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Comment Pet Peeve: Imperial units (Score -1, Offtopic) 381

Five tons in this instance would be 10000 pounds? Otherwise it would be the same $%^$%^ that got you guys in trouble with the Mars Orbiter. Let's translate for the rest of the (metric) world: "...it is nearly 22,000kg heavier than the ~50,000kg GBU-43 MOAB surface bomb, sometimes called the 'mother of all bombs.' 'Our past test experience has shown that 4,400kg penetrators carrying 1100kg of high explosive are relatively ineffective against tunnels,..."

Comment Re:Really? (Score 1) 182

I agree about the hypothethical part, altough it is more like complete fiction. Now even Slashdot is perpetuating the myth that Far IR cameras can see through walls... Far IR cameras can't even see through normal glass, never mind concrete or brick walls. Far IR radiation is essentially heat, so to see through say a brick wall, you would have to detect the body heat of a person (or another source) through the bricks. The person's (or other source's) body heat would have been dispersed so evenly through the wall that distinguisinh it from the wall itself will be impossible.

Comment Re:Absorbed not necessarily equal to electricity (Score 1) 439

It sounds as if the cells has a high quantum efficiency as well. From the article:

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons—in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance."

Almost too good to be true, but if it is (and it scales well), invest in some desert land area, because solar has just become viable.

Comment Re:What about copper? (Score 1) 211

Never mind copper, what about lithium? Lithium is about as abundant as Nickel in the earth's crust: From Lithium's wikipedia entry ->

At 20 mg lithium per kg of Earth's crust, lithium is the 25th most abundant element. Nickel and lead have the about the same abundance

Not apparently a crisis, although it might be more expensive to mine due to the use of electrolysis.

Comment Re:Stop scaremongering (Score 1) 179

Mod parent up: *rant* Hollywood has totally violated the laws of physics with fictional law enforcement agencies that can use IR to see through walls. Unless the walls are transparent to IR (and not even glass is transparent to micrometer range IR), there is no way to peer through walls with FLIR.*rant over*

Comment Resolution (Score 3, Informative) 179

3.5GHz translates to a ~8cm wavelength (maybe a bit less with the speed of light being slower in air). Resolving features that vary in amplitude of say less than 2cm (breathing and swaying) requires VERY accurate phase detection and time measurement equipment. Which translates to some very fast hardware doing phase correlation etc. From the article:

Instead, the L-3 CyTerra device sends pulses on 200 different frequencies, one at a time, ranging in sequence from 3101 to 3499 MHz at 2 MHz intervals.

and

The system is sensitive enough to detect the chest motions of a person who is unconscious but breathing, or the slight swaying of a person trying to stand perfectly still

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