"If you were trying to imply that Q is the energy added to the system that the light is being focused upon,"

No, I'm guessing Q would be the heat added to the magnifying glass on the sun side, which is very small compared to the heat produced on the side where the light is focused; the latter heat does the work you want (lighting a fire or whatever). Since Q is small, and W is large, U should be negative. But it's not.

"The process of compressing your data costs more than decompressing it. Rule of thumb holds."

Costs more in what sense? Energy cost? Lines of code cost? Time cost? In any event, it is not something that I consider when zipping a file. Zip and unzip are treated as equivalent from the user's standpoint.

"A magnifying glass, simply put, directs the energy that hits its outside lens surface to a much smaller area, at the cost of the loss due to diffraction of light."

The point that confuses me is: the energy on the outside lens surface can't light a fire, but the energy produced by the glass can. What work was done on the outside energy? It was redirected inside the lens, but how is that work? Doesn't work in thermodynamics reduce to the lifting of a mass in a gravitational field? How is the lens doing any work, in that sense?

All models are flawed, by definition. These holy "Theories" you have such emotional attachments to simply use models. In a 100 years, they will be superseded and allow us to do things we can't think of today. Like GPS wouldn't work if we relied on Newton's theory of gravity.

Where is the waste heat, or change in internal energy, in a magnifying glass system, used to focus the sun's rays to produce a concentrated, high-temperature Airy disk?

U = Q - W

The U (internal energy) of a magnifying glass does not change appreciably during use. Q is heat added to the system; it is much less than the W, or heat produced by the focused rays, which do the work of lighting a fire.

U is small, Q is small, W is large. In theory, U should be large and negative. But it's not...

http://www.askamathematician.c... says: 'A good rule of thumb for entropy is, "if you can reverse it, then the entropy is constant".'

But a zipped file has lower (information) entropy than the same file uncompressed, and the process is reversible. So that rule of thumb doesn't hold for information entropy?

The other question I have about the "ask a mathematician" response is: it assumes the energy input to the magnifying glass system is the temperature of the sun. That is not true: the atmosphere, at least, reduces the sun's irradiance. The input to the system should be the temperature on the sun's side of the glass, which can be less than zero since you can light fires on cold or windy days when the sun is out.

Wikipedia notes that a 2011 report found the problems were all mechanical, not electrical. Barr's report seems to be a lot of "what if"s like a cosmic ray causing a bit flip.

I think there's enough plastic crap all over the US that we wouldn't have to import the resin. Recycle.

3D-print it at home.

Lesson: the US government should be doing far more investment in firms like Solyndra, to catch up with the Chinese government.

Right, because if you aren't talking about global warming, you won't breathe either!

Let's get away from the bus paradigm altogether. Use small (self-driving) vehicles to move people, instead of large buses. Small vehicles are more flexible and don't clog up traffic as much. They can be disinfected easily between uses by providing wipes or a spray for each new patron to clean the surfaces with.

Instead of a single bus driving around picking people up and dropping them off, have stands with small electric vehicles for individuals. Instead of waiting for a bus, you go to a stand and check out a vehicle and drive it to where you want. Or it drives itself. With self-driving electric vehicles, you could keep all the stands in supply.

Pretty sure those runaways were caused by morons who put their floormats over the accelerator, not software.

Ah, but I like my caffeine to be naturally coffee flavored and I control any other ingredients (half and half first thing in the morning, straight up through the day and then maybe a little Bailey's or similar cream liquor in the evening). Never any sugar! So, none of artificial stuff in "energy drinks", thank you very much.

Cheers,
Dave

Funny how this is posted to /. in the wake of the "Architecting the Cloud" book review. There were some comments made about AWS and how it is so wonderfully PCI compliant and I just left a comment that was probably a bit derogatory against the entire concept of PCI compliance, but what can I say, after going through that process with my own stuff I am absolutely not anywhere near confident about PCI compliance meaning anything at all whatsoever. You can be tripple PCI compliant with some sugar on top and you will still have security problems that will get you cracked.

PCI compliance is a joke really, I also doubt that AWS does everything that PCI compliance actually says you have to do, because there are contradictory things in there and beside that, do they truly scan all of their data-centres and networks for any 'unauthorised wireless activity', etc.? It's a bunch of smoke and mirrors.

The problem with that, is that very few applications are now isolated these days. You typically have a DB back-end, data export/import and RPC to other system services. Setting a different locale is error prone since some data might be simply misinterpreted and end up corrupted. And that is real problem, since lots of user data are actually stored in textual form (even in DB!).

IME, the per-application locale has its uses, but in real world it causes more problems than it solves. In fact, since most Linux distros support quick account switching, the cheapest solution right now is to use two accounts with different locales.

There is no sane way to solve that problem on the level of OS. (Even "primary language; secondary language" is not enough, since for example I have to deal daily with three languages (Russian, English, German).) Most of the time this ends up being in the responsibility of the application developers: if they care enough, they offer a possibility to use a language different from the system one.

Think of the flip-side: you might accidentally force all Japanese and all English iPhones to download both English and Japanese locale data. And this is pretty large amount of the data to just sit around idly, just in case when user might once decide to hear the street names in different language.