Author: Sean Carroll

I just got back from a jaunt to the University of Arizona, so I missed out on the happy blogospherical wallowing in the aftermath of the Presidential debate. By now the consensus has hardened into a permanent shape — Bush was scared and slouchy, but did manage to repeat his three talking points over and over with eerie consistency, while Kerry was straight-backed and Presidential, and managed to say some very clear things about why the war in Iraq was a bad idea, coming out the overall winner. And I basically agree.

Still, far be it from me to deprive the Kerry campaign of my insights, especially as I understand they are running low on free advice from bloggers. So here are a couple of quotes I would love to see Kerry use in the debates:

“The President has asked what kind of message my positions send to our troops. Let me just say this: the troops know what is going on. Don’t underestimate the men and women of our armed forces. They know when a military operation is a boondoggle, and when the situation on the ground has become a quagmire. They also know when a statesman is standing up for their rights, and when a politician is just blowing smoke. They understand that we live in a free country, and that there is a difference between criticizing the troops and criticizing the failed policies of this Administration.”

“For a long time, Republicans have had a reputation as the party of small government. But this administration has changed all that. The new slogan of the Republican party is ‘Trust us — we’re the government, we know what’s best for you.’ Under this administration, the government has increased spending, made it a policy to violate our personal privacy, inserted itself into bedrooms and private lives, and given itself the right to arrest and detain American citizens without any right to talk to a personal lawyer. If you believe in getting the government off of people’s backs, you must vote Democratic this November.”

“Harry Truman had a motto — ‘The Buck Stops Here.’ George W. Bush also has a motto — ‘Don’t Blame Me.’ No matter what goes wrong with our policies, there is always a senior member of the Bush administration ready to step up and say ‘Not our fault.’ This administration has been in total control — the Republican-dominated congress hasn’t passed a single bill the President has wanted to veto. Yet, in the face of any problem, from the economy to the prisons of Iraq, they feel completely free of blame. It’s time we had a President who will take responsibility for his actions.”

“The President likes to tell us that his job is hard work, and that he never expected that he would have to send troops into combat. Of course it’s hard work, and sending troops into combat is part of the job description. It’s time we had someone in the Oval Office who has a better grasp on what it really means to be the President.”

“A lot of detailed negotiations went into setting up the format of these debates. One of the things that the President’s negotiator insisted on was that we couldn’t use charts and graphs as visual aids. Why not? Because if I could show you a simple chart of the budget deficit, you would be shocked and scared. This administration has turned a record surplus into a record deficit in record time. George W. Bush is the first President to have a degree in business administration, but it’s hard to know what he learned at Harvard Business School. As a businessman he drove companies into the ground, and now he’s doing the same for the Federal treasury. Because of his mismanagement, important programs are going to have to be cut, but he won’t tell us which ones — will it be Social Security? Medicare? Education? National defense? Homeland security? Right now, the nation can’t afford to be governed by someone who doesn’t know how to balance the books.”

These are gems, people! Free of charge! Normally I wouldn’t give away wisdom like this so cheaply, but these are desperate times.

Last night I went with a friend to the Harvard Film Archive to see Painters Painting, a 1972 documentary by Emile de Antonio. (The Archive’s film copy of the movie had been ruined and they were forced to show it from 80’s-era laser disk, as a result of which embarrassment the showing was offered for free). The subject was American painters, focusing on the Abstract Expressionists and their Pop-Art and Color-Field successors. Many of the artists who were alive at the time were featured in interviews (Mark Rothko and Jackson Pollock, of course, had each died violently before the movie was made). Interesting to see how this tight-knit group of people interacted with each other, with the dealers and collectors, and with the outside world.

What stuck me, ungenerous soul that I am, was what terrible theorists the painters all were. By which I mean, they had very strong ideas about what they are doing and what other people should be doing and what kinds of art are good and bad, but these ideas are all visceral and impressionistic (as it were), rather than flowing from some set of basic axioms about what art should be. They would offer various opinions in the guise of fundamental principles, of course, but the principles were often incoherent and never really fundamental, in the sense that they could be reasonably applied to a wide variety of aesthetic moments. Instead, they were rules of thumb that happened to serve this particular person well in their particular set of circumstances. You were as likely to hear, for example, about how it was absolutely necessary to make your brushstrokes vivid and recognizable, as you were to hear that brushstrokes should always be completely imperceptible. I can imagine perfectly good reasons for either position, but these stances were offered as self-evident truths, rather than as flowing from some deeper theory.

And I don’t blame the artists in particular; the few critics that were featured (Clement Greenberg and Hilton Kramer) didn’t do much better. Again, they had strong opinions justified by appeals to comprehensive-sounding statements, but although their sentences were longer and more complex they didn’t seem to come any closer to possessing a set of fundamental axioms from which we could begin to derive their specific judgments. Nor do I by any means think that one needs to be a good theorist to be a good artist; the empirical evidence might argue for the converse. The one artist who seemed to have a full-blown theory was Frank Stella, who spoke convincingly about why the appropriate response to gestural painting was to move toward geometric forms and liberation from the rectangular canvas. Unfortunately, at the level of a personal reaction, I found his actual paintings to be the most lifeless and least beautiful of the bunch. The poor guy couldn’t seem to understand why the same people who found his work cold and uninviting were so taken with that Rothko fellow.

This is also not to say that the artists were in any way unintelligent or even inarticulate (although some were); many were very interesting to listen to. Willem de Kooning had provocative things to say about the “lightness” of American culture in contrast with that of Europe, and Jasper Johns and Barnett Newman made enlightening remarks about their use of texture and space. But you nevertheless got the feeling that they wouldn’t be able to offer a good reason why, for example, it was interesting to eliminate color entirely from a deeply textured representation of the American flag; only that it seemed to work (which is a fine reason, just not a theory).

The other thing that strikes you (or me, as an underinformed amateur who is making this up as he goes along) is how reflective and tightly-coupled the painting world really is. So many of these works are simply baffling when viewed in isolation, but begin to make sense when viewed as pointed reactions to some specific innovation by some other painter. It gets even better when the artists are dragging each other to shows or even quasi-collaborating, as when Robert Rauschenberg thinks it would be fun to first draw something and then carefully erase it, but realizes that it’s no fun to erase his own drawings, so convinces de Kooning to donate one of his. For my next paper, I want to convince Ed Witten to donate an unpublished manuscript, from which I will delete all of the interesting parts — I think it would be a ground-breaking collaboration.

By James Fenton.

A nasty surprise in a sandwich,

A drawing-pin caught in your sock,

The limpest of shakes from a hand which

You’d thought would be firm as a rock,

A serious mistake in a nightie,

A grave disappointment all round

Is all that you’ll get from th’Almighty,

Is all that you’ll get underground.

Oh he said: ‘If you lay off the crumpet

I’ll see you alright in the end.

Just hang on until the last trumpet.

Have faith in me, chum-I’m your friend.’

But if you remind him, he’ll tell you:

‘I’m sorry, I must have been pissed-

Though your name rings a sort of a bell. You

Should have guessed that I do not exist.

‘I didn’t exist at Creation,

I didn’t exist at the Flood,

And I won’t be around for Salvation

To sort out the sheep from the cud-

‘Or whatever the phrase is. The fact is

In soteriological terms

I’m a crude existential malpractice

And you are a diet of worms.

‘You’re a nasty surprise in a sandwich.

You’re a drawing-pin caught in my sock.

You’re the limpest of shakes from a hand which

I’d have thought would be firm as a rock,

‘You’re a serious mistake in a nightie,

You’re a grave disappointment all round-

That’s all you are, ‘ says th’Almighty,

‘And that’s all that you’ll be underground.’

Please rest assured that Mr. Fenton is a Major Poet, even if the above example of his work does seem like something Eric Idle should be singing.

I am sitting in a friend’s apartment, a couple Negronis to the wind, in rejuvenation mode after my colloquium this afternoon at Brandeis (convincing the locals that the universe is accelerating, but that we don’t know why — not a hard sell, really). So I’m in no condition to comment on the mild kerfluffle that has broken out, ironically immediately after the announcement of 411blog, in response to Matthew Yglesias’ lament that there aren’t enough expert bloggers. But I was glad to see my honor (and, incidentally, the honor of some other people) defended by PZ Myers and other bloggy luminaries.

However, given my druthers, I’d prefer to have Fafblog exhort people to send me money. Flattery is nice, but it doesn’t pay the mortgage.

(Honestly, there’s a pretty basic fact here — by percentage, most people in the world are not experts. They’re not especially good writers, either. This is one of the first things you realize, I thought everyone knew, when you rambled around the internet — there’s a very good reason why magazines have editors, rather than just being first-come-first-published. The worthwhile stuff is there, but you do have to look for it a little.)

Here’s an idea: rather than waiting for mistakes to enter the mainstream media and subsequently be jumped on by the blogosphere, why not offer up the expertise of the bloggers (or some delicately selected subset thereof) as a resource to journalists as the stories are actually being written? This turns the standard picture of bloggers-as-manic-guardians-of-accuracy on its head, but the category of “bloggers” is so diverse as to be an overgeneralization almost by definition, so it might work.

That’s the notion, anyway, behind 411blog, a new venture set up by Andrew Cline of rhetorica.net and Jay Manifold of A Voyage to Arcturus. They are offering up a list of bloggers who have some credentials in various areas, primarily science-oriented, as a resource to journalists who would like a quick answer on some technical question.

We’ll see how it goes. Success will require both that journalists avail themselves of the service, and that the bloggers offer useful input. Most science journalists have their own private lists of trusted experts in the various areas they write about, but good ones are always looking to extend their horizons. Being a blogger doesn’t convey any special expertise in and of itself, but it may indicate a willingness to make an effort to reach out to a wider audience. Or, as in my case, it may just serve as a convenient outlet for one’s extravagant narcissism. But as long as we can channel our neuroses in socially useful directions, what more can we ask?

I tend to travel a lot for work purposes, spreading the word about the accelerating universe to rapt audiences across the country. And I like the travel, and enjoy giving the talks, especially to people who are still skeptical about this whole dark-energy thing and appreciate a balanced telling of the story. But it does take time, and I am not an efficient traveler; on flights I am more likely to curl up with a good novel than to pull out the laptop and work on a paper or a referee report. So I promised myself that I would do no more than two trips per month from now on. As it turns out, in the next five weeks I will be visiting Boston (Brandeis), Tucson (University of Arizona), Urbana-Champaign, Philadelphia (University of Pennsylvania), Baltimore (Johns Hopkins), Pasadena (Caltech), and San Diego (UCSD). So you can judge for yourself how successful I’ve been at keeping my own promise.

It’s a shame in a way, because this is my favorite time of year to be on campus. For one thing, September is a little oasis of calm in Chicago’s playfully rambunctious weather patterns, and the lake and the sky are glowing magnificently. But at any university, it is always a thrill to see the campus come alive with the students returning (or arriving for the first time) after the summer exodus. We start late at Chicago because we’re on a quarter system, with one quarter before New Year’s and two after, so this week is actually the first week of school. I’m teaching Physics 300, “The Teaching and Learning of Physics,” a required course for first-year graduate students in which we help them learn how to be good teachers. It’s great for the students, if only because it conveys the impression that the department cares about the quality of teaching. (Sadly, we cannot force the faculty to take the course.) And it’s great for me, as I get to meet all of the new graduate students. They are full of enthusiasm spiced with trepidation, and contemplating hard questions like whether they should refer to professors by their first names. (Answer: yes, but with exceptions, and the rules concerning exceptions can only be learned from experience.)

Speaking of traveling: a common prediction of technological triumphalists is that easy access to computers and comprehensive connectivity will eventually do away with the notion of a “conference” at which people physically assemble. From the evidence of the recent DPF meeting I attended, the reality is precisely the inverse. Conferences will continue as scheduled, but members of the assembled audience will each sit with their laptops open, connected through their wireless links to the internet, ignoring the speaker as they always have. The flaw in the triumphalists’ prediction is the assumption that people don’t like to travel, they just want the content you get from the conference talks. It’s just the opposite: people do like to travel, and especially to shmooze at the coffee breaks, but they hate to be stuck in talks. Now that technology has liberated us from that onerous requirement, conferences will become more popular than ever. At the end of each talk, of course, some member of the audience will still ask a question that is really more of a comment.

An interesting contrast comes to light by jumping around the blogosphere (kind of like playing your CD’s on “shuffle”).

• From Anomalous Data, via Pandagon and Pharyngula: If you strip the candidates of personality and presentation, leaving only issues, you get overwhelming support for Kerry.
• From Stanley Fish (writing in the New York Times) via Karl Fornes: If you completely ignore substance and look only at the clarity with which ideas are being articulated, you get overwhelming support for Bush.

The target audiences were upper-class 11-year-old schoolchildren in the first case, and University of Illinois at Chicago undergraduates in the second case, but that hardly seems to matter.

The good news is: Kerry’s problem would seem to be more easily correctible than Bush’s (we hope).

By Adrienne Rich:

Thinking of Caroline Herschel (1750-1848), astronomer, sister of William; and others.

A woman in the shape of a monster

a monster in the shape of a woman

the skies are full of them

a woman         ‘in the snow

among the Clocks and instruments

or measuring the ground with poles’

in her 98 years to discover

8 comets

She whom the moon ruled

like us

levitating into the night sky

riding the polished lenses

Galaxies of women, there

doing penance for impetuousness

ribs chilled

in those spaces         of the mind

An eye,

        ‘virile, precise and absolutely certain’

        from the mad webs of Uranusborg

                      encountering the NOVA

every impulse of light exploding

from the core

as life flies out of us

        Tycho whispering at last

        ‘Let me not seem to have lived in vain’

What we see, we see

and seeing is changing

the light that shrivels a mountain

and leaves a man alive

Heartbeat of the pulsar

heart sweating through my body

The radio impulse

pouring in from Taurus

        I am bombarded yet         I stand

I have been standing all my life in the

direct path of a battery of signals

the most accurately transmitted most

untranslatable language in the universe

I am a galactic cloud so deep         so invo-

luted that a light wave could take 15

years to travel through me         And has

taken         I am an instrument in the shape

of a woman trying to translate pulsations

into images         for the relief of the body

and the reconstruction of the mind.

This is fun, I may just turn this into a poetry blog.

Something I didn’t get around to in last week’s discussion of dark energy and its equation of state parameter was the question of priors — i.e., what do we expect the parameter to be? Physically, this is equivalent to asking how we expect the dark energy to evolve with time, if at all.

We have to admit that there is one special value that the equation of state parameter w might have: namely, w=-1, corresponding to a dark energy density that is strictly constant (equivalent to vacuum energy or Einstein’s cosmological constant). In that case, the dark energy is simply a constant amount of energy that is inherent in each cubic centimeter of spacetime. Any other possibility means that the dark energy density is dynamical, and is presumably obeying some equations of motion. In the comments, Serenus was hoping that I would encourage people to be completely open-minded, and not favor w=-1 over any other value; rather, just collect the data and take the results at face value. In other words, he wants a uniform prior, in which the a priori probability of w=-1 is the same as w=-0.99 or w=-1.01.

Although I hate to disappoint anyone, I can’t agree. The reason is pretty straightforward; I think it was Tolstoy who said, “Cosmological constants are all alike; every model of dynamical dark energy is dynamical in its own way.” Tautological enough, but it points to an important feature of dynamical dark energy candidates — because they have more features than simply their energy density, there are more ways they could be detected and thus more parameters you need to fine-tune to explain why we haven’t noticed them yet.

The simplest example of dynamical dark energy (although by no means the only interesting one) is quintessence, a light scalar field gradually rolling down a potential. Since the field is rolling slowly, the kinetic energy is extremely small and the potential is nearly constant, giving us a nearly-constant energy density, which is just what you want for dark energy. But as soon as you allow for dynamics in this way, there are things you need to explain. For any dark-energy candidate, you need to explain why the energy density is small. But for quintessence, you also need to tell me why it is rolling so slowly; this translates into the fact that the potential must be very shallow, which then translates into the fact that the mass is very small. (The mass is a measure of the curvature of the potential; this is not exactly the same as the slope, but they should be related unless you want to do even more fine-tunings.) In particle physics, masses of scalar fields tend to be very large. The Higgs boson purportedly has a mass of order 10¹¹ electron volts, and a big problem (the “hierarchy problem”) is why this number is so much smaller than the Planck scale, 10²⁷ electron volts.

The quintessence field, meanwhile, would have to have a mass of order the present Hubble constant, about 10^-33 electron volts. So if 10¹¹ electron volts is very small, how do we hope to explain 10^-33 electron volts?

Once you know the mass is so small, you realize that low-mass particles tend to give rise to observable long-range forces. The two forces we know from our macroscopic experiences are gravitation and electromagnetism, mediated by two zero-mass particles (the graviton and the photon); the nuclear forces are less manifest because they are such short-range. So the quintessence field should give rise to an observable, long-range “fifth force.” The typical way out of this conundrum is to simply declare by hand that the new quintessence field doesn’t interact with ordinary matter, so we can’t feel the force. But this is a cheat; we know that quintessence interacts with gravity, and gravity interacts with ordinary matter, and the miracle of quantum field theory tells us that if A and B both interact with C, then A and B will interact with each other. We can even estimate the strength of this interaction, imagining that it is suppressed by the Planck scale. Then we go look for it, for example in the delicate torsion-balance experiments at the University of Washington. The idea is that the strength of the quintessence force will necessarily be different for objects of different compositions; it’s a rule that only gravity can couple to objects in a way that is completely indifferent to what they are made of. So by looking for tiny anomalous accelerations of, say, Aluminum and Copper in the direction of the Sun, we can put limits on the strength of any purported new long-range forces.

The answer is that we don’t see any such forces, at least not yet. From the upper limits we currently have, the forces must be about 10^-5 times less than what you might have expected. That’s pretty small, although not so small (especially given the roughness of the theoretical estimate) that there’s no reason to keep looking.

What’s more, there is another way to constrain the direct interactions of quintessence. If you have a scalar field that is slowly evolving as the universe expands, all of the “constants of nature” tend to change along with it. That’s because what we think of as constants of nature, like the mass of the up quark or Newton’s constant of gravitation, are actually parameters that depend on the quantum state of the universe (just as the speed of sound depends on properties of the medium through which it is traveling). This is interesting, because there are claims that the fine-structure constant, which determines the strength of the electromagnetic interaction, has actually been experimentally observed to be varying with time. Now, to be honest, these measurements are very hard to do, and people have obtained conflicting results, and the most likely situation is that the experiments are simply in error. So there is some possibility that we have actually already detected the signature of quintessence in a time-variation of the fine structure constant, but it’s somewhat safer to simply imagine that we’ve put a good upper limit on any such variation.

All of the above gives some reason to think that a constant vacuum energy is preferable to dynamical dark energy, simply because it makes more sense that we haven’t yet detected any direct interactions (because constant vacuum energy doesn’t have any). This is not really the same thing as just using Occam’s Razor, which is an important principle but usually only reliable when everyone already agrees on what the correct answer is.

Of course, the idea that dynamical dark energy is a simple scalar field is a nice one, but not unique; there are other possibilities. An especially exciting possibility is that the dark energy does have non-trivial interactions, but only with hard-to-detect particles like dark matter or neutrinos. But the moral of the story remains: once you admit the possibility of dynamics, the models generally allow for all sorts of ways to detect them in principle, and you have to do more fine-tunings to explain why the dark energy hasn’t been seen directly. The idea of an absolutely constant vacuum energy (w=-1) is the simplest and most robust; it’s therefore perfectly permissible to imagine that it’s a little more likely than the other possibilities. Personally, I give about a 10% chance that the dark energy is dynamical. But it’s a testable hypothesis, and if you find some variation then you get in line for the Nobel Prize. So even if it’s something of a long shot, it’s well worth looking for.

The latest Tangled Bank is now up at Lean Left. TB is a collection of the (self-nominated) best science writing in the blogosphere over the previous couple of weeks. This edition is especially strong on bugs, in various senses of the word.

The next Tangled Bank will be hosted right here at Preposterous Universe on October 6th. All you have to do is email me (carroll@theory.uchicago.edu) with a pointer to an interesting science-oriented post you have recently written, and our world-class panel of experts will make an impartial determination of your worthiness as a scientist, a blogger, and a human being (not necessarily in that order). If you are fortunate enough to pass through this rigorous screening process, you just may be included in the upcoming edition. (Sure, if you read the ground rules, you might get the impression that it’s pretty easy to get accepted into the lofty company of Tangled Bank authors. Don’t get complacent, that’s all I’m saying.)

The Tangled Bank idea was originated by the redoubtable PZ Myers, and there was a natural slant towards things biological in the early days. (More recently it has been hosted by ornery liberals, a phenomenon still imperfectly explained.) But participation is wide open to those of us in the less squishy sciences, and I want you physicists out there to represent. If you don’t volunteer I may have to hunt you down. Let’s show the world that we can be lucid and enthusiastic explainers of recondite ideas, not merely the flamboyant show-offs that unfair stereotypes so often paint us to be.

Also, I’m thinking of instituting a dress code.