Dolphin in fresh water?
R. L.
from captivity inland. I hope they can't just throw her in the nearest
river and let her swim home.
In our world what effect does fresh water (even if same temperature or
warm) have on a dolphin?
R.L.
R. L.
PS. What about natural "salt springs" kind of water?
R.L.
Dorothy J Heydt
Over the long term it would give them skin trouble. A short
exposure wouldn't hurt. (I don't know exactly where the boundary
between "short" and "long" is, but twenty-four hours ought to be
okay.)
Dorothy J. Heydt
Albany, California
djh...@kithrup.com
http://www.kithrup.com/~djheydt
Charlie Allery
R. L. wrote in message ...
Sorry, can't give you a specific on this. The main problem is absorption of
water through the skin. Dolphins breath air, so it's not as serious a
problem as for fish where the flow over the gills would speed the process. I
suspect it's similar to problems caused by fresh water immersion for humans,
so you might try googling on that issue and find out how long humans can
survive in fresh water and what the effects are, then work on that.
Basically you're talking about kidneys working the opposite way from normal
(trying to retain salts in the body instead of excrete them) and general
swelling of cells particularly in the skin. I think after a while (a day, 2
days?) the skin becomes very tender?
There are of course fresh water dolphins which live in fresh or brackish
water, such as the Indus river dolphin, but not much info on-line, and I
can't find my Cousteau dolphin book!
Ref 'salt springs', it depends what the salts are and the concentrations.
The relevant 'salts' are sodium and potassium. If the concentrations of
these are similar to sea water this should solve the problem.
Possible options - spend some time out of the water, 'drying out'. Dangerous
since it's possible to 'dry out' too much, but at least being air-breathing,
suffocation will not be an issue. Suggest she swims during the day and gets
out of the water during the cooler night, preferably onto a bank with some
vegetation. You've seen dolphins 'beach' themselves at aquariums. She
wouldn't be able to get far from the water, but onto a low bank and back
into the water shouldn't be a problem. Presumably she'll hunt fresh water
fish on her way? This will involve ingestion of more water and her
metabolism will be straining to dilute the urine sufficiently to get rid of
the excess this way.
Charlie
Ray Drouillard
"Charlie Allery" <cha...@charlieallery.demon.co.uk> wrote in message
news:b50k5a$q03$1$8302...@news.demon.co.uk...
> Sorry, can't give you a specific on this. The main problem is
absorption of
> water through the skin. Dolphins breath air, so it's not as serious a
> problem as for fish where the flow over the gills would speed the
process. I
> suspect it's similar to problems caused by fresh water immersion for
humans,
> so you might try googling on that issue and find out how long humans
can
> survive in fresh water and what the effects are, then work on that.
> Basically you're talking about kidneys working the opposite way from
normal
> (trying to retain salts in the body instead of excrete them) and
general
> swelling of cells particularly in the skin. I think after a while (a
day, 2
> days?) the skin becomes very tender?
Ever take a long bath? The skin tends to get "pruned" because the
tissue just underneath expands due to water absorption. I don't know if
this happens with dolphins, but it would make it harder for her to swim.
It would probably be a very tiring experience for her.
I have found that when I take a really long swim in the lake, I have to
urinate a lot -- and I don't drink any water during the swim. It would
appear that humans, at least, absorb water rather readily. I didn't
measure the amount, but I suspect that the rate is half a liter to a
liter an hour.
Dolphin skin is different, so absorption will probably be different.
Ray Drouillard
R. L.
<cha...@charlieallery.demon.co.uk> wrote:
>
>R. L. wrote in message ...
>>On Sun, 16 Mar 2003 00:22:24 GMT, R. L.
>><zzzm...@zzsoniczzz.zznetsss> wrote:
>>
>>>In a fairytale world novel, I've got an intelligent dolphin escaping
>>>from captivity inland. I hope they can't just throw her in the nearest
>>>river and let her swim home.
/ Good info snipped and saved./
>Ref 'salt springs', it depends what the salts are and the concentrations.
>The relevant 'salts' are sodium and potassium. If the concentrations of
>these are similar to sea water this should solve the problem.
Of course I'm looking for plausible reasons why she would not try to
escape by river, as the plot needs her to be carrired overland.
Someone elsewhere mentioned sea mammals getting confused in a brackish
bay. He thought the water chemistry might affect their mental
functioning.
Does this seem plausible? For an intelligent dolphin, hallucinations,
delusions?
R.L.
Richard Cavell
news:b50q0k$hh8$1...@sun-news.laserlink.net...
> I have found that when I take a really long swim in the lake, I have to
> urinate a lot -- and I don't drink any water during the swim. It would
> appear that humans, at least, absorb water rather readily. I didn't
> measure the amount, but I suspect that the rate is half a liter to a
> liter an hour.
Humans don't absorb water through the skin (frogs do), but being immersed in
water stimulates diuresis (production of urine). There are water sensors
throughout our skin.
silvasurfa
"R. L." <zzzm...@zzsoniczzz.zznetsss> wrote in message
news:npf77v017s9brd0ai...@4ax.com...
Don't know. We have some river living dolphins locally but I'm not sure how
far past the salty tidal bit of the river they willingly swim. You could
google "Port River Dolphins" and see if you get anything useful.
Charlie Allery
Richard Cavell wrote in message ...
Well, we do, but to a much lesser extent than say frogs. As Ray says, it's
water absorption that causes pruning. I think it would take a day or two of
immersion at least to cause any real problems.
Charlie
Charlie Allery
R. L. wrote in message ...
>On Sun, 16 Mar 2003 01:44:21 -0000, "Charlie Allery"
><cha...@charlieallery.demon.co.uk> wrote:
>
>>
>>R. L. wrote in message ...
>>>On Sun, 16 Mar 2003 00:22:24 GMT, R. L.
>>><zzzm...@zzsoniczzz.zznetsss> wrote:
>>>
>>>>In a fairytale world novel, I've got an intelligent dolphin escaping
>>>>from captivity inland. I hope they can't just throw her in the nearest
>>>>river and let her swim home.
>
>/ Good info snipped and saved./
>
>>Ref 'salt springs', it depends what the salts are and the concentrations.
>>The relevant 'salts' are sodium and potassium. If the concentrations of
>>these are similar to sea water this should solve the problem.
>
>
>Of course I'm looking for plausible reasons why she would not try to
>escape by river, as the plot needs her to be carrired overland.
>
Pollutants in the water? Big waterfalls or rapids? Dolphins aren't salmon,
and a big fall could be damaging. Sonar won't work well in rapids, nor if
the river has high levels of suspended sediment - it would tend to 'fog'
reception. Dams/hydroelectric power turbines? Any kind of physical block
that will allow water and small fish through, but would stop a 10 or 12 foot
mammal without legs should do the trick. :-)
>Someone elsewhere mentioned sea mammals getting confused in a brackish
>bay. He thought the water chemistry might affect their mental
>functioning.
>
>Does this seem plausible? For an intelligent dolphin, hallucinations,
>delusions?
>
There's the still-unsolved mystery of whale beachings, often pilot whales or
dolphins. I note a recent theory that Naval sonar may be implicated in some
of these, but there are all kinds of theories. As for brackish water
specifically causing mental problems ... not directly, but having a
different density, it could of course screw up the sonar which might account
for some beachings (kind of like flying a jet into a hillside) and of course
if your major position-finding sense has gone to pot, well I guess that
would give you mental problems. Like being blind but not realising it. If
you're beached yet your sonar is saying you should still be in open water,
that's going to confuse anybody.
Charlie
jhetley
"Charlie Allery" <cha...@charlieallery.demon.co.uk> wrote in message
news:b50k5a$q03$1$8302...@news.demon.co.uk...
>
>
> Sorry, can't give you a specific on this. The main problem is absorption
of
> water through the skin. Dolphins breath air, so it's not as serious a
> problem as for fish where the flow over the gills would speed the process.
I
> suspect it's similar to problems caused by fresh water immersion for
humans,
> so you might try googling on that issue and find out how long humans can
> survive in fresh water and what the effects are, then work on that.
> Basically you're talking about kidneys working the opposite way from
normal
> (trying to retain salts in the body instead of excrete them) and general
> swelling of cells particularly in the skin. I think after a while (a day,
2
> days?) the skin becomes very tender?
>
> There are of course fresh water dolphins which live in fresh or brackish
> water, such as the Indus river dolphin, but not much info on-line, and I
> can't find my Cousteau dolphin book!
>
Also fresh-water dolphins in the Amazon system.
Dolphins and whales can stand a fair amount of variation in salinity for
short periods of time -- we sometimes get them in the tidal river here, in
water that varies from brackish to nearly fresh depending on the state of
the tide and the river's flow. However, many of the ones that get this far
inland (20-30 miles from the actual "coast") usually have skin problems.
--
Jim
THE SUMMER COUNTRY, by James A. Hetley
a novel of dark contemporary fantasy from Ace Science Fiction & Fantasy
2002 LOCUS magazine "Recommended Reading" selection.
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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John F. Eldredge
I have read that many beachings occur where the slope of the beach is
very gradual, meaning that it wouldn't return a very strong sonar echo
compared to a more steeply sloping beach. On the other hand, it would
seem that once a whale or dolphin ran aground on such a shallow slope,
it would be relatively easy to back away from the beach, except in the
case of getting stranded by an outgoing tide.
I wonder how dolphin sonar deals with strongly turbulent water, such
as can occur at the meeting place of two currents, or where a
waterfall pours over a cliff into the sea? It seems to me (as an
non-expert in sonar) that sound waves passing through such turbulence
would be difficult to interpret.
--
John F. Eldredge -- jo...@jfeldredge.com
PGP key available from http://pgp.mit.edu
"Reserve your right to think, for even to think wrongly is better
than not to think at all." -- Hypatia of Alexendria
Charlie Allery
John F. Eldredge wrote in message ...
Both very plausible explanations and I suspect that the reason that no one
has pinned down the exact reasons yet is because there are probably a
variety of reasons for beachings dependent on local conditions and the
species involved. Certainly there are accounts of 'un-beached' whales
immediately swimming back onto the shore despite human efforts to prevent
them.
Charlie
Jonathan L Cunningham
<jo...@jfeldredge.com> wrote:
>I wonder how dolphin sonar deals with strongly turbulent water, such
>as can occur at the meeting place of two currents, or where a
>waterfall pours over a cliff into the sea? It seems to me (as an
>non-expert in sonar) that sound waves passing through such turbulence
>would be difficult to interpret.
Human vision verges on the miraculous, when you understand how
difficult the processing problem is[1]. And dolphins have a lot more
brain devoted to interpreting sonar than we do to interpreting
visual data[2]. So I wouldn't be surprised if the world's greatest
experts in sonar had very little clue about what a dolphin can
or can not perceive.
Jonathan
[1] I would be inclined to think it's impossible, except there seems
to be a certain amount of evidence that some life forms on earth
make a good stab at solving the problem.
[2] Something not usually taken into account when discussing how
intelligent dolphins might be.
--
(Replace netspam by jlc when appropriate)
Ray Drouillard
I can't claim to have done any scientific studies, but anecdotal
evidence supports the idea that we absorb water. If soaking in the
water had merely caused my kidneys to produce extra urine, I would have
ended up becoming dehydrated. As it was, I didn't get thirsty while
swimming, nor did I get thirsty soon afterward.
Ray Drouillard
Pat Bowne
"Ray Drouillard" <cos...@nospam.quixnet.net> wrote :
> I can't claim to have done any scientific studies, but anecdotal
> evidence supports the idea that we absorb water. If soaking in the
> water had merely caused my kidneys to produce extra urine, I would have
> ended up becoming dehydrated. As it was, I didn't get thirsty while
> swimming, nor did I get thirsty soon afterward.
I saw a paper at the Experimental Biology meetings in which submersion in
water was used to produce diuresis and dehydration in elderly people,
specifically in order to test their thirst response. I believe the pressure
exerted on the periphery of the body by the weight of water causes an
increased flow of blood through the central arteries (it is known to cause a
spike in blood pressure). This could lead to reflex diuresis, as could an
increased blood flow in the renal arteries.
Cold-induced diuresis is also a well-known phenomenon. It works in a similar
fashion, except that the blood is diverted to internal organs by
vasoconstriction of vessels in the skin, and its dehydrating effect is one
of the issues that has to be addressed in studying survival in cold water.
For more info, see:
http://www.sintef.no/units/unimed/Artikler/Kuldeartikkel.htm
Pat Bowne
Charlie Allery
Pat Bowne wrote in message ...
Interesting stuff, and pronbably what explains Ray's observations. The
absorption of water directly into the skin cells by osmosis is going to be a
slower effect. The 'pruning' is what I remember from 'O' level biology (our
teacher would always give us interesting facts). The skin is not as
waterproof as we would assume it to be, and what looks like loss of water,
is in fact net gain. Of course dolphins have a different texture of skin
surface and a thicker layer of blubber than us, so may resist the effect
better. Info on the river dolphins seems to mostly refer to the adaptation
of senses necessary to the river environment and the one paper I found
reference to by googling was on absorption of water by seals in fresh water.
Charlie
Brooks Moses
> I wonder how dolphin sonar deals with strongly turbulent water, such
> as can occur at the meeting place of two currents, or where a
> waterfall pours over a cliff into the sea? It seems to me (as an
> non-expert in sonar) that sound waves passing through such turbulence
> would be difficult to interpret.
That would depend heavily, I think, on several things.
If there are a lot of bubbles in the water, as one would expect from a
waterfall, they could affect the sound travel, much like they distort
vision underwater.
If the turbulent fluctions are of high mach number -- that is, if they
are some significant fraction of the speed of sound -- then the
variations in sound travel times will cause distortion. Since the speed
of sound in water is much higher than in air, this seems unlikely to
have a notable effect except in special cases; one not only needs
velocities higher than a few hundred miles per hour, but velocity
_fluctuations_ that high.
If the densities of the two fluids are notably different, and they
aren't well-mixed, this density variation is likely to distort the sound
waves. My guess is that this would look like a somewhat wavy and
distorted glass panel, with some minor amount of reflection. Except in
extreme cases, I suspect it's also unlikely to have much practical
effect.
Aside from those three things, I don't think the turbulence will affect
the sonar at all. A meeting place of two currents that are of similar
water, for instance, will have almost no effect on passage of sound
waves. (It might be a little noisy, though.)
- Brooks
Pat Bowne
"Charlie Allery" <cha...@charlieallery.demon.co.uk> wrote
> Interesting stuff, and pronbably what explains Ray's observations. The
> absorption of water directly into the skin cells by osmosis is going to be
a
> slower effect. The 'pruning' is what I remember from 'O' level biology
(our
> teacher would always give us interesting facts). The skin is not as
> waterproof as we would assume it to be, and what looks like loss of water,
> is in fact net gain.
This was actually discussed on the Anatomy and Physiology listserv earlier
this year. I believe the 'pruning' happens because the surface layers of the
skin absorb water faster than the lower layers.
Pat
Keith F. Lynch
> This was actually discussed on the Anatomy and Physiology listserv
> earlier this year. I believe the 'pruning' happens because the
> surface layers of the skin absorb water faster than the lower layers.
Then why doesn't it occur when there is nerve damage?
--
Keith F. Lynch - k...@keithlynch.net - http://keithlynch.net/
I always welcome replies to my e-mail, postings, and web pages, but
unsolicited bulk e-mail (spam) is not acceptable. Please do not send me
HTML, "rich text," or attachments, as all such email is discarded unread.
Marilee J. Layman
wrote:
My fingers are permanently "pruned." In the second renal failure, I
gained about 300 pounds of water weight -- it even started coming out
drip by drip from the sides of my hips -- and when the doctor found
the experimental med that worked, the water all came off Whoooosh! in
about three weeks. I have stria (stretch marks) everywhere except my
feet, hands, and face, and my hands and feet are permanently wrinkled.
I don't expect to have to give fingerprints anytime soon, but they
won't match the ones in the federal database.
--
Marilee J. Layman
Handmade Bali Sterling Beads at Wholesale
http://www.basicbali.com
Pat Bowne
"Keith F. Lynch" <k...@KeithLynch.net> wrote in message
news:b561qg$on0$1...@panix2.panix.com...
> Pat Bowne <pbo...@execpc.com> wrote:
> > This was actually discussed on the Anatomy and Physiology listserv
> > earlier this year. I believe the 'pruning' happens because the
> > surface layers of the skin absorb water faster than the lower layers.
>
> Then why doesn't it occur when there is nerve damage?
> --
What kind of nerve damage? Sensory, motor, or both? Is it just the fingers,
or the entire arm that is affected? I'm thinking it may have something to do
with muscle tone and venous blood flow, but if you give me details I'll ask
the A&P group next week.
Pat
Richard Cavell
news:3e750456...@usenet.plus.net...
> brain devoted to interpreting sonar than we do to interpreting
> visual data[2]. So I wouldn't be surprised if the world's greatest
> experts in sonar had very little clue about what a dolphin can
> or can not perceive.
That's a very interesting point. We can 'visualize' the world in a way that
a blind species that had invented a light sensor could never do. Even with
the most incredible mathematics, the blind species would never 'see'. We
perceive colours as though they were something other than variations in
wavelength. With dolphins they can probably 'see' textures, colours,
contrast and form with their sonar, the likes of which we cannot comprehend.
Richard Cavell
> I can't claim to have done any scientific studies, but anecdotal
> evidence supports the idea that we absorb water. If soaking in the
> water had merely caused my kidneys to produce extra urine, I would have
> ended up becoming dehydrated.
You hardly feel dehydration until you've lost a kilogram or two.
> As it was, I didn't get thirsty while swimming, nor did I get thirsty soon
afterward.
Thirst doesn't work purely on the loss of water in the urine. It's a
complex reflex.
Jonathan L Cunningham
And in true 3D too. Like, what other dolphins ate for breakfast
(fish!) and how far advanced pregnancies are, etc. They can
distinguish a counterfeit coin from a real one at the other end of
a swimming pool, IIRC.
I wonder how easily they could spot cancers? Want a check up? Put
on your swimming costume and get into the pool ...
"Squeak!" (No cancer, but you have an aortic aneurysm which needs
attending to ...)
Jonathan
Tim S
The philosopher Thomas Nagel wrote a very famous essay, _What is it like to
be a bat?_ using this sort of thing as a jumping-off point for a discussion
of consciousness and the mind-body problem.
Richard Dawkins touched briefly on this sort of thing in one of the chapters
in _The Blind Watchmaker_.
Tim
Jonathan L Cunningham
It's reproduced in "The Mind's I" by Hofstadter and Dennett, and if
you can easily borrow a copy, it is also worth reading the
"Reflections" on it (and most of the other essays and stories in
the book).
Otherwise, if you are only interested in Nagel's essay, it is easy
to find on the web, e.g.
http://members.aol.com/NeoNoetics/Nagel_Bat.html
which even includes a mugshot of Nagel (I presume, but the silly
people didn't use an ALT tag saying what the picture is about).
>Richard Dawkins touched briefly on this sort of thing in one of the chapters
>in _The Blind Watchmaker_.
Does he? Must re-read it.
Jonathan
David Friedman
"Richard Cavell" <richar...@mail.com> wrote:
> That's a very interesting point. We can 'visualize' the world in a way that
> a blind species that had invented a light sensor could never do. Even with
> the most incredible mathematics, the blind species would never 'see'. We
> perceive colours as though they were something other than variations in
> wavelength.
But note that we actually perceive less than a (sufficiently good)
sensor would report to the blind species. What we see as color is not a
frequency but a frequency distribution--and two quite different
distributions could end up as the same color. furthermore, the same
distribution might be perceived by us as two different colors, depending
on the rest of what was in the visual field.
The information incoming to our built-in processing is, as best I
recall, three numbers (for each point in the visual field)--the signals
representing the three different weighted averages of the frequency
distribution produced by the three kinds of color receptors in the
retina.
There is a good discussion this in one of the chapters of _The Adapted
Mind_.
Jonathan L Cunningham
<dd...@daviddfriedman.com> wrote:
>In article <V3Dea.10489$L57....@news-server.bigpond.net.au>,
> "Richard Cavell" <richar...@mail.com> wrote:
>
>> That's a very interesting point. We can 'visualize' the world in a way that
>> a blind species that had invented a light sensor could never do. Even with
>> the most incredible mathematics, the blind species would never 'see'. We
>> perceive colours as though they were something other than variations in
>> wavelength.
>The information incoming to our built-in processing is, as best I
>recall, three numbers (for each point in the visual field)--the signals
Don't forget that we also have a monochrome system, which works in
poor light. So four numbers ...
>representing the three different weighted averages of the frequency
>distribution produced by the three kinds of color receptors in the
>retina.
>
>There is a good discussion this in one of the chapters of _The Adapted
>Mind_.
I haven't read _The Adapted Mind_ so don't know whether it covers
internal processing. Internally, the colour information is recoded
into antagonistic pairs: red v. green, and red+green[1] v. blue.
(And last time I said that, someone corrected me to point out that
this was a simplification, because there is also a red v. blue
antagonistic pair. Unfortunately I haven't read any more on this, nor
can remember the details.)
Jonathan
[1] Which is why, subjectively, yellow seems like a colour of equal
importance to red, green and blue, yet cyan looks subjectively
like a mixture of blue and green.
Tim S
wrote:
> I haven't read _The Adapted Mind_ so don't know whether it covers
> internal processing. Internally, the colour information is recoded
> into antagonistic pairs: red v. green, and red+green[1] v. blue.
>
> (And last time I said that, someone corrected me to point out that
> this was a simplification, because there is also a red v. blue
> antagonistic pair. Unfortunately I haven't read any more on this, nor
> can remember the details.)
Probably me. The first pair is red+blue vs green, accounting for the
apparent reddish tinge at the violet end of the spectrum.
Tim
Jonathan L Cunningham
Thanks. (So it's not red v. blue. Mea culpa.)
I blame misrembering on evolution: given the likely history, I can't
see that red+blue v. green is an obvious development. But *this* time
I'll make sure it sticks in my memory.
Er, why *does* violet look reddish? You seem to be saying "because
it's not green" (so it looks like both blue and red). Is that right?
And why do you say "the first pair is red+blue v. green"? Why first?
Ok, Tim, sit in this chair. Just a moment while I arrange the
spotlights. Don't worry if you can't see anything. Sorry about
the restraints, but they are traditional.
Let's start with something simple. Name?
Now, what can you tell us about colour vision? Please remember that
we've already heard all this from our other pri^H^H^H guests. This is
just to confirm a few details, which we already know. And we can tell
if you lie to us ... You don't want to do that ...
Jonathan
Mary K. Kuhner
David Friedman <dd...@daviddfriedman.com> wrote:
>But note that we actually perceive less than a (sufficiently good)
>sensor would report to the blind species. What we see as color is not a
>frequency but a frequency distribution--and two quite different
>distributions could end up as the same color. furthermore, the same
>distribution might be perceived by us as two different colors, depending
>on the rest of what was in the visual field.
Compare this to the octopus, whose color vision does not involve
wavelength-specific receptors, but measuring displacement of light
through tiny prisms. So it sees in true color rather than
our rough approximation. (This is apparently useful to an animal
that turns color to match its background, and wants to choose the
right color for a variety of possible predators.)
An octopus-like alien, while seeing in color "much as we do", would
find our RGB video screens and so forth completely bizarre. Why
*should* red paint plus blue paint make purple? It just looks like
red-and-blue to the octopus--not a hint of purple, which is a far
different color.
I don't know if the octopus also has the "same color against different
background is perceived differently", which is a processing artifact
rather than a direct consequence of color vision, as I understand it.
If they don't, our art would be even more incomprehensible. Why is
this woman greenish?
Mary Kuhner mkku...@eskimo.com
David Friedman
net...@softluck.plus.com (Jonathan L Cunningham) wrote:
> I haven't read _The Adapted Mind_ so don't know whether it covers
> internal processing. Internally, the colour information is recoded
> into antagonistic pairs: red v. green, and red+green[1] v. blue.
The part I found most interesting was the explanation of how the
processing software solves the apparently impossible problem of making
the same object appear the same color independent of the spectral
distribution of incident light, over a wide range of (natural) lighting.
David Friedman
mkku...@kingman.gs.washington.edu (Mary K. Kuhner) wrote:
> An octopus-like alien, while seeing in color "much as we do", would
> find our RGB video screens and so forth completely bizarre. Why
> *should* red paint plus blue paint make purple? It just looks like
> red-and-blue to the octopus--not a hint of purple, which is a far
> different color.
Which raises the interesting possibility of an alien civilization,
technologically at least equal to ours, which still uses greyscale
monitors (not necessarily grey, but intensity rather than
color)--because true color is a much harder problem for them, and just a
few colors for accent and such isn't worth the trouble.
Mark Atwood
>
> I don't know if the octopus also has the "same color against different
> background is perceived differently", which is a processing artifact
> rather than a direct consequence of color vision, as I understand it.
> If they don't, our art would be even more incomprehensible. Why is
> this woman greenish?
It's worse than that. Often two different pigments will have
different frequency distribution curves. To someone who sees "colors
truely", two different "skin colored paints" will look competely
different, and neither one will look anything like skin.
To a being that sees "colors truely", until and unless you know enough
about about their visual processing system to identify the
assumptions, shortcuts, and compression tricks, you will need a
display monitor where every pixel can display a complete
multifrequency color curve, and each pixel will have to be lit all the
time. (You can't depend on the existance of the "persistance of
vision" optical illusion that makes scanning CRTs work.)
Say we sample the frequency range at 256 points, each point at 16 bits
of accuracy. A slightly better than TV resolution image would be 640 *
480 * 256 * 16 = 1258291200 bits = 150 megabytes. Per frame.
Such a monitor is possible. In theory. Each pixel will have to be a
bundle of quantum harps, either vibrating at visible light frequences,
or else behind some sort of stepup/stepdown broadspectrum optics.
Our aliens will need one hell of a brain to keep up with that.
(If they are sensitive to *direction* at a scale finer than our simple
two-point sensor binocular vision, then the bitrates get even more
insane.)
The entire human sensorium, after peripheral processing and
compression takes place (mainly in the retinas and optic nerves), is
*only* about 10 megabits per second. (That's right, if you could
figure out where to tap the signal, you can fit over a 3 days of
a sensed human experience on a off the shelf 320G hard disk.)
--
Mark Atwood | Well done is better than well said. m...@pobox.com |
http://www.pobox.com/~mra
Ross Smith
I think it _would_ be worth the trouble (assuming something like human
psychology). After all, we found colour displays useful back when they
could only manage 16 colours.
--
Ross Smith ......... r-s...@ihug.co.nz ......... Auckland, New Zealand
I march before a martyred world, an army for the fight
I speak of great heroic days, of victory and might
I hold a banner drenched in blood, I urge you to be brave
I lead you to your destiny, I lead you to your grave
-- Motorhead
David Friedman
Ross Smith <r-s...@ihug.co.nz> wrote:
> David Friedman wrote:
>
> > In article <b5fv8e$v50$1...@nntp3.u.washington.edu>,
> > mkku...@kingman.gs.washington.edu (Mary K. Kuhner) wrote:
> >
> >> An octopus-like alien, while seeing in color "much as we do", would
> >> find our RGB video screens and so forth completely bizarre. Why
> >> *should* red paint plus blue paint make purple? It just looks like
> >> red-and-blue to the octopus--not a hint of purple, which is a far
> >> different color.
> >
> > Which raises the interesting possibility of an alien civilization,
> > technologically at least equal to ours, which still uses greyscale
> > monitors (not necessarily grey, but intensity rather than
> > color)--because true color is a much harder problem for them, and just
> > a few colors for accent and such isn't worth the trouble.
>
> I think it _would_ be worth the trouble (assuming something like human
> psychology). After all, we found colour displays useful back when they
> could only manage 16 colours.
And we do figures in textbooks using black, white, and one or two
colors.
Clearly color is worth something, but I'm not sure it would be worth
enough for people to develop it if they were sure they couldn't make
anything that came close to looking right.
But perhaps you are right; they would have color screens, they would
just be using colors for purposes other than showing realistic pictures.
No digital photography.
Ross Smith
No photography at all. Conventional photography uses a trichromatic
system too (three layers of coloured dye). Printing usually uses more
than three colours, but still the same principle. I don't think Mary's
aliens would have any way to do colour images or representational art
at all.
This may have interesting cultural effects. Maybe they'd conclude that
only the gods can create true colour; after all, it's obvious that
mortals can only manage a very poor imitation.
Neil Barnes
news:ddfr-A13FCB.1...@sea-read.news.verio.net:
Technological deviation... just thinking out loud for a moment...
We traditionally use RGB displays because tuned RGB phosphors are
(a) easy to obtain and (b) can be used to trigger the required
response in the eye with a remarkable amount of ease. We ignore
the fact that some (most) substances absorb light as well as
reflecting it because in most cases it's not significant. (My TV
theory lecturer used to harp on about 'sucking phosphors' but I
think he just liked saying the words!)
When we invented LCD screens we continued to use the same
colours, and things work mostly the same way.
But... we also have dichroic filters - which rely on the spacing
between two semireflective surfaces to allow light of a
*specific* wavelength through. They're very effective,
particularly on axis, and can be made to a wide range of
wavelengths.
I wonder if one could make a display screen where the filter
spacing was controlled by a voltage, thus changing the colour
discretely and accurately. You'd end up with a continuously
changing colour which would work equally well for both people and
octopussies - and any aliens with similar colour vision to
either. No reason why it would have to be restricted to (human)
visible light, either...
Neil
--
note - the email address in this message is valid but the
signal to noise ratio approaches -40dB. A more useful address
is a similar account at ntlworld-fullstop-com.
Neil Barnes
news:b5gvhn$cae$1...@lust.ihug.co.nz:
<ahem> Conventional photography uses photosensitive metal salts
to produce a monochrome image - colour photography uses three
layers of conventional photography separated by filters, and
replaces the salts with dyes in processing. I think it unlikely
that photochemistry would work any differently there than here.
I'm curious to wonder what the effect of aliasing of colours
might be in such an eye. If there are two colours - say red and
green stripes - too finely drawn to resolve on the aliens' colour
receptors, how would it interpret it? As having both colours, or
some mix of the two?
>
> This may have interesting cultural effects. Maybe they'd
> conclude that only the gods can create true colour; after all,
> it's obvious that mortals can only manage a very poor
> imitation.
Pish-tosh! (er, I mean, I politely disagree with your conclusion)
Black body radiation, dichroic filters, tunable lasers, LEDs,
organic dyes... they'd probably do better at display than
painting, though - it seems logical that colour mixing isn't
going to work (though see earlier - colour paint mixing is mixing
very small absorbtive/reflective particles)
Manny Olds
> I blame misrembering on evolution: given the likely history, I can't
> see that red+blue v. green is an obvious development. But *this* time
> I'll make sure it sticks in my memory.
Fruit vs. foliage?
--
Manny Olds (old...@pobox.com) of Riverdale Park, Maryland, USA
"Feel free to provide authoritative references; in the meantime, you
won't mind if we conclude that you're simply making this up." -- Ian York
Manny Olds
> No photography at all. Conventional photography uses a trichromatic
> system too (three layers of coloured dye). Printing usually uses more
> than three colours, but still the same principle. I don't think Mary's
> aliens would have any way to do colour images or representational art
> at all.
Not necessarily. Printing can use inks other than CYMK. Many current
formulations are based on adding up pigments, but not all of them. If our
eyes demanded it, we would have a lot more non-built-up colored inks. I
don't think we would get anything like "true color" for all possible
images, but there would be enough choices to do something with.
--
Manny Olds (old...@pobox.com) of Riverdale Park, Maryland, USA
Some people are alien creatures who apparently have been left here on the
earth to torment us normal folk.
Jonathan L Cunningham
>mkku...@kingman.gs.washington.edu (Mary K. Kuhner) writes:
>>
>> I don't know if the octopus also has the "same color against different
>> background is perceived differently", which is a processing artifact
>> rather than a direct consequence of color vision, as I understand it.
>> If they don't, our art would be even more incomprehensible. Why is
>> this woman greenish?
>
(snip)
>The entire human sensorium, after peripheral processing and
>compression takes place (mainly in the retinas and optic nerves), is
>*only* about 10 megabits per second. (That's right, if you could
>figure out where to tap the signal, you can fit over a 3 days of
>a sensed human experience on a off the shelf 320G hard disk.)
IIRC, we can only store a few bits per second of information in
long term memory. So if you could figure out the compression scheme
used by the brain, an entire lifetime's memories should fit
comfortably in 1 GB. Maybe onto a single CDROM.
OTOH, if you also have to store information about the particular
encoding used by a particular brain (because brains are all
slightly different) you *might* need Terabytes (or more) of
description before you get to the first byte of long term memory.
For illustration, suppose that one year when I eat
breakfast it is always a full english breakfast: two rashers of
bacon, a sausage, fried egg, plum tomatoes, mushrooms, fried bread,
buttered toast and marmalade, coffee etc. For each day in that
year I only need one bit of data to fully describe that day's
breakfast (i.e. whether I ate breakfast, or skipped it).
Similarly with describing character: you don't need to keep
talking about "the wine dark sea" and "bright eyed Athena" after
you've introduced the setting and told us Athena is bright eyed.
Of course, you might have other, artistic, reasons for the repetition.
(Wheee! Back on topic.)
Lucinda Welenc
Sculpture is a representational art that does not depend on color to
define a form.
--
Alanna
**********
Saying of the day:
When Dogs Crossbreed:
Labrador Retriever + Curly Coated Retriever = Lab Coat Retriever, the
choice of research scientists
Tim S
wrote:
> On Fri, 21 Mar 2003 20:45:20 +0000, Tim S
> <T...@timsilverman.demon.co.uk> wrote:
>
>> on 21/3/03 7:18 pm, Jonathan L Cunningham at net...@softluck.plus.com
>> wrote:
>>
>>> I haven't read _The Adapted Mind_ so don't know whether it covers
>>> internal processing. Internally, the colour information is recoded
>>> into antagonistic pairs: red v. green, and red+green[1] v. blue.
>>>
>>> (And last time I said that, someone corrected me to point out that
>>> this was a simplification, because there is also a red v. blue
>>> antagonistic pair. Unfortunately I haven't read any more on this, nor
>>> can remember the details.)
>>
>> Probably me. The first pair is red+blue vs green, accounting for the
>> apparent reddish tinge at the violet end of the spectrum.
>
> Thanks. (So it's not red v. blue. Mea culpa.)
>
> I blame misrembering on evolution: given the likely history, I can't
> see that red+blue v. green is an obvious development. But *this* time
> I'll make sure it sticks in my memory.
>
> Er, why *does* violet look reddish? You seem to be saying "because
> it's not green" (so it looks like both blue and red). Is that right?
Sorry, ambiguous terminology. Here's a better attempt:
There are three receptors, R (long wavelength), G (medium wavelength) and B
(short wavelength).
There are two systems which translate receptor signals to colour perception.
One gives R+B vs G. If R+B outweighs G, then we see red. If G outweights
R+B, we see green.
The other gives R+G vs B. If R+G outweighs B then we see yellow. If B
outweighs R+G then we see blue.
>
> And why do you say "the first pair is red+blue v. green"? Why first?
Because that's how it's traditionally presented, I guess...
>
> Ok, Tim, sit in this chair. Just a moment while I arrange the
> spotlights. Don't worry if you can't see anything. Sorry about
> the restraints, but they are traditional.
:-)
>
> Let's start with something simple. Name?
Tim. You don't get me that easily.
> Now, what can you tell us about colour vision? Please remember that
> we've already heard all this from our other pri^H^H^H guests. This is
> just to confirm a few details, which we already know. And we can tell
> if you lie to us ... You don't want to do that ...
On the internet?
Tim
Ray Drouillard
"Neil Barnes" <nailed_...@hotmail.com> wrote in message
news:b5hh5k$29vu76$3...@ID-123172.news.dfncis.de...
The crux of the problem with alien color vision compared to our own is
that they may use different color receptors. We have red, green, and
blue receptors in our eyes. If we look at monochromatic yellow light,
it activates our red and green sensors. If we look at that same shade
of yellow on a CRT, we are actually looking at a mixture of red and
yellow light.
What if aliens have orange, cyan, and ultraviolet sensors? Our pictures
aren't going to look good to them. Even if we ignore the missing
ultraviolet part, the fact that our primary colors don't match with
their primary colors is going to throw it all off.
I believe, however, that the previous poster was postulating a totally
different color system. What if, instead of having separate red, green,
and blue sensors, the aliens managed to evolve a bunch of little
spectroscopes arranged behind a lens or set up in a compound array?
(Hey, the original bug-eyed monster!)
If this alien looked at one of our computer screens, he wouldn't see
yellow or cyan or magenta or orange or any shade like that. He would
see red, green, and blue.
Take a look at sunlight through a spectroscope and you see a more or
less continuous band of wavelengths (with some bright bars in certain
areas, to be sure). Do the same with a color CRT and you'll see a
strong line at red, another at green, and another at blue.
The CRT looks to us like it can reproduce all the colors of the rainbow
because we perceive colors by the relative amount that they stimulate
the three types of cones in our eyes. To an alien who perceives the
actual spectrum of each point, the CRT is going to be very limited in
its ability to reproduce a real image -- though it'll work fine as a
device that separates data by showing it in different colors.
By the way, the vision system doesn't have to be a literal spectroscope.
It can be more like that new type of digital camera sensor that was
invented recently.
Ray Drouillard
Julie Pascal
>
> The crux of the problem with alien color vision compared to our own is
> that they may use different color receptors. We have red, green, and
> blue receptors in our eyes. If we look at monochromatic yellow light,
> it activates our red and green sensors. If we look at that same shade
> of yellow on a CRT, we are actually looking at a mixture of red and
> yellow light.
>
> What if aliens have orange, cyan, and ultraviolet sensors? Our pictures
> aren't going to look good to them. Even if we ignore the missing
> ultraviolet part, the fact that our primary colors don't match with
> their primary colors is going to throw it all off.
How believable would it be that the color receptors would be
shifted into the ultraviolet for an alien species? (I think I want
ultraviolet.) I'd thought a bit once about having my aliens
see differently such that the "cave paintings" found by my
people were only partially visible until bathed in black light
or something similar. If this is workable at all, what are the
likely visible-to-humans colors that would correspond?
--Julie
Brooks Moses
> > This may have interesting cultural effects. Maybe they'd
> > conclude that only the gods can create true colour; after all,
> > it's obvious that mortals can only manage a very poor
> > imitation.
>
> Pish-tosh! (er, I mean, I politely disagree with your conclusion)
> Black body radiation, dichroic filters, tunable lasers, LEDs,
> organic dyes... they'd probably do better at display than
> painting, though - it seems logical that colour mixing isn't
> going to work (though see earlier - colour paint mixing is mixing
> very small absorbtive/reflective particles)
Oh, I don't know about that. Painting, after all, uses lots and lots of
different pigments -- even if they've got enough wavelength resolution
to distinguish three dozen different shades, that's no larger than the
range of different pigments available in a typical art-paint line. Even
if the process involves a transparent monochrome paint for essentially
each color they can distinguish, it's still not infeasable.
And I suspect that the range of color resolution that their vision
system would have, while it would be far higher than "three colors",
would not be anywhere near infinite in practical effect. The difference
between a sharp peak (for, say, a sodium lamp) and a peak that was broad
enough to encompass 3% (for instance) of their visual range probably
wouldn't be that notable.
Also, on a different note, this strikes me as rather like human hearing,
in some ways; we can distinguish vast numbers of notes -- if they're
pure. But we can't distinguish many at once, and sound also tends to
come much more in pure tones than light does. (Could you tell the
difference between static hiss centered at A or B-flat?)
- Brooks
Jonathan L Cunningham
>Jonathan L Cunningham <net...@softluck.plus.com> wrote:
>
>> I blame misrembering on evolution: given the likely history, I can't
>> see that red+blue v. green is an obvious development. But *this* time
>> I'll make sure it sticks in my memory.
>
>Fruit vs. foliage?
Oh, yeah. That would be the teleological[1] explanation, but what
bemused me (and made it hard to remember) was that red and green
receptors seem to have a common origin, so (I presume) some
distant ancestor had red (or green) receptors and blue receptors.
If so, a contrast between those (hypothetical) ancestral receptors
and blue ones could "easily" (ISTM) evolve into a contrast
between red+green v. blue. The brain wiring needed wouldn't need
to evolve: it would be the same.
Only *after* you evolve a new kind of receptor, does it make sense
to have brain wiring that makes use of it. For some reason, I was
assuming the new wiring would "naturally" distinguish the new
difference (between the descendants of the original hypothetical
ancestor) and would leave blue out of it. Now that I think about
it, there's no reason why it should. Evolution would naturally
"try" *all* possibilities, and the most "useful" would get
selected. So fruit could easily be part of the explanation.
It's also complicated by tetrachromats (women[2] with four
different colour receptors). It's not known whether their brain
wiring makes specific use of the difference between their two
different kinds of green (or red) receptor.
Jonathan
[1] I like big words ;-).
[2] I think my own mother may have been a tetrachromat, since
I have non-standard green[3] receptors, and must have inherited
them from her (since my father had normal colour vision).
[3] Might be the red ones: I'm not sure how to tell which it is.
Jonathan L Cunningham
wrote:
>
>"Ray Drouillard" <cos...@nospam.quixnet.net> wrote in message
>news:b5jc61$ut5$1...@sun-news.laserlink.net...
>How believable would it be that the color receptors would be
>shifted into the ultraviolet for an alien species? (I think I want
>ultraviolet.) I'd thought a bit once about having my aliens
>see differently such that the "cave paintings" found by my
>people were only partially visible until bathed in black light
>or something similar. If this is workable at all, what are the
>likely visible-to-humans colors that would correspond?
I wouldn't have any problem, because insects already can see
further into the UV than we can (flowers usually have guidelines
on them, often visible only in UV so we think the flower is all
one colour, or whatever).
I'm not sure what you mean by visible-to-humans correspond. AFAIK,
your UV pigments could look any visible colour you liked. If you
want us to *see* them only when bathed in black light) you are
talking about fluorescence. Again, you can get stuff to fluoresce
in any colour you like (AFAIK) so it's your choice, really.
The thing to be careful about is transparency of the atmoshphere.
Our atmosphere absorbs UV light, and the shorter the wavelength
the more it absorbs it. Ditto IR at the other end of the spectrum.
So *near* IR and *near* UV are completely ok, far UV gets trickier.
I would have trouble believing an alien that evolved to see light
that never penetrated to the surface. (Except that there are fish
with lights on in the deep abyss, where it is permanently dark,
so with only a passing nod to some hand-waving, I could believe
almost anything. But, again, lights are only useful to these deep
sea fish because the water is reasonably transparent to light.)
Jonathan
Tim S
It's not only plausible, but highly likely. A lot of insects on our very own
dear planet see into the ultraviolet. The human visual range is very narrow
and there's nothing particularly special about it's precise boundaries.
On the other hand, 'ultraviolet' covers a great big range: I'd expect the
aliens to see only a small part of the ultraviolet spectrum. Animals on
earth tend to have vision in the region of the spectrum where sunlight is
brightest. If your planet's star's spectrum is significantly different from
the sun's, I'd expect the vision of the planet's inhabitants to cover a
different range from that of life on earth.
On the other hand, I'm not sure that the question about 'corresponding
colours' is meaningful. I can't even be sure that your sensation of 'red' is
the same as mine -- I have no idea what sensation a bee has when it looks at
a flower, and I don't think there's any reason why I should be able to
imagine it.
Or have I misunderstood that last question -- was it a question about
pigments? If so, it depends entirely on which pigments were used. It's not
possible to be specific without more details.
Tim
Suzanne A Blom
Jonathan L Cunningham <net...@softluck.plus.com> wrote in message
news:3e7dc816...@usenet.plus.net...
Some fishes & squid make their own lights, tho. If you can handwave the
right stimulus, I can imagine an arms race (like some plants have with their
predators, for instance {tho that is not quite the right example}) of
increasing light intensity in a certain range of the spectrum leading to
critters being able to see in some otherwise unlikely ranges.
Joshua P. Hill
L Cunningham) wrote:
>On Fri, 21 Mar 2003 18:21:04 GMT, David Friedman
><dd...@daviddfriedman.com> wrote:
>
>>In article <V3Dea.10489$L57....@news-server.bigpond.net.au>,
>> "Richard Cavell" <richar...@mail.com> wrote:
>>
>>> That's a very interesting point. We can 'visualize' the world in a way that
>>> a blind species that had invented a light sensor could never do. Even with
>>> the most incredible mathematics, the blind species would never 'see'. We
>>> perceive colours as though they were something other than variations in
>>> wavelength.
>
>>The information incoming to our built-in processing is, as best I
>>recall, three numbers (for each point in the visual field)--the signals
>
>Don't forget that we also have a monochrome system, which works in
>poor light. So four numbers ...
But because the response of the rods overlaps that of the cones, that
number is very similar to the weighted sum of the outputs from the
three color receptors. That's why only three independent values are
necessary for color photography and television.
The mind interprets the sum of the three primaries/output of the rods
as luminance, or black and white, then characterizes the output of the
cones in two quantities, hue and saturation, which can be represented
in polar coordinates, with hue being the phase, and saturation the
amplitude of the vector.
AFAIK little work has been done on the difference between the four-
and three-color values, and the discrepancy is overlooked in all the
discussions of colorimetry I've seen, but IIRC Edwin Land wrote an
article years ago in Scientific American on some experiments he did
that demonstrated that the output of the rods actually contributed to
color discrimination. I think his experiments demonstrated that one
could, by mixing white with colored light, produce the subjective
impression of colors that shouldn't be there according to the three
value model (which is, IIRC, Maxwell's).
(I've always suspected that this might have something to do with the
exaggerated sensitivity of three-color systems to color temperature,
but it's merely a hypothesis.)
>>representing the three different weighted averages of the frequency
>>distribution produced by the three kinds of color receptors in the
>>retina.
>>
>>There is a good discussion this in one of the chapters of _The Adapted
>>Mind_.
>
>I haven't read _The Adapted Mind_ so don't know whether it covers
>internal processing. Internally, the colour information is recoded
>into antagonistic pairs: red v. green, and red+green[1] v. blue.
>
>(And last time I said that, someone corrected me to point out that
>this was a simplification, because there is also a red v. blue
>antagonistic pair. Unfortunately I haven't read any more on this, nor
>can remember the details.)
>
>Jonathan
>[1] Which is why, subjectively, yellow seems like a colour of equal
>importance to red, green and blue, yet cyan looks subjectively
>like a mixture of blue and green.
Josh
Joshua P. Hill
L Cunningham) wrote:
>On Fri, 21 Mar 2003 20:45:20 +0000, Tim S
><T...@timsilverman.demon.co.uk> wrote:
>
>>on 21/3/03 7:18 pm, Jonathan L Cunningham at net...@softluck.plus.com
>>wrote:
>>
>>> I haven't read _The Adapted Mind_ so don't know whether it covers
>>> internal processing. Internally, the colour information is recoded
>>> into antagonistic pairs: red v. green, and red+green[1] v. blue.
>>>
>>> (And last time I said that, someone corrected me to point out that
>>> this was a simplification, because there is also a red v. blue
>>> antagonistic pair. Unfortunately I haven't read any more on this, nor
>>> can remember the details.)
>>
>>Probably me. The first pair is red+blue vs green, accounting for the
>>apparent reddish tinge at the violet end of the spectrum.
>
>Thanks. (So it's not red v. blue. Mea culpa.)
>
>I blame misrembering on evolution: given the likely history, I can't
>see that red+blue v. green is an obvious development. But *this* time
>I'll make sure it sticks in my memory.
>
>Er, why *does* violet look reddish? You seem to be saying "because
>it's not green" (so it looks like both blue and red). Is that right?
Because they brain interprets hue in polar coordinates. Check out the
color wheel at http://home.att.net/~rocq/SIHwheel.html There was a big
discussion of this a while back on one of the physics groups, if you
want to Google it.
Josh
Joshua P. Hill
Also, you could add color to a story (sorry) by noting that an alien
with even a slightly different system of color receptors would likely
find our three-color images bizarre, and vice-versa.
Josh
David Friedman
Joshua P. Hill <josh...@snet.net.REMOVE.THIS> wrote:
> AFAIK little work has been done on the difference between the four-
> and three-color values, and the discrepancy is overlooked in all the
> discussions of colorimetry I've seen, but IIRC Edwin Land wrote an
> article years ago in Scientific American on some experiments he did
I also remember an article by Land in Scientific American describing
experimental results on color vision that seemed impossible in terms of
the usual description of how color work.
> that demonstrated that the output of the rods actually contributed to
> color discrimination. I think his experiments demonstrated that one
> could, by mixing white with colored light, produce the subjective
> impression of colors that shouldn't be there according to the three
> value model (which is, IIRC, Maxwell's).
That fit's my memory. But I had thought it had to do, not with
rods+cones, but with the way in which the vision system uses what it
sees in one part of the visual field to interpret what it sees in
another. I'm pretty sure he wasn't showing a uniform field of something.
Decades later, reading the discussion in _The Adapted Mind_, I wondered
if what he was observing was the system by which the vision system
calculates the characteristics of the illuminating light from the whole
visual field, then compensates to get things to the same color with
different illuminations.
Joshua P. Hill
<bmoses...@cits1.stanford.edu> wrote:
>(Could you tell the
>difference between static hiss centered at A or B-flat?)
Curiously enough, if you put white noise through a tuneable bandpass
filter and change the center frequency, you'll find that you can. We
seem to have evolved some kind of sensitivity to the spectral
characteristics of hiss, or maybe it's just a natural outcome of the
way we hear and process sound?
Josh
Joshua P. Hill
wrote:
The Lippmann plate works that way. Like holography, it uses a
fine-grained monochromatic photographic emulsion capable of resolving
a wavelength of light to record interference patterns, in this case
those of the incident light beam with its reflection from a pool of
mercury. When the processed plate is illuminated with white light and
viewed from the angle at which the photograph was taken, you see a
full color image, but when it's viewed at an angle, it's black and
white!
AFAIK, it's the only photographic process that can reproduce the full
gamut of hue and saturation (I assume that luminance is limited by the
maximum density of the emulsion).
Check out the pictures near the bottom --
http://chem.ch.huji.ac.il/~eugeniik/history/lippmann.html
Josh
Jonathan L Cunningham
:-).
Same difference.
(I mean, it's the same question. Why does the brain interpret hues in
polar coordinates?)
But no thanks, it's unlikely that a physics group would be the best
place to discuss neuroanatomy. Even if they did, I think I'll settle
for Tim's answer for now. Life's too short to read everything.
Jonathan
(Nice color wheel, but it's much like the one you get in photo editing
software, so I've seen them before.)
John F. Eldredge
Also, the brain can be fooled into seeing color from a pulsed
black-and-white signal. To see this, use a drawing compass to mark a
circle on a piece of white cardboard. Color 1/2 of the circle solid
black. On the other half, draw a series of concentric arcs, with one
end of each arc connected to the black half. For example, make one
arc extend 15 degrees, one 60 degrees, one 75 degrees, one 90 degrees,
and so on. Cut the circle out, fasten it through the center point
with a thumbtack, and flick it with your finger to make it spin.
Under incandescent light or sunlight, you will see a illusion of a
series of murkily colored circles. This doesn't work as well under
fluorescent lights, probably because they flicker on and off 120 times
per second. Apparently, the optic nerve encodes the color as a
pulsed-width signal, with the width of the pulse indicating the color.
An alien whose optic nerve encoded colors differently might see
different colors, or only a black-and-white pattern.
I have read that some early experiments in color television tried
encoding the colors this way, but the current scheme, involving
different signals for each of the primary colors, turned out to be
more practical.
--
John F. Eldredge -- jo...@jfeldredge.com
PGP key available from http://pgp.mit.edu
"Reserve your right to think, for even to think wrongly is better
than not to think at all." -- Hypatia of Alexendria
Ray Drouillard
"Tim S" <T...@timsilverman.demon.co.uk> wrote in message
news:BAA3832F.1807D%T...@timsilverman.demon.co.uk...
Actually, I was talking about us and the aliens looking at each others'
pictures and monitors. A picture that is made up of red, green, and
blue dots (or yellow, cyan, and magenta image layers) can look very
realistic and vibrant to us, but will look very strange to an alien that
has sensors that are sensitive to a different set of colors. If the
alien's vision goes outside of the standard (humanly) visible spectrum,
the pictures will look even stranger.
Ray Drouillard
Ray Drouillard
"Joshua P. Hill" <josh...@snet.net.REMOVE.THIS> wrote in message
news:q3is7v8i7814r9sv8...@4ax.com...
Our sound sensor is essentially a spectrum analyzer. The sound is fed
into a "snail shell" looking organ, and sensor hairs along the length
sense each frequency.
Thus, we can easily distinguish three and four part chords. Not only
that, we can sense all of the harmonics that accompany the sound --
making it easy for us to tell if it's a piano, saxophone, or trumpet
that's playing that A flat.
Imagine an alien race that has three sound sensors, each tuned to a
different frequency. The three sensors will send those signals to the
brain, and the brain will decipher which one note is being played based
on the relative strength of the three signals.
This alien would not be able to hear a chord, nor would it be able to
distinguish a piano from a saxophone. It would just know that an a flat
is being played.
Similarly, if we see a light source that has two peaks, one in red, and
the other in green, we perceive it as yellow. An alien race that uses
an array of spectrum analyzing sensors instead of the three color system
that we use would be able to see the individual red and green
components. To them, the light from a yellow LED would be totally
different from the light of a red LED mixed with the light mixed with a
green LED. They would be able to glean information from the spectrum of
light generated or reflected -- just like we can tell what instrument is
being played by the timber of the note.
Ray Drouillard
Neil Barnes
I *knew* I'd come across it somewhere before. No doubt it's
somewhere in my collection of photography stuff from the last
hundred-fifty years! Thanks.
Marilee J. Layman
<bmoses...@cits1.stanford.edu> wrote:
> (Could you tell the
>difference between static hiss centered at A or B-flat?)
Yep.
--
Marilee J. Layman
Handmade Bali Sterling Beads at Wholesale
http://www.basicbali.com
Julie Pascal
"Tim S" <T...@timsilverman.demon.co.uk> wrote in message
news:BAA3832F.1807D%T...@timsilverman.demon.co.uk...
> On the other hand, I'm not sure that the question about 'corresponding
> colours' is meaningful. I can't even be sure that your sensation of 'red'
is
> the same as mine -- I have no idea what sensation a bee has when it looks
at
> a flower, and I don't think there's any reason why I should be able to
> imagine it.
>
> Or have I misunderstood that last question -- was it a question about
> pigments? If so, it depends entirely on which pigments were used. It's not
> possible to be specific without more details.
I'm marking these responses as unread and saving a thoughtful
reply for when it's not quite so late at night for me, except to
hopefully clarify what I meant by "corresponding colors."
Perhaps it's just a matter of looking at a spectrum. If the
wavelengths that my aliens can see overlaps human sight
and goes into UV what are the wavelengths likely to be
common to both species? I need a small range
of overlaping visible wavelengths for this to work.
Pigments is a question for after I've slept.
--Julie
Paul Repacholi
> Er, why *does* violet look reddish? You seem to be saying "because
> it's not green" (so it looks like both blue and red). Is that right?
Because the response of the Red cones in the eye increases at the
Violet end of the spectrum. So a intense violet light would look very
reddish. Keep in mind that the response of the eyes cells does not
drop to zero, it only gets very small.
BTW, Dolpins regularly come quite far into the Swan River in Perth.
Also, they have a HUGE third section of the cortex used for hearing
that is between the visual centers at the read of the brain, and the
rest. It would not be out of place to call it the anterior visual
cortex in fact.
--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
Raw, Cooked or Well-done, it's all half baked.
EPIC, The Architecture of the future, always has been, always will be.
Manny Olds
> In article <r4gs7v8m2sr612f5c...@4ax.com>,
> Joshua P. Hill <josh...@snet.net.REMOVE.THIS> wrote:
>> AFAIK little work has been done on the difference between the four-
>> and three-color values, and the discrepancy is overlooked in all the
>> discussions of colorimetry I've seen, but IIRC Edwin Land wrote an
>> article years ago in Scientific American on some experiments he did
> I also remember an article by Land in Scientific American describing
> experimental results on color vision that seemed impossible in terms of
> the usual description of how color work.
>> that demonstrated that the output of the rods actually contributed to
>> color discrimination. I think his experiments demonstrated that one
>> could, by mixing white with colored light, produce the subjective
>> impression of colors that shouldn't be there according to the three
>> value model (which is, IIRC, Maxwell's).
> That fit's my memory. But I had thought it had to do, not with
> rods+cones, but with the way in which the vision system uses what it
> sees in one part of the visual field to interpret what it sees in
> another. I'm pretty sure he wasn't showing a uniform field of something.
Is there any literature on how people with non-functional rods vision see
in good light?
--
Manny Olds (old...@pobox.com) of Riverdale Park, Maryland, USA
"One of the things that I've never understood is the attitude that we
cannot use reason to test leadings of faith. Truth is truth. I see no
proper reason why we should not use science to pursue goals set by faith."
-- Paul Butzi
Tim S
If there's a small overlap, it'll be at the blue/violet end of the spectrum.
(Unless there's a gap in the aliens' spectral coverage -- but that would be
_really_ weird.)
Tim
David Friedman
Tim S <T...@timsilverman.demon.co.uk> wrote:
> If there's a small overlap, it'll be at the blue/violet end of the spectrum.
>
> (Unless there's a gap in the aliens' spectral coverage -- but that would be
> _really_ weird.)
Two different sensor systems for light, evolved for different purposes,
using different organs?
Humans, after all, can feel infrared on their skins, although we can't
image it.
Mary K. Kuhner
Julie Pascal <ju...@pascal.org> wrote:
>How believable would it be that the color receptors would be
>shifted into the ultraviolet for an alien species? (I think I want
>ultraviolet.)
Extremely plausible; several different groups of Terrestrial animals
have evolved this, including pigeons, bees, and ... drats, I forget
the third. It seems handy for cloudy-day navigation and flower
detection. The usual mechanism seems to be mutating the blue pigment
until it reacts to UV; you also have to change the eye a bit to get
rid of UV-opaque compounds. (Humans could actually see a little into
the near UV, using our blue pigment, if only our eyes weren't so well
defended against it. People with artificial lenses apparently can.
Alas, it stimulates the blue pigment so it pretty much looks blue, not
a wild new color.)
You might try a Web search on Shozo Yokoyama; he gave a great lecture
on color vision in a variety of animals at last year's Molecular Evolution
workshop, and his lecture notes might be on the web somewhere, though
I didn't find them on my first try.
Mary Kuhner mkku...@eskimo.com
Mary K. Kuhner
Jonathan L Cunningham <net...@softluck.plus.com> wrote:
>I would have trouble believing an alien that evolved to see light
>that never penetrated to the surface. (Except that there are fish
>with lights on in the deep abyss, where it is permanently dark,
>so with only a passing nod to some hand-waving, I could believe
>almost anything. But, again, lights are only useful to these deep
>sea fish because the water is reasonably transparent to light.)
I particularly like the deep-sea fish which was found, when examined,
to have a red-receptor gene. Normally deep-sea fishes only have
blue receptors, because red light does not penetrate water very
well; so what was it doing with this gene?
It turns out that the fish is red-lighting its prey; it has a red
light on its head, useful for spotting food, and invisible to the
intended victims!
I think it would be quite interesting to have aliens for whom vision
is an active sense, like sonar; they do not expect much, if any,
ambient light but produce a lot of it themselves. It's a little tricky
to see how this system evolved (the deep-sea fishes come from
surface ancestors, they didn't have to evolve vision in the dark)
but I'm sure there's a way.
Mary Kuhner mkku...@eskimo.com
Lucinda Welenc
> series of murkily colored circles. This doesn't work as well under
> fluorescent lights, probably because they flicker on and off 120 times
> per second.
And thereby trigger migraines....
I could (and did) work under fluorescent lights in England, where
presumably they flicker only 100 times per second, but not here in the
US.
--
Alanna
**********
Saying of the day:
When Dogs Crossbreed:
Newfoundland + Basset Hound =
Newfound Asset Hound, a dog for financial advisors
Lucinda Welenc
>
> In article <b5je4...@enews1.newsguy.com>,
> Julie Pascal <ju...@pascal.org> wrote:
>
> >How believable would it be that the color receptors would be
> >shifted into the ultraviolet for an alien species? (I think I want
> >ultraviolet.)
>
> Extremely plausible; several different groups of Terrestrial animals
> have evolved this, including pigeons, bees, and ... drats, I forget
> the third.
Goldfish, I think.
David Langford
Wasn't this a tiny plot strand in Vernor Vinge's =A Deepness in the Sky=,
whose alien "spiders" have something like full-spectrum receptors?
Dave
--
David Langford
ans...@cix.co.uk | http://www.ansible.co.uk/
Mary K. Kuhner
Tim S <T...@timsilverman.demon.co.uk> wrote:
>If there's a small overlap, it'll be at the blue/violet end of the spectrum.
>(Unless there's a gap in the aliens' spectral coverage -- but that would be
>_really_ weird.)
It doesn't seem all that weird to me.
Evolution often proceeds by co-opting existing structures. The Terrestrial
insects and birds with UV vision have co-opted their blue receptors. If
selection kept pushing them further and further into the UV they might
lose their blue vision, if it wasn't as useful. It would be "more efficient"
to have separate blue and UV receptors, but the gene duplication required
might not happen to arise.
Humans have these ghastly blind spots in our eyes, even though that makes
very little sense and the octopus demonstrates that a better design is
biologically possible.
So if you wanted an alien which could see red, blue and UV, say, but not
green or yellow, I wouldn't balk at all. I'd presume its environment
just didn't offer much useful green or yellow information.
Mary Kuhner mkku...@eskimo.com
Keith Morrison
> So if you wanted an alien which could see red, blue and UV, say, but not
> green or yellow, I wouldn't balk at all. I'd presume its environment
> just didn't offer much useful green or yellow information.
I know there has to be a story out there with it, but I've always
been amused by the thought of the alien military that's developed
excellent camouflage for their uniforms who are unaware that they
stand out like sore thumbs to human vision. Or vice-versa.
--
Keith
Mark Atwood
>
> I know there has to be a story out there with it, but I've always
> been amused by the thought of the alien military that's developed
> excellent camouflage for their uniforms who are unaware that they
> stand out like sore thumbs to human vision. Or vice-versa.
The real-world DARPA is already thinking along those lines...
--
Mark Atwood | Well done is better than well said.
m...@pobox.com |
http://www.pobox.com/~mra
Brett Paul Dunbar
Friedman <dd...@daviddfriedman.com> writes
>In article <BAA4B9A1.18194%T...@timsilverman.demon.co.uk>,
> Tim S <T...@timsilverman.demon.co.uk> wrote:
>
>> If there's a small overlap, it'll be at the blue/violet end of the spectrum.
>>
>> (Unless there's a gap in the aliens' spectral coverage -- but that would be
>> _really_ weird.)
>
>Two different sensor systems for light, evolved for different purposes,
>using different organs?
Some snakes have infra-red visual organs ( for example the facial pits
of pit vipers) in addition to their eyes, so they see light in two
distinct spectra with a gap in between. They use the infra red organs to
see the heat produced by warm blooded prey animals.
--
Great Internet Mersenne Prime Search http://www.mersenne.org/prime.htm
Brett Paul Dunbar
To email me, use reply-to address
Ray Drouillard
"Keith Morrison" <kei...@polarnet.ca> wrote in message
news:3E7F7F3...@polarnet.ca...
When I was in the Army, we used to use camouflage paint and camouflage
netting that was also effective when viewed in infrared.
Ray Drouillard
John F. Eldredge
The military has long used black-and-white reconnaissance photography
as well as color photography, because some forms of camouflage are
more effective in black-and-white and other forms are more effective
in color.
I have known several men with red/green color blindness who couldn't
see the difference between a purple object and a green object, for
certain shades of purple and green.
James A. Donald
Tim S <T...@timsilverman.demon.co.uk>:
> > If there's a small overlap, it'll be at the blue/violet end
> > of the spectrum.
> >
> > (Unless there's a gap in the aliens' spectral coverage --
> > but that would be _really_ weird.)
David Friedman <dd...@daviddfriedman.com> wrote in message
news:<ddfr-
> Two different sensor systems for light, evolved for different
> purposes, using different organs?
Lots of snakes have excellent infrared vision, using organs
separate from, but close to, their eyes. It seems like a
logical arrangement.
--digsig
James A. Donald
6YeGpsZR+nOTh/cGwvITnSR3TdzclVpR0+pr3YYQdkG
UJgWhvGi+P3bxSMV/Is+g1uyV3nlDjEw7Qe5AOc9
4avteYl3lKAddQS2JWhhuXii2GFnL0tVPUhxJMcuv
Julian Flood
"Mary K. Kuhner" wrote
> Extremely plausible; several different groups of Terrestrial animals
> have evolved this, including pigeons, bees, and ... drats, I forget
> the third.
Kestrels see glowing trails of mouse urine.
Does the aqueous humour preclude near IR vision?
Thinks... zivvers... a cross-eared look at the human race. Stones going
plunk into a pool too small to be seen by echo location... The Law against
moving bulky objects... No, the name has gone. Probably early sixties.
Langford!
JF
Geoff Wedig
And I remember reading (probably in Science News, but it was so long ago, I
don't recall) about using spectrum filters on binocculars that would make
certain kinds of camoflage stand out from the vegetation, since the
camoflage used different kinds of pigments to achieve the same color.
Filtering out the wavelengths not absorbed by the foliage would leave the
camoflaged stuff in 'plain' sight.
Geoff
Geoff Wedig
There was a lot of issues with translation of images and so on in that book.
It was also a (very small) point in _Mote in God's Eye_ when the humans
visit the Motie museum and remark on the weirdness of the paintings and
such.
Geoff
Elf M. Sternberg
> Thinks... zivvers... a cross-eared look at the human race. Stones going
> plunk into a pool too small to be seen by echo location... The Law against
> moving bulky objects... No, the name has gone. Probably early sixties.
> Langford!
This would make an excellent haiku.
Elf
Keith Morrison
>>>I know there has to be a story out there with it, but I've always
>>>been amused by the thought of the alien military that's developed
>>>excellent camouflage for their uniforms who are unaware that they
>>>stand out like sore thumbs to human vision. Or vice-versa.
>
>>When I was in the Army, we used to use camouflage paint and camouflage
>>netting that was also effective when viewed in infrared.
>
> And I remember reading (probably in Science News, but it was so long ago, I
> don't recall) about using spectrum filters on binocculars that would make
> certain kinds of camoflage stand out from the vegetation, since the
> camoflage used different kinds of pigments to achieve the same color.
> Filtering out the wavelengths not absorbed by the foliage would leave the
> camoflaged stuff in 'plain' sight.
I've seen prototype materials that were being tested for uniforms.
Great cammo pattern in visual, decent suppression of infrared.
Sadly, they were well into the development cycle before someone
bothered to ask what would happen in UV light (the fabric glowed).
Reading about the history of military camouflage is interesting and
full of forehead-slapping moments of "D'oh! How could they not think
of that?" For instance, it was some time before the military
officially recognized that outfitting troops in camouflaged or low-
visibility combats, but then making them wear solid black boots (which
had to be clean and often shiny) wasn't the best idea they ever had.
(As an experienced sniper told me once, you look for the bouncing black
dots and then aim up a metre.)
--
Keith
Tim S
Indeed, after I'd sent off that post, the idea you describe occurred to me.
Yes, it would be much less surprising than a single kind of eye with a gap
in its spectrum. Though anything's possible, of course.
Tim
Jonathan L Cunningham
wrote:
Too many syllables.
To me, the whole point of a discplined form is the discipline.
Otherwise, it's not a haiku, it's something else.
Jonathan
--
(Replace netspam by jlc when appropriate)
Ray Drouillard
"Geoff Wedig" <we...@darwin.epbi.cwru.edu> wrote in message
news:b5pptc$r5f$1...@eeyore.INS.cwru.edu...
This takes us back to the discussion about being able to detect the
spectrum of each pixel, rather than being limited to some kind of
average representation.
If we have a yellow background that reflects only pure yellow light, and
place in front of that an object that reflects red and green, that
object will look yellow to us and therefore blend in with the
background.
If, however, we use a sharp filter to filter out the pure yellow,
allowing red and green to pass, the object will stand out very well.
We can therefore postulate aliens who can tell the difference between
yellow light and light that contains a mixture of red and green --
similar to the way we can hear all the notes in a chord (to reference
something up-thread).
Such a system would require a whole lot more processing than our current
system, but it would make it extremely difficult to create effective
camouflage.
Ray Drouillard
David Langford
<j...@floodsclimbers.freeserve.co.uk> wrote:
>Thinks... zivvers... a cross-eared look at the human race. Stones going
>plunk into a pool too small to be seen by echo location... The Law against
>moving bulky objects... No, the name has gone. Probably early sixties.
>
>Langford!
[FX: deep bass] You rang ...?
Sir is no doubt alluding with his customary erudition to =Dark Universe= by
Daniel F. Galouye, 1961.
Julian Flood
"David Langford" wrote
> [FX: deep bass] You rang ...?
>
> Sir is no doubt alluding with his customary erudition to =Dark Universe=
> by Daniel F. Galouye, 1961.
<jumps> How the hell do you _do_ that?
JF
Ta.
Geoff Wedig
> We can therefore postulate aliens who can tell the difference between
> yellow light and light that contains a mixture of red and green --
> similar to the way we can hear all the notes in a chord (to reference
> something up-thread).
> Such a system would require a whole lot more processing than our current
> system, but it would make it extremely difficult to create effective
> camouflage.
Well, no. Effective *artificial* camoflage, yes, but people have been tying
branches and leaves to their clothing as camoflage for millenia.
Geoff
Elf M. Sternberg
> On Tue, 25 Mar 2003 09:43:23 -0800, Elf M. Sternberg <e...@drizzle.com>
> wrote:
>>"Julian Flood" <j...@floodsclimbers.freeserve.co.uk> writes:
>>> Thinks... zivvers... a cross-eared look at the human race. Stones going
>>> plunk into a pool too small to be seen by echo location... The Law against
>>> moving bulky objects... No, the name has gone. Probably early sixties.
>>> Langford!
>> This would make an excellent haiku.
> Too many syllables.
Actually, syllable count is irrelevant for haiku. Traditional,
calligraphic haiku is based on the number of Kanji characters (2-3-2),
which can be one, two, or three syllables long.
The discipline you're describing, in which syllable count is
important, is senryu.
And it could probably be re-written a few times to make a nifty
senryu or tanka.
Elf
Ray Drouillard
I have tied foliage to my steel pot (helmet) and truck many times. The
disadvantage of doing it that way is that the stuff eventually
(sometimes quickly) wilts. That isn't as much of a problem with
personal camouflage as it is for vehicular camouflage.
Also, it isn't going to work very well in the desert.
Ray Drouillard
Geoff Wedig
Both true points. I guess it comes down to what you consider to be
'effective' camoflage.
Geoff
Beth Friedman
<cos...@nospam.quixnet.net>, <b5tss7$jsg$1...@sun-news.laserlink.net>,
wrote:
>I have tied foliage to my steel pot (helmet) and truck many times. The
>disadvantage of doing it that way is that the stuff eventually
>(sometimes quickly) wilts. That isn't as much of a problem with
>personal camouflage as it is for vehicular camouflage.
>
>Also, it isn't going to work very well in the desert.
Nor is dark-green camouflage in the desert, despite the fact that
that's what many American troops are wearing.
http://slate.msn.com/id/2080736/
--
Beth Friedman
b...@wavefront.com
Suzanne A Blom
Ray Drouillard <cos...@nospam.quixnet.net> wrote in message
news:b5tss7$jsg$1...@sun-news.laserlink.net...
foliage would grow on them.
Keith Morrison
>>I have tied foliage to my steel pot (helmet) and truck many times. The
>>disadvantage of doing it that way is that the stuff eventually
>>(sometimes quickly) wilts. That isn't as much of a problem with
>>personal camouflage as it is for vehicular camouflage.
>
> Actually, when this first came up, I was picturing vehicles designed so
> foliage would grow on them.
Oh great. Something *else* for sergeants to yell about.
"Private! Did you water the flowers?"
--
Keith
Ray Drouillard
"Suzanne A Blom" <sue...@execpc.com> wrote in message
news:v86r458...@corp.supernews.com...
I have seen vehicles with foliage on them, but I don't think it was by
design.
Ray
Boudewijn Rempt
.
>
> Oh great. Something *else* for sergeants to yell about.
>
> "Private! Did you water the flowers?"
>
I can see that part of the drill becoming really attractive, though.
--
Boudewijn Rempt | http://www.valdyas.org