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Uncertain Principles

Physics, Politics, Pop Culture

Friday, April 16, 2004

How Taxing

I like Jim Henley. He's a very smart guy, and terrifically nice both on-line and in person. Every now and then, though, he says something that's just completely alien to me. Such as his recent post about taxes, in which he notes that software makes doing your tax return too easy:

That means that we libertarians face a serious annoyance gap: not only are middle-class voters not feeling especially taxed, they're not feeling the pain of our bizarrely involuted tax code either.

Those lucky duckies.

Fred Clark also has some thoughts on income tax day, that I find a little more agreeable.

(Personally, I'm not feeling any pain at all-- Kate did our taxes, and I just signed the papers. I contributed nothing other than some faint bogglement that we make as much as we apparently do...)

Posted at 2:50 PM | link | follow-ups | 2 comments

To Get to the Other Side

In the past year or so, I've gotten out of the journal-reading habit. That's "journal" as in "academic journal," mind, not blogs or LiveJournals. I used to carefully go through Physical Review Letters as soon as each new issue came out, and scan the titles of papers in Science and Nature every week.

In an effort to try to get back in touch with the research world, I've signed up to have the PRL table of contents mailed to me, so I at least have a vague idea of what's currently happening. This hasn't really made a hug improvement in my level of engagement, yet, but it has led to the rediscovery of one of the minor pleasures of reading a broad scientific journal: the daft titles some people tag on their work.

I'm not just talking about joke titles, which are more often found on talks than papers (journal editors frown on that sort of thing). That's a rich subject in itself. I'm talking about titles that are fairly straight, but just sound weird to people not in the field.

For whatever reason, the categories "Gravitation and Astrophysics" and "Elementary Particles and Fields" are rich sources of this kind of material. I don't know if that's because physicists in those fields are just kind of punchy as a matter of course, or if it's just that the dopey titles in AMO physics make perfect sense to me. My all-time favorite was a gravitation paper, titled "Black Holes Have No Short Hair." I don't even know where to start with that one.

This week brings one from "Elementary Particles and Fields," that's just pure comedy gold:

What Does a Strongly Excited 't Hooft–Polyakov Magnetic Monopole Do?

I don't know. What does a strongly excited 't Hooft-Polyakov magnetic monopole do?

Apparently, it "does not radiate the entire energy of the exciting pulse toward future null infinity." Who knew?

Posted at 2:43 PM | link | follow-ups | 4 comments

Thursday, April 15, 2004

Cat Vacuuming

This is an attempt to add that spiffy Technorati search feature to this blog. We'll see if this works.

Update: Seems to work, more or less. Now I have a whole new way to make myself depressed about my blog traffic...

Posted at 8:32 PM | link | follow-ups | 7 comments

Wednesday, April 14, 2004

Jim Henley to the Low-Carb Courtesy Phone

For reasons that are completely unclear to me, I've been invited to have dinner next week with the author of The South Beach Diet. I'm not sure if this is the administration's way of telling me that I need to lose some weight, or if they're just looking for someone who can hold up both ends of a conversation if need be. Either way, I'm having dinner with a diet guru.

Other than a quick check to make sure that "South Beach" doesn't refer to a diet consisting solely of fresh grapefruit, spandex swimwear, and silicone breast implants, I know nothing of this plan. Any fitness-minded blog types out there who have opinions on the topic, or penetrating questions you'd like to have answered by Dr. Agatston, post them in the comments.

(Why am I posting this sort of fluff today? Because I find our animatronic president too depressing to contemplate, let alone watch on tv. If you want Serious Issues, go somewhere else. At Chateau Steelypips, we'll be accentuating the physics and pop culture for the next little while.)

Posted at 7:59 AM | link | follow-ups | 3 comments

Why I Don't Watch Baseball

Buried in today's column about Barry Bonds, Tony Kornheiser has two wonderful paragraphs explaining what's wrong with sports these days:

We concentrate too much on statistics, like what a guy is hitting with runners in scoring position in the late innings in night games on the road against lefties. The numbers guys all think like this: Bob is hitting .333 in that exact position, so let's send him up to pinch hit. Never mind that the .333 is because he's 2 for 6 for his career in that position, and the last time he got a hit in that circumstance was 2001. And the guy he's going to pinch hit for is batting .315 at the moment, and doubled his last time up. The numbers say Bob is the right guy right now. So of course Bob strikes out. Game over. Thank you, drive home safely.

We have made a profession for people who keep ever-increasing layers of sports statistics and deliver them to us like coal for a furnace. And instead of appreciating games we end up shoveling stuff, if you know what I mean. We have honored the ability to look at a beautiful sunset and calibrate only the percentage of pale orange in a 20-colored sky. These are folks who not only don't see the forest for the trees -- they don't even see the trees, because they're too busy counting the pine cones that fell between the hours of 6 and 10 p.m. on a Thursday night after the temperature dropped below 45 degrees.

Personally, I think (but have no real evidence for this) that computers are to blame for this. As computers have gotten cheaper and faster, it's become easier and easier to crunch numbers to get ever more ridiculous statistics, and people have begun to lose track of the fact that there are actual games played by actual human beings going on here. It's worst in baseball, which was a haven for stat-wanking back when people did the calculations with pencil and paper, but it's slowly creeping into sports that I actually give a damn about.

As with the proliferation of cheap CGI in all sorts of media, I don't think there's anything that can actually be done about this problem, but I'm going to bitch about it anyway.

Posted at 7:44 AM | link | follow-ups | 6 comments

Tuesday, April 13, 2004


(In keeping with Easter tradition, Teresa posted a very nice statement of beliefs. I probably ought to put this in her comments, but I'd rather have it here. Apologies if parts of this are too flippant...)

I believe that there are more things in heaven and earth, Horatio, than are dreamed of in any philosophy. And a good thing, too, because life would be awfully boring otherwise.

I believe that more people are religious because of organized religion than because of thoughtful belief in God, Making Light comments notwithstanding.

I believe that quantum electrodynamics is the strangest and most wonderful theory in the history of thought, and if there's a God who set the whole thing up, I'm truly awed.

I believe that religion is as much a matter of culture as faith.

I believe that anything not forbidden is mandatory, for quantum particles at least.

I believe that clawing our way to the pinnacle of creation from muck and slime by way of apes and hominids is far more awe-inspiring than being on top because we were created there.

I believe that light under flawless tutelage knows no limits, but the "flawless" part is hard to manage.

I believe that all men are created equal, and that "men" is gender-neutral in that sentence.

I believe that the three-point shot has forever altered the game of basketball, not necessarily for the better.

I believe that no accident of birth can deprive anyone of essential rights, nor confer special privileges. I believe that any law, policy, or attitude that holds otherwise is an abomination.

I believe that a team that plays with discipline and intelligence will beat an undisciplined bunch of superior athletes, nine times out of ten.

I believe that "I have sworn upon the altar of God eternal hostility against every form of tyranny over the mind of man" may just be the best sentiment ever carved into marble.

I believe Terry Pratchett when he writes that treating people as things is the origin of the only true sins.

I believe that's enough beliefs to make a point of some sort.

Posted at 9:18 AM | link | follow-ups | 13 comments

Monday, April 12, 2004

Yeah, Well, Interpret This, Bub

Picking up on last week's theme of creationist-bashing, PZ Myers boldly takes up the one literary task that's less palatable than reading the Left Behind series, namely reading World magazines creationist metafiction. Normally, I would let this pass with little more than a chuckle, but this particular article contains a line that's just designed to get my blood boiling. In attempt to hand-wave an explanation for how "Darwinism" was defeated, Jeffrey Schwartz offers:

Specifically, the theory of physics called quantum mechanics was seen to be closely related, especially in humans, to the discovery in brain science called neuroplasticity: the fact that throughout the lifespan the brain is capable of being rewired, and that in humans at least, this rewiring could be caused directly by the action of the mind.

Hey! Get your filthy paws off my theory, you damn dirty ape!

Of course, I blame Roger Penrose for the whole thing. Penrose, you may or may not know, is a famous mathematical physicist (though not noted for his sense of humor), who wrote a book (The Emperor's New Mind) in which he argued that quantum mechanics was intimately involved in human intelligence. This has always struck me as a classic example of misplaced transitivity: a flippant summary of the argument would be "We don't understand quantum mechanics. We also don't understand intelligence. Therefore, the two are related."

That's being a little unfair to Penrose, but I wasn't really blown away by his take on quantum mechanics (As my former boss put it, he sounds like someone who's never heard of the density matrix). And really, Deepak Chopra probably beat him to the magic quantum powers of the mind, but Penrose helped make this sort of thing respectable.

This is all incredibly arcane stuff, though, having to do with complicated issues of the interpretation of quantum mechanics. Weirdly, though, this became something of a hot topic in the little corner of the "blogosphere" where I hang out, with one smart person after another, after yet another writing posts on the topic of interpretations of quantum mechanics. The moment has passed, of course, so this post of mine will sink into obscurity, but I've been thinking about this stuff for a while now, anyway, so I may as well babble about it a bit.

The key issue here comes back to something I wrote about ages ago, namely the ideas of superposition and entanglement. Stated formally, quantum mechanics is a linear theory, which means that the sum of any two valid wavefunctions is itself a valid wavefunction. Stated less formally, if you have a system with two possible states ("alive" and "dead" for the famous Schroedinger cat example), the system can also be in a combination of those two states. That is, the cat is simultaneously both alive and dead.

This is a real head-scratcher, and has led to innumerable books on the topic, simply because that's not what we see at all. When we see cats, they're either alive or dead, never both at the same time. And yet, quantum mechanics tells us that the system can be in both states at the same time. Indeed, in certain circumstances, it has to be in both states at the same time, and this superposition can have measurable consequences.

On one level or another, this property leads to most of the really cool consequences of quantum mechanics. Quantum computers, quantum cryptography, matter-wave interference-- these are all things that come about only because of quantum superposition. It's also the source of most of the deep philosophical issues with the theory, because nobody's really sure just how you get from the quantum world of superposition states back to the everyday world in which objects are only in one state at any given time.

Appropriately enough, this is simultaneously a problem of extremely deep philosophical interest, and an extremely narrow technical point of quantum theory. On a practical level, there is no disagreement about how quantum mechanics works: Quantum theory allows superposition states, and indeed requires them in certain circumstances. It also states that superposition states are fragile things: when a measurement is made, the system will be found to be in one state or the other, not both. The former is needed to properly calculate anything in quantum mechanics, while the latter is needed to apply those predictions to the real world.

The only real point of disagreement is what happens at the point where the measurement is made. And it's not even really the measurement itself that's at issue (few theories even attempt to deal with that in detail), it's how to interpret the result of the measurement. On the one hand, this is a tiny, tiny fraction of the full range of phenomena covered by quantum theory. On the other, though, it's absolutely essential to the process of understanding the world. It's basically theoretical physics's version of the "filioque" clause, only without the mass slaughter of heretics. Not literally, anyway.

When it comes to interpreting quantum mechanics, everyone has his or her own favorite interpretation, and many of them are happy to mail unsolicited mimeographed copies of it to researchers all over the world. While there are countless variants, the interpretations can generally be grouped together into three rough categories: the "Copenhagen Interpretation" and related models; the "Many-Worlds" interpretation and variants thereof; and the "Shut Up and Calculate Interpretation."

The Copenhagen Interpretation is the grand-daddy of 'em all, as Keith Jackson is unlikely to ever say, tracing back to famous Dane Niels Bohr. It states that at the instant of measurement, the wavefunction changes at once from a superposition state to one of the possible outcomes (this is the "collapse of the wavefunction" that you'll sometimes hear mentioned). Subsequent measurements will show the system to be in that state, and that state only, and only indirect evidence of the other state will remain.

This raises a whole host of problems, not least among them the question of what counts as a measurement. Really old-school Copenhagen adherents claim that a conscious observer is required to collapse the wavefunction, which leads to endless debates over what counts as an observer, not to mention a lot of really annoying science fiction (whether you want to count Penrose's book in here is up to you...). Hardly anybody believes the strict form of Copenhagenism any more, which is probably a good thing.

A somewhat more sophisticated analysis relies on the coupling between a quantum system and its environment. The idea is, basically, that when a simple quantum system (an atom in a superposition state, for example) comes into contact with a much larger, more complicated system (a typical measurement apparatus, say), the simple system interacts with each of the billions and trillions of atoms making up the measurement system, and those interactions destroy whatever superposition was there. This idea, called "decoherence," takes care of most of the heavy lifting, as it has been shown to reduce most systems from a weird quantum superposition state to a more classical state of affairs, where the system is in either one state or the other. What it doesn't do is tell you how or why you end up with only one of those outcomes when you actually make a measurement...

The "Many-Worlds" interpretation is a more radical approach. It denies the existence of wavefunction collapse at all, insisting that there is only one wavefunction, which evolves in a smooth and continuous ("unitary" in geek-speak) manner. While this is a nice idea, it just shifts the discontinuous stuff around. The wavefunction evolves smoothly, but the rest of the universe suffers a discontinuity-- it splits into two (or more) parallel universes, each containing one "branch" of the wavefunction.

According to the Many-Worlds interpretation, then, at the instant when the Schroedinger catbox is opened, the universe splits into two. In one of them, the cat is alive, in the other, it's dead. As with the Copenhagen interpretation, any subsequent measurement will find only one of the possible states, because the other outcome has moved to another universe.

There are a couple of big issues with this theory, too. For one thing, many people find the sheer number of universes sort of inelegant. Strictly speaking, each time an electron strikes the surface of my CRT monitor, we've spawned a whole slew of new universes, one for each of the pixels it might've hit. You get to a really big number of universes really quickly this way, and that seems like a lot of overhead for no clear purpose.

Another problem with Many-Worlds is that it doesn't tell you why we only see one of the possible universes, or how the particular universe we end up in is determined. This, too, has led to some bad SF, as well as some really annoying pop-science explanations (I tend to cringe at explanations of quantum computing which involve the multiple universes calculating in parallel).

In the end, I tend to lean toward the Shut Up and Calculate school. Neither of the other interpretations really gets to the most interesting question, namely why is it that we only see one outcome? Copenhagen shuffles this off on some mystical property of observation, while Many-Worlds writes it off as a limitation of observation (namely, that we can't see all the parallel worlds over which the wavefunction is spread), but neither of those is an answer to the question. "Shut Up and Calculate" doesn't have an answer, either, opting instead to pretend not to hear the question, so as to be able to get some work done.

Ultimately, these are interpretations of quantum mechanics, and not, strictly speaking, theories unto themselves. Neither makes any testable predictions at this point (the eponymous many worlds are by definition inaccessible, and Copenhagen provides no clear mechanism for wavefunction collapse), so there's no way to distinguish between them. In the end, they both make exactly the same concrete predictions about the real world, so the question is hardly worth considering unless you're a philosopher, an eminent elderly physicist, or really, really stoned. Or a physics blogger looking to fill some space.

Posted at 8:51 PM | link | follow-ups | 4 comments

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