Preposterous Universe

Monday, February 28, 2005
A year, leapt

Here's how bad I am at advance planning: one year ago, I started this blog on leap day, February 29th. You can look it up. Which means that I have to wait another three years before I can celebrate a proper anniversary. Not that I have the patience to wait.

I only really discovered blogs slightly over a year ago. The idea seemed interesting, but the signal-to-noise ratio was awfully low. Of course, that's mostly a matter of finding the really good blogs out there, and eventually I was astonished at the quality of these things that people were apparently throwing together in their spare time. Roger Ailes, Pandagon, The Poor Man -- how did these guys do it?

Admittedly, there weren't many physicists out there -- Jacques Distler being the lonely pioneering voice from the particle/string/cosmo crowd that I would be familiar with in my professional life. (One year later, among others, we have all of Quantum Diaries!) So, although I've had my own web page since about 1994, I was a little leery about jumping into this blogging thing myself. The last thing I needed was extra stuff to do.

The tipping point was noticing Michael Bérubé's blog. Now here was a famous academic whose work I had admired for years, who was clearly much more busy than I am, who nevertheless had recently started a blog that he was regularly filling with marvelously entertaining and provocative posts, all while maintaining a rigorous hockey schedule, it seemed. If he could do it -- well, okay, just because Michael can do it doesn't mean that I could do it, but at least it means that it can be done, so why not give it a try?

So I actually emailed Michael to ask about how blogging fit in with the usual chores of academic life, and he immediately responded with words of encouragement. I still didn't want to go through any significant wrangling with new software or any such thing, but I devoted one Sunday to trying to figure out how the basic mechanics worked. I found that blogspot provided hosting and software for free, and Haloscan did the same for comments and trackbacks, so I just went that route of least resistance. Longtime Preposterous readers will recognize that I've never put much effort into tweaking the aesthetics of the site, but after an afternoon of effort it seemed to be working, and we went live on February 29th.

And, lo and behold, people started visiting! My first link was from PZ Myers at Pharyngula, who soon became another blog role-model, although I will never have a fraction of his energy. Henry Farrell at the incomparable Crooked Timber added me to their blogroll, and offered other useful advice. Soon after starting up, I was invited to appear on Science Friday after a producer found the blog, and whenever I travel somewhere to give a talk I hear nice things from people who are regular or occasional readers. We're up to about a thousand visitors per day, not that I notice or anything. Growth still seems to be linear, although you never know when it might plateau.

I've been pretty good at keeping to my self-imposed goal of having about one post per weekday (helped along the way by guest-bloggers Gretchen Helfrich, Lindsay Beyerstein of Majikthise, and Risa Wechsler [who has a great blogging career ahead of her when she decides to take up the challenge]). And, glancing through the archives, I actually really liked some of the posts! (Others were kind of pot-boilers, I admit.) Here are some of my personal favorites, for those of you who haven't been regulars from the start.
I'm always asked how I can find the time to do the blog. It does take time, but it's leisure time to me, and I honestly don't think it affects work in any noticeable way. (Reading other people's blogs -- that's a different matter.) Still, I would certainly never want it to become a burden. As you may have noticed, this is not a public-service blog -- it exists only to amuse me. I might write a lot about physics, but that's just because it's what I'm often thinking about, not because I'm trying to fill any systematic science-news-reporting niche. (Although I was greatly tickled/horrified to get email from Chris Mooney saying that he was going to send me a copy of his upcoming book, in my role as a member of the media. That's not the side of the divide that I think of myself as being on, but okay.) So, I certainly intend to keep it up, although I'll be more than willing to reduce the pace of posting or to take a sabbatical if that seems necessary to maintain my sanity.

Thanks to everyone for reading over the last year. In celebration, I will depart from my usual custom and actually ask for suggestions on how to make the blog even better. This is your chance to sound off, so what do you think? More pictures of me? Switch to a purple background? More basketball content? Not that I will take any advice, but at least I'll think about it.

Sunday, February 27, 2005
Intellectual diversity

Stanford student Aaron Swartz, via boing boing, via the apostropher:

A shocking recent study has discovered that only 13% of Stanford professors are Republicans. The authors compare this to the 51% of 2004 voters who selected a Republican for President and argue this is "evidence of discrimination" and that "academic Republicans are being eradicated by academic Democrats".

Scary as this is, my preliminary research has discovered some even more shocking facts. I have found that only 1% of Stanford professors believe in telepathy (defined as "communication between minds without using the traditional five senses"), compared with 36% of the general population. And less than half a percent believe "people on this earth are sometimes possessed by the devil", compared with 49% of those outside the ivory tower. And while 25% of Americans believe in astrology ("the position of the stars and planets can affect people's lives"), I could only find one Stanford professor who would agree. (All numbers are from mainstream polls, as reported by Sokal.)

This dreadful lack of intellectual diversity is a serious threat to our nation's youth, who are quietly being propagandized by anti-astrology radicals instead of educated with different points of view. Were I to discover that there were no blacks on the Stanford faculty, the Politically Correct community would be all up in arms. But they have no problem squeezing out prospective faculty members whose views they disagree with.

I guess the question we should be asking is: are Republicans held back from academic achievement by fear of long work weeks, or just a lack of intrinsic aptitude?

Friday, February 25, 2005
Dark galaxies?

According to our current inventory of the universe, there is a great deal more dark matter than ordinary matter (where the dark matter is made of some particle that has never yet been observed in the laboratory). Indeed, the lovely pictures we see of galaxies should be interpreted as sprinkles of shining gas and stars settled into the lower reaches of large, extended halos of dark matter.

Of course, this idea suggests the possibility that there might be galaxies which are almost entirely made of dark matter, with very few stars at all. You might even expect that such objects should exist; there are various ways, for example, that some sort of shock wave or galactic collision could remove most of the ordinary matter from a galaxy while leaving the dark matter intact. And now there is a claim that a dark galaxy has been found. Here is the astro-ph paper being referred to in the news article. (Someday, people will understand the internet so well that they will link news stories directly to the technical papers.)

How do you find a dark galaxy? In principle you could do it by looking purely at its gravitational field, for example through gravitational lensing of background galaxies. In this case, however, the astronomers are simply using the fact that the galaxy is not 100% dark -- it contains neutral hydrogen that can be detected by radio observations. But it's not very much hydrogen; perhaps 108 solar masses, while the galaxy as a whole comes in at 1011 solar masses.

If it's true, the existence of this galaxy would have important consequences for models of galaxy formation in the presence of dark matter. Even better, it would make it very hard to maintain that there might not be any dark matter, and instead gravity is modified on galactic scales (as in the MOND model). It's too early to jump to conclusions, though. A skeptical note has been sounded by my erstwhile graduate-school office mate, Mike Merrifield, who points out that a chance superposition of two different small hydrogen clouds could trick you into thinking that there was one big rapidly-rotating cloud. But the observers will keep looking, gradually piecing together the ingredients of this preposterous universe.

Thursday, February 24, 2005
Old-world sensibilities

Tony Judt, writing in the New York Review about the differences between Europe and America:
Consider a mug of American coffee. It is found everywhere. It can be made by anyone. It is cheap—and refills are free. Being largely without flavor it can be diluted to taste. What it lacks in allure it makes up in size. It is the most democratic method ever devised for introducing caffeine into human beings. Now take a cup of Italian espresso. It requires expensive equipment. Price-to-volume ratio is outrageous, suggesting indifference to the consumer and ignorance of the market. The aesthetic satisfaction accessory to the beverage far outweighs its metabolic impact. It is not a drink; it is an artifact.
Ah, so unfair, and yet so true. And reminds me clearly of why I have a deeply European sensibility, although I'm much happier living in America. I remember one trip to Firenze, where amidst all the lovely art and culture and so forth, what really caught my eye was this La Pavoni espresso machine for sale in a shop window. A gleaming sculpture in chrome and black, clearly destined to be a kitchen icon as much as a functional appliance. For some reason (perhaps related to the price tag) I was able to resist the impulse to buy on one on the spot -- still don't own one, actually. But some day I will. (Perhaps an amazon.com wish list is in order?) Reviews on the web make it clear what a difficult, high-strung machine it is; getting a good pull of espresso out of it is purported to be an unpredictable labor of love. But I would be more than willing to undergo the rigorous training and practice regimen that is required, in order to enjoy the shiny presence of this marvel of design.

But I wouldn't want to be forced to put up with such an elevated artistic temperament whenever I wanted anything to eat or drink. Sometimes you just want a cheesesteak (gourmet or otherwise). And if there's one thing we've mastered here in America, it's the lifestyle of convenience. So I'm a true American at heart. That's why they invented airplanes, I suppose.

Wednesday, February 23, 2005
The scientific method

As much as we like to pretend that science is a rationally objective endeavor, sometimes looking at data is like doing a Rorschach test -- people see what they want to see. Some of the commenters to the post below do not quite draw the same conclusions that I do from the AIP study. So let's go through the exercise slowly.

President Summers presented three hypotheses for why there are fewer professional women scientists than men. (Picking on Summers as an individual is certainly not the point, and it's getting kind of tiresome, but he did try to provoke people, after all.) They are:
  • "80-hour work weeks" -- women have family responsibilities, and don't want to devote the huge effort required to being a science professor.
  • "Intrinsic aptitude" -- something in women's brains makes them just not as good at science, at least at the upper levels.
  • Systematic biases -- women are discriminated against, or at least pressured away from, becoming scientists.
These are in decreasing order of importance, in Summers' estimation. (Although, sympathetic as he is, he'd love to be proven wrong.) They are good solid hypotheses, in that they make predictions that can be compared with the data. So let's do it.

The AIP study considered the representation of women in science at different levels up the ladder, from high school to full professors. It found that the biggest leakage of women from the pipeline was between high school and college; once women got their bachelor's, their representation at higher levels is consistent with what we expect from a gender-independent rate of success, given the obvious time lags it takes for people to progress through the various stages. What do our hypotheses predict? The 80-hour-work-week idea makes a pretty clean prediction: as we travel up the ladder and the competing pressures of work and family become more real and more evident, women should preferentially be dropping out. And this prediction is -- false. If the workload and childrearing pressures are to blame, why would the effect be localized during high school and college? Of course, a good theorist can wriggle out of any experimental finding. For example, we could imagine that female undergraduates very effectively anticipate the upcoming work/family squeeze, and get out while the getting is good. Except that, they don't. Of all the reasons why college students have given me why they wouldn't become physics majors, "I'm worried that some day I won't have time to both be a good science professor and also raise children, and therefore I'm going to medical school instead" has never been one of them.

So let's consider "intrinsic aptitude." The idea here is that there is a bell-curve distribution of cognitive abilities, and that the curves are different for men and women. Either the mean for women is simply lower, or the standard deviation is smaller. In either case, as we get far out along the exponential tail at high levels of achievement, there is a very clear prediction: the ratio of successful women to successful men should become dramatically smaller and smaller. So as we look up the pipeline, women should be dropping out more and more as we climb up the ladder. And again the prediction is -- false.

What about the idea of systematic biases? Unfortunately, this hypothesis doesn't really make any good predictions for this particular test. Until you tell me what the biases are, I can't predict when they will operate most strongly. Of course I can come up with glib stories after the fact, suggesting that the biases are most pronounced at the point when students are making choices about what major to pick -- and indeed I did come up with that story, and I think it's likely to be true. But these data don't really give us much evidence one way or the other.

The "biases" hypothesis does make predictions for other experiments, of course. For example, it would predict that women would suffer subjective biases in blind experiments where people are asked to judge work by men and women. And indeed, they do.

Likewise, the intrinsic-aptitude hypothesis makes other predictions. For example, it would predict that the fraction of women is basically the same everywhere, since it's intrinsic rather than due to social factors. That's wrong. It would also predict that the number of women in the field is remaining approximately constant, for the same reason. That's wrong, too. Of course, you could claim that the true, unbiased fraction of women receiving Ph.D.'s should be about five percent, and is only 18% now because of the pressures of political correctness forcing unqualified women into this role. You would, to be sure, be implicitly admitting that social factors can easily trump intrinsic differences, except that you'd be thinking that these factors work in women's favor. You should also look into loosening the elastic band on your tinfoil hat.

When do women leave physics?

When do women leave physics? Short answer: between high school and college. Afterwards, women and men perform approximately as you would expect at getting into grad school and getting jobs, given the dearth of women with bachelor's degrees.

That's the conclusion of this American Institute of Physics study (pdf), as reported in the New York Times. At the high school level, almost half of physics students are female (46% in 2003). But then less than a quarter of students who earn bachelor's degrees are women. After that, women seem to advance at the same rate as men; the "pipeline" doesn't seem to be all that leaky, except for the one huge geyser during undergraduate years. Which means that, among other things, it's really hard to place the blame on something inherent in women's brains, unless that something chooses to manifest itself only in college. (Meanwhile, college is the easiest place for systematic biases to be important, since that's when students are choosing what fields to concentrate in.)

So, the news is mixed. There is good news in that the numbers continue to improve, and there's every reason to believe we will eventually reach essentially fifty-fifty numbers of men and women in the field. According to the study, the percentage of Ph.D's in physics that are awarded to women has gone from about 5% to over 15% in the last twenty-five years. Still a long way to go, but getting there. Also good news is that there doesn't seem to be much discrimination at the highest levels of the academic food chain. (There certainly are fairly obvious individual examples of discrimination, but fortunately they don't seem to be having a large impact overall.)

The bad news is that there is still a systematic bias turning women away from physics during the college years, and that we really do have a long way to go. While it's true that things are likely to continue to improve, it's not because the natural tendency of things is to automatically get better, but because people keep fighting for them to do so.

Oh yes, it's also bad news for those rigorous scholars who propose that the leading causes of women's underrepresentation are that they don't want to work as hard, and that they lack the necessary intrinsic aptitude. Because studies like this show that those ideas are, how should we put it, inconsistent with the data. And therefore, by ordinary scientific standards, wrong. But don't let that stop you from suggesting hypotheses!

Tuesday, February 22, 2005

Here's an interesting graph from the most recent issue of symmetry. As cognocenti well know, there are a number of subject classifications for physics preprints on arxiv.org. These include the original hep-th for formal high-energy theory, hep-ph for more phenomenological theory, hep-ex for high-energy experiment, gr-qc for general relativity and quantum cosmology, and so on. The histogram indicates the percentage of papers in hep-th and hep-ph that cite papers from astro-ph, the astrophysics archive. The connection with phenomenology is no surprise, as issues of dark matter and baryogenesis are driving some of the most interesting questions in particle physics today. But the connection with "formal" theory (largely string theory) is interesting. I'm willing to bet that the biggest driver of this connection is the discovery of the accelerating universe -- string theorists are now catching on that they shouldn't be thinking about compactifications with zero cosmological constant, but rather vacua with a small amount of dark energy. Of course, it took a couple of years to catch on, as the acceleration of the universe was discovered in 1998. But it's nice to see research in quantum gravity influenced by real data.

Monday, February 21, 2005
Dark Matter and Dark Energy: from the Universe to the Laboratory

Here's an html version of the slides from my public lecture that I gave in Aspen last week. It's also available as pdf, coming in at a healthy 3MB. I was pretty ambitious, explaining not just the observational situation with respect to dark matter and dark energy, but also going into fermions and bosons, and theoretical ideas of extra dimensions and supersymmetry. It was the first time I gave this particular talk; next time I'll try to take out a couple of slides and go at a more leisurely pace.

Sunday, February 20, 2005
AAAS report

I'm back from the annual meeting of the American Association for the Advancement of Science, which was held this year in Washington, DC. The AAAS is a useful organization whose existence is largely ignored by physicists. Their most obvious contribution is publishing Science, which (like its UK counterpart Nature) tends to deal more with biology, chemistry, medicine, and the environment than with physics. The annual meetings reflect this emphasis; physics is only a tiny part of the proceedings, although some of us would like to see it be more prominent.

The thing that separates AAAS from professional societies such as the American Physical Society or American Astronomical Society is the word advancement. The AAAS is especially concerned with the interactions between science and the outside world -- through education, public policy, and media outreach. One of the main purposes of the annual meeting (maybe the main purpose) is to bring scientists in contact with interested journalists. Something that surprised me when I first realized it, but seems obvious in retrospect, is that science journalists don't typically have the luxury of flying around to topical conferences to get a feel for what is interesting within some specialized field. Except at the very largest outlets, most science writers have to pore through press releases to find their stories; if they're especially dedicated, they may scan Science or Nature or even the arxiv, but those are the exceptions. So the AAAS meeting provides a nice opportunity for scientists and journalists to mingle in the flesh; not coincidentally, the annual meeting of the National Association of Science Writers is usually held in conjunction with the AAAS.

(I won't even bother to make the argument that it is good for scientists and journalists to mingle -- good for science, and good for the interested public [which is most of the public]. Some scientists stay away from journalists because they think they won't be taken seriously if they appear in the media, and some are quite explicitly disparaging of their colleagues who do. That's a rant for another day.)

My main role this year was as the organizer of a symposium on Understanding Dark Energy. (That's a link to the symposium web page I set up; you can also read our press release, or the symposium summary in pdf.) I thought it was successful, with maybe 150 people in the audience. We had three hours and six speakers, so the talks were short and sweet. I opened with a brief description of why we believe in dark energy, what the theoretical puzzles are that we are trying to solve, and the things we hope to learn from new experiments. Adam Riess went next; Adam was the lead author on the first of the 1998 papers that presented evidence for an accelerating universe from observations of high-redshift supernovae. He talked about the future of supernova cosmology, both from ground-based and space-based observations, and how we can simultaneously constrain the equation-of-state parameter w and its time derivative. Lenny Susskind went next, saying how happy he was to be at an AAAS meeting giving a talk on biology. That's because he went on to compare the number of possible vacua of string theory (the "landscape") to the number of possible biological organisms you could get by arranging base pairs in a DNA molecule -- the former is perhaps 10500, while the latter is maybe 1025000000000. So biology wins, but the lesson we are supposed to learn is that a large variety of possibilities is what enables the development of intelligent life; in the context of string theory, it is the large number of stable vacua that makes it possible to find one with a sufficiently small vacuum energy so that life can evolve. (This is the press release that Peter Woit was lamenting.)

Next up was Licia Verde, talking about what we could learn from structure in the universe, combining constraints from early times (the cosmic microwave background) and late times (galaxy surveys). She had a nice analogy with waves on the ocean, driven by wind until they become non-linear and interesting to surfers: if the ocean were made of honey, the waves would evolve quite differently. Likewise, structure in the universe evolves in a way that depends on the underlying constituents, which can be used to discover properties of dark matter and dark energy. Switching back to outlandish speculations, Gia Dvali talked about how we could get an accelerating universe even without dark energy, if gravity were modified on large scales. An important point from his talk is that you can never modify gravity only on cosmological scales -- effects always leak down to smaller distances. In the case of a simple theory like mine, these effects are dramatic, and rule out the model definitively. In the case of a more subtle theory like Gia's, the effects are less pronounced, and the model is not yet ruled out; but it is certainly testable, especially by high-precision measurements of the orbit of the Moon. We closed with a fantastic talk by John Carlstrom, who described how clusters of galaxies will be a new method to probe the expansion history of the universe. John is the world's expert at observing the Sunyaev-Zeldovich effect, the scattering of microwave-background photons by the hot gas in galaxy clusters. Since what you observe in the SZ effect is a shadow on the CMB rather than the direct emission of light, the effect does not diminish as the clusters get farther away -- they can be found at any redshift, and the rate at which they assemble as a function of time reveals a lot about the way the universe evolved. John and his collaborators are building two impressive projects to make SZ surveys: an array of eight telescopes in California, and one giant radio telescope at the South Pole (a similar project, the Atacama Cosmology Telescope, is also underway in Chile). With all these new data coming in, it won't be surprising if theorists are once again startled by something we discover in the real world.

There are a plethora of different symposia at the AAAS, and the sexiest and most media-friendly are granted separate press conferences. For some reason, the press briefings are held before the symposia themselves; this gives reporters the feeling that they have first access to the news, but it means that they are asking questions before they've actually heard the talks. Still, we had a well-attended and sprightly press briefing. Since we didn't announce any stunning new results, I think the effect will be largely in the background, helping journalists understand what is going on and preparing them for future discoveries. But there have already been a couple of stories, prompted by those wild theoretical ideas: one on the landscape, and one on modified gravity. (Update: Here's another, from Astronomy magazine.)

Somehow I was also involved with another press conference, this one as part of the celebration of Einstein's miraculous decade, 1905-1915. Einstein started off the decade with three spectacular papers, any one of which would be the highlight of the career of an ordinary physicist: explaining Brownian motion in terms of atoms, inventing the photon as an explanation for the photoelectric effect, and establishing special relativity. But he was just getting started, and ten years later he came out with his capstone achievement, the general theory of relativity. The other panelists for this briefing were Rolf Sinclair, Richard Wolfson, and Barry Barish. (The three of them also appeared on Science Friday with Ira Flatow, while I was busy at the dark energy symposium.) The highlight of this briefing was the unveiling of Einstein@Home, a screensaver program that uses your unwanted CPU cycles to look for signals of spinning pulsars in real data from LIGO, the Laser Interferometric Gravitational-Wave Observatory. Barry introduced Bruce Allen of the University of Wisconsin-Milwaukee, who has been instrumental in developing the Einstein@Home software. The ultimate pay-off is not quite as exciting as for SETI@Home, but the likelihood of actually finding something is much higher!

Barry Barish, by the way, is one of the most impressive physicists you will ever meet. He was trained as a particle physicist, and did some of the first experiments to discover weak neutral currents, key to the Glashow-Weinberg-Salam model of the electroweak interactions. And now, having smoothly shifted gears, he is Director of the LIGO laboratory. But Barry hasn't forgotten about particle physics; he is extremely active in planning for future experiments, most recently as the head of the committee to decide on the basic technology for the planned International Linear Collider, the hoped-for follow-up to the Large Hadron Collider. He gave a great talk at a session on high-energy colliders, in which he explained the process by which the committee decided on the "cold" (superconducting) option rather than the "warm" option. The miracle is how quickly the worldwide community has dropped what they were doing to rally around this decision; that wasn't so hard for the folks at DESY in Germany who had developed the superconducting technology (TESLA) in the first place, but the people in Japan and at SLAC who were pushing for the warm technology were also very quick to get on board once the decision had been made. Now all that remains is to figure out where to build it (outside Fermilab would make sense), and who will pay. (For info on the current climate, see comments at Peter's blog.) The total cost is estimated to come in around five to eight billion dollars, which for comparison purposes is about one percent the cost of a manned mission to Mars.

My final event at AAAS was a TV interview with ScienCentral. This is an interesting outfit that makes short science stories, then sells them to other media outlets (like your local news program). They interview you on tape for half an hour or so, and then will chop it up into TV-sized morsels afterwards. (After some practice, I'm pretty comfortable on radio and TV by now, but I still need work on speaking in sound bites instead of elaborate paragraphs.) The woman interviewing me, Joyce Gramza, was initially skeptical about the whole cosmology thing, since she had just finished a bunch of interviews with scientists whose work actually had a tangible impact, like getting flu shots to people. Of course science does have an important impact on our daily lives, but that's not the whole point of it -- there's also the straightforward human pleasure of learning about the universe around us. Most people will accept that if you tell it to them honestly, rather than trying to pretend that we really study dark energy because it will someday lead to a cure for cancer. Joyce seemed to buy my argument, and by the end was saying that I should get my own show, which was nice of her. She also complained that she was interested in mathematics and physics as a student, but was consistently discouraged from studying them because she was a girl. I guess she just wasn't honest enough with herself to admit that she probably didn't have the intrinsic aptitude that us boys are blessed with.

One of the pleasures of combining a big meeting like the AAAS with a power center like DC is that you keep bumping into celebrities. I ran into Shirley Ann Jackson, who is President of the AAAS and also of Rensselaer Polytechnic Institute (I guess she hasn't been honest with herself either). And I went to a panel discussion on how to write and sell popular-level science books, which featured none other than John Derbyshire. Okay, he's not really a celebrity outside the blogosphere, but still. He was generally charming in an English-public-school sort of way; but no mention of LSD trips, and I didn't have the heart to ask. Finally, as I was heading out of my hotel I noticed Ralph Nader in the lobby chatting with some people. He's taller than he seems on TV.

I almost didn't write this post because I thought there wasn't that much to say. But I see I've gone on at unseemly length. This is what you get when I have an hour to kill in the airport before my flight back to Chicago.

Friday, February 18, 2005

Seems like everyone on the left-hand side of the blogosphere is having great fun with David Horowitz's latest misadventure, DiscoverTheNetwork: A Guide to the Political Left. (See e.g. Michael Bérubé, Pharyngula, Crooked Timber.) The website tracks the many connections between the vast left-wing conspiracy that has been so effective at keeping conservatives out of power in this country. It's pure comedy gold, I have to admit. I mean, consider the following set of people:

Quite a motley crew, wouldn't you say? Anyone who thinks that these folks are part of some common "network" is just a fruitcake. To any right-wingers out there who might harbor suspicions, trust me on this: Bruce Springsteen is not lunching with Abu Musab al-Zarqawi, nor is Howard Dean planning on bringing Fidel Castro to help him on the Democratic National Committee. Look, guys: the Ayatollah Khomeini was not a leftist, okay?

But beyond the laughs, there is something ugly and offensive going on. Look at the last paragraph of the entry for Barack Obama:
Who and what is the real Barack Obama? "I am a Christian," he told the Chicago Sun-Times last April to assuage all those who had asked if he had any religion at all. "I have a deep faith." The mother that a decade ago he described in his book as a "lonely witness for secular humanism" he now describes as "a Christian." It is here we are told that his stepfather in Indonesia, where Barack spent two years in a Muslim Madrassah, was a "non-practicing Muslim." Obama and his wife and two young daughters now attend Chicago's liberal Trinity United Church of Christ. "Obama doesn’t believe he, or anyone else, will go to hell," wrote Sun-Times reporter Cathleen Falsani, "But he's not sure if he’'ll be going to heaven, either."
I presume the insinuation here isn't too subtle for anyone to decode. Sure, this guy with the funny name "Obama" claims to be a Christian, and apparently is devious enough to actually attend church (albeit a "liberal" one). But don't let that fool you: his stepfather was a Muslim, and he spend two years in a Madrassah. In Horowitz's crazed world, this is tantamount to an al-Qaeda membership card. As Matthew Yglesias says: What's wrong with you people?

Thursday, February 17, 2005
Improving Euclid's Fifth Postulate

Michael Chabon (author of The Amazing Adventures of Kavalier and Clay), writing in the New York Review of Books, discusses The New Annotated Sherlock Holmes. He quotes Holmes in The Sign of Four:
Holmes remarks to Watson, referring to A Study in Scarlet, and continues:
Honestly, I cannot congratulate you upon it. Detection is, or ought to be, an exact science, and should be treated in the same cold and unemotional manner. You have attempted to tinge it with romanticism, which produces much the same effect as if you worked a love-story or an elopement into the fifth proposition of Euclid.
Some of us feel, of course, that the fifth proposition of Euclid would only be improved by a nice juicy elopement.
What? I hope not too many people believe that. Juicy elopements are all well and good, but they would not improve Euclid's Fifth Postulate:
If a straight line crossing two straight lines makes the interior angles on the same side less than two right angles, the two straight lines, if extended indefinitely, meet on that side on which are the angles less than the two right angles.
The postulate is already cumbersome enough! Mixing elopements into the act would only degrade an already-confusing situation. What would you want, the two indefinitely-extended straight lines to exchange secret vows of eternal love on the side on which the angles are less than right angles? Madness.

Of course, the Fifth Postulate (or Parallel Postulate) is not necessarily "true"; by relaxing this assumption, we are led to non-Euclidean geometry, which ultimately provides the basis for the geometric understanding of spacetime achieved by Einstein in general relativity. Everyone knew that the parallel postulate was suspiciously ugly, but it took quite a while to gather up the courage to simply discard it and see what happens.

Likewise, of course, I doubt that many elopements would be improved by Euclid's Fifth Postulate. Like it or not, the beauty of mathematics springs from its rigorous austerity; it's a different kind of beauty than we might find in a clandestine marriage, but no less compelling for that.

Wednesday, February 16, 2005
The highest energy physics

Greetings from Aspen, where tonight I'll be giving a public talk on Dark Matter and Dark Energy: From the Universe to the Laboratory. It's at 8:00 pm, any blog readers in the neighborhood are encouraged to drop by. The talk is part of the Aspen Winter Conference on The Highest Energy Physics, which is in turn part of a sequence of annual conferences held at the Aspen Center for Physics. Physicists know how to live, I tell you.

Right now the highest-energy physics we have here on earth is being conducted at Fermilab, a short drive from Chicago. The Tevatron accelerator is crashing protons into antiprotons to see what comes out. The hope is that we see something good like the Higgs boson, or supersymmetry, or large extra dimensions of space. If not, the Large Hadron Collider at CERN in Switzerland is scheduled to turn on in 2007, and will be operating at notably higher energies. There's almost a guarantee that the LHC will see something interesting, although of course you never know what until you look.

In the meantime, you are welcome to go look at the actual events at the Tevatron in real time! The two main experiments, CDF and D0, both have displays where you can see live events. I wish there was a little more explanation about what the displays actually mean; right now it's more gee-whiz than really being informative. But still, pretty gee-whiz; this is a schematic of the cylindrical volume of the CDF detector, with all those curly lines representing particles produced by a collision.

Of course, there are much higher-energy particles that are not made on Earth, namely ultra-high-energy cosmic rays. These are being observed by the new Pierre Auger observatory, which has a facility in Argentina and hopes to build another in the U.S. The analogy I will use tonight is that particle astrophysics and collider physics are like eavesdropping and interrogation. When you eavesdrop on someone, they might reveal things that they would never tell you outright; similarly, the ultra-high-energy cosmic rays could teach us something about particle physics that we couldn't get to by accelerating particles ourselves. But the problem with eavesdropping is that you can't just ask the questions you want to; besides, most of the time the conversations you overhear are just boring. If you are interrogating someone, perhaps they will clam up about some interesting questions, but at least you can be precise about what you are asking. And who knows, they might just tell you the answer.

Tuesday, February 15, 2005

TigerHawk points to another one of those 0nly-on-the-internet cool things: the NameVoyager, which allows you to find out the relative popularity of different names given to children since the year 1900. Even better, it plots the frequencies of all names that begin with the letters you've entered, so that you can see which first letters are most popular. The amount of fluctuation in names is really quite impressive. One interesting thing his how we've recently become infatuated with exotic-sounding names, as evidenced by the zoom in popularity of names beginning with letters like "Q", "X", and "Z":

Of course, the Z demographic is dominated by Zachary, which points to another trend towards solid Old Testament names: Joshua, Isaiah, and Hannah have all seen surges in popularity. No sign of Jezebel or Baal, though.

Monday, February 14, 2005
The road ahead

Daniel Wallechinsky, writing for Parade magazine (that high-powered foreign policy journal), has consulted with Human Rights Watch, Freedom House, Amnesty International and Reporters Without Borders to construct a list of the World's Ten Worst Dictators. Since we are now told, somewhat belatedly, that our invasion of Iraq was actually a humanitarian venture designed to spread democracy throughout the world (and the bits about weapons of mass destruction and ties to al-Qaeda were just honest mistakes), this list will serve as a helpful finding-chart for our future foreign policy objectives. I figure we'll be invading each in turn, from the worst at the top down to the not-quite-so-evil at the bottom. By the time we get through them all, the ineluctable logic of the Bush Doctrine will no doubt convince all remaining dictators to abdicate in a hurry.
  1. Omar al-Bashir, Sudan.
  2. Kim Jong Il, North Korea.
  3. Than Shwe, Burma.
  4. Hu Jintao, China.
  5. Crown Prince Abdullah, Saudi Arabia.
  6. Muammar al-Qaddafi, Libya.
  7. Pervez Musharraf, Pakistan.
  8. Saparmurat Niyazov, Turkmenistan.
  9. Robert Mugabe, Zimbabwe.
  10. Teodoro Obiang Nguema, Equatorial Guinea.
We can quibble about the list, but the top three are consensus picks to be sure. al-Bashir and Shwe will likely fold like a cheap suit after the first hundred cruise missiles, so they shouldn't be any problem. Kim Jong Il is trickier, with those nuclear weapons and all. Fortunately he doesn't yet have the capability to launch them all the way to California, so South Korea and Japan will likely take the brunt of the carnage. (Maybe they can borrow our missile defense system?) China will be tougher yet, what with a substantial military and over a billion people. Might have to call up more of the Guard. But we know about their nefarious plans to put an Asian person on the Moon, and we have to act swiftly before the Chinese flag is flapping in the Lunar breeze overhead.

Saudi Arabia will be awkward, since they're our close allies and all, but frankly we could use the oil, and our armed forces are already in the area. (The fact that al-Qaeda actually has support there is just a bonus.) I'm surprised to see Qaddafi so high on the list; I thought he had lost the will to be a really brutal dictator, but apparently he's rebounded in the last year, punishing entire towns for "collective guilt." Pakistan -- again, awkward, and heavily armed. But perhaps we could take out bin Laden in the process, which would be a PR coup. Personally I think Niyazov should be ranked even higher; he has quite a fondness for erecting statues of himself, which will make for great visuals after Turkmenistan is liberated. Mugabe and Nguema have slipped in the rankings over the last year, but that's as much a reflection of the tough competition as it is their own faults. Fact is, both regimes condone the use of torture against their suspected enemies, and that's a no-no in this new era of enforced Enlightenment values. Freedom is on the march!

Sunday, February 13, 2005
Pushing back

Brad DeLong has a nice post about receiving a challenging undergraduate education. He was prompted by an article by Ross Douthat in the Atlantic Monthly, which apparently whines about how it is possible to skate through Harvard without working very hard or learning very much. DeLong points out that it was, and still is, also possible to receive an extraordinarily rewarding education at a place like Harvard -- it's in the hands of the student to go out and get it.

I would just point out that this lesson is completely universal, not specific to Harvard. At almost any university in the United States, it's possible to graduate without being challenged very much, if that's your major goal (perhaps places like MIT and CalTech are exceptions). And at the same time, any halfway-decent institution of higher learning can provide a fantastic education to a student who makes the effort to get it. In my experience, students consistently underestimate the extent to which the quality of their education depends much more on themselves than on the place they are studying. The same is even true, albeit to a lesser extent, in graduate school: students who go beyond their coursework, who go to seminars and try to catch on with what is being discussed, who knock on professors' doors to talk about research, who speak up in meetings to politely ask questions -- these students will learn a tremendous amount no matter where they are.

I was an undergraduate at Villanova, a middle-class Catholic school most notable for winning the NCAA men's basketball championship my first year. While many of my classmates were biding time until the weekend, I was being constantly challenged and amazed by faculty in astronomy, physics, mathematics, biology, philosophy, English, sociology, religious studies, political science, history, and elsewhere. So, to Edward Guinan, Frank Maloney, Mike Burke, Jack Doody, Colleen Sheehan, Peter Knapp, Felix Beiduk, Tony Godzieba, Bill Werpehowski, Earl Bader, John Caputo, Bill Marks, Bill Fleishman, and many others who inspired me to be a better thinker and person -- thanks.

Saturday, February 12, 2005
Why we do what we do

In the comments to the post about Easterbrook's nonsense, the question arises about the practical usefulness of fields like particle physics. This deserves a more careful response, but I think the basic idea is straightforward: There are parts of science that are worth doing just because we want to know the answer, not because they will lead to tangible results. And we shouldn't be reluctant to admit it -- the "we" who want to know the answer isn't just professional scientists, it's a healthy fraction of people in all professions.

(And by the way -- does anyone other than me detect irony here? I mean, a complaint that society spends too much of its resources on the frivolous pursuit of high-energy physics is contained in a column about football?)

Matt McIrvin
points to a very nice post of his about neutrino astrophysics. But I agree with the spirit of the response by CapitalistImperialistPig, which I take to be that this really isn't the point. Pure science is worth doing for its own reasons, not because of hypothetical future spin-offs (even though such spin-offs have been remarkably important).

But CIP's comment contains one very bad idea: that we should require some sort of outreach from every professional scientist. The crucially important job of explaining ourselves to our fellow humans is a duty that inheres in the field as a whole, not in each individual. Outreach is a crucial part of the scientific enterprise, along with things like "theory" and "experiment" and "mentoring students" and "writing grant proposals." But there's no reason to require that every single scientist participate in experiments, for example (and thank goodness). What we need to do is to recognize the importance of outreach (not to mention education) for the continued health of science, and identify the best ways to get it done. Perhaps, as budgets are squeezed and money is diverted from real science to Bushian wild-goose chases, the scientific community will overcome its reluctance to give outreach the credit it is due.

Friday, February 11, 2005

Photographs by Chicago artist Nate Larson.

Update: Obviously he hasn't read my post on Life and the forces of nature.

Thursday, February 10, 2005
Bad cosmology hurts America

Chad Orzel just wants to be a good citizen and read some post-Super-Bowl football commentary. But he can't, because Gregg Easterbrook can't resist the temptation to spice up his respectable (or at least unobjectionable) football writing with utterly senseless remarks about science.
Recently some astronomers proposed that the universe is shaped like a gigantic donut. Then a competing group proposed that the universe actually is shaped like a gigantic soccer ball. The cosmic-doughnut group, based at the University of Pennsylvania, took exception to the cosmic-soccer-ball gang, who are mainly French academics. Cosmic-donut supporters asserted if the whole universe is a soccer ball, then individual views of the sky should resemble a sliced bagel.

Both the donut and soccer-ball camps hold that when astronomers scan deep space, the infinity they think they see is an illusion. In some doughnut-shaped or soccer-inspired or bagel-sliced way, the cosmos appears much larger than it is. Cosmologists estimate there are at least 100 billion galaxies; actually, these researchers contend, what we observe is reflections of a much smaller number of galaxies: a traveler moving at super-speed straight out into the universe would eventually end up back at the starting point, not continue forever. The universe is an illusion? Well, this seems easier to swallow than the idea that all material for the entire cosmos popped out of a single point with no content, as Big Bang theory maintains.
And in a comment, Kip Dyer points to Easterbrook's mindless attack on the entire enterprise of particle physics. Chad puts it best: "Just... stop. You're hurting America. Take your cue from John Madden, and just disappear until August."

Wednesday, February 09, 2005

I wanted to say something about the essay by Robert Laughlin (no relation to this McLaughlin fellow, nor for that matter this one) that was pointed to by 3 quarks daily. Laughlin, of course, is a towering figure in theoretical condensed-matter physics, winner of the 1998 Nobel Prize for his work on the fractional quantum Hall effect. He is also a well-known proponent of "emergence" as a crucial concept in modern physics. This notion of emergence is held up in contrast with reductionism -- the latter attempts to understand things by breaking them down into their component parts, while the former focuses on collective behaviors that only become apparent at the macroscopic level.

This is an interesting distinction, but for some reason people feel compelled to raise it to the status of some sort of competition, arguing that either emergence or reductionism is somehow more important than the other. I don't know why they feel that way. An unfortunate side-effect of this attitude is that it causes very smart people to say very silly things. Laughlin, for example, talks about the current view of string theorists -- the ultimate reductionists -- as represented by Brian Greene's book The Elegant Universe.
The worldview motivating my uncle's attitude toward Yosemite, and arguably also Brian Greene's attitude toward physics, is expressed with great clarity in John Horgan's The End of Science (Addison-Wesley, 1996), in which he argues that all fundamental things are now known and there is nothing left for us to do but fill in details. This pushes my experimental colleagues beyond their already strained limits of patience, for it is both wrong and completely below the belt. The search for new things always looks like a lost cause until one makes a discovery. If it were obvious what was there, one would not have to look for it.
Now, nobody could possibly have read The Elegant Universe and come away characterizing it as saying "all fundamental things are now known and there is nothing left for us to do but fill in details." The book goes into great detail about all of the things that we don't know, even just within the (quite considerable) scope of string theory. It doesn't talk a lot about condensed-matter physics, but that is hardly the same as arguing that condensed-matter physics isn't important. And it clearly does emphasize the need for experiments, even though they are very hard to do at this point.

The reason why such a smart person could say something so obviously wrong becomes clear in the next paragraph:
Unfortunately this view is widely held. I once had a conversation with the late David Schramm, the famous cosmologist at the University of Chicago, about galactic jets. These are thin pencils of plasma that beam out of some galactic cores to fabulous distances, sometimes several galactic radii, powered somehow by mechanical rotation of the core. How they can remain thin over such stupendous distances is not understood, and something I find tremendously interesting. But David dismissed the whole effect as "weather." He was interested only in the early universe and astrophysical observations that could shed light on it, even if only marginally. He categorized the jets as annoying distractions on the grounds that they had nothing in particular to tell him about what was fundamental. I, by contrast, am fascinated by weather and believe that people claiming not to be are fibbing.
Well, sure. There are cosmologists who are not interested in non-cosmological astrophysics. There are particle physicists who are not very interested in superconductivity. Likewise, there are condensed-matter physicists and astrophysicists who are not very interested in relativity or string theory. And there are biologists who are not interested in poetry, and historians who are not interested in number theory. Let's face it -- there are academics of all stripes who are more interested in their own fields of research than in other fields. They're not fibbing, but neither does their attitude translate into an objective statement about the worthiness of other questions.

Interestingness is like beauty -- it is not located out there in the world, it is a function of the relationship between a person and a phenomenon. Things are not intrinsically interesting, they are found to be interesting by people. (In a truly precise language, it wouldn't even be grammatically possible to say "X is interesting"; we'd only be able to say "I find X to be interesting," or "X is found to be interesting by most people.") I personally am interested in the nature of the dark energy that apparently constitutes seventy percent of the universe. But if someone else is not interested, they aren't making a mistake, that's just their honest feeling. If David Schramm wasn't that interested in jets, we can't simply extrapolate that one data point to a general conclusion that those arrogant reductionists are unwilling to appreciate the allure of collective behavior -- some of us think that weather is fascinating, and are more than happy to admit it, even if it's not what we want to do research on. (Not to mention the most likely explanation for the recounted conversation, which is that Schramm was simply yanking his chain.)

Unfortunately, we need to act as if these incommensurable levels of interestingness are somehow real, since we live in a world of finite resources and need to decide how they should be allocated. The good news is that there really is enough to go around, at least at the moment -- we can simultaneously pursue high-energy physics and cosmology, and also contemplate astrophysics and biophysics and condensed matter. Not everyone feels that way, of course, which is why we get unfortunate incidents like Phil Anderson's undercutting of the Superconducting Super Collider. Perhaps someday they will notice that, when funds get cut for massive reductionist experiments, they tend not to flow to research into the fascinating world of emergent phenomena, but rather to simply disappear. Can't we all just get along?

Do you like pina coladas?

Okay, sometimes things don't always end so happily.
AMMAN (AFP) - A budding romance between a Jordanian man and woman turned into an ugly public divorce when the couple found out that they were in fact man and wife, state media reported.

Separated for several months, boredom and chance briefly re-united Bakr Melhem and his wife Sanaa in an Internet chat room, the official Petra news agency said.

Tuesday, February 08, 2005
Prudent management

The folks at 3 quarks daily have been on a roll lately, picking out all sorts of interesting things. I do want to comment about the essay by Robert Laughlin. But for the moment I am lazy, and will just grab a quote from a book review they link to on a completely different topic. The review is by Peter Beinart, and the book is Gilles Kepel's The War for Muslim Minds: Islam and the West. Kepel argues that Islamism is not an ascendant ideology, but rather one that has turned to violence only because it is losing support overall. At least, for the most part; here's an excerpt from the review:
The book's argument is faint, and submerges during chapter-length digressions. But at its core The War for Muslim Minds tries to explain why al-Qaeda, contrary to the predictions in Jihad, is not fading. Although Kepel concedes that the organization has inherent strengths, he still assumes that if left to its own devices, it would fail to draw a mass following. The problem, he suggests, is that it is not being left to its own devices. Rather, the Bush administration's war on terror -- expressed in disastrous policies toward both the Palestinians and Iraq -- is gaining for al-Qaeda an appeal it could never win on its own. In contrast to President Bush, who has responded to 9/11 with an audacious effort to redirect the course of Muslim history, Kepel implicitly calls for something far more modest: prudent management of a threat that -- if we let it -- can be beaten from within. The war for Muslim minds, Kepel suggests, will be won in Riyadh, Cairo, and the suburbs of Paris. In Washington it can't be won -- only lost.
I tend to agree with Beinart's review, both in his agreement with the basic thesis about al-Qaeda, and also in where he disagrees with Kepel about the Israeli-Palestinian conflict. Kepel seems to want to blame American neo-cons for even more terrible things than they are actually responsible for; hard to manage, but not metaphysically impossible.

What Chaos when the curtain rises

On the spur of the moment, we went to the Green Mill last night to listen to Patricia Barber. Longtime Preposterous readers already know that she is one of my favorites, but it's worth saying again.

Barber is a pianist, composer, singer, and lyricist, who is accomplished and innovative in all these areas. You'd most likely classify her as a jazz musician, but she happily combines a pop sensibility ("Norwegian Wood" was one of last night's highlights) with classically-influenced structures. She recently won a Guggenheim fellowship to develop Mythologies, a cycle of songs based on Ovid's Metamorphoses, and we got to hear some of the pieces debut last night. It was startling to see these jazz musicians (Michael Arnopol on bass, Eric Montzka on drums, and guest Zach Brock on violin) suddenly pull out these elaborate pieces of sheet music to play the new songs -- they were intricate formal arrangements, enlivened by spaces for improvization within the work.

It's such a pleasure to hear music that is simultaneously gorgeous and challenging, that can be immediately appreciated while repaying close attention. Who says that we can't be passionate and intellectual at the same time? The highlight of last night's show was a rocking rendition of The Moon, from Verse, which starts with some avant-garde squeals and then gets funky.
should i leave Erebus
to his own device?
what Chaos when the curtain rises
and the houselights dim

with whitecake
on my face
the actress backstage
laying a Universal egg

still a broken heart
is a broken heart
and Illumination
is in fact

in the dark
in the cold
in the sky
i can fly

i am old
but i can see
for miles
and miles

i am silver
i am gold
i am white
i am blue

i am rock
i am chaste
i am time
i am truth

when twilight falls
among the stars
i sit and tinker
with your moods
i hear your thoughts
i move the tides
i am your God
i am your Muse
i can be fire
i can be war
i am the daughter
of Zeus
but tonight
there won't be light
cause I can't shine
without you

but tonight
there won't be light
cause I can't shine
without you
You have to hear it, especially the insistent bass line, to get the full effect.

And tonight I will go hear Vonski. Have I mentioned that Chicago is the greatest city in the world?

Monday, February 07, 2005

So, the master plan is coming along nicely. First cut taxes down to the bone, turning a budget surplus into a truly alarming deficit. Then use that deficit as an excuse to slash goverment programs not directly tied to invading new countries. Science will not be spared. David Appell reports on the situation in high-energy physics:
Bush's budget is shaping up to be a real disaster. A friend writes that outlays for high-energy physics are due to be cut from $736M (2005 est.) to $714M (2006 est.), a 3% cut in before inflation terms and therefore about a 5% cut in inflation-adjusted terms. What ever happened to the rich (who've received the bulk of the tax cuts under this administration) subsidizing good science? Or, failing that, simply American's committment to cutting-edge and important research? Must all our money go to militaristic aims and tax cuts for the wealthy? How much more anti-science do we tolerate from this administration?
Meanwhile, in my email this morning I found an informational message from the American Astronomical Society about the House Science Committee Hearing on the Hubble Space Telescope.
Ranking member Bart Gordon echoed chairman Boehlert's remarks and at the end of the hearing stated, "It was clear from the testimony of the witnesses at today's hearing that there is consensus on the high scientific importance of Hubble. One had to come away impressed by the unambiguous consensus findings of a National Academies committee that included such noted space authorities from such diverse viewpoints. Hence, the burden of proof when it comes to saving Hubble must be placed on anyone who markedly disagrees with the National Academies' conclusions." [...]

The President's budget will be released on Monday and is rumored to contain no funding for any kind of Hubble servicing mission. As warranted, the AAS will release Informational Emails and Action Alerts on budgetary and policy issues of importance to our members.
I wonder if this is what it felt like in the final days of the Roman Empire. Bread and circuses, anyone?

Sunday, February 06, 2005

This humble blog offers congratulations to the New England Patriots, who were simply the better team today than the heroic Philadelphia Eagles. Same time next year, guys?

This humble blog also counts its blessings that it is no longer based in Boston, whose sports fans can be insufferable even when they are suffering through decades-long losing streaks. The mind reels at how they must be dealing with success.

Friday, February 04, 2005
Hallucinatory neurophysics

Everyone knows what it's like to experience the hallucinations that accompany certain kinds of drug use (among other mind-altering contexts) -- if not from direct experience, at least from depictions in movies and literature. We've seen the colorful, swirling patterns, or the illusory tunnels stretching before us. It turns out that hallucinations are by no means random; there are certain recurrent patterns reported by people who experience them. These patterns were studied by Heinrich Kluever in the 1920's and 30's, and classified into four different structures: spirals, spokes, honeycombs, and cobwebs. Subsequent work has suggested more complicated hybrid forms, such as that portrayed here, but the basic types seem to be robust.

Here's the good part: the appearance of these particular hallucinations can be explained by physics! I know this because I'm sitting on the thesis committees for two students, Tanya Baker and Michael Buice, working with Jack Cowan of the math department. Cowan is a pioneer in mathematical neurophysics, developing sophisticated physical models of the behavior of neurons in the brain. He is a co-originator of the Wilson-Cowan equations to model neural behavior, and his students and collaborators have been thinking recently about hallucinations and other emergent properties of the brain.

The cerebral cortex of the human brain is basically a thin crumpled sheet, about three millimeters thick and one square meter in area. Naturally, physicists are going to think of it as a two-dimensional problem. The visual field, as observed by our eyes, maps smoothly (but with distortion) onto an area called V1, the primary visual cortex. (I'm glossing over details, including the fact that we have two eyes and our brain has two hemispheres. This is because I don't really know what I'm talking about, and will try to limit what I say to stuff in which I am confident.) So if we see two parallel lines, it activates a set of neurons that describe two non-intersecting curves in the physical layout of our visual cortex. How do we know the map from the visual field to the cortex? Well, it involves monkeys, or sometimes cats, and electrodes, and noble sacrifices in the name of science. We won't dwell on the details.

The brain is complicated, so we begin by making approximations. There are enough neurons that we don't worry so much about the discreteness of cells, but model the cortex as a smooth plane. At each point is a neuron, which can be either be activated or deactivated, or any value in between. The complication comes in when we consider the stimuli to which the neurons respond. These include not just the color and brightness of the point in the visual field to which it corresponds, but also interactions with other neurons, near and far.

These interactions allow the neurons to be sensitive to nonlocal features of the image, such as spatial or temporal frequencies in the brightness pattern, or the presence of correlated orientations within the image. This last capability makes us sensitive to the existence of straight lines -- so much so that our brains fill them in when they aren't even there, such as in the triangle illusion illustrated at right. The space of features of visual stimuli to which neurons are sensitive is not only high-dimensional, it can even be topologically nontrivial.

So as physicists (or applied mathematicians) we want to come up with a mathematical model describing the state of the neurons as a function of the input stimuli and the state of all the other neurons. We end up with an equation of the schematic form
da(x,φ,t)/dt = -a(x,φ,t) + I(x,φ,t) + ∫ dx' dφ' f(x-x',φ-φ')a(x',φ',t)
Here, a(x,φ,t) represents the state of the neuron -- either activated, deactivated, or in between. The variable x is the position on the cortex, t is the time, and φ represents all of the things to which the neurons can be sensitive -- brightness, spatial frequencies, color, orientation, and so forth. On the right-hand side, the first term -a(x,φ,t) is just minus the current state of the neuron, which makes an unstimulated neuron decay back to the deactivated state. I(x,φ,t) represents the direct stimuli received from the optic nerve, whatever they may be. The interesting part is the final term, an integral representing the interaction with other neurons in the visual cortex. The function f(x,φ) tells us how sensitive the neuron is to the states of other neurons a certain distance away, which can be different for different features of the visual field (frequencies, orientations, etc.). This function typically has a "Mexican Hat" form -- it is positive for short distances, negative for intermediate scales, and goes to zero far away.

Okay, the previous paragraph may or may not have made any sense to you. But here is the punchline: patterns of hallucinations reflect normal modes of the neurons in the visual cortex. By "normal modes" we mean the characteristic patterns of vibration, just as for a violin string or the head of a drum. The idea is that a drug such as LSD can alter the ground state of the visual cortex, so that it becomes excited even in the absence of stimuli. In particular, certain oscillating patterns can appear spontaneously. Generally these would take the form of different configurations of straight lines in the cortex itself; however, due to the distortion in the map from our visual field to the brain, these appear to us as spirals, tunnels, and so on. Indeed, Cowan and collaborators have shown that these normal modes can successfully account for all of the basic forms of hallucination classified by Kluever decades ago.

So, the next time you have a near-death experience, and see a tunnel stretching before you leading to a beckoning light, it's not Jesus calling you into the afterlife. It's just some characteristic jiggling of the neurons in your weakened brain. Which, to my mind, is much more interesting.

Thursday, February 03, 2005
Two wrongs

Remember when I gave a bad review to Fahrenheit 9/11, criticizing Michael Moore for cheap theatricality, such as scoring political points by squeezing tears from a woman whose son was killed in action in Iraq?

So, just to be clear, it's not any better when the President does it.

Important substantive message of the day

Sir Paul McCartney is an Eagles fan.

I understand that this is not nearly as cool as, say, having John Lennon be an Eagles fan. Or George Clinton, even better. But we'll take what we can get.

Wednesday, February 02, 2005
Metaphors wanted

Here I go again, stepping well outside my sphere of competence. On two separate occasions in March I'll be giving talks on literature and science. The first time will be at a conference at the KITP in Santa Barbara on Science, Theatre, Audience, Reader: Theoretical Physics in Drama and Narrative. I'll be giving a short talk with the grandiose title of "From Experience to Metaphor by Way of Imagination: How Science Can Lead to Literature." (I'll also be participating in a panel discussion on writing cosmology and another one on Einstein, but those are actually in my domain of expertise.) Then on March 20th I'll be giving a Literary Lecture in association with the performance of Charlotte Jones' Humble Boy at Chicago's Remy Bumppo Theatre.

I do have a tiny idea of what I want to say. I'm not so interested in how we can actually talk about science in a literary setting, at least not in a way that tries to teach scientific concepts via works of fiction (although that is interesting in its own right). Instead, I'm thinking about how scientific ideas can be useful to literature as raw material for metaphors. The idea is that science, in looking at the world and trying to understand it, is driven to invent dramatic ideas (the uncertainty principle, curved spacetime, chaos theory) that imagination alone would never have hit upon. (To paraphrase Sidney Coleman, a thousand philosophers working for a thousand years would never have come up with quantum mechanics.) It's the interplay in science between theory and experiment that forces us to conclusions we would otherwise have never reached. In turn, these concepts can be used in literature as powerful metaphorical tools.

A simple example is The Congugation of the Paramecium. The poem looks at first to be very non-metaphorical, just a straightforward description of what happens. But there's that little bit in the middle about "when / the paramecium / desires renewal / strength another joy" -- that's not literal, you know. The paramecium doesn't actually desire another joy. But Rukeyser is elegantly using the exchange of bits of nucleus as a metaphor for human interaction. That kind of move is something that science can quite consistently offer to literature.

What I need is a better set of examples. So, anyone have any? Again, I'm not so much interested in direct discussion of science in a literary context, as examples of when scientific concepts are put to use metaphorically. Any suggestions are welcome. (Let's make this blog thing actually be useful.)

Tuesday, February 01, 2005
Now get back to work

Andrew Hill demonstrates a typical pose of the University of Chicago graduate student in its native environment.


In the comments to the last post, Jeff Harvey points at an interesting article in today's New York Times. It's an essay by Cornelia Dean about her experiences as Science Editor for the Times. My favorite part:
I encountered the attitude again shortly after I became science editor, taking up a position I was to hold from 1997 to 2003. I went to the annual meeting of the American Association for the Advancement of Science, a convention that attracts thousands of researchers and teachers. My name tag listed my new position, and the scientists at the meeting all seemed to have the same reaction when they read it: "You're the new science editor of The New York Times!?"

At first I was deluded enough to think they meant I was much too delightful a person for such a heavy-duty job. In fact, they were shocked it had been given to a woman.

This point was driven home a few weeks later when, at a dinner for scientific eminences, a colleague introduced me to one of the nation's leading neuroscientists. "Oh yes," the scientist murmured, as he scanned the room clearly ignoring me. "Who is the new science editor of The New York Times, that twerpy little girl in short skirts?"

Dumbfounded, I replied, "That would be me."

A few weeks after that I was in another group of scientific eminences, this one at a luncheon at the Waldorf. The spokeswoman for the group that organized the event introduced me to one of the group's most eminent guests, a leading figure in American science policy.

"Oh," he said kindly but abstractedly, "you work for The New York Times. How nice." The spokeswoman explained, again, that I was the newspaper's science editor. "An editor," he said. "How nice." The woman explained again, but again he could not take it in. "Oh, science," he said, "How nice." At this point the spokeswoman lost patience. She grabbed the honored guest by both shoulders, put her face a few inches away from his and shouted at him - "She's it!"

Not long after, I answered the office telephone, and the caller, a (male) scientist, asked to speak to several of my colleagues, all male and all out. "May I help you?" I inquired. "No, no, no," he replied. "I don't want to talk to you, I want to talk to someone important!"

Even at the time, I could laugh at these experiences. After all, I was a grown-up person who could take care of herself. (I informed the caller that all the men he wanted to talk to worked for me, and then I hung up. As for Dr. Twerpy, he should know that he was not the first man to refer to me professionally as "that little girl." I reported on the doings of the other one until he was indicted.)
"Until he was indicted." Doesn't get much sweeter than that.

Ideas on culture, science, politics.
Sean Carroll

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