Doubling your computational effort to extend your weather forecast to a 24th day might well be justified, as might doubling it again to get an extra hour. Doubling again to get the next few minutes, or again for an extra few seconds is far harder to justify - especially as other addressable factors might have greater influence on the uncertainty of the predictions.

We clearly have a different subjective take on the typical practical value of calculations at the cutting edge of 'brute-force' computation. Without specifics we are unlikely to progress the debate. There are, undoubtedly, some problems that can only be tackled by more grunt (tightly coupled computation) but - in my opinion - progressing these problems head-on, typically, does not offer benefits commensurate with the cost.

The diminishing returns implied by the Lyapunov exponent definitely lend credibility to my claim that much of supercomputing is objectively pointless, but I was anxious not to focus upon only one of the ways in which calculations might be irrelevant.

I'd agree that "bigger is better" - but only if we exclude cost from our assessment.With significant financial overheads for marginal improvement in accuracy, I have to wonder - at the extremes of industry practice - might the same funding might been more effectively deployed otherwise? Might a better strategy be to simply accept the limits of inexpensive computing, and focus on finding more effective approaches to practical problems?

I like supercomputers in the same way I like architectural monuments - there's an element of beauty in stretching technology to ever more extreme goals, but I'm far from convinced that there's an objective, practical, point to any of the calculations they make.

I'm very sceptical about climate change prediction - because, without any calculation, it's blindingly obvious that climate will change (all evidence suggests vast changes throughout history) and - because mankind is significant among life on earth - obviously we should assume a fair chunk to be 'man made'. I seldom see the questions that matter addressed... for example, in what ways can we expect climate change to be beneficial to mankind? When we ask the wrong questions, no matter how large-scale or accurate our computation, it will be worthless. Don't get me wrong, I see immense value in forecasting... but I don't see available computational power as a limiting factor... in my opinion there are two critical issues for forecasting: (1) collecting relevant data accurately; (2) establishing the right kind of summaries and models. While some models are computationally expensive - in my opinion - the reason for attempting to brute-force these models has far less to do with objective research and far more to do with political will to have a concrete answer irrespective of its relevance... The complexity of extensive computation is exploited to lend an air of credibility, in most cases, IMHO.

"Don't worry about the future. Or worry, but know that worrying is as effective as trying to solve an algebra equation by chewing bubble gum. The real troubles in your life are apt to be things that never crossed your worried mind, the kind that blindside you at 4 p.m. on some idle Tuesday."

The reason is simple: avoidable disasters occur not because we haven't done enough calculations - but because the calculations we do are done for the wrong reasons and produce irrelevant results. If we want to move forwards, we need more observation and more intelligent consideration. Iterating existing formulas beyond the extent possible with off-the-shelf technology, IMHO, is unlikely to yield anything significant.

I use various desktop PCs, and I want to share my passwords and bookmarks between them... but I am not comfortable with this personal data in the cloud - even on Google's servers. This is exactly the same reason I use Thunderbird and Lightning with my own mail and calendar servers rather than Google Mail/Calendar... even while I'm disappointed with Thunderbird and Lightnig's progress in recent years. I don't want my (potentially sensitive) data lurking in the cloud.

With Firefox, I solved this using XMarks and a personal DAV server on my own hardware accessed over HTTPS.

With Chrome, while XMarks has been ported, it doesn't support personal DAV servers... which is a sticking point for me.

Chrome would probably win me over if it could synchronise bookmarks and passwords against my own server... in spite of my wider concerns about its integration with Google services.

I'm aware that the solution has been leaking out onto the net...

Starting later than most, in spare time, I've trudged through stages One and Two... I've been playing with the stage-3 executable and have disassembled it... though there remains further tedious trudging for me to demonstrate by sensible sequential steps how to go about solving stage-3.

I'm finding it difficult to convince myself that it's worth the effort... I'm sure I can fathom any remaining steps - based upon the fact that there has been little about stages one and two that was actually 'challenging'. It seems silly to plod onwards without 'cheating'.

I was interested principally to try and find out what sort of skills GCHQ actually want... I never assumed I'd be (one of the) first to solve it. The experience has left me wondering what sort of job this sort of tom-foolery would suit one for. Sure debugging and OS-level skills can be valuable - but the challenge is most time consuming as one is required to guess the objective - identifying the intentions of the challenge setter rather than to address real-world issues.

I guess it's a "no brainer" if you're paying with someone else's money.

:) I understand how the angular momentum is conserved. What I want to know is where it came from in the first place.

A question that's bugged me for years.

Whenever I've been shown a picture of any galaxy, I've noted a swirly thing as flat as a pancake.

My question: Why are galaxies "flat as a pancake"? If the universe arose from random gas clouds, I'd not expect stable swirling galaxies - at least not on every occasion... I'd have expected to see a cluster of bodies tumbling chaotically. What gives?

My bullshit detector is going off - and it's not because I don't believe this sort of technology is just around the corner - because it is. I just don't have confidence that it will be brought to us by HP... given recent evidence HP seems quite capable of snatching any defeat from the jaws of victory.

Will more people die as a result of more widespread distribution - in your opinion? Do you have any evidence that genuine assassins need help from Slashdot to gain access to leaked intelligence data?

My perspective is that this seems weird... JA and Wikileaks went to great lengths not to release non-redacted data... I don't believe that the Guardian mistakenly published the key... I can hardly believe that JA/Wikileaks gave it to them - and I find it inconceivable that they did this without making clear that the key was in strictest confidence. If the Guardian published the key, then the Guardian - not Wikileaks - released the data without redactions... somehow I doubt that the Guardian (journalist) will suffer the same reaction as JA/Wikileaks.

I am **extremely** impressed. It's, by far, my favourite Python IDE (I'm using it in the free Visual Studio shell...)

One drawback is that it encourages editing python under Windows rather than on a Unix-like platform, but that's something I can live with when it delivers productivity.

I'm yet to use it for a real project - but I'm looking forwards to that experience.

I'd definitely encourage anyone to, at least, give it a try.

From the "Homomorphic Encryption" page linked from the article:
"Only in 2009 did Craig Gentry of IBM publish a mathematical proof showing fully homomorphic encryption was possible."

In the past (in a very hand-wavy kind of way) I've argued that it should be possible to "prove" that homomorphic encryption isn't feasible... because, in order to implement multiplication and addition of integers, I need a total-ordering over my data... and if I have a total ordering, my data is (effectively) decrypted. This, of course, doesn't preclude obfuscation and scrambling - but I (used to) believe strong homomorphic encryption was not worth investigation.

Does anyone have a reference to this proof? Has anyone read it? Can anyone summarise what Gentry concludes?

I've been thinking about reliability of connectivity quite a bit recently... Using a 3G dongle as a backup is one option - but with this option attracting either a noticable monthly charge or requiring a pre-pay to be renewed every 1 or 3 months... it is a bit frustrating... for a service I hope I never need to use. I'm currently wavering on the brink of taking the plunge - the clincher will be if I find time to convince myself that I can configure automatic fail-over satisfactorily.

The first interesting idea that springs to mind is this: if 0.5mb/s is free, what's stopping me buying N wi-fi dongles and channel-bonding their connections to give a ~N/2 mb/s connection, also for free?

Another interesting idea is that if Virgin had this service when I moved in, they'd have me as a customer... The way things actually panned out, I paid a deposit - they jerked me about and gave me absolutely no clue when I'd be given service - so I told them to sling-their-hook and went with Sky (who proved similarly useless - but eventually provided a DSL line.)

The real losers will surely be the telephone companies. Why bother with a pay-go mobile for texts if you can be connected to the web at 0.5mbps everywhere you go?

I believe that the greatest benefits of computer technology relate to social networking...

However...

I think that centralised services like - erm - all the social networks - are, on balance, a terrible idea - both for participants and for society as a whole.

In an information age, one's knowledge (and an important part of this is the social connections one makes) is the ultimate asset. It needs to be maintained carefully in order for it to present mutually beneficial outcomes. If this information is shared publicly, there is no motivation for reciprocity and there's a great tendency to abuse the personal information of those we've never met or communicated with directly. Thus - even if they're a tiny minority - those who leech and use information from social networking sites make them a greater risk than benefit - IMHO.

What's really needed is a distributed, mobile, system - where people actually make stronger connections with other people - in real life. We need systems that help build and maintain those relationships... and that demands a level of privacy that is incompatible with centralised social networking.

What really cripples things is when process is deemed a substitute for understanding the specifics of individual situations - where a one-size-fits-all-problems approach is adopted and imposed - usually by people who have no practical experience with the processes they espouse.

If software development could be successfully reduced to a process, I'd have automated it. Where there's a considerable burden of process, either the process is inappropriate - or developing the software itself is inappropriate as it amounts merely to re-inventing the wheel... an exercise in task creation that benefits no-one.

We should think of software development techniques and apply them judiciously - and the more techniques a developer masters, the wider their skill-set and the better they will adapt to new challenges. The critical question that needs to be asked is this: why is a technique being used and is it providing tangible benefits? If this question can't be adequately answered, everyone involved is wasting their time.