Hacked

I think my site has been hacked.

The IP responsible is 58.65.236.89.

All sorts of stupid crap is appearing in my WordPress pages. Please hold while we resolve the difficulty and beat up the people responsible.

UPDATE (2:39 AM): I think the damage has been un-done. While for about thirty seconds I was panicked and a little flattered that I might finally have pissed off somebody important, it looks like it was just a script kiddie from Hong Kong. Now, I just need to see how it happened and how I can stop it from happening again.

UPDATE (3:29 AM): Well, the good news is, it doesn’t look like the problem is my fault. In fact, I’m rather expecting that every PHP and HTML file hosted on SiteGround has been tagged with two extra lines of code.
Continue reading Hacked

Intermezzo: The Dirac Equation

After you’ve been Pharyngulated a couple times, you develop a protective strategy to deal with the aftermath. “How,” you ask yourself, “can I get rid of the extra readers whom I’ve probably picked up?” The answer, for me at least, is clear:

Math!

RECAP

Science After Sunclipse has been presenting an introduction to supersymmetric quantum mechanics. This area of inquiry stemmed from attempts to understand the complicated implications of supersymmetry in a simpler setting than quantum field theory; just as supersymmetry began in string theory and developed into its own “thing,” so too has this offshoot become interesting in its own right. In a five-part series, we’ve seen how the ideas of “SUSY QM” can be applied to practical ends, such as understanding the quantum properties of the hydrogen atom. I have attempted to make these essays accessible to undergraduate physics students in their first or possibly second term of quantum theory. Having undergraduates solve the hydrogen atom in this fashion is rather unorthodox, but this is a safe kind of iconoclasm, as it was endorsed by three of my professors.

The posts in this series to date are as follows:

Having solved the “Coulomb problem,” we have attained a plateau and can move in several directions. The solution technique of shape-invariant partner potentials is broadly applicable; virtually all potentials for which introductory quantum classes solve the Schrödinger Equation can be brought into this framework. We can also move into new conceptual territory, connecting these ideas from quantum physics to statistical mechanics, for example, or moving from the non-relativistic regime we’ve studied so far into the territory of relativity. Today, we’ll take the latter route.

We’re going to step aside for a brief interlude on the Dirac Equation. Using some intuition about special relativity, we’re going to betray our Vulcan heritage and take a guess — an inspired guess, as it happens — one sufficiently inspired that I strongly doubt I could make it myself. Fortunately, Dirac made it for us. After reliving this great moment in TwenCen physics, we’ll be in an excellent position to explore another aspect of SUSY QM.

REFRESHER ON RELATIVITY

Let’s ground ourselves with the basic principles of special relativity. (Recently, Skulls in the Stars covered the history of the subject.) First, we have that the laws of physics will appear the same in all inertial frames: if Joe and Moe are floating past each other in deep space, Joe can do experiments with springs and whirligigs and beams of light to deduce physical laws, and Moe — who Joe thinks is moving past with constant velocity — will deduce the same physical laws. Thus, neither Joe nor Moe can determine who is “really moving” and who is “really standing still.”

Second, all observers will measure the same speed of light. In terms of a space-time diagram, where time is conventionally drawn as the vertical axis and space as the horizontal, Joe and Moe will both represent the progress of a light flash as a diagonal line with the same slope. (This video has some spiffy CG renditions of the concept.) To make life easy on ourselves, we say that this line has a slope of 1, and is thus drawn at a 45-degree angle from the horizontal. This means we’re measuring distance and time in the same units, a meter of time being how long it takes light to travel one meter.
Continue reading Intermezzo: The Dirac Equation

Your Funny for Today

This one comes from Ellen Wulfhorst on the Reuters wire:

Unlike traditional, mainstream media, blogs often adopt a specific point of view. Critics complain they can contain unchecked facts, are poorly edited and use unreliable sources.

I sense a great disturbance in the Schwartz, as if a million monitors were just sprayed with soda. (Well, no, I don’t have that many readers, but Dave Neiwert, Athenae and Coturnix have already picked up on it.) And here’s another puzzling statement from the same piece, describing the poll which found that “a majority of Americans do not read political blogs.”

The poll was conducted online from January 15 to January 22 among 2,302 adults. Harris said it does not calculate or provide a margin of error because it finds such figures can be misleading.

Is anyone else concerned by the sampling bias which this procedure could entail? If you ask people online what websites they read, you’re going to get (at best) a measure of what people who spend time online read, not what Americans in general are reading. Sure, that’ll probably increase the percentage of blog readers, skewing the poll towards “new media,” but it’s still bias. (They claim to have used “propensity score weighting” to “adjust” for this.)

On their website, Harris Interactive lays out their rationale for not reporting margins of error. Basically, they assert that people are too poorly educated to know what “margin of error” means: people don’t know that the phrase refers only to sampling error, not to other possible sources of obfuscation (which are harder to get a quantitative handle on). Therefore, people will assume that polls are more accurate than they really are; to avoid this problem, and to save the wear-and-tear on a newscaster’s mouth which the tediously long phrase “margin of sampling error” would produce, Harris will not admit fallibility at all.

Gee, how nice of them to make that decision for us, so that even the people who know statistics can’t get the figures. I just loooove suffering for the sins of innumerate America.

UPDATE: I also get a kick out of this:

Just one in ten (19%) Echo Boomers (those aged 18-31) regularly read a political blog

One in ten. Nineteen percent. Oops.

I Know Link-Fu

I have more things to write about than time to write them in. Hooray!

So, whilst I vainly strive to catch up with a few of my goals, what are other people on the Network doing these days?

First, Happy Jihad’s House of Pancakes hosts the 82nd Skeptic’s Circle.

Then, Martin Rundkvist discovers what a Wikipedian edit war is like, the poor fellow. Which reminds me: one of my ideas for a semi-regular feature I want to try on this blag is a “Friday Wikipedia Woo” series. The “Human Design System” article I wrote about before has been deleted, but sadly, there’s always plenty more where that came from. (If you want to hunt for it yourself, I suggest starting with what links to the “quantum” page.) Give people a free encyclopedia they can edit themselves, and you’ll wake up to find it’s been turned into an advertising service. Sigh.

Elsewhere, Russell Blackford has spelled out his own version of Dawkins’s “Ultimate 747” gambit. Go forth and discuss! Talking of “gambits” naturally makes me think about chess. “White opened with the Blackford Variation on the Dawkins 747. . . .” Maybe chess fiend Jason Rosenhouse can extend the analogy further — recently, he’s put up a couple interesting posts, too.

Meanwhile, a review of Michael Shermer’s new book, The Mind of the Market (2008), prompted Tyler DiPietro to say a few words of his own. Expect more from that quarter in the future (and hang around for a bonus rant of mine in the comments).

Brian Switek has been keeping up an astonishing output, on tapirs and monkeys and hermit crabs, among other things. And then Abbie describes how some viruses which infect bacteria carry genes which the viruses themselves don’t need, but which are helpful to the bacteria they infect.

Life is pretty ^%$)(&@ weird, isn’t it? Fortunately, Masala Skeptic has a few appropriate swear words to use when it all gets too much.

Poll: What’s Broken?

It occurs to me that I need a book I don’t have at hand right now in order to finish the post I had hoped to complete today, so in lieu of something which requires actual work on my part, I’ll pose a question to my Gentle Readers. By reading this now, you’re kind of by definition a “person who reads science blogs,” and most likely you read others besides mine; many of you might have homes of your own on the Interblag. I figure, then, that the people passing through here have perspectives from both sides, producer and consumer (a division we often try our darndest to narrow). So, then:

If you could fix one thing about the science-blogging experience, what would it be?

Aaronson on Turing, Gödel and Searle

Computer-science guru Scott Aaronson has begun to put lecture notes for his “Great Ideas In Theoretical Computer Science” course online. (That’s 6.080 in MIT-speak: words are for the weak.) Prepared by the students and edited by the instructors, the notes are terse but clear and enjoyable. I particularly like lecture 6, “Minds and Machines,” of which the following is a taste:

We already established that no Turing Machine exists can solve the halting problem. If we had a proof system that could analyze any Turing machine and prove if it halted or did not halt, we could use this system to solve the halting problem by brute force (also known as the “British Museum algorithm”) by trying every possible string that might be a proof. You would either terminate and find a proof that it halts or terminate and find a proof that it doesn’t halt. If this proof system was sound and complete, it would violate the unsolvability of the halting problem. Therefore, there is no such sound and complete proof system.

I also like this bit:
Continue reading Aaronson on Turing, Gödel and Searle

Physics on the Brain, Part 1

Blogging on Peer-Reviewed ResearchCan physics tell us about ourselves?

To phrase the question more narrowly: can the statistical tools which physicists have developed to understand the collective motion of large agglutinations of particles help us figure out what our brains are doing?

If Jack Cowan and his colleagues are correct, ideas from statistical physics can tell us important facts about our own brains. By studying the recurring motifs of hallucinations, we can construct a geometry of the mind.

"Honeycomb" form constant generated by marijuana
“Honeycomb” form constant,
from Bresloff, Cowan et al. (2002)
It’s hard to imagine any sort of regularity in a phenomenon as eccentric as visual hallucinations. Our culture is brimming with psychedelia, music and art produced “under the influence” of one or another infamous chemical. Yet the very fact that we can label artwork as “psychedelic” suggests that the effects of those mind-bending substances have a certain predictability. In the 1920s, long before the days of review boards and modern regulations for human experimentation, the neurologist Heinrich Klüwer ingested mescaline and recorded his observations. He reported visual hallucinations of four distinct types, which he called “form constants.” These form constants included tunnels and funnels, spirals, honeycomb-like lattices and cobweb patterns. Similar structures have been reported with other drugs, like LSD; these same form constants also appear during migraines, in “hypnogogic” (falling asleep) and “hypnopompic” (waking up) states, when pressure is applied to closed eyes, and even in ancient cave paintings.

If the same hallucinatory images appear from many causes, might they be indicative of some more general property of brain structure?
Continue reading Physics on the Brain, Part 1

Yet Another Relativity Denier

BPSDBExercise: find the mistake in this attempt to challenge Einstein. Hint: if an observer in one Lorentz frame measures the position of a particle to be changing as [tex]x = ct[/tex], then that particle is traveling at the speed of light, and all observers in other Lorentz frames will agree.

Bonus point: explain the difference between the speed of light in a vacuum and the speed of light as measured when light is passing through matter.

(Thanks to the reader who noticed the “relativity challenge” Google ad in my sidebar. You know, it’s not quite cricket for me to plead that the Gentle Reader click on those links, but I can’t help it if other people appreciate the irony of pseudoscience making micropayments to science.)

Currently Reading

Karen M. Page and Martin A. Nowak, “Unifying Evolutionary Dynamics.” Journal of Theoretical Biology 219 (2002): 93–98 (PDF). Abstract:

Darwinian evolution is based on three fundamental principles, reproduction, mutation and selection, which describe how populations change over time and how new forms evolve out of old ones. There are numerous mathematical descriptions of the resulting evolutionary dynamics. In this paper, we show that apparently very different formulations are part of a single unified framework. At the center of this framework is the equivalence between the replicator–mutator equation and the Price equation. From these equations, we obtain as special cases adaptive dynamics, evolutionary game dynamics, the Lotka-Volterra equation of ecology and the quasispecies equation of molecular evolution.

Page and Nowak disavow interest in explicitly spatial models, although they do incorporate frequency-dependent selection by writing the fitness of strategy [tex]i[/tex] as a function of the population distribution:

[tex]f_i(\vec{x}) = f_i(x_1, x_2, \ldots, x_n),[/tex]

where [tex]x_i[/tex] denotes the frequency of strategy [tex]i[/tex].

The Dark Universe

Digging through my drafts pile to find something to post that doesn’t require too much extra writing, I found that I hadn’t yet released this item into the tubes. After The Halting Oracle and The Leech Lattice comes the third volume in our saga of good fantasy-novel titles, Lambda and The Dark Universe.

A few weeks back, Edward Kolb gave a series of talks at CERN on dark matter and dark energy, and how they fit into the standard “ΛCDM” model of the Universe. The abstract is as follows:

According to the standard cosmological model, 95% of the present mass density of the universe is dark: roughly 70% of the total in the form of dark energy and 25% in the form of dark matter. In a series of four lectures, I will begin by presenting a brief review of cosmology, and then I will review the observational evidence for dark matter and dark energy. I will discuss some of the proposals for dark matter and dark energy, and connect them to high-energy physics. I will also present an overview of an observational program to quantify the properties of dark energy.

Kolb’s presentations are, I found, entertaining and informative. At least, I laughed at his jokes — take that as you will. Much of the technical content can also be found in written form in, e.g., Cliff Burgess’ “Lectures on Cosmic Inflation and its Potential Stringy Realizations” (2007).

(Tip o’ the fedora to Jester.)

UPDATE (5 March): the newest figures, from the five-year WMAP results, are that the Universe is 72.1% dark energy, 23.3% dark matter, and 4.62% — everything else.

Angels and Ministers of Taste Defend Us

The following xkcd has, lately, been everywhere:

Other installments of the strip have been criticized for ambiguity, but until today, I hadn’t seen anyone complain about the construction of this one. Thus it was with some bewilderment, not to say bemusement, that I read Mark Liberman’s note saying that someone on the Internet believed the correct phrasing should be the following:

SOMEONE ON THE INTERNET IS WRONG.

Now, both choices of word order are perfectly grammatical, because “on the Internet” can be a locative adverbial phrase or a reduced relative clause. The question is one of timing, emphasis and not least euphony: people are wrong day in and day out, but it’s on the Internet that we can’t stop ourselves from criticizing them.

This past Saturday, I watched Kenneth Branagh’s Hamlet (1996) with two friends (he needed to write an essay about the play, and she’d wanted to see the movie since a few months back). Thus, I’m naturally primed to wonder if, according to the Internet, Marcellus should have lamented, “Something in the state of Denmark is rotten.”

Many Ways to Lose the Oldest Game

Like most people I know, this year I’ll be voting the straight “whom do I loathe least” ticket. Occasionally, I or a friend of mine felt a dram of enthusiasm about a candidate; all of them have vanished from the race, one by one. My expectation is that come November, my fellow Americans and I will have the privilege of pretending to choose which alleged human will be the next face of the parasite rasping and sucking all truth and decency from our country. However, the anonymous creativity of the Internet can still make me smile; for a brief, shining moment, this made politics something a little better than abject despair. Click to watch the animation cycle:

I figured out where it was going before it got there, which didn’t stop the LOL from working its way out of my belly.