51–60 of 84 posts
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I thought black objects absorb all wavelengths, and white objects reflect them all away.
Real world materials are rarely ideal black bodies (or ideal reflectors).
I live off-grid, and have done so for nearly 20 years, and I never needed indoor lighting during daylight hours. I also dislike the idea of poking holes in my roof, for any reason. I'm much more intersted in the gravity light which was featured here a few months ago. http://www.indiegogo.com/projects/gravitylight-lighting-for-... Although the initial cost may be prohibitive for the poverty stricken, it may be well wi…
Lights are used indoors all day long in much of the world. If you don't like poking holes in your roof, then you probably don't like sun windows either. The gravity light requires manual labor to produce light, has moving parts that are more likely to fail, is more costly, and produces less light.
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Proud to be poor? Not paying taxes into NSA surveillance/military state or any whatever exploitive capitalism as other collared proles. Some people are far too busy than to concern themselves with financial vanity and the distractions that follow it. Teeming masses of slum youth with linux netbooks must be high on the list of Fort Meade's threat matrix.
Oh FFS, the whole world does not revolve around the damn NSA. You're obsessed, go see a shrink or take a day or two off from the internet.
EDIT: I reread it twice and laughed each time. This is literally the funniest serious comment I've seen on Hacker News in weeks.
EDIT2: Yes, I thought it was funny enough to make this comment, and no I'm not being sarcastic at all.
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Oh FFS, the whole world does not revolve around the damn NSA. You're obsessed, go see a shrink or take a day or two off from the internet.
Thanks for making me laugh out loud while making a legitimately good point at the same time. Super A+. EDIT: I reread it twice and laughed each time. This is literally the funniest serious comment I've seen on Hacker News in weeks. EDIT2: Yes, I thought it was funny enough to make this comment, and no I'm not being sarcastic at all.
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All I can think of is that a black cap won't degrade as quickly because of ultraviolet exposure. Most plastics (long polymers) have chemical bonds that can be broken by the energy level provided by ultraviolet photons, so over time they turn from polymers into quasicrystals and lose their strength -- disintegrate. But a black plastic, by excluding the ultraviolet light, protects itself and lasts much longer. So a bot…
I thought black objects absorb all wavelengths, and white objects reflect them all away.
The point about a black piece of plastic is that the energy is absorbed at the surface -- it can't penetrate the plastic to any significant depth. That means the majority of the plastic is protected from the ultraviolet wavelengths that would destroy it.
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I thought black objects absorb all wavelengths, and white objects reflect them all away.
Real world materials are rarely ideal black bodies (or ideal reflectors).
That's true, but it's also true that all objects eventually reach thermal equilibrium with their surroundings. Were this not the case, it would violate the law of energy conservation, and that's a law that's never broken.
In that sense, most objects, solids and plasmas in particular, are reasonable black bodies once they achieve equilibrium. Some of them show spectral lines -- emission, absorption or both -- but in most cases those lines appear on top of a blackbody curve. The sun, for example -- perhaps surprisingly, it exhibits a classic blackbody spectrum appropriate to its surface temperature, with many spectral lines contributed primarily by its comparatively low-pressure atmosphere (http://commons.wikimedia.org/wiki/File:Solar_Spectrum.png).
The state of matter least like a black body is a low-pressure molecular cloud in space, which often shows only emission and absorption lines, no classic blackbody curve. The lowest pressure gases show the narrowest spectral lines, which is how we can estimate the pressure of a remote cloud of gas illuminated by distant energy sources.
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My neighborhood is under served by municipal utilities (No telephone, no electricity, no water, no sewage, no cable, no pavement,) so for water most here use rainwater catchment systems using above ground cisterns or pools for storage, and various treatment methods such as UV, RO, and charcoal filtration. (Many haul drinking water from county provided spigots) For sewage most use cesspools dug a minimum of 12 feet de…
Thank you. I've been interested in going off-grid for a while, but never could find the appropriate time (or the location, since land here is pricey as well). If you do find those pictures, I'd love to see how you've setup everything. There's a big demand these days for off-grid and sustainable living so if you happen to document your experiences, a la blog or similar, that could be invaluable for a lot of folks. Not…
While the initial expenses related to going off-grid may be exorbitant (to some) the resulting savings more than makes up for it, and you can always incrementally add to your system as finances permit.
I have had damage due to electrical storm, but placing a TV antenna higher than the panels has worked for the past 10 years or so.
Another concern is equipment replacement, with batteries being replaced at about a five year interval, depending on usage and maintenance. Most of the newer panels are warranted for 25 to 30 years at 90% of rated output but the panels will continue to produce power for many years afterward.
You'll learn to be frugal if you begin with a small setup, as I did, but that's what we're trying to to so I've adjusted well.
My electronics are definitely better off as a result of cleaner power from my pure sine wave inverter, which produces much better electricity and no voltage sags or spikes unlike our local municipal power monopoly.
I'm definitely a believer in alternate energy.
