paper and write something in big, black assymetrical letters. E.g., "LEGGLER." For future reference, write some small clock numbers at the appropriate locations ('12' above, '3' to the right, '6' below, and '9' to the left).

2) Flip the paper over. Trace the letters of your word. (Do not trace the clock numbers).

3a) Stand in front of a mirror. Hold up the paper so you can read the letters directly (not in the mirror), with 12 O'clock touching the mirror. Now flip the paper left to right (you'll be revealing the backside of the paper). Are the letters in the mirror normal? Nope. The mirror does not flip L-R.

3b) Return to the original orientation, with 12 o'clock touching the mirror. Now rotate the paper 180 degrees (do not flip it) so that 6 o'clock is touching the mirror. Are the letters in the mirror normal? Nope. The mirror does not flip everything around a point.

3c) Hold the paper off to your left, so that you can read the letters. 3 o'clock should be touching the mirror. Now flip the paper up to down (again, you'll be looking at the back side of the paper). Are the letters in the mirror normal? Nope. The mirror does not flip up to down.

3d) Hold the paper normally, so that 12 o'clock is touching the mirror. Now flip the paper FRONT to BACK (remember that "front" is toward the mirror). Again, you'll be flipping the paper over. Are the letters in the mirror normal? Yep.

Front-to-back inversion. Quod erat demonstrandum.

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