Slashdot is powered by your submissions, so send in your scoop

 



Forgot your password?
typodupeerror
×

Comment Some details from the paper (Score 5, Informative) 145

For those fortunate enough to have institutional access, the research paper is here.

Quickly picking some highlights:
The atmospheric transmission window is between 8 and 13 microns. They achieved 4.9C below ambient in direct sunlight at 850 watts per square metre. Cooling power was 40.1 watts per square metre. Emissivity (equivalently absorptivity) averages about 70% in the 8-13 micron window (estimated from a plot.)

Here's a quick back-of-the-envelope calculation
90% reflective white paint: absorbs 85W/m^2
97% reflective foil: absorbs 25.5W/m^2, an improvement over white paint of ~60W/m^2
This film: emits 40W/m^2, an improvement over simple foil of ~60W/m^2.
So in this scenario, the special film gives twice the benefit compared to just going for something simple and reflective. (The 90% for white paint is guess-work. The 97% for 'foil' is just matching the special film. Perhaps someone can update the calculations with better founded values.)

The summary title is highly misleading.

It is not paint, it is a manufactured film. It cools buildings, not planets. Yes, with enough you could cool the planet, but if you wanted to take that route, it would be much more cost effective to just use aluminium foil and use a marginally larger area of it (or, indeed, white paint.) Back in the real world, the way this invention cools the planet is by reducing electricity demand for air conditioning. (I saw another article about this in which one of the authors makes exactly this point.)

Comment Every single transaction is broadcast to the world (Score 2, Informative) 115

And you can absolutely guarantee that the three letter agencies remember every one of them. They can look at who you've made transactions with and usually get a very good idea just from that who you are. I imagine they get more from fronts and hacked/infiltrated organizations. If they need more and you've ever transacted with a commercial entity within their jurisdiction, you are a National Security Letter or local equivalent away from being identified.

This IP address thing is like discovering that the back door is unlocked and open when the front door is secured by a piece of string.

Comment The minus 10 billion dollar woman (Score 1) 433

The market capitalization of Hewlett Packard leapt something like 10 billion dollars on the news that she had been fired. That is to say, the stock market values her at negative 10 billion dollars. If she enters the race, how long can it be until someone labels her 'the minus ten billion dollar woman', and how long can she stay in the race with that label?

Comment Re:In Finland (Score 3, Informative) 516

Wooden houses as opposed to what? I don't think a well built wooden house is at all a problem in an earthquake zone. It is better than brick, probably worse than reinforced concrete or steel, but who builds single dwellings from reinforced concrete or steel?

I'm from New Zealand, where we have quite high earthquake hazard, and an overwhelming majority of our houses are wooden. Fatalities in the Christchurch earthquake were (mostly? entirely?) not due to wooden buildings but to poor quality 1980s high-rise and ~100 year old brick low-rise commercial buildings. People did die in wooden houses, but in the cases I am aware of this was due to boulders or cliffs falling on them, which no reasonable house would withstand, or heavy furniture falling on them, again independent of house construction.

Comment Re:I'd love to have a self driving car, but... (Score 1) 454

Planes are essentially self-driving now, at least runway-to-runway.

No, they are not. That is like saying a company is self-running just because it has an automated production line. Much of the flight is under auto-pilot, but the human pilots are frequently changing the auto-pilot's instructions. There is a lot of training and skill maintaining in being a pilot. They aren't just there to keepen das hander in das pockets und watschen der blinkenlichten.

All take-offs are manual. Nearly all landings are manual. Mostly 'auto land' just takes the plane to just short of the runway, at which point a pilot takes over for the actual touchdown. Full auto land is possible, but with good visibility it is simply less work to manually land than to set up the auto land.

Comment Heat pollution (Score 3, Insightful) 523

You're trying to study a temperature-sensitive environment in its natural state. An RTG produces lots of heat. (They are only about 5% efficient, so they produce twenty times as much heat as electrical power.) The presence of the RTG might perturb or destroy the environment you're there to study. I don't have the detailed knowledge to say if this is the case.

Plus the issues others have raised: mass, scarcity of suitable isotopes, and launching highly radioactive material on top of hundreds of tonnes of potentially explosive fuel is something you'd rather avoid if possible.

Comment Re:So? (Score 1) 271

What does any of that have to do with the story here? The tracking device wasn't added by the police or even at the behest of the police, but by the buy-here-pay-here dealer, operating a business of the same respectability as payday lending and rent-to-own stores, who expect their customers to default. This wasn't done for cops but for repo men.

By all means complain about a violation of privacy, but it isn't by the state. Rather this is the result of a financial system that promotes, aggravates, and profits off of poverty.

Comment Re:Would this kind of system have saved Challenger (Score 1) 44

OK, lets rephrase a little, and concentrate on the Challenger failure mode, rather than the actual shuttle.

Imagine a rocket that was compatible with an LES, and also compatible with the Challenger failure mode. (Remove the shuttle, put the liquid fuel engines on the bottom of the external tank, throw a capsule on the top, keep the solid rockets.) Now have the boosters fail in the same way they did with Challenger. Would the LES have sufficient notice to get the capsule to safety?

Slashdot Top Deals

"It is better for civilization to be going down the drain than to be coming up it." -- Henry Allen

Working...