Einstein special on PBS - the nature of light

[askold]

The recent PBS special got me thinking of some aspects of light that were not covered in the program: its dual nature as an electromagnetic wave and as photons.<br /><br />Which of these phenomema allow us to "see" - the EM wave or the photons? To the best of my knowledge, humans can not detect any other part of the EM spectrum - for example, I don't pick up HBO inside my head from a Dish satellite.<br /><br />My guess is we "see" the photons. So, basically, is it wasn't for this interesting duality in light, we wouldn't be able to see at all.<br /><br />Is this just good luck that light has this interesting characterisitic in one part of the EM band and coincidence that animals have developed organs to detect it?

 

[askold]

Oh, I didn't know that all EM energy also had photon characteristics. My recollection from physics class (a long time ago) was that photons were only associated with light.<br /><br />So, it's not a lucky coincidence peculiar to visible light.<br /><br />Though human sight is still amazing to me - the fact that we can detect energy in, what? the gigaHz range?

 

[askold]

And I thought it was interesting that Einstein dumped his frumpy wife and hooked up with a young babe as soon as he gained success! Just like celebrities today.

 

[newtonian]

ranur - Hi! (I'm the former paulharth6, btw). How are you?<br /><br />Good responses.`<br /><br />Concerning seeing light being a matter of luck or just how nature works:<br /><br />I would be more inclined to consider it evidence of our Creator's love for us.<br /><br />Not all animals see in color, btw.<br /><br />One might ask why we have such beautiful flowers, sunsets, nebulae, etc.?<br /><br />Nature is sure beautiful in color!<br /><br />You all - I missed the PBS episode. Feel free to post some highlights or new things learned!

 

[askold]

Sure it could be our Creator's love - just like all our other senses - smell, hearing, touch. I've always thought that the world was a much more delightful place than absolutely necessary.

 

[kauboi]

<font color="yellow">Visible light is in the range of approx 400 to 800 Tera Hertz</font><br /><br />A question: <br />What about non-visible light? which is the calculated range?

 

[perplexvex]

intelligent design

 

[newtonian]

ranur - Of course, beauty is in the eye of the beholder.<br /><br />Askold has a point though - plants do not have to have beautiful flowers to survive - but it sure makes earth a more beautiful place!<br /><br />There are many plants which survive just fine without flowers, or with just tiny flowers, etc.<br /><br />So, why do you think we consider beautiful flowers beautiful? <br /><br />You note exceptions, but generally man's pollution does not make earth more beautiful - far from it!<br /><br />And why do we see in color when many other animals do not?

 

[newtonian]

ranur - Overviews are good and I always enjoy your posts.<br /><br />A little added detail on the blessings of color vision:<br /><br />"THE retina is a small membrane that fits over the back of the eye. As thin as paper, it contains over a hundred million neurons arranged in different layers. “The retina,” states the book The Living Body, “is one of the most remarkable pieces of tissue in the human body.” It is “the envy of the computer scientist, performing approximately 10 billion calculations every second,” states Sandra Sinclair in her book How Animals See.<br /><br />As a camera focuses an image on photographic film, our eye focuses on the retina an image of what we see. Yet, as Dr. Miller explains, camera film “does not even begin to compare with the versatile sensitivity of the retina.” With the same “film” we can see by moonlight or in sunlight 30,000 times more intense. Furthermore, the retina can discern fine details of an object part of which is bathed in light and the rest of which is in shadow. “The camera,” explains Professor Guyton in his Textbook of Medical Physiology, “cannot do this because of the narrow critical range of light intensity required for proper exposure of film.” Hence, photographers need flash equipment.<br /><br />The “versatile sensitivity of the retina” is due, in part, to 125 million rods. These are sensitive to small amounts of light, making vision possible at night. Then there are about 5.5 million cones that respond to brighter light and make possible detailed color vision. Some cones are most sensitive to red light, others to green and others to blue. Their combined response enables you to see all the colors in this magazine. When all three types of cones are excited equally, the color you see is pure white.<br /><br />Most animals are limited in their ability to see in color, and many do not see color at all. “Colour vision adds immensely to the joys of life,” says surgeon Rendle Short, adding: “Of all the organs of the body not absol

 

[newtonian]

sluggah316 - Excellent point - Eagles are amazing in their vision, as noted in the Bible:<br /><br />(Job 39:27-29) 27 Or is it at your order that an eagle flies upward And that it builds its nest high up, 28 That on a crag it resides and stays during the night Upon the tooth of a crag and an inaccessible place? 29 From there it has to search for food; Far into the distance its eyes keep looking.<br /><br />As to how far the Eagle sees, and also owls that see in the dark (and the cones and rods involved in their eyes):<br /><br />"How far into the distance can an eagle actually see? “Under ideal conditions a golden eagle (Aquila chrysaetos) can detect the slight movements of a rabbit from more than [1 1/4 miles] [2 km] away,” explains The Guinness Book of Animal Records. Others have estimated that the eagle can see even farther!<br /><br />What gives the eagle such acute vision? First of all, the golden eagle has two huge eyes, which occupy a large portion of the head. The Book of British Birds notes that in the case of the golden eagle, its eyes “are, in fact, as large as they could be without becoming so heavy as to impair flight.”<br /><br />Furthermore, an eagle’s eye has approximately five times the number of light-receptor cells that we have—some 1,000,000 cones per square millimeter compared to our 200,000. Practically each receptor is connected to a neuron. As a result, the eagle’s optic nerve, which carries messages from the eye to the brain, contains double the number of fibers found in that of a human. Little wonder that these creatures have keen color perception! Finally, birds of prey, like other birds, have eyes equipped with a powerful lens that can change its focus quickly from objects an inch away [a few centimeters away] to those at a great distance. Their eyes far outmatch ours in this respect as well.<br /><br />The eagle’s vision excels during broad daylight, but at night the owls have the advantage. These nocturnal raptors have eyes with abundant light-sen