Sean Carroll

Author: Sean Carroll

  • Soliciting Advice: Non-Academic Careers for Ph.D.’s

    While the previous post bemoans the lack of simple world-changing ways to make the career path for aspiring academics more pleasant (other than bushels of money falling from the sky, of which I would approve), there is one feasible thing that everyone agrees would be good: better career counseling for Ph.D. students, both on the realistic prospects for advancement within academia, and concerning opportunities outside.

    I always try to be honest with my own students about the prospects for ultimately landing a faculty job. But like most faculty members, I’m not that much help when it comes to outside opportunities, having spent practically all my life within academia. I’m happy to give advice, but you’d be crazy to take it, since I have no idea what I am talking about.

    But that’s a correctable state of affairs. So: I’m hereby soliciting good, specific career advice and/or resources for students who are on the track to get a Ph.D. (or already have one) and are interested in pursuing non-academic jobs. This might be particular jobs that are Ph.D.-friendly, or websites with good information, or relevant fellowships or employment agencies, or just pointers to other resources. (For example: do you know the difference between a CV and a resume?) The more specific the better, and including useful links is best of all. General griping and expressions of bitterness should be kept in the previous thread; let’s try to be productive. And there’s no reason to limit it to physics, all fields are welcome. Advice that is useful for only a tiny number of people, but extremely useful for them, is certainly sought. We’re looking for things that have a nontrivial chance of actually helping some specific person at a future date.

    Most of all it would be great to have input from people who actually got a Ph.D. and then went on to do something else. But it’s the internet, everyone can chime in.

    I will take what look like the most helpful suggestions and collate them into a separate post. Spread the word, let’s get as much input from different sectors as we can.

  • Toward More Comfortable Bottlenecks

    Jessica at Bioephemera posts a provocative quote about the way we train and employ young people who are seeking careers in academia:

    They’re doing exactly what we always complain our brightest students don’t do: eschewing the easy bucks of Wall Street, consulting or corporate law to pursue their ideals and be of service to society. Academia may once have been a cushy gig, but now we’re talking about highly talented young people who are willing to spend their 20s living on subsistence wages when they could be getting rich (and their friends are getting rich), simply because they believe in knowledge, ideas, inquiry; in teaching, in following their passion. To leave more than half of them holding the bag at the end of it all, over 30 and having to scrounge for a new career, is a human tragedy.

    — William Deresiewicz, The Nation

    The author goes on to bemoan this “colossal waste of human capital” — all those talented young people spending time getting Ph.D.’s, then not eventually landing faculty jobs, when they could be going right into productive careers in some other field.

    I’m sincerely unsure what to think about the occasional complaints one hears along these lines. On the one hand, I firmly believe that the grad school/postdoc/junior faculty years should be enjoyable ones, not days of peril and gloom living under a cloud of uncertainty. If there were a way to make the journey easier, I would be all for it. I can think of small ways to do so, and am certainly in favor of such incremental improvements.

    But on the other hand, I really can’t think of any sensible major improvements, for a simple reason: there are many people who would like to be academics, and few available jobs. Short of multiplying the number of college professorships by a factor of three or so, I’m not sure how to address the primary cause of this anxiety — the difficulty in getting jobs. If you knew you were going to land a tenured spot at a good place, it would be much easier to bear the indignities of grad-student/postdoc level salaries for a few years. Deresiewicz says, “If we don’t make things better for the people entering academia, no one’s going to want to do it anymore.” But if that were true, why are there so many “highly talented young people who are willing to spend their 20s living on subsistence wages when they could be getting rich”? These seem to be contradictory worries.

    Obviously one thing to do would be to dramatically cut down on the number of people who get into graduate school. But that just moves the bottleneck around, it doesn’t change its overall size. And I don’t want to be the one who says to a somewhat-promising-but-not-superstar-quality grad school applicant, “Sorry, I’d enjoy working with you, but we’ve decided not to admit you because in our judgement your chances of eventually getting a faculty job aren’t quite as good as some of our other applicants. So you see, it’s for your own good.” Generally the people who advocate this kind of strategy are the ones who have already been admitted to grad school. (If you’re waiting for Deresiewicz’s solution, here it is: “The answer is to hire more professors.” Well, okay then.)

    Again, I honestly don’t know what should be done. I would love to improve the lifestyle and general well-being of students and postdocs in any feasible way. Not sure what that way would be.

  • Thor Points

    Having finally seen Thor on screen, I’m happy to give it thumbs-up. It works well as a summer superhero movie, and the acting — especially Tom Hiddleston as Loki, but also Chris Hemsworth as Thor — was much better than average for this kind of fare. (See takes from Adam Frank and Kyle Munkittrick.)

    Also, needless to say, it did a great job of advancing the secret atheist agenda.

    And the science? I was pretty happy with how it turned out. It was made clear that all of the super-ness was ultimately based on (some hypothetical set of) laws of physics, not just magic pulled out of the air — without descending into a dreadful level of midichlorian-like overexplanation. There is one phrase used in the movie that I think is directly attributable to my input: “Einstein-Rosen bridge.” This came about from a conversation between producer Kevin Feige and me that went something like this:

    KF: We need the Bifrost Bridge to provide a way for the characters to travel great distances in space in a very short period of time.

    SC: Sure, you probably want to say that it makes use of wormholes.

    KF: Well, we can’t call it a “wormhole.”

    SC: Why not?

    KF: Sounds too Nineties.

    SC: I suppose … you could call it an “Einstein-Rosen bridge.” Means the same thing.

    So naturally, in the finished film, Jane Foster calls it an Einstein-Rosen bridge, and someone says “what’s that?”, and she replies “it’s a wormhole.”

    Jennifer pointed out afterward that, while Jane Foster’s scientist character was appealing and a good role model, they did miss a chance to make use of her love of science in the service of the story. While we see our Earth-based heroes zooming around the desert chasing atmospheric anomalies, the connection to astrophysics is never explained, nor do they really talk that much about science. In one scene Jane makes goo-goo eyes at Thor as he talks about all this apparent magic just being very advanced science. Goo-goo eyes are fine, but any real scientist in that situation would have started asking questions about spacetime and exotic matter and quantum stability and so on. It would have been great if we had seen Jane fall for Thor, not because of what he looked like without his shirt on, but because behind the gruff exterior he knew more deep physics than she did. Maybe in a sequel.

    I hinted that there was one thing all the scientists warned the moviemakers not to do, and indeed they didn’t do it. In one conception, the planet of the Frost Giants was to be shaped like a disk. Not a ringworld-style band that used rotation to mimic gravity, but just a flat planet in the shape of a record (or a DVD, for you youngsters). Which is fine, if somewhat fanciful. The potential disaster was that they wanted to have a big fight scene where frost giants would fall off the edge of the planet. Pulled by … what, exactly? Total gravity Fail. Fortunately they ditched that idea, although the concept survived in less egregious form in the depiction of Asgard, which looks like a mountain that sits on top of a galaxy. That also makes no sense, but it’s so far from trying to make sense that the audience just sees it as poetic license, not a simple mistake.

  • 3tweets

    It started with an innocent, and possibly joking, request on Twitter: “Can you explain M-theory?” Having previously been asked to defend the Many-Worlds Interpretation of quantum mechanics and various other topics, I didn’t take it very seriously.

    But upon further reflection — why not? Obviously nobody is going to give a full and comprehensible account of any reasonably complex topic when limited to 140 characters, but it might be fun and even useful to try to distill the basic point of something down to its tweetable essence. Still, in a single tweet there is almost no chance to do much but introduce jargon, so I decided to allow myself three tweets. Here’s my go at summarizing M-theory. (Remember chronology is bottom-up.)

    Obviously, there is more to be said, but I think some actual information is conveyed. Different people might choose different aspects of a subject to spend their precious three tweets on, but that’s part of the beauty. As someone pointed out, a poetic aspect results from subjecting yourself to such stringent limitations on what you can say.

    And if it works for M-theory, what else? And thus a hashtag was born: #3tweets. Yesterday I took a stab at the Higgs boson.

    This reminded me that quantum field theory is probably the single most under-popularized subject in all of fundamental physics. Particle physics, yes; string theory, sure; quantum mechanics, endlessly; but the structure of QFT itself is rarely explained in its own right. It’s worth at least a few tweets.

    I certainly hope to try a few more examples. But — it’s everyone’s internet. Feel free to join in, with new topics or ones previously covered. I’m sure someone has a different take on quantum field theory than I do.

  • Science and Philosophy Interview

    Fabio Gironi recently interviewed me at length for an issue of Speculations, a “Journal of Speculative Realism.” The subject was science and philosophy, which I’ve been known to opine about at some length. But here we’re talking great length indeed. The interview isn’t available separately, but you can download the pdf of the whole issue here (or buy it as a bound copy). My bit starts on page 313. (The rest of the issue is also worth checking out.)

    I’m a big believer that academic disciplines should engage in messy interactions, not keep demurely separate from each other. But it’s a tricky business. Just because I’m (purportedly) an expert in one thing doesn’t make me an expert in everything else; on the other hand, it is possible that one area has something to offer another one. So I am in favor of dabbling, but with humility. It’s good for people to have thoughts and opinions about issues outside their immediate expertise, and to offer them in good faith, but it’s bad if they become convinced that experts in other areas are all idiots. So when you find yourself disagreeing with the consensus of expertise in some well-established field, it might very well be because of your superior insight and training, or maybe you’re just missing something. Hopefully in an exchange like this I have something to offer without making too many blunders that would make real experts cringe.

    Here’s a sample of the interview.

    SC: I would be extremely suspicious of any attempts to judge that the world must ‘necessarily’ be some way rather than any other. I can imagine different worlds—or at least I think I can—so I don’t believe that this is the only possible world. That would also go for any particular feature of the laws this world follows, including their stability. Maybe the laws are constant through time, maybe they are not. (Maybe time is a fundamental concept, maybe it isn’t). We don’t yet know, but it seems clear to me that these are empirical questions, not a priori ones. Because we want to understand the world in terms that are as simple as possible, the idea that the underlying laws are stable is an obvious first guess, but one that must then be tested against the data. Said in a slightly different language: any metaphysical considerations concerning what qualities the world should properly have can be taken seriously and incorporated into Bayesian priors for evaluating theories, but ultimately those theories are judged against experiment. We should listen to the world, not decide ahead of time what it must be.

  • Cheerful Renaissance Thought of the Day

    Wayne Knight, who played Newman on Seinfeld, also appeared in Space Jam, surely one of the top ten movies about cartoon characters and basketball ever made. When asked what it was like to work with Michael Jordan, he diplomatically replied: “Acting with Michael Jordan is like bowling with Picasso.” Just because you’re the best in the world at one thing doesn’t mean you will excel at something else.

    Which brings me to Michelangelo’s poems. I am sufficiently uncultured that I always thought of Michelangelo as basically a sculptor, perhaps a bit of a painter. But then I reviewed a book for Princeton University Press, and they offered as recompense to let me choose a few volumes from their back catalogue; that’s where I came upon his Complete Poems. Who knew?

    Michelangelo was not exactly writing Hallmark cards. Think early Leonard Cohen. He specialized in sonnets and madrigals, and while there are a number of love poems, usually he ranges from grumpy and forlorn to deep existential despair. Here’s a sunny little ditty you can reach for whenever you feel your own artistic endeavors are falling short. (Translation by Creighton Gilbert.)

    I keep a hornet in a water jar,
    Inside a leather sack some strings and bones,
    And in a canister three balls of tar.

    My pale blue eyes are powdered into grounds,
    My teeth are like keys on an instrument,
    So, when they move, my voice is still or sounds.

    My face has the shape that causes fright;
    In wind when there’s no rain my clothes would scare
    Crows from the seed, without another dart.

    A spider web is nestled in one ear,
    All night a cricket in the other buzzes;
    With spitting breath I do not sleep, but snore.

    Love, and the flowered grottoes, and the muse,
    My scrawls for tambourines or dunces’ caps,
    Go to innkeepers, toilets, bawdy houses.

    What use to want to make so many puppets,
    If they have made me in the end like him
    Who crossed the water, and then drowned in slops?

    My honored art, wherein I was for a time
    In such esteem, has brought me down to this:
    Poor and old, under another’s thumb,

    I am undone if I do not die fast.

  • Happy Birthday David Hume

    David Hume, famous scolder of those who would derive “ought” from “is,” was born 300 years ago today. In point of fact Hume, while not enjoying the name recognition of Plato/Aristotle/Descartes/Kant, is certainly in the running for greatest philosopher of all time. He was a careful thinker, resistant to dogmatic answers, and a relatively sprightly writer as philosophers go. An empiricist who was as persuasive about the temptations of radical epistemological skepticism as anyone, but was still able to resist them. His tercentenary is well worth celebrating.

    Dan Sperber, via Henry Farrell, suggests that we celebrate by posting quotes from Hume. When I first encountered him as a college freshman, it was in the context of a theology course where we were reading Dialogues Concerning Natural Religion. I was intrigued when our professor pointed out a passage that seemed to prefigure Darwin’s theory of natural selection, which wasn’t going to appear until 82 years later. My dog-eared copy seems to have gone missing, but I found the quote at The Rough Guide to Evolution.

    “And this very consideration too, continued PHILO, which we have stumbled on in the course of the argument, suggests a new hypothesis of cosmogony, that is not absolutely absurd and improbable. Is there a system, an order, an economy of things, by which matter can preserve that perpetual agitation which seems essential to it, and yet maintain a constancy in the forms which it produces? There certainly is such an economy; for this is actually the case with the present world. The continual motion of matter, therefore, in less than infinite transpositions, must produce this economy or order; and by its very nature, that order, when once established, supports itself, for many ages, if not to eternity.

    But wherever matter is so poised, arranged, and adjusted, as to continue in perpetual motion, and yet preserve a constancy in the forms, its situation must, of necessity, have all the same appearance of art and contrivance which we observe at present. All the parts of each form must have a relation to each other, and to the whole; and the whole itself must have a relation to the other parts of the universe; to the element in which the form subsists; to the materials with which it repairs its waste and decay; and to every other form which is hostile or friendly. A defect in any of these particulars destroys the form; and the matter of which it is composed is again set loose, and is thrown into irregular motions and fermentations, till it unite itself to some other regular form.”

    To me now, it looks like something of a cross between Darwin — successful forms persevering among the chaos — and the Lucretius/Boltzmann scenario of the universe coming into existence through the random motion of atoms. (What makes Lucretius and Hume brilliant thinkers but Boltzmann and Darwin influential scientists is that the latter grappled closely with data, not just with ideas.)

    The common thread among all these thinkers: trying to explain the origins of order in the absence of teleology. The fact that we can do that successfully in biology, and are hot on the trail in cosmology, is a milestone achievement in the history of human thought.

  • Can’t Really Blame Them

    Very excited to learn that my talk from TEDxCaltech is featured on the TED home page today. They have their own comment thread, and in a couple of weeks we’ll have a live call-in “conversation with the speaker” deal. If the Twitters are to be believed, these TED talks are pretty darn popular.

    The talk is a punchy, 15-minute version of my usual cosmology-and-the-arrow-of-time schtick. Glad to see the arrow of time get some more publicity; sophisticated Cosmic Variance readers know all about it, but not everyone is so lucky. When Brian Cox did an episode of Wonders of the Universe that discussed the arrow of time, the comments were all “Wow, what an amazing concept, never heard of that!” Obviously reading the wrong blogs.

    But I can’t help but notice something about the presentation on the TED home page…

    Each talk is advertised by an image from the video; in most cases it’s a picture of the speaker actually giving the talk. But for mine, they (wisely) went with the Hubble Deep Field.

    Lesson: you can’t compete with the universe! It’s bigger, smarter, and prettier, too.

  • The Mighty THOR

    I know everyone is excited about this weekend’s premiere (at least here in the U.S.) of Thor, the latest superhero extravaganza from Marvel studios. At least I am, for my usual selfish reasons: I helped do some consulting (through the Science and Entertainment Exchange) for the movie. Also, there is a mystical hammer that smashes things; what’s not to like?

    Thor – Trailer 2 (OFFICIAL)

    Unlike TRON: Legacy, where we came in after the screenplay had been drafted, on Thor we came in near the beginning. Marvel had done a lot of work on the idea, but there wasn’t yet a script. The Exchange set up a consult meeting with director Kenneth Branagh, the screenwriter, and few people on the design and production side of things, along with three scientists — Jim Hartle from USCB, Kevin Hand from JPL, and myself.

    We bandied around lots of issues relating to the Thor universe and how it fit in with Marvel’s bigger plans. Once there was a script, I came in to read it and offer some more comments. Since that time, the script was re-written by the dynamic duo of Ash Miller and Zack Stentz, and I haven’t actually seen the film yet, so I can’t speak to what kind of impact we had in the end. Let’s just say that there was one thing in particular that they were planning on doing in the movie that drove all the scientists batty — I think we convinced them to fix it, but we’ll have to see. And once filming started, they recruited Caltech student Kevin Hickerson to help with the tech-gadgetry end of things. So I have high hopes. (Early reviews are very positive. And of course, Agent Coulson returns, with a larger role than in the Iron Man films. Everyone loves Agent Coulson.)

    You might be wondering, where is there room for any sort of science in a comic-book movie about a Norse god in a red cape who swings a magical hammer? Well I’m glad you asked. Actually there were a couple of different things where the movie people were very interested in our input. One was constructing a coherent framework for the Marvel universe — ultimately, this story about Thor the thunder god is going to have to be compatible with Tony Stark’s Iron Man world, since the two characters are both part of the Avengers. (I also got to read the script for that, and yes — it is as great as the rumors suggest.)

    Kevin Feige, president of production at Marvel Studios, is a huge proponent of having the world of these films ultimately “make sense.” It’s not our world, obviously, but there needs to be a set of “natural laws” that keeps things in order — not just for Iron Man and Thor, but all the way up to Doctor Strange, the Sorcerer Supreme who will get his own movie before too long. The thinking here is very much based on Arthur C. Clarke’s “any sufficiently advanced technology is indistinguishable from magic.” In the trailer above, Thor basically gives exactly this pitch to Jane Foster.

    That’s the other area where we science consultants were able to help out: (more…)

  • Dark Matter is Just Messing With Us Now

    The state of play in dark matter searches just refuses to settle down. Just a few weeks ago, the XENON100 experiment released the best-yet limits on WIMP dark matter (a two-dimensional parameter space, “mass of the dark matter particle” and “cross section with ordinary matter”). These limits seemed to firmly exclude the hints of a signal that had been trickling in from other experiments. But… the story isn’t over yet.

    Remember that XENON, like CDMS and other experiments, tries to find dark matter by making a very quiet experiment and picking out individual events where a dark matter particle bumps into a nucleus inside the detector. There is a complementary strategy, looking for annual modulations in the dark matter signal: rather than being very picky about what event is and is not a DM interaction, just take lots of events and look for tiny changes in the rate as the Earth moves around the Sun. Dark matter is like an atmosphere through which we are moving; when we’re moving into a headwind, the rate of interactions should be slightly higher than when our relative speed through the ambient dark matter is smaller. The DAMA experiment was designed to look for such a modulation, and it certainly sees one. The problem is that lots of things modulate on a one-year timescale; as Juan Collar explained in a guest post here, there were many questions about whether what DAMA is detecting is really dark matter.

    Now one of Juan’s own experiments, CoGeNT, has seen (very tentative) hints of an annual modulation itself! CoGeNT had already teased us with a hint of a dark matter signal, which (like DAMA) seemed to imply lower masses (about 10 GeV, where 1 GeV is the mass of a proton) rather than the usual masses for weakly-interacting dark matter favored by theorists (hundreds of GeV). But the competitor experiment CDMS, and later of course XENON, seemed to put the kabosh on those claims. The CDMS result was especially hurtful to CoGeNT’s claims, as both experiments use germanium as their detector material. Theorists are very clever at inventing models in which dark matter interacts with one substance but not some other substance (see e.g.), but it’s harder to invent models where dark matter interacts with one substance in one experiment but not the same substance in some other experiment.

    Yesterday Juan Collar gave a talk at the April Meeting of the APS, where he revealed something about CoGeNT’s latest findings. (I don’t think there’s a paper yet, but it’s supposed to come very soon, and they are promising to share their data with anyone who asks.) Now, unlike for their earlier results, they are explicitly looking for annual modulation. And … they see it. Maybe. Well, not really enough to take it seriously, but enough to be intrigued. Or, in science-speak: it’s a 2.8 sigma result. It doesn’t seem to have hit the news very hard, but there are writeups by Valerie Jamieson and David Harris. The CoGeNT folks have 442 days of data, with a rate of about three events per day.

    Ordinarily, a tasteful physicist would claim that a 2.8 sigma result doesn’t even rise to the level of “intriguing”; you need three sigma to count as “evidence,” and five sigma for “discovery,” by the accepted standards of the field. The reason this is even blogworthy (a low bar indeed) is that it’s the first attempt to check DAMA by looking for an annual modulation signal, and the result matches the phase of DAMA’s oscillation, and is claimed to be consistent with its amplitude (the experiments use different materials, so it’s hard to do a direct comparison). Also, of course, because the team was looking to bury DAMA, not to praise it: “We tried like everyone else to shut down DAMA, but what happened was slightly different.” On the other hand, what you would need to explain this purported signal is at first glance still very much incompatible with XENON’s limits.

    In the end: probably still nothing to get too excited about. But at least it will keep the pot boiling a while longer. Don’t fear; the experiments are getting better and better, and temporary confusions eventually evaporate. Or are swept away by the dark matter wind.