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Ocean Sponge May Be Best for Fiber Optics
TheViffer writes "ABC News is reporting that scientists say they've identified an ocean sponge, living in the darkness of the deep sea, that grows thin glass fibers capable of transmitting light better than industrial fiber optic cables used for telecommunication. 'You can actually tie a knot in these natural biological fibers and they will not break - it's really quite amazing,' said Joanna Aizenberg, who led the research at Bell Laboratories."
apparently you're no physicist yourself.
the speed of light in a medium does not equal the the speed of light in a vacuum. here is a handy chart for you.
---- El diablo esta en mis pantalones! Mire, mire!
As a general guess I'm going to venture that these things are asexual, being sponges, and it's not for mating displays. but then again, I couldn't RTFA 'cos it's slashdotted
Banaaaana!
Bottom line, idiot, is that humankind has absolutely no effect on the ocean compared to what the earth itself and the sun dish out.
:-[
Oh, boy.....here we go.
Imagine the sun flared. Just a little one. What could happen to the earth?
The sun flares all the time. Our atmosphere and the ozone layer protect us.
Why, the entire atmosphere could be blown away, and the oceans could dry up. The deserts would turn to glass. All from a small solar flare.
*Sigh.......* No. This is not correct. See above comment for clarification.
What about a volcano? How many megatons of carbon dioxide and other noxious chemicals does that dump into the atmosphere, not to mention the pollution in the oceans?
CO2 release into the oceans is common and the CO2 flux is truly massive. However, what we need to worry about are some of the non-naturally occurring chemicals such as estrogens and chemicals found in fertilizers and run off from mining such as cyanides. We also have to worry about what is happening from all of the nuclear reactors that the former Soviet union has dumped into the sea among other things.
The algae blooms are there because the sun put them there. We had nothing to do with it.
Wrong. Human intervention most likely primarily from excess nitrogens are at the root of many of these. Other causes are world wide shipping, which carries algae to new homes in water contained in ballast tanks, global warming, and pollution draining into the oceans from coastal development and farmland, which provides again nitrogenous compounds essential for algae metabolism.
You are an idiot. spouting out half-truths and whining about it.
There is no call for that sort of treatment. Lighten up, eh?
Go crack a real science book, not the pseudo-crap they are passing off in high school today.
Your credentials are what?
Go take a look at how much water there is in the ocean, and try and figure out how much pollution we could actually dump in there if we really tried. You'll see that we would have barely any effect at all.
Many, many studies are being performed on just this and the results are sobering.
And how do you pillage the ocean? The natural resources in the ocean are going to die anyway. Rather than allowing the fish to float to the bottom of the ocean and rot and pollute the ocean, we are harvesting the excess every year so that we can feed a starving world. How is that pillaging?
With a comment like this, I am not even sure where to start. Is this a troll? You can't be serious.......
Visit Jonesblog and say hello.
Sorry dude. Yes the IOR is important; however the refractive index has nothing to do with the flexibility.
It directly determines the critical angle for total internal reflection, which affects the ratio of bending radius to fiber diameter that you can support without unacceptable light loss.
It also has everything to do with the materials you make the fiber with. A minimum required refractive index limits materials choices, which limits mechanical properties. A carefully-doped glass fiber will have a higher refractive index than a carefully doped plastic one.
I work in a research group that did some stuff in this field a couple of years ago. I didn't work directly on the sponge spicules and I'm not at the lab so some of this info is only as accurate as my memory.
Pretty much all sponges contain small glass needles called spicules which primarily act as a deterrent to being eaten. Some species of Antarctic sponges evolved spicules to the point of using them as light collectors. The species we were working with (can't recall the scientific name right now) lives about 100m below the ocean surface where there is virtually no light. Despite this, the sponge is dependent upon a symbiotic relationship with algae living inside of it.
Unlike normal sponges that have spiclues 90% light gathering efficiency over something like a 200 degree angle. The light is then concentrated and piped down that long body of the spicule where it shines onto the algae so they can photosynthesize.
What makes these fibers quite unique is their durability and construction technique. As mentioned, you can tie a loose overhand knot into these fibers and they not only fail to break but retain high light transfer efficiencies. This is due to a layered glass/protein structure that provides a slip plane for flexing and also works to prevent catastrophic crack propagation. This sort of layering is fairly common in hard biological tissues. (eg: mother of pearl)
The synthesis is fairly striking as it occurs in water at approximately 0 degrees C. Normal glass fiber pulling is at something like 2500 C in a completely water-free environment. (water has strong absorbance peaks in the IR wavelengths used in telecommunications) How the shape of the fibers is created is still a bit of a mystery but the biochemical process is fairly well understood. For those who are interested, look up work from the Dan Morse group. They isolated the enzymes responsible for the silica polymerization a few years ago and created a recombinant analog. Also look at work by the Morley Stone group more recently for some additional work done in this area.
Actual sponges would never be harvested for these applications, it would just be too impractical to get enough raw material and to splice those pieces together. However, it is conceivable that a biochemical process could be implememted to make the same sort of layered fiber. The advantages would be a fiber that is highly crack and bend resistant and that would require vastly lower amounts of energy to produce. The downside is that the silica is full of water and is useless for telecom frequencies. However, I see a potential market for in-house cables - Cat5 replacement if you will. The data rates in-house are much lower so visible wavelengths could be used with standard LED/photodiodes. Also, with in-house applications, the low-cost and high strength would be highly advantageous.
The thing about bending fibre optics that nobody ever points out, is that if you bend even an infinitely-elastic fibre optic through too tight a curve, then you will get light leakage.
.....
Fibre optics work on the principle of total internal reflection. The angle at which the light strikes the interface between glass and air is too shallow for it to get refracted out into the air, so instead it bounces off. As far as a beam of light is concerned, a length of fibre optic is just like a tube whose inside walls have a perfect mirror finish.
If you put a tight enough bend into the fibre, then the light will no longer be striking at an unrefractable angle, and therefore will escape. {You can try this with cheap 1mm. acrylic fibre if you remove the outer jacket and warm it in a pan of boiling water}.
Now, glass fibres exhibit very nice thermoplastic behaviour, and can actually be bent without breaking to tighter radii than acrylic. Unfortunately, they begin leaking light long before they break
Je fume. Tu fumes. Nous fûmes!
Just like spider silk, which by all definitions is the strongest substance made in nature, yet we cannot replicate its composition.
If we could, we could make bullet proof vests that were like 1/8 thick...