The chocolate bar melted because a lot of power is absorbed very efficiently in a very small volume. I don't think the absorption achievable on a "stealth bird" could possibly reach the tens (or hundreds) of watts per cubic centimetre you get when something is cooked in a microwave oven...
I've been trying to find some numbers for radar power, without success. However, it would have to be very, very powerful to raise the temperature of a plane by any appreciable amount from a distance of the order of kilometres. Obtaining a precisely-focused beam at such a distance is also very difficult (impossible?).
I don't think the "bird in the beam" would die, even if it were coated with highly absorbing stealth material!
Our precious eyes requires a wavelength of 7800 Armstrong to 3800 Armstrong approximately to see stuff and the wavelength of a car or a man is much much larger than that.
Agreed: for this technique to work, the object to be hidden needs to be smaller than the wavelength you are dealing with, which means macroscopic objects will not be made invisible in the wavelength range you describe (although the unit is angstroms, not armstrongs).
However, this does not make the technique useless: the authors of the original article cite non-invasive field nanoprobes (presumably working at visible frequencies) as one possible application. They also mention stealth technology of course - their work is funded by DARPA.
This wouldn't work. The radar would pass through the molecules, only to reflect off of the aircraft skin
Exactly. Hopefully someone will mod you up...
Now, if it could be set up so that the radar would pass through once, and bounce around between the skin and the coating before finding the right angle to escape, it would probably make the radar bounce off the plane at all kinds of weird angles (making the radar useless).
The problem I'm wondering about is: What happens if the radar can't find a way out? Will it keep bouncing around, loosing energy all the while, heating up both the skin and the coating (this may become an issue)?
These are the two conventional approaches to stealth: either deflect incoming waves anywhere but back towards the detector, or absorb as much as possible, in which case the coating inevitably heats up. I don't think this is much of an issue though: probably much more heat is generated simply by flying at high speeds.
For a big body like a car or a human, the wavelength would be so large that finding a monochromatic source of light with that big wavelength is impossible.
That's not the problem. As, in fact, you go on to point out:
However, this will prove useful in hiding a building for radio waves because long range radio waves have high wavelengths too.
Radio waves are light. And it is possible to engineer materials (the "metamaterials" referred to in TFA) which support plasmon resonances at these low frequencies.
I'm a scientist (though not a climatologist) and I find it incredibly frustrating to read posts like this.
They're not going to be out there proving that global warming isn't happening or that it is a natural phenomenon when doing so, in sufficient numbers, will guarantee that funding will dry up on the topic and they'll have to find another research gravy train.
This is pretty offensive. Research is not a "gravy train": it's something we do because it's stimulating, challenging and interesting. Scientists don't want to spend their lives working on ideas that they know are wrong.
That's not to say that they we are never wrong, and many of the greatest leaps in our understanding came about when someone went against the general consensus. However, what you're suggesting is that scientists are wilfully suppressing the truth because it's in their own personal interest.
This also doesn't consider how many studies may have been done, submitted for publishing, and rejected. This could be just as much a political condemnation on those that decide whether or not a study is worthy of being published as it is any comment on the validity of global warming and/or its possible human sources.
There is an excellent response to this point later in the thread, by someone involved in scientific publishing.
Any time you see every scientist agree (or at least no scientist disagree) on a very controversial topic, be very suspicious.
Why? The subject is only controversial because (if true) it means we have to make some painful changes to our lifestyles. Just because that's hard to swallow doesn't make it a conspiracy by the scientific community.
Slashdot Mirror
The chocolate bar melted because a lot of power is absorbed very efficiently in a very small volume. I don't think the absorption achievable on a "stealth bird" could possibly reach the tens (or hundreds) of watts per cubic centimetre you get when something is cooked in a microwave oven...
I don't think the "bird in the beam" would die, even if it were coated with highly absorbing stealth material!
Agreed: for this technique to work, the object to be hidden needs to be smaller than the wavelength you are dealing with, which means macroscopic objects will not be made invisible in the wavelength range you describe (although the unit is angstroms, not armstrongs).
However, this does not make the technique useless: the authors of the original article cite non-invasive field nanoprobes (presumably working at visible frequencies) as one possible application. They also mention stealth technology of course - their work is funded by DARPA.
Exactly. Hopefully someone will mod you up...
These are the two conventional approaches to stealth: either deflect incoming waves anywhere but back towards the detector, or absorb as much as possible, in which case the coating inevitably heats up. I don't think this is much of an issue though: probably much more heat is generated simply by flying at high speeds.
That's not the problem. As, in fact, you go on to point out:
Radio waves are light. And it is possible to engineer materials (the "metamaterials" referred to in TFA) which support plasmon resonances at these low frequencies.
This is pretty offensive. Research is not a "gravy train": it's something we do because it's stimulating, challenging and interesting. Scientists don't want to spend their lives working on ideas that they know are wrong.
That's not to say that they we are never wrong, and many of the greatest leaps in our understanding came about when someone went against the general consensus. However, what you're suggesting is that scientists are wilfully suppressing the truth because it's in their own personal interest.
There is an excellent response to this point later in the thread, by someone involved in scientific publishing.
Why? The subject is only controversial because (if true) it means we have to make some painful changes to our lifestyles. Just because that's hard to swallow doesn't make it a conspiracy by the scientific community.
Yep.. that's the problem.. all those stupid uniforms. Puts me right off!