Author: Sean Carroll

Via MetaFilter, via Syaffolee, something that is pretty cool, but also annoying, because it could have been so much cooler: bubble chamber art. Beautiful images generated to resemble pictures taken from bubble chambers, the devices that physicists used to use to observe elementary particle interactions before we switched to fancy electronics.

Here’s the problem: the particle identities don’t make any sense. “Axions exist in a slightly higher dimension and as such are drawn with elevated embossed shadows. Axions are quick to stabilize and fall into single pixel orbits axions automatically re collide themselves after stabilizing.” Nonsense both grammatically, and as physics. (Axions, if they exist at all, do so in our ordinary dimensions, but they are stable neutral particles, and as such they wouldn’t make any tracks in a bubble chamber at all.) I don’t mind if people take license with scientific truths in order to make interesting art, but here it just seems so gratuitous — the pictures would look just as beautiful if the interactions had made sense, and the descriptions would have sounded even more intriguing. Another lost opportunity for bringing the two cultures together.

For the last two months I’ve been pretty good at staying in Chicago, with only the one jaunt to Aspen and DC. Now it gets hectic again, with multiple trips per month for the foreseeable future. But it’s going to be quite the world tour this year: France, India, Turkey, Canada, Korea, and China, not to mention various exotic domestic locales.

The fun begins today, when I fly to Santa Barbara for the previously-mentioned conference on Theoretical Physics in Drama and Narrative, where I get to pretend to be a literary critic. To set the mood, here’s a short excerpt from one of the central texts of the conference, Tom Stoppard’s Arcadia. (Thomasina is a precocious thirteen-year-old, and Septimus is her tutor; the year is 1809.)

Thomasina When you stir your rice pudding, Septimus, the spoonful of jam spreads itself round making red trails like the picture of a meteor in my astronomical atlas. But if you stir backward, the jam will not come together again. Indeed, the pudding does not notice and continues to turn pink just as before. Do you think this is odd?

Septimus No.

Thomasina Well, I do. You cannot stir things apart.

Septimus No more you can, time must needs run backward, and since it will not, we must stir our way onward mixing as we go, disorder out of disorder into disorder until pink is complete, unchanging and unchangeable, and we are done with it for ever. This is known as free will or self-determination.

He picks up the tortoise and moves it a few inches as though it had strayed, on top of some loose papers, and admonishes it.

Sit!

Thomasina Septimus, do you think God is a Newtonian?

Septimus An Etonian? Almost certainly, I’m afraid. We must ask your brother to make it his first enquiry.

Thomasina No Septimus, a Newtonian, Septimus! Am I the first person to have thought of this?

Septimus No.

Thomasina I have not said yet.

Septimus `If everything from the furthest planet to the smallest atom of our brain acts according to Newton’s law of motion, what becomes of free will?’

Thomasina No.

Septimus God’s will.

Thomasina No.

Septimus Sin.

Thomasina (derisively) No!

Septimus Very well.

Thomasina If you could stop every atom in its position and direction, and if your mind could comprehend all the actions thus suspended, then if you were really, really good at algebra you could write the formula for all the future; and although nobody can be so clever as to do it, the formula must exist just as if one could.

Septimus (pause) Yes. (Pause.) Yes, as far as I know, you are the first person to have thought of this. (Pause. With an effort.) In the margin of his copy of Arithmetica, Fermat wrote that he had discovered a wonderful proof of his theorem but, the margin being too narrow for his purpose, did not have room to write it down. The note was found after his death, and from that day to this–

Thomasina Oh! I see now! The answer is perfectly obvious!

Septimus This time you may have overreached yourself.

They hadn’t, of course, read my ideas about the arrow of time. What I’m not quite sure of is, should they have been talking about “atoms” in 1809? (And I still don’t understand what’s up with the tortoise.)

Never let it be said that I don’t listen to the voice of the people.

I’m sure you’ve all heard the big news: my beloved Philadelphia 76ers, stuck playing .500 basketball and nipping at the edges of making the playoffs, made a bold move at the trade deadline when they dealt for Chris Webber. Philadelphia fans, hardened by generations of disappointment, will nevertheless consistently allow their hopes to be lifted by a big transaction, and this definitely qualifies.

As realistic as I might want to be, this was just about a perfect move for the Sixers. They gave up three solid players who just weren’t that important to the team (Kenny Thomas, Corliss Williamson, and Brian Skinner). In return, they get a five-time all-star who essentially addresses all of their major needs at once: height, passing, rebounding, and a second scorer to complement Allen Iverson. There is some risk, of course — both Webber and Iverson are aging, have huge contracts, and Webber in particular has knee problems that keep him from playing at 100% effectiveness. But if you can average 21 points, 9 boards, and 5 assists while playing on a bum knee, I’ll take it.

For the first time in a long while, the Sixers have a starting lineup that actually makes sense, with nobody playing out of position. Their two veteran stars are joined by three extremely talented youngsters — athletic prodigy Samuel Dalembert at center, sharpshooter Kyle Korver at small forward, and promising rookie Andre Igoudala at shooting guard. Sure, I’d like to see Dalembert play smarter, Korver be a little more versatile, and Igoudala be a little more aggressive on offense, but it’s great to know that we won’t be automatically outclassed at some position coming into most games. With veteran savvy coming off the bench (Aaron McKie, Marc Jackson, and Rodney Rogers), there’s absolutely no reason why this team can’t make serious noise in the playoffs. Suddenly, instead of wondering if we will make the postseason at all, we’re a contender to march through a weak Eastern Conference all the way to the NBA Finals. Where, as you know, anything can happen in a seven-game series. (Trying to fit in all the cliches I can here.) Kudos to general manager Billy King for pulling this one off. It will be remembered when he runs for Governor some day.

Queen Elizabeth II (right), greets Jeff Beck, Eric Clapton, Jimmy Page (looking good!) and Brian May (L to R). Apparently the actual Queen didn’t recognize the lead guitarist of Queen, nor his even-more-talented compatriots. I understand she is more of an Yngwie Malmsteen fan.

And I didn’t even know that the Yardbirds came out with an album a couple of years ago.

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.

• Career choices explained
• Full disclosure
• Life and the forces of nature
• God: threat, or menace?
• The terrible ambiguity of Godzilla science
• Dinosaur report I (and II)
• What is this quintessence of dust?
• Worldline demographics
• What we know, and don’t, and why
• Sex and science!
• Hallucinatory neurophysics

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.

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?

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.

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.

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? 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!