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H4p10
2008-Sep-22, 05:01 PM
I was watching Predator the other day, and wondered how they (the predators) got so technologically advanced without being able to see in visible light (the narrow band that we do)... and began wondering if any technologically advanced civilization could be reached seeing in IR or UV... or even radio and microwave, instead of visible light...

Couldn't get anywhere, I suppose it's possible, but I'm really not sure. I think most species here see in visible (the bees see in UV I seem to recall)...

So, would it be possible?

Thanks and best regards!

alainprice
2008-Sep-22, 05:11 PM
If a predator can't see in visible, why can they camouflage themselves from visible light? Interesting.

Yes, our alien counterparts do not need to see in visible to understand us. Radio is the norm for talking back and possibly forth.

p.s. goldfish can see infrared.

Metricyard
2008-Sep-22, 05:13 PM
I was always under the impression that the predator used ir vision to assist in his/her/its hunt. I could be wrong though.:)

But there should be no reason that some civilization that can only see in the ir/uv spectrum couldn't succeed. I'm sure that they would find it weird that we managed to survive in our limited visual spectrum. Let's face it, once the sun goes down, you can't see without assistence. IR/UV vision would be a major advantage.

Metricyard
2008-Sep-22, 05:25 PM
Here's a cool page (http://www.indianchild.com/what_do_animals_see.htm) that shows the different senses of animals.

I like these..

Falcon
* Can see a 10 cm. object from a distance of 1.5 km.


Penguin
* Has a flat cornea that allows for clear vision underwater. Penguins can also see into the ultraviolet range of the electromagnetic spectrum.

Cockroach
* Can detect movement as small as 2,000 times the diameter of a hydrogen atom.

cjameshuff
2008-Sep-22, 05:31 PM
I was watching Predator the other day, and wondered how they (the predators) got so technologically advanced without being able to see in visible light (the narrow band that we do)... and began wondering if any technologically advanced civilization could be reached seeing in IR or UV... or even radio and microwave, instead of visible light...

I seem to recall they could see, just not very well.
It seems to me that hearing could substitute to a fair degree. Some sort of long-range, indirect sensing is likely required, but sonar can give a decent map of the surroundings. I have doubts about the chances of a complex organism developing without developing at least one of those two.

Another interesting thing to consider is how an intelligent, technological species, blind at least to the point of being unable to form clear optical images of their surroundings, would become aware of stars. The predators were at least able to see in IR. Perhaps they would first become aware of the spherical nature of their world through sonar experiments, or by comparing trip times to various points. Once they developed radio, they might become aware of radio sources in the sky, and when they get radar, they might become aware of other bodies in their solar system...

Digix
2008-Sep-22, 06:43 PM
Actually, in Predator 2 (I believe), the creatures were able to tune their visors to different spectral ranges. That's how the creature being hunted was able to discover that the human hunters had tagged it with a phosphorescent material that glowed in "black" light. Perhaps the creatures' native visual range is close to the human visible spectrum. Of course, these are fictional creatures so they could natively see whatever the writers choose for them to...
Regards,
Tes

Yes, I remember they just used some thermo visor like earth soldiers do,
that mode is great for hunting. since you can see living things even if they hide.
later he turned off that or changed into light amplifier mode.

also there is no way that some creature which sees deep IR could evolve because it is very hard to make thermal cameras and they still have very bad resolution we have your predators on th earth that can sense deep IR and we call them snakes.
also there is almost no theoretical way to see radio waves unless you have eyes comparable to size of satelite dish.

our light range depends on practical reasons,
humans can see uv , but eye filters it out to avoid damage
deep IR is just too low energy to sense separate photons.
but it is possible to see a bit deeper red than we see.

Argos
2008-Sep-22, 06:52 PM
There is an evolutive advantage to seeing in visible wave lengths, because it is both abundant and unharming to life as we know [though there are earthly creatures capable of seeing in the near UV and IR].

clint
2008-Sep-22, 06:52 PM
They might have evolved on a permanently foggy world.
Infrared would be superior to our visible spectrum.

kleindoofy
2008-Sep-22, 07:06 PM
They might have evolved on a permanently foggy world. ...
Or maybe the screenwriter just thought it would be cool to have an imaginary character see a different spectrum. ;)

Digix
2008-Sep-22, 07:39 PM
They might have evolved on a permanently foggy world.
Infrared would be superior to our visible spectrum.

no, a bit depper infrared is highly absorbed by water and CO2 almost everyone know that now because of climate changes.

so if you somehow manage to see some of thermal range IR it will look like living in eternal fog

deep IR is almost insave evolutionary advantage for any predator animals, and no less usefull for their prey, since nobody can hide anymore

but that is just impossible for biotechnology.
because you cant use water as lens and no living animal can make eyes of zirconium crystal. or at least some plastic and even more problems with eye cryocooling if you want good sensitivity

mugaliens
2008-Sep-22, 10:06 PM
If a predator can't see in visible, why can they camouflage themselves from visible light? Interesting.

Because, being technically advanced, they know we humans see in visible, and bees see in UV.


Yes, our alien counterparts do not need to see in visible to understand us. Radio is the norm for talking back and possibly forth.

From a technological perspective, yes, radio is a norm. From a biological perspective, we know for a fact that some animals communicate using the EM band. Bioluminescence is common throughout the animal kingdom, and many plants bioluminesce, too.

As for the much lower frequency of radio, I suppose electric eels may send out pulses (via the Sachs organ) which can be detected by other electric eels, but as to how much communication actually happens...


p.s. goldfish can see infrared.

So can I - with the palms of my hands. Not very good resolution, though. Something like 20/10,000.


Cockroach

* Can detect movement as small as 2,000 times the diameter of a hydrogen atom.

Good! Then he'll have no problem detecting my shoe as I slam it down on top of his head!

RussT
2008-Sep-22, 11:01 PM
Owls also see in the UV...They can see the urine trails of mice, through the snow...how deep I am not sure.

They have UV receptive cones in their eyes, as well as the visible light cones that we Humans do not.

Romanus
2008-Sep-24, 11:28 AM
I think it's definitely possible for near-IR through near-UV. Farther in the red, though, and you start seeing a loss of resolution; farther in the blue, and you're (by definition) dealing with more intense, potentially harmful UV radiation.

Ivan Viehoff
2008-Sep-24, 02:30 PM
Quite a lot of birds have a fourth colour cones which operates in (what is to us) the UV, in addition to 3 cones in the "human-visible" region. Now if 3 colour cones give us 6 basic colours (3 possible singlets plus 3 possible pairs) plus white (all 3 cones) and black (none), 4 would give 14 basic colours (4 possible singlets, 6 possible pairs, and 4 possible triplets) plus white and black. What a rich colour world birds have. I feel really rather disabled and deprived living in such a drab colour world in comparison to birds.

Romanus talks about "potentially harmful" UV radiation. The further UV is harmful to us, because we live in an environment where there isn't very much of it naturally, so we didn't have to protect ourselves from it, and so unsurprisingly we didn't evolve that protection. I see no reason why life shouldn't grow in a world where it is present having evolved protection for themselves from it.

Infrared has wavelengths from 750nm (0.75 microns) to 1 mm. Certainly at the long wave end of that there is not much resolution in an instrument the size and granularity of our eye. But I don't see why you can't get good resolution for quite some range at the lower end, and perhaps you can extend the range where you get good resolution by having a larger detector.

mugaliens
2008-Sep-24, 06:47 PM
Quite a lot of birds have a fourth colour cones which operates in (what is to us) the UV, in addition to 3 cones in the "human-visible" region. Now if 3 colour cones give us 6 basic colours (3 possible singlets plus 3 possible pairs) plus white (all 3 cones) and black (none), 4 would give 14 basic colours (4 possible singlets, 6 possible pairs, and 4 possible triplets) plus white and black. What a rich colour world birds have. I feel really rather disabled and deprived living in such a drab colour world in comparison to birds.

I think that's overcomplicating things a bit. With capability for three primary colors, we can see the range of hues between these colors quite well, the main exception being between S and M cones, where our perception dips to about 30% of intensity at 485 nm. Thus, we've got better than 20% from around 405 nm to 640 nm. The CMY compliments are merely additive results from our three SML receptors.

In addition to have a fourth set of cones, some animals have specialized oils in the cones which further narrow the frequencies received by those cones. Varying oils in certain proportions gives some animals a far greater ability to differentiate between adjacent colors.

Honey/bumblebees has trichromatic vision. Pigeons are thought to have pentachromatic vision. Papilio butterflies, tetrachromatic vision, and stomatopods with up to 12 different spectral receptor types.

Meanwhile, marine mammals are monochromats.

Some humans have been tested and found to have a degree of tetrachromatic vision, and up to 10% of women have an extra type of color receptor, as the OPN1LW gene, which codes the pigment that responds to yellowish light, is highly polymorphic.

cjameshuff
2008-Sep-24, 07:18 PM
Romanus talks about "potentially harmful" UV radiation. The further UV is harmful to us, because we live in an environment where there isn't very much of it naturally, so we didn't have to protect ourselves from it, and so unsurprisingly we didn't evolve that protection. I see no reason why life shouldn't grow in a world where it is present having evolved protection for themselves from it.

It's harmful because it contains enough energy per photon to break up or damage biologically important molecules. It's possible to see a little further into that range, but if there's a great deal of ambient far UV, the better tactic seems to be to develop protective barriers so you don't have to constantly rebuild retinal tissue.



Infrared has wavelengths from 750nm (0.75 microns) to 1 mm. Certainly at the long wave end of that there is not much resolution in an instrument the size and granularity of our eye. But I don't see why you can't get good resolution for quite some range at the lower end, and perhaps you can extend the range where you get good resolution by having a larger detector.

Resolution's not the problem. As you go further into IR, the heat radiated by the eyeball drowns out the IR coming into it from outside more and more.

However, there's plenty of room in the near-IR spectrum, and many cameras are capable of producing images in that portion of the spectrum, even with filters to block most of that range. Look at a IR remote through a web cam sometime. A likely reason for the lack of vision in that range is the low energy per photon making detection more difficult, and the lack of a strong benefit to it.

jlhredshift
2008-Sep-25, 12:20 PM
I was watching Predator the other day, and wondered how they (the predators) got so technologically advanced without being able to see in visible light (the narrow band that we do)... and began wondering if any technologically advanced civilization could be reached seeing in IR or UV... or even radio and microwave, instead of visible light...

Couldn't get anywhere, I suppose it's possible, but I'm really not sure. I think most species here see in visible (the bees see in UV I seem to recall)...

So, would it be possible?

Thanks and best regards!


Richard Fortey; Senior paleontologist at the Natural History Museum of London; wrote in his book Trilobite on pgs 84-85:



Crystal Eyes

It might seem hardly worth questioning the idea that the world is made for seeing, or that eyes are consequent upon the undeniable fact that there is so much to be seen. Yet think for a moment and the inevitability of vision is much more uncertain. The world is full of signals that may be used to describe it: there are smells, chemical signals both subtle and ubiquitous, and touch is as sensitive to shape as site- more so, because it cannot be misled by trompe l’oeil or by camouflage. Imagine a world in which the eye had never developed- not the eye of the insect, nor of fish, nor of mammal, nor yet Mankind. It easy to conceive of the other senses having taking over the comprehension of their surroundings. It would be a world of palpation, of feelers, a world in which caresses would have rendered glances superfluous. The twitching and waving of antennae would accompany every action. It is not difficult to imagine that a different evolutionary course would have selected those organs most delicately attuned to the passing molecule: even now we know of moths so sensitive to the pheromones of the opposite sex that the most evanescent whiff of a mate can stimulate a love flight across kilometers. In a sightless world, sensitivity to such stimuli would be selected and refined: it would be a world of nuance so delicate that our gross maulings would be inconceivable.

In conscious animals this most sensory of environments would entail everywhere the language of touch and smell: beauty would be aural or tactile or olfactory. Poetry would not celebrate the unfathomable mysteries of eyes and their unplumbable depths, or compare hair with flax, for visual similes would be redundant. Rather, the texture of skin might be the supreme erotic stimulus, or natural selection might have favored an ever more elaborate array of perfumes and chemical attractants, which in turn would evolve a language of which we can only dream. There might be symphonies of perfume, Mozarts of musk. Novelists might construct nasal narratives, versifiers sonnets of scent. Sculpture would entail subtleties of shape that only fingers trained through hundreds of millions of years of tactile evolution could discriminate. There would be no word for “blindness”.

So I don’t believe that light inevitably engendered sophisticated sight, simply that that particular path was taken by life on this planet, elaborating and improving upon the simple photosensitivity of single-celled organisms. The eyes of the trilobite are tangible proof of a selection of one special branch of evolution from an array of possible alternatives- an innovation that made the world visible. Once passed, this threshold could not be forgotten, even if some animals- trilobites included- once more lost sight of the world in favor of fumbling in the dark.

The Trilobites eyes were made of calcite or high magnesium calcite, a novel solution.

H4p10
2008-Sep-26, 05:31 AM
Thanks all for the replies... so much insight!

mugaliens
2008-Sep-26, 05:57 PM
However, there's plenty of room in the near-IR spectrum, and many cameras are capable of producing images in that portion of the spectrum, even with filters to block most of that range. Look at a IR remote through a web cam sometime. A likely reason for the lack of vision in that range is the low energy per photon making detection more difficult, and the lack of a strong benefit to it.

This isn't quite accurate, and the eyeball is especially adept at handling this issue.

The problem is one of where the background radiation is thousands of times more energetic than the image. Let's say it's exactly a thousand times stronger.

Thus, the image impacts the eyeball with an energy level of 1,000, whereas the image only impacts it with an energy level of 1.

The key here, however, is that the image adds to the background radiation. Thus, the image on the retina would contain an energy of 1,001.

There are two ways to cause that image to stand out.

The first is by means of employing a noise floor filter, which is particularly good if you know the level of the noise floor is 1,000. By setting this filter to 1,000.5, you've just filtered out everything except the signal itself.

The second is by means of a difference engine, which looks at the difference between adjacent receptors and sends a signal only if there's any contract.

As it turns out, our eyes contain both mechanisms!

Our eyes adjusting to the ambient lighting is an example of a noise floor filter, and they do that two ways. The fastest (full affect takes about 4 seconds) is by means of your iris, which blocks out unneeded additional light. The slower way, which takes about 30 minutes for the full effect is by chemical means through the Purkinje effect (http://en.wikipedia.org/wiki/Purkinje_effect).

Less well known are the on-center and off-center types of center surround structures in the retina. "The center surround structures are mathematically equivalent to the edge detection algorithms used by computer programmers to extract or enhance the edges in a digital photograph." Thus, they're "difference engines," which enhance even slight contrasts. All this happens before any information reaches your optic nerve - thus, this "preprocessing" does a considerable amount of work which saves both optic nerve bandwidth and brain power.

dodecahedron
2008-Sep-27, 01:59 AM
I was watching Predator the other day, and wondered how they (the predators) got so technologically advanced without being able to see in visible light (the narrow band that we do)... and began wondering if any technologically advanced civilization could be reached seeing in IR or UV... or even radio and microwave, instead of visible light...

They can still see with UV and IR. I don't see what'd be so different about the mechanic of sight under different spectra.