Bhindi Bhagee

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Regardless of how unhip I may be now (a matter for everyone to decide for themselves), it’s nothing compared to how unhip I was growing up, especially when it came to music. The first 45rpm single I ever purchased was by Kiss, and the first full-length LP was by the Electric Light Orchestra; let us say no more about that.

In particular, I didn’t know anything about punk rock, and certainly didn’t come close to appreciating the genius of the Clash. Sure, I knew Rock The Casbah from the video on MTV (although little did I suspect it would some day become a conservative rock anthem, the Clash being secret Republicans at heart). But I didn’t at all understand the skill and passion with which the band blended hard-core punk sensibilities with a disparate palate of musical influences.

Joe Strummer Which is just as well, as my lack of familiarity allowed me to fall in love with frontman Joe Strummer on the basis of his solo work with backing band The Mescaleros. After the Clash broke up in 1986, Strummer’s output waned, while he appeared in a couple of films and contributed some soundtrack music. Then, starting in 1999, he released a series of three albums of astonishing range and beauty: Rock Art and the X-Ray Style, Global a Go-Go, and Streetcore. The last of these, sadly, was posthumous, as Strummer died unexpectedly of a heart attack in 2002. (I’m sure everyone else knows all this. Me, I never whould have discovered Strummer if Mondo Bongo hadn’t been prominently featured on the soundtrack for Mr. and Mrs. Smith. Thanks, Brad and Angelina!)

Reviews of Strummer’s solo work have been largely positive, but somewhat tempered by confusion due to a lack of obvious continuity with his punk roots. Personally, I think that if the albums are considered in their own right, rather than as “by the guy from the Clash” with all the preconceptions that implies, they are an amazing achievement. Strummer was always interested in different genres of music (and reggae was an important influence on the Clash), but here he mixes a mad panopoly of styles — from punk to folk to reggae to rockabilly to Middle Eastern to Latin to African and on — with equally eclectic instrumentation and colorful lyrics. (Where “colorful” should occasionally be taken to mean “surreal bordering on nonsensical,” unless I was patrolling a Pachinko / Nude noodle model parlor / in the Nefarious zone is more transparent to you than it is to me.) Along with drums/bass/guitar, a Mescaleros song might feature violin, whistle, mandolin, organ, conga, bells, bodhran, udu, accordion, saxophone, dulcimer, and/or whatever else was lying around. While he could still rock with the best of them, Strummer could also step back with an acoustic tune like Bob Marley’s Redemption Song (also recorded elsewhere in a duet with Johnny Cash).

You can get a good idea of the playful energy, at once exuberant and reflective, of Strummer’s later music from the lyrics to Bhindi Bhagee. It’s a song about eclectic food choices, but there is an explicit parallel (which the lyrics are happy to spell out) with eclectic musical choices. Of course, if you listen to a bit, the energy is even more obvious.

Well, I was walking down the High Road
And this guy stops me
He’d just got in from New Zealand
And he was looking for mushy peas
I said, no, we hadn’t really got ’em round here
I said, but we do got

Balti, Bhindi, strictly Hindi
Dall, Halal and I’m walking down the road
We got rocksoul, okra, bombay duck-ra
Shrimp beansprout, comes with it or without – with it or without
Bagels soft or simply harder
Exotic avocado or toxic empenada
We got akee, lassi, Somali waccy baccy
I’m sure back home you know what tikka’s all about – what tikka’s all about

Welcome stranger to the humble neighborhoods
You can get inspiration along the highroad

Hommus, cous cous in the jus of octopus
Pastrami and salami and lasagne on the go
Welcome stranger, there’s no danger
Welcome to this humble neighborhood

There’s Balti, Bhindi, strictly Hindi
Dall, Halal and I’m walking down the road
Rocksoul, okra, bombay duck-ra
Shrimp beansprout, comes with it or without

So anyway, I told him I was in a band
He said, “Oh yeah, oh yeah – what’s your music like?”
I said, “It’s um, um, well, it’s kinda like
You know, it’s got a bit of, um, you know.”

Ragga, Bhangra, two-step Tanga
Mini-cab radio, music on the go
Um, surfbeat, backbeat, frontbeat, backseat
There’s a bunch of players and they’re really letting go
We got, Brit pop, hip hop, rockabilly, Lindy hop
Gaelic heavy metal fans fighting in the road
Ah, Sunday boozers for chewing gum users
They got a crazy D.J. and she’s really letting go

Oh, welcome stranger
Welcome stranger to the humble neighborhoods

Well, I say, there’s plenty of places to eat round here
He say, “Oh yeah, I’m pretty choosy.”

You got
Balti, Bhindi, strictly Hindi
Dall, Halal, walking down the road
Rocksoul, okra, bombay duck-ra
Shrimp beansprout, comes with it or without
Let’s check it out

Welcome stranger to the humble neighborhoods, neighborhoods
Check out all that

Por-da-sol, por-da-sol
Walking down the highroad

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The String Theory Backlash

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In October 1984, it was announced that the Nobel Prize for Physics had been awarded to Carlo Rubbia and Simon van der Meer, for the discovery of the W and Z bosons at the UA1 experiment at CERN just the previous year. This was the capstone discovery in the establishment of the Standard Model of particle physics. The third generation of fermions had already been discovered (the tau lepton by Martin Perl in 1977, the bottom quark by Leon Lederman also in 1977), and the nature of the strong interactions had been elucidated by deep-inelastic scattering experiments at SLAC in the late 1960’s and early 1970’s. Unsuspected by many, particle physics was about to enter an extended period in which no truly surprising experimental results would emerge; subsequent particle experiments have only been able to confirm the Standard Model over and over again, including the eventual discovery of the top quark at Fermilab in 1995. (Astrophysics, of course, has provided substantial evidence for physics beyond the Standard Model, from neutrino oscillations to dark matter and dark energy.)

A month earlier, in September 1984, Michael Green and John Schwarz submitted a paper on anomaly cancellation in superstring theories. String theory had been around for a while, and it had been understood for ten years that it predicted gravity, and was a candidate “theory of everything.” But there were many such candidates, each of which had run into significant difficulties when taken seriously as a theory of quantum gravity. Most people who were paying attention had presumed that string theory would face the same fate, but the Green-Schwarz result convinced them otherwise. A brief article in Physics Today was entitled “Anomaly Cancellation Launches Superstring Bandwagon,” and theorists everywhere jumped to learn everything they could about the exciting new possibilities the theory offered.

So here we are, over twenty years later, still with no surprising new results from particle accelerators (although hopefully that will change soon), and still with strings dominating the landscape (if you will) of theoretical high-energy physics. And still, one hardly needs to mention, with no clear path to connecting string theory to low-energy phenomenology, nor indeed any likely experimental tests of any sort.

In the circumstances, it’s not surprising there would be something of a backlash against string theory. The latest manifestation of anti-stringy sentiment is in two new books aimed at popular audiences: Peter Woit‘s Not Even Wrong: The Failure of String Theory and the Continuing Challenge to Unify the Laws of Physics, and Lee Smolin’s The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next. I haven’t read either book, so I won’t presume to review them, but I think we’ve heard the core arguments expressed on this blog and elsewhere. I’m a firm believer that it’s good to have such books out there; I’m happy to let the public in on our internecine squabbles, just as I’m happy to keep them updated on tentative experimental results and speculative theoretical ideas. It seems unduly patronizing to think that we can’t reveal anything to the wider world until everyone in the community agrees on it.

But I don’t actually agree with what the books are saying. Here is the main point I want to make with this post, trite though it may be: the reason why string theory is so popular in physics departments is because, in the considered judgment of a large number of smart people, it is the most promising route to quantizing gravity and moving physics beyond the Standard Model. I don’t necessarily want to rehash the reasons why people think string theory is promising — I’m not positing an objective measurement of the relative merits, but simply an empirical observation about people’s best judgments. Rather, I just want to emphasize that, when you get right down to it, people like string theory for intellectual reasons, not socio-psycho-political ones. It’s not a Vast String Theory Conspiracy, funded by shadowy billionaires who funnel money through Princeton and Santa Barbara to brainwash naive onlookers into believing the hype. It’s trained experts who think that this is the best way to go, based on the results they have seen thus far. And — here’s the punchline — such judgments could change, if new results (experimental or theoretical) came along to suggest that there were some better idea. The way to garner support for alternative approaches is not to complain about the dominance of string theory; it’s to make the substantive case that some specific alternative is more promising. (Which people are certainly trying to do, in addition to the socio-psycho-political commentating about which I am kvetching.)

That is, after all, the way string theory itself became popular. Green and Schwarz labored for years on a relatively lonely quest to understand the theory, before they were able to demonstrate anomaly cancellation. This one result got people psyched about the theory, and off it went. It’s not a matter of impressionable young physicists docilely obeying the dictates of their elders. Read Jacques Distler’s (absolutely typical) story about how he dived into string theory as a graduate student, despite the fact that his advisor Sidney Coleman wasn’t working on it. In a completely different field, listen to Nobel-winning economist Gary Becker on the response to his ideas (via Marginal Revolution):

“There was a sea change. I began to notice it in the 1970s and 1980s. A lot of the younger people coming out of Harvard, MIT and Stanford were very interested in what I was doing, even though their faculty were mainly – not entirely – opposed to the sort of stuff I was doing.”

This is just how academics act. They are stubborn and willful (even at a charmingly young age!), and ultimately more persuaded by ideas than by hectoring from their elders. And it’s not just the charmingly young — if good ideas come along, supported by exciting results, plenty of entrenched middle-aged fogeys like myself will be happy to join the party. If you build it, they will come.

There’s no question that academic fields are heavily influenced by fads and bandwagons, and physics is no exception. But there are also built-in mechanisms that work to protect a certain amount of diversity of ideas — tenure, of course, but also the basic decentralized nature of university hiring, in which different departments will be interested in varying degrees in hiring people in certain fields. Since the nature of science is that we don’t yet know the right answers to the questions we are currently asking, different people will have incompatible intuitions about what avenues are the most promising to pursue. Some people are impressed by finite scattering amplitudes, others like covariant-looking formulations, others don’t want to stray too far from the data. The thing is, these considered judgments are the best guide we have, even if they are not always right. Green and Schwarz were lonely, but they persevered. If you want to duplicate their success, find a surprising new result! You can’t ask a department to hire people in an area they don’t think is promising, just because it serves the greater goal of diversifying the field overall. Crypto-socialist pinko though I may be in the political arena, when it comes to intellectual life I’m a firm believer in the free market of ideas, and would tend to resist affirmative-action programs for underrepresented theories.

…

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Help Public Schools, Protect the Honor of Physics

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In the noble tradition of using the power of blogs for good, Janet at Adventures in Ethics and Science has organized an effort at ScienceBlogs to raise money for school teachers who want to get their students excited about science. It’s an unimpeachably good cause, no matter where your political sympathies might lie.

Donors Choose So all the ScienceBloggers are kicking in, with only one problem: they are dominated over there by the squishy sciences, leaving physicists in the dust. So we here at Cosmic Variance, in the spirit of disciplinary solidarity, are suggesting that you visit Chad at Uncertain Principles and drop a few dollars onto his donor list. Let’s see if we can’t teach those life-science types a thing or two about altruistic selection. (There are even contests you can win, so any Objectivists motivated entirely by enlightened self-interest are also encouraged to participate.)

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Welcome to the Blogosphere

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No, not you; you’re already here in the blogosphere. I’m talking about all those physicists out there to whom “blog” sounds like something you feel compelled to do after doing too many Smirnoff shots the previous evening, rather than the place you go for the most erudite and challenging large-scale conversation in human history.

Blogs are a tool of immense power that people haven’t quite figured out how to use quite yet. Physicists, in particular, have been slow to take advantage of this new medium (with a few brave and laudable exceptions, of course). A peek at our blogroll or a visit to Mixed States would give the impression that there is a lot of physics blogging out there, which is certainly true; but “a lot” needs to be compared with the dominance of more traditional forms of communication (papers, talks, conferences, books, journalism), or the much more eager adoption of blogging by the tech community, or even within academia by law professors and social scientists. Professional physics, let’s face it, is a step removed from the concerns of most people on the street, and rather than work to overcome this barrier by making the excitement of their research more accessible, most working physicists are happy to remain relatively isolated within their research communities. Besides, blogging takes time, and who has that?

It was with Luddite preconceptions such as these in mind that I recently wrote a Back Page article for APS News, the house newsletter of the American Physical Society, on the joys of blogging. I was invited by Jennifer Ouellette, who is the assistant editor of APS News when not blogging up a storm in her own right at Cocktail Party Physics (and who was also at YearlyKos). Most people don’t know anything about blogs, and if they haven’t actually started reading them it’s quite difficult to give an accurate description. So I tried right from the start to defuse some of the most pernicious stereotypes.

I know what you’re thinking. You’ve heard of these things called “blogs,” some sort of web journals feverishly updated by pajama-wearing authors convinced that the world is in desperate need of access to their innermost thoughts. Who has time to pay attention to such frivolities? Fortunately, as serious physicists we need not worry that our lives will be affected by this latest example of overhyped cyber-enthusiasm. Just like our lives were unaffected by the advent of email and electronic preprints.

When I’m asked what blogs are all about, I start by saying they are like magazines—collections of serially presented articles (called “posts” in the blog context), published on the internet instead of in bound paper editions. Blogs are a technology for conveying information. Like magazines, blogs can be about anything. The purposes to which we choose to put this technology are nearly infinitely flexible.

I go on to talk about some of these purposes, in particular the distinct (but complementary) ideas of using blogs for technical conversations between researchers, vs. spreading news and musings about science to a wider audience, vs. random discussions about whatever you want because hey, it’s your blog.

One of the things that people really don’t quite get, until they’ve taken the plunge themselves, is how easy it is to start up a new blog. At the lowest level of effort, anyone can start a brand-new blog for free within minutes by popping over to Blogger and just signing up. Give yourself an hour or two to choose a name and a color scheme, and you’re off. If you spend another hour setting up a blogroll and remember to occasionally link to other bloggers, they will notice you and link back, and you’ll actually get visitors. If you want your visitors to join the conversation, just pop over to Haloscan to sign up for free commenting and trackbacks. (Blogger also has comments now, but I’m not so fond of their system.) Continuing your search for free services, sign up with Sitemeter so that you can obsess over how many people are visiting, and who is linking to you. Very rewarding, I promise. At a slightly higher level of ambition, you can install software like WordPress or TypePad, either on your own machine, or at some web host you pay for. That’s what we’ve done here at Cosmic Variance, since the features of WordPress are especially useful for a group blog. And then if you’re extremely ambitious, you can put a lot of work into fine-tuning the look and feel of your blog template — or make it easy for yourself and hire Lauren to do it for you.

Of course there are too many blogs out there already, so it’s not as if I’m encouraging people. Only the right people. Actually, there’s no reason why everyone can’t have multiple blogs, serving different purposes. I don’t have an especially clear view of what the blog landscape will look like ten or twenty years down the road, except that it will be substantially more active and diverse than it even is today. You don’t want to miss out, do you?

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The View of the Universe from the South Side of Chicago

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This last term I taught Introduction to Cosmology, a course for graduate students at the University of Chicago (although some undergrads typically do take it). While I have been known to pass myself off as a professional cosmologist, I’ve never found it a particularly easy course to teach. The straightforward reason is that it’s a big universe out there, and not much time to cover it. The UofC is on a quarter system, so a term is only ten weeks of classes; this makes it hard to squeeze in as much material as you would be able to in an ordinary semester.

More importantly, though, cosmology is a mess. Unlike most other subjects that would have a course devoted to them, there is no sense in which cosmology is a single logical structure that is built up from a small number of axioms. To discuss various crucial topics, you need to bring in general relativity, thermodynamics, particle physics, astrophysics, and occasionally the kitchen sink. In particular, neither GR nor particle physics are prerequisites for taking the course, so the basics of those subjects need to be covered when necessary.

A substantial fraction of contemporary cosmology is devoted to investigating structure formation and the cosmic microwave background. To do those subjects any justice requires not only the basics of general relativity, but a pretty well-grounded understanding of relativistic perturbation theory, which is an intricate and subtle discipline all its own. So the prospective cosmology instructor has a choice: go whole-hog in doing structure formation and perturbation theory, skipping past many of the fun topics in early-universe cosmology, or do the converse, putting some effort into inflation and relic abundances and nucleosynthesis while waving hands briefly about large-scale structure and the CMB. Since there is a separate cosmology course taught in the Astronomy department, which inevitably concentrates on structure formation and the CMB, I chose the latter route. We covered the basics of general relativity (enough to derive the Friedmann equation for the expansion of the universe) and particle physics (enough to understand the basics of cross-sections and calculate relic abundances). Hopefully, the students who don’t decide to become full-time working cosmologists will nonetheless, ten or twenty years down the line, recall the basic ideas of how to calculate the density of a dark matter candidate or why primordial nucleosynthesis provides such strong constraints on the physics of the early universe.

There were problem sets every week, but no final exam. Instead, the students each wrote a final paper, and the good news is that you get to read them. The final papers have been put on a web page (as pdf files), and you could do much worse by way of reviewing the hot topics in current cosmology research than to read through these papers. (The indended audience for the papers was “people who have just taken this course,” so they do tend to get a little technical.) In the past I’ve asked each student to pick a somewhat narrow topic and do a little review on it. This year, as an experiment, I instead asked them to find one specific research paper that had appeared in the past year or so, and write an overview of it that explained the main results as well as some of the background. Topics include:

  • Nucleosynthesis contstraints on the variation of constants
  • Origin of cosmological magnetic fields
  • Alternatives to dark energy
  • Anomalies in the cosmic microwave background
  • Methods for probing cosmic acceleration
  • Properties of perturbations generated by inflation
  • Thermal field theory in the early universe
  • Quantum-computational cosmology
  • Characterizing CMB polarization
  • The quantum vacuum and the cosmological constant
  • Origin of supermassive black holes
  • The birth of the universe in string theory
  • Searches for dark matter
  • The topology of the universe
  • Limits on primordial gravitational waves

Overall, they did a fantastic job, and I’m proud to share the results with the wider world.

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The View of the Universe from the Nevada Desert

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The first-ever YearlyKos get-together has now come and gone. For me it was an interesting experience on several levels. First and foremost, it was an opportunity to meet in person several bloggers whose work I had long admired from afar: PZ Myers of Pharyngula, Chris Mooney of The Intersection (and The Republican War on Science), Lindsay Beyerstein of Majikthise (a guest blogger from way back), Stephen DarkSyde of Daily Kos and Unscrewing the Inscrutable, and a number of others. Only secondarily, I kicked butt at the Riviera poker tables, held my own at slightly higher limits at the Wynn, and got destroyed at the MGM Grand.

There was a great feeling of history being made — a real-life collection of committed political bloggers and diarists, talking politics and ideas and strategies and generally trying to figure out how to move things forward from these early days of promise in which the blogosphere finds itself. And there were plenty of big names around to verify that something important was going on — Harry Reid, Wesley Clark, Bill Richardson, Mark Warner, Tom Vilsak, Howard Dean, Joe Wilson, Maureen Dowd. The place was thick with journalists, guaranteeing that the gathering would not pass unnoticed.

Deep down, though, I learned once again that an environment of political activism is not for me. I’ve volunteered and been active politically in very minor ways in the past, and I am always reminded that I should go back to academia where I belong. Of necessity, political action feeds on fervent commitment to the cause and a deep-seated conviction that one’s opponents are worthless scoundrels. Even when I do believe those things, I can’t quite give myself over to such stances uncritically. I’d rather contemplate the ins and outs of different aspects of an argument, even if I do end up resolutely on one side; politics (as opposed to governance) has little time for such nuances. At the same time, when I do take a position, I have little interest in softening its edges for political consumption, or reducing complexities to soundbites in order to convey a message. The complexities are the fun part! Don’t get me wrong; somebody has to do it, and I have incredible admiration for those who fight for the right side with passion and perseverance in the political arena. I just don’t want it to be me.

The good news is: science! Thanks largely to DarkSyde’s efforts, there was a substantial presence of science bloggers at YearlyKos. A “Science Bloggers Caucus” on Thursday night, which I expected to collect a dozen or so misplaced souls who weren’t interested in the gatherings sponsored by some of the big political blogs, instead packed a room to overflowing with over fifty energetic participants from a wide cross-section of demographics. The bad news is: politics! Even when the science bloggers got together, there wasn’t much (any) talk about the substance of science; it was all about how to combat skepticism of evolution and climate change and stem cell research and so on. Not that this was anything other than inevitable; it was a political-blogging conference, after all. The tragedy is that our society finds itself in a place where scientists need to waste time combatting Intelligent Design when they could be sharing exciting news about the latest developments in evolutionary theory. We do have to keep up this fight, but it’s important to simultaneously mix in a healthy dose of science for its own sake (which all the great science bloggers actually do), to remind people why it’s so fascinating and worthwhile in the first place.

Besides the Thursday science bloggers caucus, DarkSyde also organized Friday morning’s Science Panel, which was a smashing success. We heard talks from Chris and PZ, as well as Wendy Northcutt of the Darwin Awards and famous science supporter and retired four-star general Wesley Clark. Lindsay took pictures.

Wesley Clark

I enjoyed the talks a great deal. Chris gave an extremely polished and hard-hitting presentation, his skills obviously honed to a fine edge by months of book-touring. PZ warmed my heart by telling it like it is:

Some like to say America is a Christian nation. I think that misses the point: we have been and are a science and engineering nation. The riches we enjoy right now arose from invention and discovery and industry.

But it was Clark’s presence that was the biggest coup, and might have had something to do with the incredible attendance for a session that started at 8:00 a.m. on a Friday. (Although, as a matter of fact, almost everyone stood around to hear the rest of the talks.) I’ve always liked Clark as a prospective Presidential candidate, and the fact that he chose a venue devoted to science as the place to give his speech was a nice bonus. The speech itself was interesting and essentially completely extemporaneous. There was some expected stuff about how great America is, and how that greatness relies in substantial measure on our scientific expertise. But he also wasn’t afraid to address the complicated relationship between science, politics, and religion. He professed to believe in God, which is what you expect a politician to do (and is likely to be perfectly sincere, I have no idea), but went on to insist without hedging that religion should be kept clearly separate from both science and politics. He even brought up stories of officers in the armed forces who told soldiers that they would go to Hell if they didn’t believe in (the right) God — and said in no uncertain terms that those officers should be thrown in jail. (One interesting thing about being a prospective national candidate is that anything you say can potentially get you in trouble. To guard against this, you are followed everywhere by a handler who sits in the audience while you speak, ready with hand signals to let you know if you are treading onto dangerous territory and should skip to another subject. Apparently no such intervention was required during Clark’s speech. But I definitely need somebody like that to follow me around.)

Best of all, we learned that General Clark’s secret dream while growing up was to be a high-energy physicist! Only once he got to West Point did the realization dawn that one could not be both a career army officer and a working scientist; becoming Supreme Allied Commander in Europe for NATO must have been lukewarm consolation. (To be fair, he did mix up the inverse-square law with the equation for motion under constant acceleration, so perhaps he made the right career choice.) And, to my delight/horror, he went out of his way during his talk to mention the string theory landscape! You can’t make this stuff up. Clark brought up Leonard Susskind’s book The Cosmic Landscape as an example of the extraordinary ideas that contemporary physicists are contemplating in their efforts to make sense of Nature, and in particular as a warning against any claim that the origin of the universe could only be understood by invoking a God of the gaps.

There was a brief question period after Clark’s talk, but I did not rush to the microphone to explain that an anthropic resolution of the cosmological constant problem relied heavily on a problematic choice of measure on the space of observers in the multiverse. You would be proud of me.

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The View of the Universe from the Perimeter

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Just left a great little workshop at the Perimeter Institute in Canada, organized by Justin Khoury. It was a focused but relaxed meeting, with plenty of opportunity for interaction; every speaker had at an hour and a half or two hours to speak, and discussion during the talks was actively encouraged. Not hard to figure out what people are interested in from looking over the talks:

  • Robert Brandenberger: String Gas Cosmology. Proposed an alternative mechanism to inflation for generating cosmological perturbations.
  • Me: Spontaneous Inflation and the Arrow of Time. (See a report on my talk by Yidun Wan, a graduate student who blogs at Road to Unification.) Proposed a way to make inflation respectable in the context of a multiverse, but tried not to mention the anthropic principle or the landscape.
  • Rocky Kolb: Acceleration from Cosmological Perturbations. Proposed an alternative to dark energy in the form of back-reaction from cosmological perturbations. Made fun of the anthropic principle.
  • Frank Wilczek: Particle Physics and Dark Matter. Used the anthropic principle (but not the string-theory landscape) to make predictions about the density of dark-matter axions.
  • Burt Ovrut: The Heterotic Standard Model. Proposed a very specific compactification of string theory that gives the Minimal Supersymmetric Standard Model (and nothing else) at low energies, with stabilized moduli and a (fine-tuned) positive cosmological contant. Made fun of the landscape.
  • Neil Turok: Perturbations in the Cyclic-Universe Scenario. Proposed an alternative mechanism to inflation for generating cosmological perturbations. Made fun of the landscape.
  • Paul Steinhardt: Ways to Calculate the Cosmological Constant, and Ways Not To. Proposed a dynamical mechanism for obtaining a small cosmological constant. Made fun of the landscape.

The themes should be clear: cosmological perturbations, inflation and alternatives thereto, dark energy, the anthropic principle and the landscape.

It’s remarkable how polarizing the whole idea of the string-theory landscape and the anthropic principle really is. It’s not a simple split of string theorists vs. cosmologists vs. everyone else; there are string theorists who love the lanscape, as well as ones who hate it, and likewise for cosmologists or anyone else paying attention. I’ve been arguing that the landscape/multiverse might very well exist and is interesting to think about, but that it’s absolutely impossible right now (and might always be) to use it to calculate anything, or even to sensibly re-calibrate our notions of what is “natural.” I was happy to learn that Paul Steinhardt and Neil Turok are basically in agreement with this view, and are even writing a paper that attempts to make it crystal clear that the landscape does not correctly predict the cosmological constant ala Weinberg. In fact, if we’re allowed to take it seriously at all, it makes quite a strong and vividly different prediction altogether: the cosmological constant should be quite large (many times the matter density, although presumably not at the Planck scale), and we should live in a single lonely galaxy in an empty universe dominated by vacuum energy. Their paper is in preparation, and I hope to say more about it when it comes out. In the meantime, there is serious and hard work to be done to understand the generation and evolution of cosmological perturbations, so it hasn’t all devolved into a shouting match over whether talking about unobservable parts of the universe should count as science.

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Church-going

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God Since today, 6/6/06, is (granted some typographical latitude) International Number of the Beast Day, I should tell you about my visit on Sunday to the Augustana Lutheran Church near the University of Chicago. (Not to disparage my kind hosts, but I have to say that sacred architecture really took a turn for the worse after the Reformation; give me those Gothic cathedrals any day.) I was invited by Shane Caldwell, a student in my cosmology class, to speak to a group that meets to talk about science and religion. Of course, my take on the matter is that science and religion are in stark conflict. But they understood where I was coming from, and were interested in hearing my spiel on cosmology and atheism. (All practiced academics understand that it’s important to have a small number of spiels that can be adapted to multiple circumstances at the drop of a hat; mine was rather different in this case than Clifford’s.)

Hot dogs and hamburgers were served, and we had a fun time debating the meaning of “knowing” and the existence of God. Robert Smith, the pastor of the church who is also the campus minister of the UofC, was very welcoming, and excited to be starting this kind of dialogue between different parts of the community. Most of the small audience were actually students, some who had taken my classes and some undergrads who were members of the church. There were also a few representatives from the Zygon Center for Science and Society, an organization across the street that is dedicated to studying the relationship between science and religion.

I’ve given my “God does not exist” talk to a couple of religious audiences before, and they’re generally very interested in hearing a different perspective and thinking about the issues in an unfamiliar way. Granted, these audiences were highly selected and undoubtedly academic, not randomly chosen evangelical churches in the heartland. And you may suspect that nothing I might say would ever change anyone’s mind, but that’s not true; I had one professional theologian tell me that I did change his mind. Not about the existence of God, but about the efficacy of the argument from design. And there is a tight (inverse) correlation between age of the listener and willingness to engage with the ideas; the students were interested and ready to tackle my claims on their own terms, while some of the older folks wanted to argue that there were plenty of scientists more famous than me who were religious, so what right did I have?

There are a million things one could talk about concerning science and religion, and the discussions tend to become rapidly unfocused (or individually focused on the concerns of each person in the room, with everyone talking past everyone else). Not to mention that theology is a rich subject with a complex history about which I know only the basics. So I make a real effort to define all the my words very carefully, and limit myself to one extremely specific chain of reasoning: science and religion do overlap in their mutual interest in understanding the basic workings of reality, and therefore it is possible to judge at least some religious claims using the ordinary empirical criteria of science, and that when one does so, a materialistic conception of reality (in which there exist nothing but stuff following unbreakable rules) comes out very far ahead of a theistic one (in which there exists a separate supernatural/spiritual category not bound by the laws of physics). There might be other interesting things to talk about, and there are other things that religion is concerned with besides the workings of nature, and there could be other criteria besides the scientific method that one might want to use in deciding between different pictures of the world. But in the quite specific question I am choosing to address, I think there is a sensible answer.

At the same time, I want to argue that the answer is not inevitable, or it wouldn’t be worth going through the exercise. There are several ways that thinking like a scientist could have led us to believe in God (or the supernatural more generally). The most obvious would be if God just kept showing up in our world and performing miracles; a sensible scientific approach in that case would be to search for the “laws of nature” that were in effect when God wasn’t around, and treat his manifestations as outside that box. More subtly, we might look for evidence of design in nature, or we might look for impassable “gaps” in our understanding (like the beginning of the universe, or the origin of life and/or consciousness) that only God could bridge. I’m perfectly happy to contemplate that such things could be part of a logically possible world; I just strongly believe that, in the actual world in which we find ourselves, there are no such fingerprints of design or unbridgeable gaps, and hence no scientific reason to appeal to the supernatural. We don’t understand everything in nature, but there’s absolutely no reason to think that it’s not understandable (even the beginning of the universe etc.) in terms of purely mechanical laws. So God, as an hypothesis, is discarded along with geocentrism and phlogiston and the Steady State universe and whatnot. Sadly, it’s taking a little while for the discarding to actually sink in, but I suspect it’s just a matter of (perhaps a very long) time.

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Physicists with Guns

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There’s an interesting discussion at Pharyngula and Uncertain Principles about a high-school physics teacher in California who is in trouble for firing a gun as part of a classroom demonstration. It’s interesting because it opposes two principles to which we bleeding-heart liberal academic types will generally be sympathetic: “guns are dangerous” vs. “teachers should be free to make their classes interesting and exciting.” In the comments it’s very clear that, not only are people disagreeing, but they find folks on the other side to be slightly nutso.

I’m happy to come down on the side of an interesting classroom in this case. Guns can certainly be dangerous, and we have some cultural issues here in the U.S. that cause special problems that most other countries don’t have. It’s far too easy for the wrong people to have guns, especially handguns and assault rifles and other darlings of the NRA. But it goes way too far to extrapolate to the idea that the very concept of a gun is somehow evil, and that the things should be banned entirely.

Ballistic Pendulum

The teacher, David Lapp, demonstrates the ballistic pendulum experiment each year by shooting a bullet into a block of wood. By measuring the block’s recoil, you can figure out the velocity of the bullet using conservation of momentum. (Or “inertia, velocity and other complex formulae,” as the newspaper article would have it.) Sure, there are ways to do it without using a rifle, but a demonstration like this makes the experiment come alive for a lot of students.

Many commenters in PZ and Chad’s threads are absolutist about the issue, insisting that any appearance of a gun in a classroom is completely insane. But the basic arguments against allowing the gun are pretty simple: either (1) there is a safety risk in having a gun in the classroom, or (2) it sends the wrong message to kids to let them see guns. I think (1) is blown substantially out of proportion. Imagine, in any of these arguments, replacing “gun” with “a dangerous thing.” Should there be an absolute prohibition against every dangerous thing in a classroom? No hazardous chemicals, no driver’s ed, no power tools in shop class? Dangerous things should be handled with care, but that shouldn’t lead to a complete loss of perspective.

The second argument, that simply letting the kids see a gun up close leads to familiarity and it’s a short step from there to Columbine, has it exactly backwards. The reason why American students go to college and engage in frequent binge drinking and other irresponsible behavior isn’t because they are exposed to alcohol too much in high school — it’s because the concept of underage drinking is a taboo that they can’t wait to violate. In other countries where children are allowed to drink in responsible amounts in a respectable context, there isn’t any outlaw romance associated with the concept of getting completely plastered once you escape from your family, and the rampant alcohol abuse that U.S. colleges have to deal with is much less widespread. I’d be very happy if the total number of firearms in American households were dramatically lower than it is, but I’d also be happy if kids were taught basic gun safety, and thought of them as tools to be used properly rather than toys out of movies and comic books.

And if they learn some conservation of momentum and other “complex formulae” in the process, so much the better.

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