Why mirror swaps left and right?
Pertti Lounesto
Has this something to do with gravity? NASA has tested
this in microgravity. See http://www.microgravity.com/.
Rolf Kleinknecht
--
rk
Stephen Montgomery-Smith
Interesting - what happens if you look into a mirror while
you are lying on your side?
--
Stephen Montgomery-Smith
ste...@math.missouri.edu
http://www.math.missouri.edu/~stephen
Steve MacGregor
Pertti Lounesto <plou...@pp.htv.fi> wrote:
> Why a mirror swaps left and right, but not up and down?
You're mistaken. Just as a mirror does not swap up and down, it does
not swap left and right; it swaps forward and backward.
--
Stamp out, eliminate, and abolish redundancy.
Sent via Deja.com http://www.deja.com/
Before you buy.
phunt
Stephen Montgomery-Smith <ste...@math.missouri.edu> wrote:
> ....
> Interesting - what happens if you look into a mirror while
> you are lying on your side?
>
Hmmm ... Obviously it must swap feet and head, so that a
careless person could end up with a foot in his mouth.
They say the lens of the eye swaps both ways but the visual
cortex is always busy making things right. This was shown
several years ago in a study where subjects wore inverting
eyeware but recovered their normal orientation within a week
or two.
/ph
- - - - - - - - - -
> --
> Stephen Montgomery-Smith
Stephen Montgomery-Smith
>
> In article <3A0CCF2C...@math.missouri.edu>,
> Stephen Montgomery-Smith <ste...@math.missouri.edu> wrote:
> > ....
> > Interesting - what happens if you look into a mirror while
> > you are lying on your side?
> >
>
> Hmmm ... Obviously it must swap feet and head, so that a
> careless person could end up with a foot in his mouth.
>
> They say the lens of the eye swaps both ways but the visual
> cortex is always busy making things right. This was shown
> several years ago in a study where subjects wore inverting
> eyeware but recovered their normal orientation within a week
> or two.
>
So maybe a mirror really keeps left and right the same, but
reverses up and down, but because our eye changes it, we see
left and right reversed, and up and down the same.
Bill Taylor
I dub thee Troll.
`-.
-._ `. `-.`-. `-.
_._ `-._`. .--. `.
.-' '-. `-|\/ \| `-.
.' '-._\ (o)O) `-.
/ / _.--.\ '. `-. `-.
/| ( | / -. ( -._( -._ '. '.
/ \ \-.__\ \_.-'`.`.__'. `-, '. .'
| /\ | / \ \ `--')/ .-'.'.'
.._/ / / / / / \ \ .' . .' .'
/ ___/ | / \ \ \ \__ '.'. . .
\ \___ \ ( \ \ `._ `. .' . ' .'
\ `-._\ ( `-.__ | \ )// .' .' .-'
\_-._\ \ `-._\)// ""_.-' .-' .' .'
`-' \ -._\ ""_..--'' .-' .'
\/ .' .-'.-' .-' .-'
.-'.' .' .' .-'
_ _____ _ ____ _ _ _ __ _
/\| |/\ | __ \| | / __ \| \ | | |/ / /\| |/\
\ ` ' / | |__) | | | | | | \| | ' / \ ` ' /
|_ * _| | ___/| | | | | | . ` | < |_ * _|
/ , . \ | | | |___| |__| | |\ | . \ / , . \
\/|_|\/ |_| |_____|\____/|_| \_|_|\_\ \/|_|\/
Pertti Lounesto
> How utmost pleasant to have Loony back with his old habits!
Kleinknecht responded to my message, calling me Loony,
although I have never insulted Kleinknecht. I have insulted
Ullrich and his cronies, who do not admit their mistakes and
validity of my counterexamples to their math-misconceptions.
The army of cronies has grown over time, along with my
service of locating the misconceptions. In spite of the size
of the army, and new recruits, the cronies have failed to
invalidate any of my counterexamples, in
http://www.hit.fi/~lounesto/counterexamples.htm,
which Ullrich and his cronies claimed all invalid, over 300
times, before an intelligent poster, Keith Ramsay, verified
one of my counterexamples, after which the cronies rushed
to argue that they never called my counterexamples invalid.
Such is the army to which Kleinknecht wants to enlist.
phunt
> > cortex is always busy making things right. This was shown
> > several years ago in a study where subjects wore inverting
> > eyeware but recovered their normal orientation within a week
> > or two.
> >
>
> So maybe a mirror really keeps left and right the same, but
> reverses up and down, but because our eye changes it, we see
> left and right reversed, and up and down the same.
And it really does emphasize the "physics" in metaphysics.
Last year we had a child-prodigy named "Seraph" hanging out
in sci-math, and he asked a very innocent question about how
to improve his rational productions via regimen or technique.
Someone replied in depth to his question, fully understanding
his predicament as a merely budding genius in need of methods
capable of unloosing all his potential for illuminating and
reformulating difficult things he knew to be within his grasp.
One of the prescriptions for achieving a rewarding state of
pure thought, was to prepare a sort of workplace insulated
from most sensory percepts. His advisor suggested a sort of
warm water bath in a dark and quiet room. That reminded me
of a quote somewhere from Einstein, where he said he could
only do good work for about 4 hours a day, and he preferred
to do that work in a bare isolated room having clerestory
windows if any.
It would seem that most of us devote enormous energy, both
mental and physical in pursuit of a sensible experience or
grasp of our most immediate world of which we are part.
/ph
- - - - - - - - - - -
> phunt wrote:
Lee Rudolph
>Pertti Lounesto wrote:
>>
>> Why a mirror swaps left and right, but not up and down?
>> Has this something to do with gravity? NASA has tested
>> this in microgravity. See http://www.microgravity.com/.
>
>Interesting - what happens if you look into a mirror while
>you are lying on your side?
Surely it's always the other side that lies, not Pertti?
Lee Rudolph
denis-feldmann
Pertti Lounesto <plou...@pp.htv.fi wrote in message :
3A0CBA04...@pp.htv.fi...
> Why a mirror swaps left and right, but not up and down?
> Has this something to do with gravity? NASA has tested
> this in microgravity. See http://www.microgravity.com/.
Is your list of new troll posts already empty? (this one was published last
year already) Or do you believe we have no memory?
>
Neil W Rickert
>Rolf Kleinknecht wrote:
>> How utmost pleasant to have Loony back with his old habits!
>Kleinknecht responded to my message, calling me Loony,
>although I have never insulted Kleinknecht.
You regularly insult all readers of sci.math.
Joel 'Twisty' Nye
When the mind tries to relate to the effect, it does so in terms of how
the left eye is similar to the right, while head and foot are still
dissimilar.
Try some science fiction scenarios:
What if people were more like weird flukes, with a fuzzy left cheek and
a tubular right cheek? If this always held true, you'd associate
fuzzy==right to facing a person's front and fuzzy==left to facing a
person's back. When looking at a reflection, you'd be more prone to
thinking that it inverted their front-and-back depth. If their head and
feet looked alike, you'd be inclined to think this trick was achieved by
them standing on their heads.
Let's write a scifi short story:
Adam and Eve are products of a new genetic experiment: their eyes are
designed to switch signals so that every 1/60th of a second, their left
eye is active for an even phase, their right eye for an odd. They live
in a glass house that shows a garden outside. Or so they believe, until
they have kids.
One day, when Abel is standing on his head, all of the outdoor imagery
is inverted inside-out: distant mountains are protruding into his face,
while nearby trees are concaving away. He stands upright, all is
normal. Eventually, he realizes that the walls are nothing more than a
video-3D-postcard, and he develops mirrored surfaces which, over long
distances, show the effects of inverting the phase of their eye-cycles.
Eventually, his brother Cain archetects a plan to get Abel outside the
walls. Abel ends up finding himself drifting in the vacuum of space
just outside the colony ship.
- Joel 'Twisty' Nye, m...@twisty.org
David C. Ullrich
Hard to believe that such an awesome expert
in rotations could be IGNORANT of the answer to this
question.
In fact it does neither. The fact that a mirror
_appears_ to swap left and right is an illusion having
to do with the fact that we like to keep our feet on
the ground: If I look at myself in the mirror it looks
like there is someone behind the mirror who looks
very much like me, except with left and right swapped.
The reason it looks this way to me is because if I
were to move to a location behind the mirror I would
do so by walking there, with my feet on the ground.
If I walked around behind the mirror I would arrive in
a position where my head was in the same place
as the other guy's head but my left hand was where
his right hand is.
If otoh I were accustomed to getting from the front
of a mirror to the back of a mirror by doing a sort
of vault over the top of the mirror instead of walking
around the sides, so that I ended up with my head
on the floor, then it would appear to me that the
person behind the mirror had up and down swapped
instead of left and right - my left hand would be
where "his" left hand is, but my head would be
where his feet are.
Pertti Lounesto
> Pertti Lounesto <plou...@pp.htv.fi> writes:
> >Rolf Kleinknecht wrote:
>
> >> How utmost pleasant to have Loony back with his old habits!
>
> >Kleinknecht responded to my message, calling me Loony,
> >although I have never insulted Kleinknecht.
>
> You regularly insult all readers of sci.math.
No. I insult the collectivity of sci.math, and that is not the
same thing as all of its individual readers. Fine individuals
can make a deplorable group, if they lack common goals.
Ron Hardin
> No. I insult the collectivity of sci.math, and that is not the
> same thing as all of its individual readers. Fine individuals
> can make a deplorable group, if they lack common goals.
Not all deplorable groups lack common goals, it should be quickly
pointed out.
It would be a shame if Godwin's law took over right away.
--
Ron Hardin
rhha...@mindspring.com
On the internet, nobody knows you're a jerk.
Erik Max Francis
> No. I insult the collectivity of sci.math, and that is not the
> same thing as all of its individual readers.
Since you continue under the deluded impression that somehow the
contributors to sci.math are addressable as a group, it most certainly
is.
Considering that in this thread you are merely trolling in an attempt to
start up ill will, you certainly are quite the pain in the ass this
week, aren't you?
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
__ San Jose, CA, US / 37 20 N 121 53 W / ICQ16063900 / &tSftDotIotE
/ \ Freedom is a road seldom travelled by the multitudes
\__/ Public Enemy
Fat Boy and Little Man / http://www.fatboyandlittleman.com/
Watch Fat Boy and Little Man go about their antics.
Doug Norris
>Why a mirror swaps left and right, but not up and down?
They do; at least here in the States, they do. What sort of mirror
do you have?
Doug
Zdislav V. Kovarik
Stephen Montgomery-Smith <ste...@math.missouri.edu> wrote:
:Pertti Lounesto wrote:
:>
:> Why a mirror swaps left and right, but not up and down?
:> Has this something to do with gravity? NASA has tested
:> this in microgravity. See http://www.microgravity.com/.
:Actually, I think I figured it out. If you put the mirror
:on the floor and stand on top of it, it really does reverse
:up and down.
:
The ceiling occurred to me first.
ZVK(Slavek).
Stephen Montgomery-Smith
Actually, I think I figured it out. If you put the mirror
on the floor and stand on top of it, it really does reverse
up and down.
--
Frank Schwartz
>Stamp out, eliminate, and abolish redundancy
AMEN!
John Savard
>Why a mirror swaps left and right, but not up and down?
>Has this something to do with gravity? NASA has tested
>this in microgravity. See http://www.microgravity.com/.
Not really.
Place a mirror on the north wall of the room.
Face the mirror.
The man in the mirror has his head up at the top.
The man in the mirror has his feet down at the bottom.
Your left hand - stick it out, it points west. The man in the mirror
moves the hand that is on his west side too.
But you are facing north.
The man in the mirror is facing south.
It is "towards" and "away" from the mirror that have been reversed.
Because left and right are attached to us, we use them as relative
directions. Because of gravity, up and down are fundamental, whereas
east and west or north and south are all the same as we move around.
So we interpret what we see in the mirror as a reversal of left and
right, because someone turning around to face us is a normal thing;
someone being turned inside-out from front to back is not.
John Savard
http://home.ecn.ab.ca/~jsavard/crypto.htm
Azymuth
all a mirror does is reflect the light reflected from our bodies back to our
eyes....imagine what you look like from an observer....
it only looks like the left became right and vica versa because we ALWAYS
are with our feet on the floor or more to the point the brain gets 'used' to
the fact that the eyes are orientated a certain way.... thus when it sees
the image it interprets accordingly....that is why the floor does not become
the ceiling, etc... when looking in a mirror
now let this thread be dead....
*sighs*
Pertti Lounesto <plou...@pp.htv.fi> wrote in message
news:3A0CBA04...@pp.htv.fi...
Lynn Killingbeck
Oh, dear, does that mean that mirrors don't work at the north pole?!?
Sorry, but that seemed appropriate for this obviously trolling thread.
At the local natural science museum, down in the kiddie's section, there
is "a mirror" that does not reverse left-right (corner reflector). And,
"a mirror" that does reverse up-down (concave cylinder with horizontal
axis), depending on the observer's relation to the focus. And funny-
houses have "a mirror" that does other wierd distortions.
I don't know, though, how all this looks to PL, standing on his side of
"a mirror" in his Alice-type world.
The original is a rather poorly defined problem statement, overall.
Lynn Killingbeck
John Savard
<kill...@pointecom.net> wrote, in part:
>At the local natural science museum, down in the kiddie's section, there
>is "a mirror" that does not reverse left-right (corner reflector).
Yes, I've read Martin Gardner's book (The Ambidextrous Universe)
covering such matters...but asking "why does a mirror do this" would
indeed refer, by default, to an ordinary mirror.
However, apparently there are substantiated claims that Pertti
Lounesto actually has published papers on Clifford algebras in
reputable journals. Has something unfortunate happened to someone who
was once a real mathematician?
John Savard
http://home.ecn.ab.ca/~jsavard/crypto.htm
Alastair Rae
<condu...@resistanceisfutile.co.uk> wrote:
>WHAT !?!
>
>all a mirror does is reflect the light reflected from our bodies back to our
>eyes....imagine what you look like from an observer....
>
>it only looks like the left became right and vica versa because we ALWAYS
>are with our feet on the floor or more to the point the brain gets 'used' to
>the fact that the eyes are orientated a certain way.... thus when it sees
>the image it interprets accordingly....that is why the floor does not become
>the ceiling, etc... when looking in a mirror
Either this is a counter-troll or you are mistaken.
Consider a light beam from your left hand, reflected off the mirror to
your eye. The beam comes from the left side of your image, its right
hand.
Now consider a beam from your feet, reflected off the mirror to your
eye. The beam is coming from upwards from your feet, the correct
direction.
So its nothing to do with the brain being used to anything. It's just
that you deduce that someone in front of you has their right hand on
your left hand side.
--
Alastair Rae, London, Europe.
Remove NOSPAM from my email address to reply.
My opinions are not necessarily those of my employers.
Ron Hardin
> Now consider a beam from your feet, reflected off the mirror to your
> eye. The beam is coming from upwards from your feet, the correct
> direction.
It's already upside-down on your retina, though, which is why it
looks normal.
phunt
NOSPA...@tertio.com (Alastair Rae) wrote:
> ....
> So its nothing to do with the brain being used to anything.
> It's just that you deduce that someone in front of you has
> their right hand on your left hand side.
This is very good and suggests the question whether there
may be any sort of impropriety in mirrors. It reminds me
of this jot from some class notes on Greek participles:
"A fellow feeling makes us wonderfully kind."
Methinks the poet would have changed his mind
If he had found some fellow feeling in his coat behind.
Cheers,
/ph
- - - - - - - - - - -
> On Mon, 13 Nov 2000 01:21:44 -0000, "Azymuth"
> <condu...@resistanceisfutile.co.uk> wrote:
>
> >WHAT !?!
> >
> >all a mirror does is reflect the light reflected from our bodies back
to our
> >eyes....imagine what you look like from an observer....
> >
> >it only looks like the left became right and vica versa because we
ALWAYS
> >are with our feet on the floor or more to the point the brain gets
'used' to
> >the fact that the eyes are orientated a certain way.... thus when it
sees
> >the image it interprets accordingly....that is why the floor does not
become
> >the ceiling, etc... when looking in a mirror
>
> Either this is a counter-troll or you are mistaken.
>
> Consider a light beam from your left hand, reflected off the mirror to
> your eye. The beam comes from the left side of your image, its right
> hand.
>
> Now consider a beam from your feet, reflected off the mirror to your
> eye. The beam is coming from upwards from your feet, the correct
> direction.
>
> So its nothing to do with the brain being used to anything. It's just
> that you deduce that someone in front of you has their right hand on
> your left hand side.
>
> --
> Alastair Rae, London, Europe.
> Remove NOSPAM from my email address to reply.
> My opinions are not necessarily those of my employers.
>
Danny Purvis
> In fact it does neither. The fact that a mirror
>_appears_ to swap left and right is an illusion having
>to do with the fact that we like to keep our feet on
>the ground(.)
Right. So in the microgravity environment of a space station, where -
depending on the architecture - residents might not have a bias toward
any particular "ground", would this illusion continue to operate? Or
would it disappear or perhaps be supplanted by a more complex
illusion? It seems to me that Lounesto's question was an interesting
foray into the psychology of vision. The question at least elicited a
number of incorrect responses (your answer was completely correct, in
my opinion), leading me to believe that some number of mocking replies
might have missed it if they had deigned to answer. (Your approach
was more admirable: mock but answer.)
Actually, the question for me elicited fond memories of a wonderful
book which I never mastered, Colin M. Turbayne's "The Myth of
Metaphor". I wonder if anybody in this forum is familiar with this
book? Turbayne's thesis is that novel explanations often begin as
metaphors but as these explanations gain acceptance the fact that they
are metaphors is, unfortunately, usually forgotten. To make his
point, Turbayne elaborates an alternative metaphor for vision.
Instead of "vision as geometry" he has "vision as language". With his
new model, he tackles an number of classic visual puzzles, including
the following questions: (1) Why does the full moon look larger when
it is near the horizon? (2) What happens if a person blind from birth
is suddenly given sight. (3) Some others that I have forgotten (it's
been many years).
Severian
>
> In article <3a0fee8a.15744379@firewall>,
> NOSPA...@tertio.com (Alastair Rae) wrote:
> > ....
> > So its nothing to do with the brain being used to anything.
> > It's just that you deduce that someone in front of you has
> > their right hand on your left hand side.
> > ....
>
> This is very good and suggests the question whether there
> may be any sort of impropriety in mirrors.
"We discovered (such a discovery is inevitable in the
late hours of the night) that mirrors have something
monstrous about them. Then Bioy Casares recalled that
one of the hierarchs of Uqbar had declared that mirrors
and copulation are abominable, because they increase
the number of men".
Jorge Luis Borges, "Tlon, Uqbar; Orbis Tertius".
--
Severian
---------------------------------------------------------------
Victor Meldrew: "The police can use sperm now as
a way of fingerprinting people."
Mrs Warboys: "I don't see what was wrong with the old inkpads."
---------------------------------------------------------------
David Renwick, _One Foot in the Grave_
Ronald Bruck
<rhha...@mindspring.com> wrote:
:Alastair Rae wrote:
:> Now consider a beam from your feet, reflected off the mirror to your
:> eye. The beam is coming from upwards from your feet, the correct
:> direction.
:
:It's already upside-down on your retina, though, which is why it
:looks normal.
And it's also BACKWARD on your retina... Which is why it looks
normal?????
The mirror problem is purely one of perception. The mirror has the same
left/right behavior as it has up/down behavior: stand with your arms
extended; the reflection of your left hand appears to come from a point
directly in front of your left hand; the reflection of your right hand
appears to come from a point directly in front of your right hand; the
reflection of your head appears to come from a point directly in front
of your head; and the reflection of your feet appears to come from a
point directly in front of your feet. It's your BRAIN which interprets
the object in the mirror as a human being and not a mirror image. Your
brain's experience is that when you shake hands with someone, his RIGHT
hand is on your LEFT: and so it interprets your image that way.
It's got nothing to do with optics.
--Ron Bruck
--
Due to University fiscal constraints, .sigs may not be exceed one
line.
David C. Ullrich
wrote:
>David Ullrich wrote:
>
>> In fact it does neither. The fact that a mirror
>>_appears_ to swap left and right is an illusion having
>>to do with the fact that we like to keep our feet on
>>the ground(.)
>
>Right. So in the microgravity environment of a space station, where -
>depending on the architecture - residents might not have a bias toward
>any particular "ground", would this illusion continue to operate? Or
>would it disappear or perhaps be supplanted by a more complex
>illusion? It seems to me that Lounesto's question was an interesting
>foray into the psychology of vision.
I caught myself before saying how ridiculous the idea
that NASA had been doing experiments on this was. I certainly
wouldn't know, but I tend to doubt that a few weeks or months in
a space station is going to matter, my _conjecture_ is after a
brief period like that people with their heads where your feet are
would still look upside-down, gravity or not. But I don't know,
and there _is_ an interesting question regarding how mirror
images would be perceieved by a person who really had no
bias regarding direction at all.
>The question at least elicited a
>number of incorrect responses (your answer was completely correct, in
>my opinion), leading me to believe that some number of mocking replies
>might have missed it if they had deigned to answer.
A lot of people tend to explain why it really _does_
swap left and right instead of up and down. Seems obviously
impossible by symettry.
>(Your approach
>was more admirable: mock but answer.)
Well it's simply incredible that Pertti Lounesto of
all people should be IGNORANT of the answer to the
question, given that he's Mr. I-Understand-what-a-Rotation-
Is-and-You-Don't and all. Strange but true.
>Actually, the question for me elicited fond memories of a wonderful
>book which I never mastered, Colin M. Turbayne's "The Myth of
>Metaphor". I wonder if anybody in this forum is familiar with this
>book? Turbayne's thesis is that novel explanations often begin as
>metaphors but as these explanations gain acceptance the fact that they
>are metaphors is, unfortunately, usually forgotten. To make his
>point, Turbayne elaborates an alternative metaphor for vision.
>Instead of "vision as geometry" he has "vision as language". With his
>new model, he tackles an number of classic visual puzzles, including
>the following questions: (1) Why does the full moon look larger when
>it is near the horizon?
That's easy: It's a tidal effect - when it's closer to the
Earth it gets stretched more by gravity, looks bigger because it's
bigger.
David C. "1 for 2" Ullrich
phunt
ull...@math.okstate.edu wrote:
> ....
> A lot of people tend to explain why it really _does_
> swap left and right instead of up and down. Seems obviously
> impossible by symettry.
>
Consider a plane mirror having a normal at some point,
which is also the vertex for a cone of two napes. All
points around the "real" nape will be reversed in the
"mirrored" nape. Maybe this is why we don't have an
eye located at our navel.
You misspelled symmettry and I caught it first.
/ph
- - - - - - - - - - -
> On 13 Nov 2000 10:23:57 -0500, danny_...@hotmail.com (Danny Purvis)
Nico Benschop
>
> On Mon, 13 Nov 2000 02:35:20 GMT, Lynn Killingbeck
> <kill...@pointecom.net> wrote, in part:
>
> >there is "a mirror" that does not reverse left-right (corner
> >reflector).
>
> covering such matters...but asking "why does a mirror do this"
> would indeed refer, by default, to an ordinary mirror.
>
> However, apparently there are substantiated claims that Pertti
> Lounesto actually has published papers on Clifford algebras in
> reputable journals.
> who was once a real mathematician? -- John Savard
...sure, he looked up from his navel
(into a mirror, and wondered about the real world...;-)
Danny Purvis
wrote:
> That's easy: It's a tidal effect - when it's closer to the
>Earth it gets stretched more by gravity, looks bigger because it's
>bigger.
Perhaps on a microscopic level, but according to Turbayne and some
other sources I consulted back when I was reading Turbayne's book "The
Myth of Metaphor", the apparent change in size of the moon is purely
psychological; if we were to use instruments to measure the moon's
diameter at various locations in the sky, all the measurements would
come out the same, at any precision a human possibly could be capable
of discerning unaided.
Dik T. Winter
> Regarding the full moon looking larger near the horizon, David Ullrich
> wrote:
> > That's easy: It's a tidal effect - when it's closer to the
> >Earth it gets stretched more by gravity, looks bigger because it's
> >bigger.
>
> Perhaps on a microscopic level, but according to Turbayne and some
> other sources I consulted back when I was reading Turbayne's book "The
> Myth of Metaphor", the apparent change in size of the moon is purely
> psychological;
Indeed, and it appears that can easily be verified. Stand with your back
to the moon, bend over and look at it between your legs. The illusion
disappears.
--
dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131
home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/
David C. Ullrich
danny_...@hotmail.com (Danny Purvis) wrote:
> Regarding the full moon looking larger near the horizon, David Ullrich
> wrote:
>
> > That's easy: It's a tidal effect - when it's closer to the
> >Earth it gets stretched more by gravity, looks bigger because it's
> >bigger.
>
> Perhaps on a microscopic level, but according to Turbayne and some
> other sources I consulted back when I was reading Turbayne's book "The
> Myth of Metaphor", the apparent change in size of the moon is purely
> diameter at various locations in the sky, all the measurements would
> come out the same, at any precision a human possibly could be capable
> of discerning unaided.
What I actually wrote was
> That's easy: It's a tidal effect - when it's closer to the
> Earth it gets stretched more by gravity, looks bigger because it's
> bigger.
>
> David C. "1 for 2" Ullrich
Two points for figuring out the distinction between this
and what you quote me as having said...
--
Oh, dejanews lets you add a sig - that's useful...
Danny Purvis
> That's easy: It's a tidal effect - when it's closer to the
>Earth it gets stretched more by gravity, looks bigger because it's
>bigger.
I misread this passage, which I now see is a witticism. I guess I
thought you were referring to relativistic light-bending, but, well, I
am an idiot.
David C. Ullrich
wrote:
>David Ullrich wrote:
>
>> That's easy: It's a tidal effect - when it's closer to the
>>Earth it gets stretched more by gravity, looks bigger because it's
>>bigger.
>
>I misread this passage, which I now see is a witticism.
"Witticism" is much too generous; "stupid joke" is
probably better.
> I guess I
>thought you were referring to relativistic light-bending, but, well, I
>am an idiot.
We all know the feeling. (Well, there are _some_ people
around here who are not aware of their idiocy - those of us who aren't
total idiots know the feeling...)
David C. Ullrich
Danny Purvis
>Indeed, and it appears that can easily be verified. Stand with your
>back to the moon, bend over and look at it between your legs. The
>illusion disappears.
Congratulations on your serendipitous discovery. It pays to keep your
eyes open no matter what you're doing.
Mike Oliver
> lust like the right hand itself
Now there's a poetic phrase!
Hendrik Boom
>
> John Savard wrote:
> >
> > On Mon, 13 Nov 2000 02:35:20 GMT, Lynn Killingbeck
> > <kill...@pointecom.net> wrote, in part:
> >
> > >there is "a mirror" that does not reverse left-right (corner
> > >reflector).
> >
> > covering such matters...but asking "why does a mirror do this"
> > would indeed refer, by default, to an ordinary mirror.
A mirror does not swap right and left. The reflection of my right
hand is near the right side of the mirror, lust like the right
hand itself. The mirror actually swapw front-to-back, otherwise
I would be looking at the reflection of the back of my neck.