Author: Sean Carroll

  • Worldline demographics

    I’ve often thought, looking around my neighborhood on Chicago’s North Side, that there must be some obscure city ordinance that force people to move out once they either hit the age of 40 or have kids. I found a way to quantify just how tightly bunched the local demographics of my neighborhood really are: City-Data.com gives you the raw data about the composition of anywhere in the U.S., and some fascinating graphical representations of who lives there.

    So I studied my personal history as told through the demographics of the zip codes in which I lived (somewhat streamlined for dramatic purposes). You can’t really choose where you are born, and I grew up in the depths of the Philadelphia suburbs, in 19067. Here is a graph of the number of people in the zip code as a function of their age; black for males, magenta for females (hey, I don’t pick the color schemes).


    You can tell instantly that it’s a middle-class child-raising family community; a bunch of kids, most of whom flee at the age of 18 to go to college, then gradually trickle back to buy homes and raise their own kids — if not the exact same people who grew up there, then their demographic equivalents. As they become slightly more prosperous or the kids move out and they don’t need a three-bedroom house with a yard, they decamp to more appropriate locales.

    Next it was on to college at Villanova, in the scenic zip of 19085.


    Clearly, nobody lives there but the college students. It must be that the zip code only includes the university proper, as the surrounding area was populated by the old-money upper class of Philadelphia’s Main Line.

    Then to grad school at Harvard and the celebrated destination of 02138, where they used to sell T-shirts proudly proclaiming it as “The Most Opinionated Zip Code in America.”


    Dominated by college students, but somewhat more inclusive; faculty, researchers, grad students, and sundry folks who just enjoyed the atmosphere of Harvard Square.

    After graduating, I took the easy way out and stayed in Cambridge for my first postdoc at MIT. But with my spiffy new postdoctoral salary I could move across the river to the South End in Boston, landing in 02116.


    A noticeably urban environment (thank God), one with a healthy dose of post-high-school students lurking around (not exactly sure why), certainly youthful but not like being in college any more.

    But alas, the academic wheel of fortune turns in mysterious ways, and my next stop was at the Institute for Theoretical Physics in Santa Barbara. As I hoped to be spirited away by an attractive faculty offer at any moment, I chose not to bother to find a place in SB proper but rather live in Isla Vista, 93117.


    IV is an entire municipality surrounded on three sides by the UCSB campus and on the fourth by the Pacific Ocean; nobody in their right mind lives there but students and surfers. Not an environment devoted to the life of the mind, but the weather was awfully nice.

    Finally I was spirited away to the Windy City, where I live in the Lakeview section of Chicago, 60613.


    Truly in my yuppie-metrosexual element, short on students but heavy on post-college strivers making the gradual transition from apartments to condos. And yes, there does seem to be some sort of upper age limit. I wonder where they all go? And will they drag me physically away, or is it a more subtle mind-control sort of thing?

  • Derrida

    Jacques Derrida, French philosopher and originator of deconstruction, passed away this Friday. Obituaries at the Guardian and the New York Times; blog posts by Michael Bérubé and Jack Balkin and Brian Leiter; comments at Crooked Timber; a nice encyclopedia article. A quick perusal is enough to give an impression of how controversial Derrida was!

    Derrida is one of those intellectual figures who is arguably more important as a symbol than for his actual work. In Derrida’s case, in the minds of many people he has come to represent a perspective that is deeply anti-intellectual, or at least anti-Enlightenment and anti-rationality. This is a completely misguided impression, but a persistent one nonetheless. Derrida enjoyed the project of undermining conventional Western metaphysics, emphasizing gaps and contradictions in the writings of major players of the philosophical tradition. More significantly (for the critics), he also enjoyed playful and elliptical language, especially in his own writings, although he could be quite straightforward in speech.

    I am by no means an expert on Derrida’s work, although I have read a couple of things and can vouch that he was not nearly as impenetrable as his reputation suggests. I couldn’t tell you whether deconstruction will end up being counted as a productive moment in the history of philosophy, but the simple caricatures of his enemies tend to make me sympathetic to Derrida’s side of the controversies. I take Derrida to be interested in highlighting the weak points and inconsistencies in grand meta-narrative systems. The question would be, do we do no more than delight in the failings of the system-builders, or do we try to nurture what remains valid, reconstructing after deconstructing? Derrida’s critics would argue that he is nothing but a nihilist, while he prefers to place himself squarely in the Enlightenment tradition of questioning authority and dispelling mysteries. Consistent with this stance, his later writings and activities had become increasingly political; a recent book describes interviews with Derrida and Jurgen Habermas over the significance of the September 11th attacks.

    You might think that scientists, who take a noisy pride in the self-critical techniques of their own disciplines, would be sympathetic to the search for weak points in philosophical theories, even if those theories were implicitly subscribed to by the scientists themselves. Okay, maybe you wouldn’t; scientists have never been excessively fond of criticism from non-scientists. Derrida rarely addressed science directly (although his brother Bernard is a well-known condensed matter physicist), but his status as a symbol of anti-reason drew substantial attention from defenders of objective truth. A famous example was of course the Sokal affair, in which physicist Alan Sokal parodied postmodern jargon in an article he managed to get published in the journal Social Text. Just like it’s more fun to attack the wingnuts at Little Green Footballs than it is to attack more respectable conservative thinkers, the critics would gleefully (and correctly) highlight the most ridiculous statements of self-described postmodernists, without bothering to engage carefully with the better thinkers on their own terms.

    Time will tell what Derrida’s legacy ultimately becomes. Deconstruction was a technique rather than a system, but not everyone needs to build a system. My guess is that, two hundred years from now, some of Derrida’s writings will be ignored as misguided or silly, while some basic insights of deconstruction will be acknowledged as useful tools for probing the limitations of ideas. And everyone will wonder what all the fuss was about.

    Update: Have to include a small joke that Ed Cohn noticed in the BBC obituary:

    He was so influential that last year a film was made about his life – a biographical documentary.

    At one point, wandering through Derrida’s library, one of the filmmakers asks him: “Have you read all the books in here?”

    “No,” he replies impishly, “only four of them. But I read those very, very carefully”.

  • May 24, 1980

    By Joseph Brodsky. Translated from Russian by the author.

    I have braved, for want of wild beasts, steel cages,

    carved my term and nickname on bunks and rafters,

    lived by the sea, flashed aces in an oasis,

    dined with the-devil-knows-whom, in tails, on truffles.

    From the height of a glacier I beheld half a world, the earthly

    width. Twice have drowned, thrice let knives rake my nitty-gritty.

    Quit the country the bore and nursed me.

    Those who forgot me would make a city.

    I have waded the steppes that saw yelling Huns in saddles,

    worn the clothes nowadays back in fashion in every quarter,

    planted rye, tarred the roofs of pigsties and stables,

    guzzled everything save dry water.

    I’ve admitted the sentries’ third eye into my wet and foul

    dreams. Munched the bread of exile; it’s stale and warty.

    Granted my lungs all sounds except the howl;

    switched to a whisper. Now I am forty.

    What should I say about my life? That it’s long and abhors transparence.

    Broken eggs make me grieve; the omelette, though, makes me vomit.

    Yet until brown clay has been rammed down my larynx,

    only gratitude will be gushing from it.

  • I would totally pay for that

    I can’t even resist the ordinary greasy Philly cheesesteaks, going so far as to search out good ones here in Chicago. (Clark Street Dog does an acceptable job.) Now they’ve gone upscale.


    To quote the article:

    Served with a small bottle of champagne, Barclay Prime’s cheesesteak is made of sliced Kobe beef, melted Taleggio cheese, shaved truffles, sauteed foie gras, caramelized onions and heirloom shaved tomatoes on a homemade brioche roll brushed with truffle butter and squirted with homemade mustard.

    Perfectly calibrated, in other words, to appeal all at once to both the shameless hedonist side and the scruffy Philadelphian within me. (Although they should skip the mustard and go with gourmet ketchup instead.) Hmm, I’m visiting Penn next week to give a colloquium; think they’ll spring for dinner?

  • Hawking bests Beckham

    … as a role model for British youth. But Hawking didn’t take first prize; he lost out to rugby hero Johnny Wilkinson. What all this means, I have no idea.

  • Tangled Bank #13

    Welcome to the Lucky Thirteenth edition of Tangled Bank! A carnival of bloggy excellence in which we collect some of the best science-oriented posts of the previous two weeks. (We have taken a loose interpretation of the “previous two weeks” requirement, to feature some worthy authors that don’t have a recent science post. As you will see, we have even taken a loose interpretation of the “science” requirement!)

    The next Tangled Bank will be hosted by Prashant Mullick, and is scheduled to appear on October 20th. You can email your contribution directly to Prashant at mullickprashant@gmail.com, or to host@tangledbank.net. We are always looking for new hosts (it’s really not so hard); if you’re interested, email PZ Myers at pzmyers@pharyngula.org.

    This edition’s nineteen (count ’em!) entries will be listed in apparently-random order, according to a convoluted algorithm known only to me.

    From Richard Hoppe at The Panda’s Thumb we have an Introduction to Multiple Designers Theory. When advocates of the Intelligent Design movement claim to be thinking purely scientifically rather than theologically, what if they were telling the truth? What conclusions would they be drawn to?

    Mainstream Intelligent Design is proving itself to be scientifically vacuous. While Dembski has his Explanatory Filter and Complex Specified Information and Specified Complexity, and Behe has his Irreducible Complexity, no actual research program utilizing those concepts has emerged from the mainstream Intelligent Design movement. Therefore a revolutionary change in the conception of ID is necessary to rouse it from its empirical and theoretical slumber and to provide appropriate material for school boards and legislatures who want an alternative to modern evolutionary theory to be taught in secondary schools. Multiple Designers Theory is that revolutionary change.

    From Selva at The Scientific Indian we have The Story of Shit. No comment on this, I’m getting in enough trouble already.

    I cooked up this story at a lighter moment (pun intended). Shit is second law of thermodynamics in action. Looking at feces from a thermodynamical perspective may somewhat unburden our mind from the inherent unpleasantness of the subject matter. Besides, I have been mulling over the second law of thermodynamics, evolution and human form for a while now. All these different ideas are connected in strange ways. As part of the story of shit I am going to explain the connections I see.

    From Chris Clarke Creek Running North we have Puma, an essay on predation including a personal account of a puma encounter.

    As I rounded yet another bend in the road, the wind picked up. The breeze off the ocean had been a little gusty that afternoon, more so as I got deeper into the ravines on the east side of the ridge. That’s the only way I can explain what happened next; that the wind was too loud for the puma to hear me walking down the road. It must not have known I was there. Why else would it have leapt the guardrail to cross the road at precisely the time I arrived at said guardrail?

    From Samuel Conway we have PSA: Save a life while you sleep! It’s a personal story of bone marrow donation.

    What is the first thing that pops into your mind when I say the words “bone marrow donation”?

    I’ll tell you what it is: PAIN. That is what everyone always talks about. We read stories about donors, usually in places like Readers’ Digest, and we shudder and squirm at the thought of how agonizing it must be. My word, we say, aren’t these people heroic? The truth, however, is that the majority of donors experience only moderate discomfort, and some report feeling little or no pain at all. True, for some the procedure can be painful, but even those donors say that they would be ready to do it again in a heartbeat.

    From George Wilkinson at Keats’ telescope we have Grab that glutamate, about the natural history of GLUD2.

    This month’s Nature Genetics (subscription required) has a cool short communication by Fabien Burki and Henrik Kaessmann about a gene that is most likely only expressed in the brain, and is only found in humans and apes. This gene, GLUD2, and its more widespread relative, GLUD1, encode proteins which help break down glutamate. Glutamate is an important neurotransmitter in the brain, and can be released in large amounts during intense neural activity. However too much released glutamate can be toxic, and these two genes are important for control of glutamate levels.

    From ema at The Well-Timed Period we have Womanhood and Menses. “Having a menstrual period does not make women inferior, nor does it empower them to rule the world.”

    There is a tendency to infuse the menstrual period with all sorts of societal meanings of almost mythical proportions (e.g., the essence of womanhood, woman power, etc.). This is detrimental, especially when it comes to women making informed period-related health decisions. Why? Because, by definition, myths aren’t to be explained; they’re to be believed. This is a dangerous proposition when it comes to your health.

    From Prashant Mullick we have Fibonacci Spiral Phyllotaxis. He must be reading the Da Vinci Code!

    Phyllotaxis is the arrangement of leaves on a stem. There are several types of arrangements. One of them is a spiral pattern.

    It turns out that among plants displaying spiral phyllotaxis about 92% of them have Fibonacci phyllotaxis – the number of visible spirals are two successive elements of the Fibonacci sequence.

    From PZ Myers at Pharyngula we have PZ Myers’ Own Original, Cosmic, and Eccentric Analogy for How the Genome Works -OR- High Geekology. Is the genome a recipe, or a village of idiots? Nope, it’s a power spectrum.

    I’m a long-time microscopy and image processing geek, and you know what that means: Fourier transforms (and if you don’t know what it means, I’m telling you now: Fourier transforms). I’m going to be kind and spare you all mathematics of any kind and do a simplified, operational summary of what they’re all about, but if bizarre transformations of images aren’t your thing, you can bail out now.

    (By the way, a Fourier transform is just a change of basis in the space of functions, from one where the basis functions are delta-functions to one where they are sines and cosines. Clear now?)

    From Charlie Wagner we have A Scientific Case for Intelligent Input. Not our usual Tangled Bank fare — it’s an apologia for intelligent design, included here in the spirit of the free market of ideas. (Without any implied promise to include pseudoscience posts in future editions!)

    As you probably know, empirical data can be either observational or experimental. Observations usually come first, and hypotheses are developed. When a sufficient number of observations are collected, a pattern emerges and a theory is formulated. Additional experiments are then performed in an attempt to falsify the theory. After numerous attempts to falsify the theory, it may be elevated to the status of Law. Of course, any theory or law is subject to new data which may or may not overturn it. I have proposed Nelson’s Law and, so far as I can tell, it has not been falsified by any observational or experimental data and must be assumed to be highly likely to be true.

    From Radagast at Rhosgobel we have a set of three connected posts — They’re not so little anymore, More Manduca Pictures: Spiracles and Tracheae, and Manduca Update: They’re Wandering! I have to admit, those caterpillars are pretty cute.

    You may or may not know that insects are supposed to have three pairs of legs (six legs total), while spiders have four pairs of legs (eight legs total). Knowing this, let’s count the legs on the caterpillar pictured above. A quick count reveals that the caterpillar has sixteen legs (eight pairs), significantly more than the six it’s supposed to have. Are caterpillars not insects? Have we been wrong all along in believing that insects have six legs?

    From Jenn at Invasive Species Weblog we have Invasive Species: The Newest Threat to Property…Rights? Science meets the pervasive phenomenon of annoying neighbors.

    Invasive species, indeed any weedy species, don’t give a hoot about your property boundaries. Sometimes things that happen on your property affect others, and it’s not fair to say tough luck just because you own that plot of land. I’m sorry, but if someone notices that a bunch of trees on your property are infested with Asian longhorn beetles, I don’t think you have a right to not do anything about it. I also don’t think you should have to pay to remove the trees, and I would like to see the government help you out by maybe replanting or giving you some money. But unless you’re going to build a biodome over your land, this is about more than you and what you “own.”

    From Stephen Brophy we have Meaning Well is No Excuse. Following Richard Dawkins, he argues that it’s not okay to make people feel better by giving them false hope.

    So, the news that yet another Cancer remedy has been touted should really come as no surprise. Nevertheless, the sight of this article made my blood boil. The con-artist pushing this particular miracle cure seems to be claiming that “It works by creating an alkaline environment in which acidic cancer cells cannot survive” (So there you have it dear reader, curing cancer turns out to be one of the many uses of baking soda!). The individual making the above quoted claim is apparently a doctor. This is obscene, and the fool should be kept away from patients (It seems clear to me that his treatment represents a gross violation of his Hippopotamus Oath).

    From Ted Woollet at Dark Energy2 we have The Anthropic Principle: Good Physics or Not?? With the surprising observational result that the universe is dominated by vacuum energy that has a much smaller value than it should, cosmologists have been tempted by the idea that our observable universe is just one of many.

    According to these ideas, we exist in a “pocket universe” with a tiny (but non-zero) effective cosmological constant. Without the cosmological constant having a value in a small range around a tiny number, our variety of intelligent observers could not have evolved to a state like the present. The tiny non-zero value of the effective cosmological constant is hard to understand using traditional particle physics arguments.

    From John Fleck at inkstain we have Extinction. Can major extinctions of 10,000 years ago be blamed on weather, or are they our fault?

    One of the classic scientific debates, on a par with “nature vs. nurture,” albeit far more obscure, is the question of what caused the great megafaunal extinction at the end of the Pleistocene.

    Pretty much everywhere you look, you find evidence of big critters roaming the earth – mastodons, mammoths, big camels, and my favorite, beavers the size of black bears. And then they “blink out,” to borrow a lovely phrase I heard a biologist use recently. In a very short period of time in geologic terms, they’re gone.

    From me at Preposterous Universe we have What is this quintessence of dust? A needlessly showy quote from Hamlet, by way of introduction to different possibilities for what dark energy might be.

    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.

    From David Winter at Science and Sensibility we have the Plight of a Bumble Bee, Part One and Part Two. This is why other people can’t understand scientists — when confronted with a bumblebee infestation, they contemplate the essence of bees rather than just spraying them dead.

    Over the last few weeks my flat has been beset by slow, confused looking bumble bees. Most days at least one gets itself stuck in the house, usually trying valiantly but ultimately futilely to fly through one of our closed windows. Of course I usually try and help these wayfarers out but I was too late for one, which I found dead in our living room. I have tried to get a photo of the unfortunate bumble bee for you but technology has conspired against me, so here is one of the same species.

    From Mike at 10,000 Birds we have Flyways And Byways. Examining the remarkably well-defined migration corridors of North American birds.

    You don’t need to be a birder to know that most birds fly from temperate northern climes to more tropical southern locales for the winter. Changes in light, temperature, and food availability trigger the instinct to migrate, an urge so powerful that only a really well-stocked backyard bird feeder can override it. Migratory birds follow a variety of routes, most of which are are far more complicated than just due south. Every species has its own path.

    From Pyracantha at Electron Blue we have One of those little victories which keep me going. Pyracantha is an artist who is teaching herself math and physics.

    The fireworks are out and it’s back to math. I’m working my way through lots of logarithm problems. As you may remember from last time, I spoke in a rather agricultural way about “raising” and “rooting” numbers. How would I describe a logarithm, then? It’s a number seed which when planted, both raises and roots at the same time.

    From Wolverine Tom we have San Andreas Fault. I was only in an earthquake once, and it was a tiny one — as if the building was suddenly floating on water rather than anchored to dry land, and just as suddenly back again.

    A few days ago, a 6.0 magnitude earthquake occurred in the San Andreas Fault out in California. For those people living in the area, this is a common occurance. But why is this area so prone to earthquakes? To understand this, the geologic of the area must be known.

    Many thanks to everyone (most of whom I didn’t get a chance to thank individually) for contributing. And if I’ve left anyone out, it was just an email snafu, not a cold-hearted editorial decision — so please let me know.

  • And in other important news

    October 5th is my birthday. So if you’ve been looking for an excuse to leave a comment about how terrific I am and how much you enjoy the blog, there you go.

    (I would not ordinarily be so shameless as to volunteer such information, except that Michael Bérubé did it, and he is my blog role model.)

  • Nobel Prize in Physics for asymptotic freedom

    The 2004 Nobel Prize in Physics has been awarded to David Gross of the Kavli Institute for Theoretical Physics at UC Santa Barbara, David Politzer of Caltech, and Frank Wilczek of MIT, for their work on asymptotic freedom in quantum chromodynamics (QCD). It was predicted by Peter Woit and many others; the most obvious response is “it’s about time.”

    QCD is the theory of the strong interactions, in which quarks possess a certain “color” (purely metaphorical, of course) and are bound together in protons and neutrons by massless particles called gluons. It’s extremely similar to how protons and electrons possess a quantity called “charge” and are bound together in an atom by photons. But there is also a crucial difference — you can pull an electron apart from an atom (and thank goodness, since TV and other necessities would otherwise be impossible), but you can’t pull quarks out of protons and neutrons. The basic reason why is asymptotic freedom — the remarkable quality that the QCD force gets weaker at higher energies (short distances) and stronger at low energies (large distances). In the early ’70s physicists were struggling to understand new data on the structure of protons and neutrons from “deep inelastic scattering” experiments at the Stanford Linear Accelerator (SLAC) and elsewhere, in which high-energy electrons were fired at these heavier nuclear particles. It all snapped into place once Gross, Politzer and Wilczek discovered asymptotic freedom (through some heroic calculations) and immediately applied it to make sense of the data — the quarks were becoming free (non-interacting) asymptotically (as the energies were increased). Bjorken and others had discussed the possibility of asymptotic freedom, but it was Gross, Politzer and Wilczek who actually demonstrated that QCD (a non-abelian Yang-Mills theory, to be specific) would have that property. These days QCD is a phenomenally successful theory, and forms a crucial part of the Standard Model of particle physics. This is a Nobel Prize that is long overdue and well deserved.

    Update: Let me add a few notes to the hurried description given above. First, both Wilczek and Politzer were graduate students at the time this research was done; Gross was an assistant professor at Princeton and Wilczek’s advisor, while Politzer was advised by Sidney Coleman at Harvard. Great ideas in theoretical physics are often (always?) originated by the young. Second, both Gross and Wilczek have at different times been kind enough to write letters of recommendation for me or support me in other ways, for which I’m sincerely grateful. I recall clearly my senior year as an undergraduate at Villanova, wandering around Jadwin hall at Princeton and knocking on David Gross’s door unannounced, and how he chatted with me about what it was really like to be a theoretical physicist. At the time I had no clue who he was; now I know. Finally, Frank Wilczek was an undergraduate here at Chicago, getting his degree in math in 1970. You may ask, does that mean the UofC will count him as yet another Chicago Nobelist? Don’t be silly; of course we will. That makes 29 Nobel Prizes in the physical sciences, and counting.

  • NASA abandoning astrophysics

    One of the many benefits of being a member of the American Astronomical Society is automatic subscription to the AAS Newsletter, which is filled with such wonderful things that the current issue is not put online, so that only official members may read it. This month’s issue contained a column by new AAS president Robert Kirshner, who talked about the new (as of this summer) NASA Mission Statement. Some of Kirshner’s comments:

    … it would be a mistake to lose sight of even bigger changes taking place at NASA. NASA’s new focus on solar system exploration is expressed in their mission statement and a new set of “Level 0” requirements (even more fundamental than Level 1!) articulated by the NASA Executive Council. You can read them for yourself [here]. You might find it odd, as I did,that there is no mention of the kind of science that has proved so successful for NASA in exploring the universe beyond the solar system, with HST and smaller but fantastically important missions like WMAP. These basic requirements don’t suggest that studying black holes, gravitational waves, dark energy, or even the assembly of galaxies at the dawn of time must be part of NASA’s portfolio.

    […]

    But these requirements are aimed quite sharply at something else: “extending human presence across the solar system and beyond.” Many AAS members will see themselves as part of that presence, but having so much astronomy compressed into “and beyond” makes me wonder if the ground has not shifted beneath our feet. The whole elaborate process of Decadal reports, followed by careful working out of roadmaps with lots of community input through a vigorous advisory mechanism has been a good thing for the astronomical community, and a good thing for NASA. This new change in direction doesn’t seem to involve any of those sources of wise counsel. I think we should pay attention to this, talk to our colleagues at NASA, and try to understand what is happening. We live in interesting times.

    Couldn’t have said it better myself (and I have tried). It’s worth taking a look at those “requirements” in the mission statement — not a single reference to the universe outside the solar system. When I give colloquia, I like to say that the 1990’s will go down in human history as the decade in which we figured out what the universe was made of, pinning down the cosmic inventory of ordinary matter, dark matter, and dark energy. Those determinations were due in large part to observations by NASA missions of galaxies, supernovae, and the cosmic microwave background. Think that stuff is interesting? Hope you enjoyed it, since we might not get any more.

    When Sean O’Keefe became the new NASA administrator, scientists were cautiously optimistic — he was not a scientist himself, but had a reputation as a manager and a results-oriented kind of guy, and astrophysics was the one thing at NASA that consistently got great results (as opposed to, let’s just say, the International Space Station). We were wrong. And as Kirshner says, there is a frustrating move away from a system of rigorous study and sensitivity to community input — a move which, if nothing else, fits in well with the overarching philosophy of the current administration.

    I’m not sure if it’s too late to stop NASA from completely abandoning astrophysics. But any time you get the chance, make noise about it to people who matter. It would be a shame if this decade went down in human history as the one in which we stopped caring about what the universe is made of.

  • Tangled Bank coming up

    Don’t forget that the next edition of Tangled Bank is due to appear here this Thursday, October 6th. So if you have any especially interesting science posts on your blog, or know of any lurking out there, just send an email my way (carroll@theory.uchicago.edu).

    In unrelated news, today is Von Freeman‘s 82nd birthday. (And The Great Divide is getting incredible reviews.) Happy birthday Vonski!