Slashdot Mirror

I took a look around and found some quantum simulators: http://www.dcs.ex.ac.uk/~jwallace/simtable.htm

Division by zero is completely meaningless. Yes there are cases where division by zero creates a removable singularity, and for continuity's sake you can define a new curve/sequence/function/whatever with the convenient value. But that doesn't make the division meaningful...

You're assuming that the familiar logical system of Calculus 101 is the only way of defining concepts like "zero" and "infinity". But that's not true. There are alternate approaches that I'm not qualified to get into (basically, some mathematicians are trying to resolve the ambiguities Newton tapdanced around when he invented Calculus).

And even if you don't get into that kind of quibble, division by zero is only undefined in the limited context of "standard" real numbers. It makes perfect sense to define division by zero in the context of complex numbers.

Every time I use my Visa information about where/when/how I spend my money are collected and stored somewhere... I can do nothing about it and I can hardly stop using credit cards unless I retire on a forgotten island.

It seems possible to create anonymous electronic money system, but actually nobody is pushing in this direction.

I don't think there're security issues slowing or avoiding the development of anonymous electronic cash, but rather credit card corporations that don't want to stop to collect approx 2-4% of each credit card transaction.

Of course sales taxes are higher than 4% and governement intrudes privacy more than Visa or Mastercard, but at least governement tries to give me security .

Seriously: if you feel you must muck around with quantum states, a simple library like QDD will probably do. Or have a look here.

If quantum computers ever do anything useful--and that's a big "if"--then most likely you will just be using it through high-level operations and datatypes.

Ignoring the implication that people are incapable of writing their own music

Which was entirely the implication. I have so far found no way to prevent myself from making the same mistake that George Harrison made.

a gathering of family and friends is not a public performance.

Correct. US copyright law, 17 USC 101, defines a public performance as a performance "at a place open to the public or at any place where a substantial number of persons outside of a normal circle of a family and its social acquaintances is gathered".

[AOL's copyright on "Happy Birthday to You"] is a much more obvious abuse of copyright

Even more obvious are the perpetual copyrights in the UK on the KJV Bible and Peter Pan and the situation in Mexico.

Ehhh ... me thinks you have 47 MPG

Yep, it's ignorance alright. ;-)

The European Flag for you enjoyment. For those watching in black and white, it's a blue flag with a ring of 12 gold stars.

Now, I'm going to take a guess that there is a high chance you don't know what the Iraqi flag looks like. In fact, very few Americans seem to know what the Iraqi flag looks like, yet they will bomb the country anyway... I wonder if this is how America always manages to bomb it's allies when they go to war.

Sure. But it's a big - no, huge - step from taking a whack at something and actually publishing it.

Absolutely. But there has been a recent history with the Poincare Conjecture of even big names rushing to publish (albeit promising) misses, and one wonders whether the prize money adds to the usual rush for priority that you see in any competitive field. I think even Wiles was in some sense racing against his 40th birthday to prove FLT, since that is the informal-but-de facto limit for the Fields Medal. Which he didn't win, as it turns out (mathematicians are *tough* :-)).

It is just very rare that professionals publish findings if they don't take them seriously themselves.

OK, so I now agree I was needlessly harsh in my words about these authors. I do have a hunch that they thought they were close if not there, but they clearly either felt time pressure of some sort (which is why their oritginal was full of typos and used non-standard notations), or they were at least a bit casual about their submission, possibly reasoning that if it really did prove to be promising, that they could get stuff ironed out during the review.

In any of the soft sciencies, that could happen, and one could stand a chance of getting away with it. But there's no fooling the mathematical community. Either you have proof or you don't.

OK, so my degree is in Psychology, and I know for sure that some marginal or under-challenged stuff gets out into the literature, but for the *most* part, stuff like that then just lies there fairly harmlessly and uselessly, going uncited and unread, because nobody finds it interesting enough to care one way or another. The more interesting or controversial stuff, though, is much more thoroughly examined. I would prefer myself if others in the field would be a bit more...circumspect about publishing some things, but I don't think you really get too far in any decent-sized and respected community in psych by just cranking out noise.

I guess I just don't see what you're saying here. Is it 1) These researchers publish a proof that they believe is incorrect, and hope nobody will notice or 2) These researchers publish a proof that they believe is correct, but they are so incompetent that this is very unlikely to be the case (in fact, so unlikely it makes your BS meter run at 11). To me, neither 1) or 2) seem to obviously be the case here.

Mostly number 2. As a psychologist (although not really *that* kind of psychologist) I am always very impressed at people's ability to engage in self-deception and magical thinking, and their frequent inability to recognize their own limitations (you've seen some of me doing that in this thread, as it turns out). What we have here is a probably sincere but possibly somewhat flakey physicist whose work doesn't really carry much weight in his own field who then finds a collaborator and publishes an idiosyncratic paper on a topic where there just happens to be a large cash prize available that is well outside his area of expertise. This does not inspire confidence. Now the point here is that we know that every attempt so far to prove this has met with utter failure, that this attempt only met with brief notice (basically negative) in the internet community as a preprint. And the last point:

In your first post you use as authorative a quote which suggests this proof hasn't received serious attention yet. This is mildly contradictory.

Ah, now that's just a misunderstanding that I did little to clarify. My take on the "graveyard of RH papers" page is not that it is pointing to possibly very worthy work (not universally true since it points to the work of Archimedes Plutonium), but to papers that likely or certainly have flaws of the type that high level math students might be able to detect and elucidate as part of their educational process. Context is everything here. The page that links to the one I quoted is a "Curiosities" page that even mentions silly discussions on Slashdot about the Riemann Hypothesis. The Riemann Hypothesis page itself explicitly mentions a recent rejoinder to Castro's earlier proof of RH, suggesting that the technique is flawed, and frankly doubtful that it can be fixed. I do thank you for the information that some novel approaches to the problem coming from physics are taken at least a bit seriously.

I agree that this is now going in circles, but my real point was that a months old pre-print using an approach that was previously panned, from an author who is not well-respected in his major field, using notation that the mathtematicians trying to read it thought was weird, whose only notice outside 37 posts of glory on sci.math is from the popular press (sorry to have mistaken the prestige of the newspaper) is not likely to be correct, and that the editors of slashdot might consider having a mathematician filter stories about math since I do think it is beyond their skills to do a good job.

Sure. But it's a big - no, huge - step from taking a whack at something and actually publishing it.

Absolutely. But there has been a recent history with the Poincare Conjecture of even big names rushing to publish (albeit promising) misses, and one wonders whether the prize money adds to the usual rush for priority that you see in any competitive field. I think even Wiles was in some sense racing against his 40th birthday to prove FLT, since that is the informal-but-de facto limit for the Fields Medal. Which he didn't win, as it turns out (mathematicians are *tough* :-)).

It is just very rare that professionals publish findings if they don't take them seriously themselves.

OK, so I now agree I was needlessly harsh in my words about these authors. I do have a hunch that they thought they were close if not there, but they clearly either felt time pressure of some sort (which is why their oritginal was full of typos and used non-standard notations), or they were at least a bit casual about their submission, possibly reasoning that if it really did prove to be promising, that they could get stuff ironed out during the review.

In any of the soft sciencies, that could happen, and one could stand a chance of getting away with it. But there's no fooling the mathematical community. Either you have proof or you don't.

OK, so my degree is in Psychology, and I know for sure that some marginal or under-challenged stuff gets out into the literature, but for the *most* part, stuff like that then just lies there fairly harmlessly and uselessly, going uncited and unread, because nobody finds it interesting enough to care one way or another. The more interesting or controversial stuff, though, is much more thoroughly examined. I would prefer myself if others in the field would be a bit more...circumspect about publishing some things, but I don't think you really get too far in any decent-sized and respected community in psych by just cranking out noise.

I guess I just don't see what you're saying here. Is it 1) These researchers publish a proof that they believe is incorrect, and hope nobody will notice or 2) These researchers publish a proof that they believe is correct, but they are so incompetent that this is very unlikely to be the case (in fact, so unlikely it makes your BS meter run at 11). To me, neither 1) or 2) seem to obviously be the case here.

Mostly number 2. As a psychologist (although not really *that* kind of psychologist) I am always very impressed at people's ability to engage in self-deception and magical thinking, and their frequent inability to recognize their own limitations (you've seen some of me doing that in this thread, as it turns out). What we have here is a probably sincere but possibly somewhat flakey physicist whose work doesn't really carry much weight in his own field who then finds a collaborator and publishes an idiosyncratic paper on a topic where there just happens to be a large cash prize available that is well outside his area of expertise. This does not inspire confidence. Now the point here is that we know that every attempt so far to prove this has met with utter failure, that this attempt only met with brief notice (basically negative) in the internet community as a preprint. And the last point:

In your first post you use as authorative a quote which suggests this proof hasn't received serious attention yet. This is mildly contradictory.

Ah, now that's just a misunderstanding that I did little to clarify. My take on the "graveyard of RH papers" page is not that it is pointing to possibly very worthy work (not universally true since it points to the work of Archimedes Plutonium), but to papers that likely or certainly have flaws of the type that high level math students might be able to detect and elucidate as part of their educational process. Context is everything here. The page that links to the one I quoted is a "Curiosities" page that even mentions silly discussions on Slashdot about the Riemann Hypothesis. The Riemann Hypothesis page itself explicitly mentions a recent rejoinder to Castro's earlier proof of RH, suggesting that the technique is flawed, and frankly doubtful that it can be fixed. I do thank you for the information that some novel approaches to the problem coming from physics are taken at least a bit seriously.

I agree that this is now going in circles, but my real point was that a months old pre-print using an approach that was previously panned, from an author who is not well-respected in his major field, using notation that the mathtematicians trying to read it thought was weird, whose only notice outside 37 posts of glory on sci.math is from the popular press (sorry to have mistaken the prestige of the newspaper) is not likely to be correct, and that the editors of slashdot might consider having a mathematician filter stories about math since I do think it is beyond their skills to do a good job.

I know the editors of this site mean well, but what we have here is a link to a site that defines the Riemann Hypothesis in very abstract terms, a link to a LANL preprint from two completely unknown researchers deposited there in November 2002, and a link to an obscure Swedish newspaper from almost two weeks ago, and no other supporting material. So my BS meter is running at 5.

The odds that "this is the one!" given that pedigree would seem to be really tiny. But the clincher for me is the following web page dedicated to would-be proofs of the Riemnann Hypothesis whose important text is (and I quote):

If you are a university mathematics lecturer who teaches analytic number theory, you might want to consider setting your students the task of deconstructing the more serious of these. They may otherwise never be given any serious attention, which would be a shame.

And the Castro and Mahecha preprint (and another grandiosely titled preprint by Mahecha) is linked to from there. Now my BS meter is running at about 9. So now I check for messages abou this at deja.com in the sci.math group. Read the thread yourself; it's pretty entertaining.

So, with my BS meter running at 11, the work having been submitted for coming up on 6 months, and no indication whatsoever that this is real, I suggest it is false.

And I also suggest that Slashdot might wish to consider contacting a real mathematician to filter their potential stories on mathematics, since I can't tell you the last time one of these "is X finally proven?" stories has panned out.

Paul Di Filippo. -- For instance The Steampunk Trilogy. Great SF set in the Victorian era.

Kim Stanley Robinson -- Somehow writes hard SF and social SF at the same time. You can't miss the Red Mars series, a mastodontic saga about the terraforming of Mars.

Some other names to look out for is Ken MacLeod and Alastair Reynolds.

I'm doing a bachelors degree, I too manage to avoid campus (apart from the pub)

I'm doing a bachelors degree, I too manage to avoid campus (apart from the pub)

Yeah, I can't see why the rest of the world hates the west, can you? We turn war into a fuckin' video game, and relegate them to attacking us with swords while riding their camels.

I know it's the natural evolution of war, but it also seems like the natural evolution of capitalism applied to the battlefield. He with the most money to make the best toys wins, and he who doesn't hopes for an aid package to be sent to his widow.

As a side note. The article mentioned that a "computer scientist at Sydney University helped Analyise the images to work out what the componenets were."

I had the pleasure of being a student on Alan's for some time. He was intensly interested in this sort of thing. He was involved in studying Babbage's work, and in the re-creation of Babbage's Difference Engine. I remember standing with him in front of a display case containing gears from one of these projects as he explained how they had been manufactured.

Alan Bromely died on August 16 this year after a long battle with cancer. I remember in 1998 I was studing a subject taught by Alan. Twice during one semester he was unable to give lectures due to his chemo therapy, but he continued to teach, and always had time to explain something to anyone who wanted to listen.

The Babbage project
An article in the Sydney Morning Herald
A university publication

To quote from your link, he actually invented "first mechanical binary digital computer".

Babbage still remains as the pioneer of programmable computing machines.

A dont forget (one of) the first computer programmers, Ada Lovelace, perhaps the Grandmother of computer programmers.

To quote from your link, he actually invented "first mechanical binary digital computer".

Babbage still remains as the pioneer of programmable computing machines.

A dont forget (one of) the first computer programmers, Ada Lovelace, perhaps the Grandmother of computer programmers.

If not, then as pointed out on the web page, the relative strength of the electrostatic force (which is also inverse square) is far larger than the puny force of gravity and it could swamp the measurement.

For your information, a common way to measure G (the gravitational constant) in the lab is by using an oscillating torsion balance and detecting the frequency change due to the introduction of large masses in the vicinity.

What the heck is a dyne anyhow, what's wrong with good old' SI? NIST for those interested there's a converter between all the old interesting things like the pole, perch, hogshead, American mile, British mile, American short ton, British long ton and various other devients of the mind Here

Or in a barber shop. Ye gods, have you seen the beard on that man?

Does anyone else see an uncanny resemblance?

1

2

3

4

G = Giga = 10^12

• A quantum computer can run any classical algorithm. There is some overhead due the reversibility constraint and due to the practical need for error correction, but it's probably a low-order polynomial overhead at worst. In particular, a quantum computer can run a Universal Turing Machine. So, it's fully programmable in respect to classical programs.
• There exists a Universal Quantum Turing Machine that acts analogously to a classical Universal Turing Machine, i.e., lets a fixed quantum computer simulate run any quantum algorithm given a description of that algorithm as additional input. (It does so to finite accuracy, but the error can be made arbitrarily small)

So go grab the tarball directly!
ftp://ftp.freeciv.org/freeciv/stable/freeciv-1.12. 0.tar.bz2

Or a UK mirror on a big uni pipe:

http://www.dcs.ex.ac.uk/ug/cs00/pjw/freeciv-1.12.0 .tar.bz2

Not quite true. Master players are much faster and more acurate analysing random positions too. See here for example

You can find more information on solar sails here.

Once upon a time, money was based on physical assets. Now capital has become fiduciary - meaning it is not based on any physical assets at all. To explain, in the UK one Pound Sterling used to be one pound of gold by weight. Now it is just valued for its intrinsic value to people. If noone exchanges money fro gold, the intrinsic value of money is irrelevant. Everyone wants money, therefore money is valuable, QED.

Furthermore you are going on to draw conclusions from your lack of understanding about what/why money is what it is. I think that is why you say capital is not based on any physical assets - which is a total non sequitor, anyway. "Capital" is a short word for "the means of production." Capital goods are different from consumer goods - you don't get capital goods to consume them, you get them to make you more productive at making other goods. Anything that helps you to produce things can be a capital good. So factory equipment are factory goods. To the extent that you use them to make things, your household tools can also possibly be considered capital. A farm tractor is also capital. You can begin to see how the lack of capital is something that separates the poor countries from the rich ones. A farmer who has to plow with a mule may work harder than his (say) american counterparts, but since american farmers have more capital (tractors as opposed to mules), they are able to produce more.

It is nonsense for you to say that "capital will be pure ideas" in 25 years. Many physical, real-world tasks - like producing food - will still need to be done, and capital equipment will be used to do them. I think you've just been confused by the abstract, intangible nature of financial tools - money, bonds, stocks - which are used to allocate and transfer capital.

The only truth to your comments - a truth I think you stumbled on accidentally - is that knowledge is a type of capital. There are plenty of abstract types of capital like this - for instance, reputational capital. These types of capital are intangible but they are incredibly important - knowledge is necessary to make other types of physical capital, for instance.

History isn't over (let's not abuse the meaning of Fukuyama's words-that annoys him). Money will continue to exist. Physical forms of capital will continue to be important.

For great justice, before writing a couple of paragraphs about these topics you could at least take the time to learn the vocabulary first. I think you could benefit from reading some of DeSoto's books and articles.

I'll note that in my experience, when a company takes on co-op students from local colleges (this does not apply to all colleges, of course, but I'm talking here about the local ones and about students that are almost finished their programs), they simply aren't capable of anything more than menial work.

My experience is similar, I work as an astronomer/programmer and have ran a couple of co-op programmes. People coming in without a PhD in my place of work are usually assigned the grunt work (they're called grad students), when we have a undergraduate (college to you 'merkins), or a school pupil (err, 'college to you 'merkins) coming in for a couple of months, its fairly rare they can contribute anything other than hard work. Which isn't to say that the work isn't appreciated, it had to get done anyway, if they weren't doing it, we'd have to!

My advice is to work hard, do the stuff they assign you to do, ask for more, and look over the shoulder of the more approachable members of the team to have a look at the cool stuff you'll be able to do after another 10 years of schooling.

Sorry, but even ``trivial'' cool projects can sometimes get complicated very quickly, they aren't going to give you anything that might get complicated because if you fail that will discourage you, and make you think that engineering is too hard, and that sort of defeats the point of a co-op programme.

The University of Exeter in England is planning to use one of those picosatellites to do various scientific studies. They have put their proposal and blueprints online

The University of Exeter in England is planning to use one of those picosatellites to do various scientific studies. They have put their proposal and blueprints online

For those that don't know about him (I've always assumed most people here would), he was in a lot of ways the first computer scientist, having designed & built the first computational devices as we know them today (i.e. something more advanced than, say, an abacus). Interestingly now, but fittingly for a Victorian inventor, they operated purely mechanically, without any of the transistors or other electronic components that are now synonymous with computers. Nonetheless, they were designed to do the same basic functions that a modern computer does, and (yes) it may well have been able to run the Linux kernel. :)

• http://www.ex.ac.uk/BABBAGE/
• http://ei.cs.vt.edu/~history/Babbage.html
• http://www.google.com/search?q=charles+babbage

I find it fitting that his assistant, Ada Lovelace, was the first programmer. It's nice to know that the field had an even 50-50 gender parity at one point, and hopefully it could again in the future. In the meantime, however, we'll make the most of the sausage party....

For those of us who like strong typing (yes, I'm a masochist) I'd like to tip the hat towards Java ML or Haskell-to-Java.

JML
J HS

Neither is an interpreter, but for sheer perversity, they're both worth a look.

Johan

Copernicus just suggested a detailed model for it, and so got the Extended Copernicus Principle named after him, which takes the idea further, saying that all points in the universe are equally unimportant.

There's a short article here which extends the argument further... to a dim end to everything :-(

Just recently read something about isotopically pure C-12 diamond being the best conductor:

http://newton.ex.ac.uk/aip /glimpse.txt/physnews.131.2.html

reports that refined C-12 carbon diamond has a thermal conductivity coefficient of "410 W/cm-K, in 99.9%-pure C-12 at 104 K". They estimate 99.999% pure C12 diamond could be as high as 2000W/cm-K.

Whats the value for CNTs? I dont see one in the article... did we give up on pure diamond films
already? A.C.Clarke would be sad!

Math.

DigiCash was founded in 1990 by cryptologist David Chaum (site apparently not updated in recent years...) who owned the two (three?) major patents covering completely anonymized digital cash. To my knowledge it still isn't certain whether it's possible to create a truly anonymous digital money scheme without violating these patents.

Like you said, David is a great mathematician, and an even greater evangelist/idealist (i once attended a lecture of his on cryptology protocols which he turned into a sort of political rally). But he wasn't an unqualified succes as a bussinessman (ahem). Due to various mismanagement problems Digicash went broke in 1998. About a year ago, all Digicash IP (including the patents, source code and the url) was bought out of the brankcupty by startup eCash Technologies inc., located in Seattle.

Though superficially somewhat similar to something like PayPal, this system, should it become viable, will have a far wider impact. Truly anonymous digital cash with a high solvability is something that will strike fear into the heart of every government economist on the planet. Should it ever become implemented, it will change the nature of the internet, and society itself won't escaped unharmed either.

That being said, they don't appear to have made much progress yet in securing deals with major financial institutions, which will probably be a neccesity to make it a success.

Go here for a good list of ecash related links.

• By assuming you expected one that would be stored distinct from the main processing unit:
  "What was the First Computer software Operating System ?"
• By assuming you expected one that would be publicly available:
  "What was the First Computer commercial Operating System ?"
• By assuming you expected one that would fit both previous conditions:
  "What was the First Computer software commercial Operating System ?"

Good idea, but those letters are already taken. SI is case sensitive.

M = 10^6
m = 10^-3 (Remember mm's?)
k = 10^3
K = Kelvin (!)

I found this link through Google: http://www.ex.ac.uk/cimt/di ctunit/dictunit.htm#prefixes (Warning, the page is much larger than it has any business being.)

I've had a Mondex card for 3 years now, its my student ID card for my Uni. Originally it was a smartcard which could be charged up (ie, out money on) in any of the university payphones, which was convenient. Now it can be charged in special mondex points around campus, and its also used to register unix passwords and gain access to computer labs.

Some info here:The University of Exeter Mondex Project

How come the page is showing no sucessful connects for Win2K when the server seems to be up?

At time of writing windows2000 is all 203 but hey...i understand this test runs for a month

Examples of short perl RSA scripts:
Crypto Sardines

The Smallest Perl Munitions

There are many other pages on this, but the second one is the official one, I believe.
---

Examples of short perl RSA scripts:
Crypto Sardines

The Smallest Perl Munitions

There are many other pages on this, but the second one is the official one, I believe.
---

The cypherpunks have been working on "non-erasable Internet space" for some time now. They call them "Eternity servers" and they already have some working prototypes running. If you would like to see a world where it is mathematically impossible to censor someone's web pages (without taking down the whole 'Net), then visit some of the following sites, and/or subscribe to the cypherpunks list and pitch in!

Well, here's two old links I had lying around...

Tattoo 1
Tattoo 2 (My favorite)

Doug

Well, here's two old links I had lying around...

Tattoo 1
Tattoo 2 (My favorite)

Doug

see for yourself...
http://dcs.ex.ac.uk/~aba/rsa/tattoo2.html

Uh, I dont know why this is *here*, but if you want you can make the dock single click, its only a bit of code...

Where is *here*?

Is the code actually available, or is that just an invitation to dive in and change it? I might be willing to, if I can dig up the free time.

(Also, have to get around to grabbing the 0.5 x version, still sitting at 0.20.1 meself.)

But I would definitely like to see that.

Oh, and BTW: your homepage (http://pendragon.ex.ac.uk/~yarn/) is broken; just gives a "Cannot connect to server."
--
- Sean