Really geeky Movable Type post. No apologies.I noticed several hours ago that for some reason the trackback section of my index page was no longer marked up properly. Such things are invariably my fault, so I started tweaking my stylesheet, then the template — all to no avail, and things really took a turn for the curious when I looked at the rebuilt code: all “class” attributes had vanished from tags inside <MTPings> tags, as well as entire <span> tags with class attributes inside <MTPings> tags.

BTW, apologies for the site’s most recent current look — it’s a bit of a shambles, and I may not be able to tweak it into submission for a while.This, of course, is impossible. And yet there they weren’t. The discovery was followed by a series of progressively more outlandish attempts to coax recalcitrant code into revealing itself, without success. What really hurt was how the comments, which were encased in the exact same html code structure, performed flawlessly. Then I remembered I had installed the new “nofollow” Movable Type plugin earlier in the day. I removed it, and my problems were goneMore about “nofollow” here..

I briefly considered being a hero and repairing the plugin, but then I saw the grep pattern that adds the “nofollow” rel attributes to comment and trackback links, and it is a monster, so I’ll settle for flagging this bug. FYI, I tried the “nofollow” plugin without the “mt-pingedentry” plugin and can confirm it’s not due to a plugin conflict (I had flashbacks of OS9 there).

CNET reports on an online petition lamenting the price differential between the US and Europe for Apple products, just as I had made a mental note to myself earlier this week that Apple Europe’s local prices had never looked as good as now. What is the price differential, then?

Using a cool new free calculator (for Mac), I set to work. I used online Apple store prices before VAT in the US, Swedish and Irish store.

Mac mini: USD 499 – SEK 3,756 – EUR 429.

Implied exchange rates: 10kr = $1.33, 1 euro = $1.16, 10kr = 1.14 euro.

20 inch screen: USD 999 – SEK 7,676 – EUR 866.94.

Implied exchange rates: 10kr = $1.30, 1 euro = $1.15, 10kr = 1.13 euro.

20 inch iMac: USD 1,899 – SEK 14,369, EUR 1,594.21.

Implied exchange rates: 10kr = $1.32, 1 euro = $1.19, 10kr = 1.11 euro.

So the average implied exchange rate across the product range seems to be pretty constant, within a range of 2.5%.

The petition uses a EUR/USD exchange rate of 1.32 to make its case. The latest interbank rate currently puts the euro at $1.30. Of course neither consumers nor Apple can ever get that rate. We as Europeans first need to convert our euros to dollars if we want to buy in the US instead of in Europe, and Apple needs to convert its revenues back to dollars when it sends them home as well. For us, the quoted credit card rate, at interbank +2%, lets you buy dollars at 1.28 to the euro and 1.41 to 10 Swedish crowns.

At these exchange rates, the $499 Mac mini would cost a European 390 euro in the US Apple store, vs 429 euro in a European store — a price differential of 39 euro. The European mini is thus exactly 10% more expensive than the US mini at current exchange rates.

The $499 mac mini would cost a Swede 3,539kr in the US Apple store, vs 3,756kr in Sweden — a price differential of 217kr. The Swedish mini is thus only around 6% more expensive than the US mini at current exchange rates.

So Swedes are getting a better deal than (the rest of) Europe. As far as I am concerned, a 6% price differential is practically negliglble. If the dollar were to strengthen back to 1.32 for 10 crowns, a rate it was at as recently as September 2004, Swedish Apple store prices would match US store prices.

The petition makes some claims that I do not think stand scrutiny. For example, European operations — both Apple’s and its retailers — almost certainly experience higher employment costs and corporate taxes than in the US. If Apple wants to maintain its and its dealers’ margins, this would translate into higher prices, even before exchange-rate fluctuations work their strange voodoo. Apple may even be giving Swedes a break, due to the fact that corporate taxes in Sweden are below the European average.

And finally, Apple doesn’t set Europe’s VAT pricesVAT is 25% in Sweden, Europe’s highest rate. I didn’t know this, but the lowest VAT an EU country can charge is 15%, by EU law.. For that, Europeans have to blame somebody else.

I think Apple’s European prices are the very model of reasonableness, so no, I shall not be signing this petition.

Follow-up to For better blogging…, which explains a simple yet effective way to stop comment spam for Movable Type installations.A week ago (I’m catching up again) Six Apart released the Six Apart Guide to Comment Spam, in which different methods for avoiding the scourge are evaluated. Among them is the Turing Test class of protection, to which my preferred solution belongs, as well as Six Apart’s own TypeKey authentication service, into which the company has invested a lot of effort over the past year or so.

The document ends up recommending TypeKey (and some other techniques like MT-Blacklist) but not any Turing Test solution. I think the reasoning behind this recommendation is faulty.

Turing Tests that operate by showing you some kind of picture — easy for you to decipher but hard for computers and blind people — are indeed not a good idea; the best software available today is far better at reading such images than a legally blind person. But the guide also writes this:

One simplistic example would be to require commenters to answer a natural language question, such as “What is the last name of the author of this weblog?”, or “Which month immediately precedes August?” The problem with this technique is that to be effective, the questions need to change frequently. If you ask the same question, spammers will seed their scripts with the answer.

This is not quite true. For this technique to be effective, you only need to change the question every time a spammer personally makes the effort to answer it in order to spam you. And it turns out from experience that this practically never happens.

That’s because the Turing Test does a sufficiently good job of raising the cost of spamming. If a spammer wants to spam your site, he first needs to visit your site personally. The reward is that he can then spam away, but only on your site; you then change the question, clean up his mess, and he’ll have to visit again. That’s no way to make a living as a spammer — imagine being forced to read all those blogs. This “simplistic” Turing Test technique works because the reward to effort ratio for spammers is so low. That’s good enough for the vast majority of blogs, who do not have the traffic of A-list bloggersAnd if more blogs were to use it, my guess is spam wouldn’t pay at all anymore..

Now compare this with part of Six Apart’s own description of how the TypeKey authentication service works:

The worst case scenario when using TypeKey in this way would be if a spammer created a TypeKey account, and used it to send spam to your weblog. However, because the first comment from any TypeKey user must be approved by your [sic] before being published, the only way a spammer could sneak spam onto your site would be to first submit a comment that appears to be legitimate. While it’s possible that some spammers might attempt this, it is highly unlikely that they would be able to do this using automated scripts. If they do and are reported to Six Apart, TypeKey’s terms of service allows us to disable their accounts.

Here too, the spammer needs to sit down, get a key, pretend to be human for a minute and behave until he gets a comment approved. That’s really just a Turing Test — “Can you write a comment that does not look like spam?” If he passes, he can then use his key to spam with abandon until his account is terminated — not just on your site, but on any TypeKey-enabled site that automatically approves TypeKey user comments (Six Apart is thus being a little optimistic even in its worst-case scenario, above.) And that’s potentially a much much bigger prize. As for “TypeKey’s terms of service allows us to disable their accounts” — I’m sorry, but that doesn’t sound very scary.

The kicker, however is this: “Also, creating a new TypeKey account requires solving a CAPTCHA (only once, during account creation), which entails certain accessibility problems.” Not to mention that after you go jump through all these hoops, your comments still sit in a moderation queue the first time on many participating sites — which raises the effort bar on legit commenters much more than if you just ask them to add 2 and 2 — all without another user id and password.

Basically, I prefer Turing Tests to TypeKey.

PS: I too remember reading about the ingenious tactic mentioned in the guide of grabbing CAPTCHAs in realtime from high-profile services and asking a continuous supply of horny guys to solve them as a condition for access to free porn. This obviously works with CAPTCHAs (as far as I know, blind people don’t surf for porn), and it would also work for questions like “What is the atomic symbol for hydrogen?” and “Type the letter ‘A'”I think it will be only a matter of time before a script tries whatever is inside quote marks as the solution.. If spammers ever apply this level of sophistication to try to spam this site, then the kind of question will have to change to something like: “What is the first letter of the title of this blog?” or “how many characters are there between the www. and .com of my URL?”. These will not be answerable by horny guys given a snippet of a comment form.

Finally, it is not beyond the bounds of possibility that spammers will outsource their efforts, paying English-speaking third worlders pennies in the hour to compile a database of answers for blogs all day long. In that case, the tactic would have to change again, and we’d have to make a Turing Test that attempts to differentiate between those who have no broad education from those who have one, such as “What’s the main language spoken in Ireland?”. However, horny western guys would likely know the answers to such questions, so in a worst-case scenario, posting a comment would entail answering two questions — one that stumps horny guys, and another that stumps sweatshop spammers…. To be continued, for sure.

Quickly now, as it is late (again.) Here are some of the objectives I wanted to achieve with the redesign:

I wanted a place to post shorter but more frequent entries about interesting things I find on my daily rounds of the web.

I wanted a blogroll/siteroll, organized by subject. I also liked how some Swedish bloggersUpdate 2004-1-11: Jag glömde Enblogomdan. have been promoting new and interesting blogging talent. Hence a running roll across the page.

I wanted to have all the newest information above the “fold” of the screen.

I wanted to be more generous in linking out from my site, and give more prominence to readers’ comments and trackbacks.

I wanted to dive into the deep end of CSS and learn it properly. This would entail letting the stylesheet do nearly all the stylingIf you’re using Internet Explorer to visit my redesigned blog, you might be wondering what on earth took me so long — all I’ve done is add a sidebar on the right into which I’ve dumped the usual blogalia. It looks boring, frankly. Well, that’s because I no longer want to design for IE, at least not for free and for me, so if you use IE around here you will be served a dumbed-down version — it’s perfectly acceptable, it lets you read my posts, but that look took as little time as possible and without any pretence of creativity or innovation. (Actually, it breaks rather badly in IE/Mac.).

I wanted to let my preferred components dictate the page layout, and not vice versa. Among other things, I made use of the newly found ability in CSS 2.1 to style adjacent columns of equal height, as demonstrated by Roger at 456 Berea Street.

I wanted to avoid the overlong page, with sidebars that go on forever. The solution I came up with is to have the most important navigation elements but a click away at all times. Hence the floating “About” layer and search bar. I stole Dan Cederholm’s javascript from SimpleBits. It’s still a bit rough (I’d prefer the ability to toggle styles, but have not explored this yet) but it seems to work in most browsers. (It’s turned off for Internet Explorer).

It’s going to take me a while to get used to this new look, trim what doesn’t work, polish rough edges, do the other templates, etc… In the meantime, do tell me what your least favorite part of this redesign is, or if it breaks in your browser.

Notes on Chapter 1, The Road to Reality, by Roger Penrose.
(Introduction)Thales of Miletus:
Many sites on the web attribute all kinds of achievements to Thales — for example, that he considered the earth to be a sphere — but this great article combs primary sources, and notes:

There is a difficulty in writing about Thales and others from a similar period. Although there are numerous references to Thales which would enable us to reconstruct quite a number of details, the sources must be treated with care since it was the habit of the time to credit famous men with discoveries they did not make. Partly this was as a result of the legendary status that men like Thales achieved, and partly it was the result of scientists with relatively little history behind their subjects trying to increase the status of their topic with giving it an historical background.

Roger Penrose doesn’t quite say that Thales invented the mathematical proof, so he’s off the hook. Thales is the first recorded person to replace existing supernatural explanations for events with natural ones, though: He proposed earthquakes happen because the earth floats on water, rather than because there exist angry gods. Thus began the long retreat of mysticism and religion as authorities for exposition. (A shorter biography of Thales.)

Pythagoras of Samos:
Another great article by J J O’Connor and E F Robertson, this time about Pythagoras. They quote Aristotle:

The Pythagorean … having been brought up in the study of mathematics, thought that things are numbers … and that the whole cosmos is a scale and a number.

Now that theoretical approaches which see the universe as a giant quantum calculating machine are in the ascendant, it may turn out that humanity’s very first naturalist guess was a remarkably good one.

Mathematical Platonism:
Penrose has argued previously, notably in Shadows of the Mind, in favor of mathematical platonism — the view that mathematical notions (numbers, primeness, the Mandelbrot set) have an existence that is independent both of the physical world and of our mental world. This is not a controversial view for mathematicians; almost all are mathematical platonists, first and foremost intuitively. But what does mathematical platonism mean to Penrose?

It may be helpful if I put the case for the actual existence of the platonic world in a different form. What I mean by this ‘existence’ is really just the objectivity of mathematical truth.

Penrose illustrates all this with an earlier image from Shadows: He sees each of these three worlds as emanating from an other, to produce an Escher-like paradox. In it, our mental states are represented by a subset of states in the physical world, the physical world is controlled by a subset of mathematical notions, and we use a subset of our mental world to grasp these mathematical conceptsFor Road, he further modifies his illustration to address the possibility that 1) not all of the mind is represented by a physical state, leaving room for a soul, 2) there exist true mathematical notions that are not accessible to our reason, and 3) that there are physical processes that lie outside the realm of mathematical control..

It’s a snug diagram. My main reservation is that the link drawn from the mental world to the mathematical notions it can grasp is not “generative,” like the other two links. We can perceive mathematical notions, but this perception does not generate them in a way that is analogous to how physical states can generate mental processes — mathematical notions are not dependent upon our perception for their existence, at least not if you are a mathematical platonist.

My own prejudices tend towards the physical world merely being a “concretized” rendition of the mathematical world, rather than separate from it. I suspect that at the most basic level, physical reality is exactly defined by fundamental mathematical processes, and the universe really is constructed from such “platonic shapes”. Penrose seems to be saying something similar, though he also appears embarrassed by this early outbreak of metaphysical supposing in his first chapter, and so heads off into 360 pages of mathematics, starting with chapter two.

The public lecture by Roger Penrose I attended this summer in Ireland was also an informal launch of The Road to RealityUS launch is only in September 2005, according to Amazon., his latest publishing effort. In the intervening months, this book has acquired something of a reputation; not just for its ambition — the dust jacket bills it as “A Complete Guide to the Laws of the Universe” — but also for its optimism — the notion that, with some dedication, these ideas are accessible to a target readership of standard-issue analytical mindsThe book’s third footnote even explains what it means to say “x to the n^th power”..

The reviews agree that Penrose’s eight-year project is a magnum opus, but differ on its chances of success. Martin Gardner’s piece in the New Criterion lauds the result as “monumental,” in the same league as Feynman’s Lectures on Physics (now also in streaming video!), but then Gardner makes mathematical puzzles for a living. John Gribbin in The Independent thinks the effort is lost on us plebeians, though he says the book should be required reading for all research physicists, as it imparts Penrose’s considered views on what’s hot and what’s not in physics todayIt’s no coincidence that the lecture he gave in Dublin was titled Fashion, Faith, and Fantasy in Modern Physical Theories; string theory being fashionable, quantum mechanics requiring a leap of faith, and inflationary models of the early universe being rather fantastical. There is streaming video of a longer version of his Dublin lecture, in three parts, on this page (which BTW is a trove of other great lectures).. Meanwhile, this MIT review and The Scotsman both note the book’s considerable girth, at 1100 pages, and Penrose’s refusal to excise equations from the book for the sake of higher sales — indeed, it makes Hawking’s A Short History of Time look like pulp fiction in comparison.

I soon bought the book, and have been on brief tentative forays into its innards. Two things stand out: First, Road spends a lot of time explicating the mathematics needed to understand the physics — over a third of the book is pure maths. Second, (unintentional alliteration alert) Penrose peppers his prose with problems, inviting interaction with the material. He even promises solutions, to be posted on the book’s website, though once there you find an apology for a delay in doing so.

Good expository writing is hard to do, but Penrose is among the best, so I intend now to embark on a thorough reading of his bookThere is some stunningly good expository writing in Prime Obsession (available in its entirety online), about the Riemann Hypothesis, which I read over the summer. It inspired me to try my hand at some mathematical writing too, in fact.. I’ll report back here with discussion, attempts at solutions for the easier problems, and online resources I might find as I work through its 34 chapters. I’ll try to go faster than one chapter a month, but I’m in no hurry. And if Penrose doesn’t begin putting up solutions soon, maybe I’ll start a wiki for it. If anyone wants to come along for the ride, the book is available at Hedengrens in Stockholm and at all respectable UK bookshops.

My last bout of metablogging for a while, I promise.When blogging in the realm of political ideas, the temptation is to not allow one’s pristine thoughts to be befouled with the graffiti of passers by. The more partisan or idealistic a post, the more likely the resultant comments will cancel out your efforts through ridicule, parody, or even worse, a good point. Complete strangers might decide the one thing they have in common with each other is that they disagree vehemently with you, and then discuss at great length, in comments appended to your post, exactly why. And you might feel obligated to issue line-by-line rebuttals, lest your devotees get all confused and don’t know what to think anymore.

That’s the nightmare scenario I imagine plays in the minds of policy wonk bloggers who decide against allowing commenting when they start blogging. Sure, if you’re any good, you’re likely to have thought more about the issues than a great many of your readers (which is hopefully why they read you), and some of them might comment without ever getting the gist of your writings; others might never see past their assumptions about your motives; but the worst, probably, is people who spring to your defense with frankly terrible arguments, of which there are plenty on any side of any issue.

Allow commenting and you lose the ability to completely control the polemic on your site. Ideas you disagree with, for good reason, will likely get an airing on your blog and on your dime.

But I think this is entirely for the good, for several reasons:

1. Exposure: If you believe your ideas are better than the competition, then comment banter is your friend, because conversations do a better job at convincing than monologues. Every direct comparison should come out in your favor, if you’re any good at arguing your point.

2. Adaptability: Comment feedback can help you tailor your message to your audience. Are people letting you know they are stumped by a counterintuitive step in your reasoning? You’ll know to explain it more clearly.

3. Inoculation: Comments can show you where your thinking needs work. Ideas might indeed spark from individual genius, but they grow strong through all kinds of vetting — cooperative, constructive, competitive and even destructive. For new ideas to get good they need to be subjected to tests that help inoculate against fatal surpises later on in their memetic trajectories. Your commenters won’t let you down in this regard.

4. Ownership: You can’t stop people from discussing you and your ideas somewhere on the web, if they want to. Why not invite this discussion onto your blog, so you can keep a certain measure of ownership over it? This way you can delete the odd insult or wingnut, or close down comment streams that get out of hand, but not so much that your commenting community feels it needs to express their unfettered opinions somewhere else. It doesn’t really matter to others where these comments are located, though it might matter to you.

5. Authority & transparency: Readers of your blog who see it is possible to append comments to your writings will read you with the knowledge that you are open to corrections. This gives your writing added authority, as you are signalling your blog’s content is being peer reviewed with every read.

If there is a trend among probloggers and their commenting largesse it is this: Those bloggers who came to blogging after having made their name elsewhere (Andrew Sullivan, Juan Cole, Virginia Postrel, Johan Norberg, Dick Erixon, PJ Anders Linder) tend not to have comments, while those who made their name by blogging (Brad DeLong, Atrios, Kos, Yglesias, Gudmundson) do tend to allow comments. I think I know the reason for this: To many readers (and writers) still, reputations built in meatspace are a much harder currency than reputations built solely in the blogosphere. Published authors with public lives are perceived as far worthier targets by the fame-obsessed, and so the temptation to get a parasitic hearing in their comments section is likely to be more compelling.

When it comes to bloggers like Andrew Sullivan, the tide of insulting crap he would accumulate is more than enough reason for him not to bother with comments, I think. But for most other bloggers, I suspect these fears never materialize. And there are added mitigating factors to ponder:

You have a smart readership, and web pages can be infinitely long. Trust them to scroll to the diamonds in the rough and tumble of comment banter.

Ignored commenters always go away in the end. I’ve never seen this rule broken. It’s no fun if they don’t get a rise out of you.

Even so, are there half-way solutions? Yes — some bloggers do just trackbacks, or just link to a page on Technorati or Google showing pages linking to that post. In effect, this amounts to outsourcing the discussion and pointing the way there. This makes sense for blogs attached to organizations and companies, where a commenting free-for-all is problematic on legal grounds.

Others, like Andrew Sullivan, are generous in posting letters from readers. Boing Boing, too, posts vetted reader contributions. This saves money if your site is extremely popular, as allowing commenting can increase bandwidth costs by an order of magnitude. Some popular sites, like LGF and Kos, do manage with comments, though there might be some serious infrastructure money backing those blogs.

But not publishing or linking to reader feedback at all just makes you come across as a little disinterested in your readership, while the only effect in terms of the online debate is that you raise the barriers to entry — not everyone has a blog. And yet, you no longer “own” the means of comment production on the web, as anyone can set up www.[your name here]-watch.com, over which you have no control at all. (I know of one such site in Sweden.) Allowing comments helps preëmpt such occurrences.

In the end, of course, your blog is your free speech zone, not anyone else’s. But purely in terms of effectiveness, I think comments enhance rather than hinder debate.