Miscellany

We are happy to report that this blog is the first page to come up in a Google search for preposterous. Out of 275,000 pages, that’s not too shabby.

Sometimes you have to love NASA. It’s the only organization I know of (although I’m sure there are countless others) that measures the success of its research programs by how many column inches are devoted to them in newspapers worldwide. As a byproduct, they’ve become very good at getting out their message in interesting ways.

This is by way of prelude to describing what I received in my mailbox yesterday: a WMAP beach ball (pictured at right). WMAP is the Wilkinson Microwave Background Anisotropy Probe, a satellite that has measured the tiny temperature fluctuations in the cosmic microwave background to unprecedented precision. The statistical properties of these fluctuations depend in interesting ways on the parameters describing our universe (such as the amount of dark matter and dark energy, or the overall geometry of space), so the WMAP results have provided a treasure trove of information for cosmologists. The cosmic microwave background radiation provides a picture of the universe when it first became transparent, at an age of about 379,000 years; it’s kind of amazing we can extrapolate our current theories back that far and come even close to the right answer, much less get things spot-on.

The beach ball is a playful public-relations gimmick, which I’m all in favor of. Other types of scientists could learn a lot about outreach from these folks.

I notice that I’m actually writing much less about politics in this blog than I originally expected to. Part of that is because there are few things I have to say that aren’t already being said more eloquently in some other blog. Another part is that the situation right now is so depressing and outrageous on multiple levels that there’s an overwhelming temptation to forget about light and just throw heat.

So instead you will get some warmed-over cosmology. In particular, I was asked a while back to come up with a list of “most prevalent misconceptions about cosmology.” I’m not sure among whom they should be prevalent; some of my colleagues have way-out ideas, but I’m not going to go about setting them all straight. Anyway, here was my suggested list of misconceptions. Comments welcome as to more misconceptions, although they have to be arguably prevalent — not just your own personal misconceptions, we could be here a long time.

• The universe is unchanging and infinitely old, or very young (thousands of years).
  These are basic misconceptions, but I think that most people actually don’t have them. At least, not the people who might be reading this list. The universe is about 14 billion years old. At least, that’s the time between the Big Bang and today.
• The Big Bang model is controversial, or inflation is an alternative.
  The BB model is completely accepted by the community. Inflation and other ideas extend the model, but the basic BB picture is secure. Three pillars of the model — the expansion of the universe, the cosmic microwave background, and primordial nucleosynthesis — make it hard to imagine any credible alternative. The idea of inflation in the early universe is an add-on to the Big Bang, not a replacement for it.
• The Big Bang is an explosion at a point in a pre-existing space.
  It’s not; all of space comes into existence at the BB.
• The universe has a center, or an edge, or something it is expanding into.
  The universe isn’t expanding into anything else, and as far as we know it’s quite homogeneous. Of course there is a point past which we can’t directly see, so we can’t say what goes on beyond there.
• The universe is expanding faster than the speed of light, or perhaps it used to be, and this seems to conflict with relativity.
  The expansion of the universe is not a “speed”, so this doesn’t even make sense. We associate a speed to distant galaxies, but that’s only an informal idea which works if they’re not too far away. The apparent recession velocity of very distant galaxies can be greater than the speed of light, but that doesn’t violate relativity, which only puts an upper limit on the relative velocity of two objects passing by each other.
• Cosmologists used to believe in dark matter, and now in dark energy, and how do they know there isn’t even more stuff out there?
  We believe in both dark matter and dark energy; the former seems to be made of particles that collect in galaxies and clusters, while the latter is evenly spread throughout space. The curvature of space puts limits on the total amount of energy, so we probably won’t discover important new components.
• Dark matter is just ordinary matter that we haven’t found yet.
  Evidence from both the cosmic microwave background and primordial nucleosynthesis gives tight bounds on how much ordinary matter there is. We compare this to the total amount inferred from gravitational effects, and come up well short. The dark matter must be some new kind of particle, not yet discovered in the lab.
• Scientists keep inventing new phenomena like dark matter and dark energy because they are desperate, or philosophically hidebound; these are just like epicycles or the aether, and will eventually go away.
  Well, maybe. But it’s important to emphasize that we have been forced into these ideas by the need to explain observational data, they’re not just cool ideas we’ve fallen for. The more data we to get, the more secure these ideas seem to become. Of course it’s possible we’re missing something big, but if so everyone would love to come up with the compelling alternative; there is no establishmentarian conspiracy to suppress other ideas.

Remember, these are misconceptions. I hope nobody reads the list without the preamble and thinks these are the “greatest discoveries of modern physics” or some such thing.

Any physicist knows the most common responses when you first tell someone what you do for a living — “I hated physics in high school” being the consensus pick for number one. Which is not inconsistent with the fact that people are fascinated by the actual physics that we do, whether it’s studying dark energy or the physics of crumpling paper. Our education system, for whatever reasons, tends to scare people away from science more than it draws them in.

Which is why the work of Project Exploration is so wonderful. Founded and run by Paul Sereno and Gabrielle Lyon, PE works to get children (especially girls and inner-city kids) interested in science by using one of the greatest draws we have: dinosaurs. Paul is an celebrated paleontologist who is our best living approximation to Indiana Jones; his wife Gabe is a professional educator who is really the soul of PE. In the short time they’ve been in operation, they’ve already made a tangible difference in a lot of people’s lives; as just one measure, almost all of the children who work with PE end up going to college, while it’s a good bet that almost none of them would have if it hadn’t been for the project.

Their latest brilliant idea is to display dinosaurs in a good approximation of their natural habitat — the Giants exhibition shows fossils and exhibits amidst the plant life at the Garfield Park Conservatory. It’s an impressive exhibit, very worth checking out if your’re in Chicago. I visited Saturday night for the Fourth Annual Dinosaur Dinner, a gala benefit for PE. It was great fun, including a benefit auction of items like a dinosaur-femur bench and a dinner with Paul and Gabe. (This is my new standard for success in life: when I can auction off dinner with myself in a reasonable expectation that someone other than my Mom would bid for it.)

Gabe is interested in expanding the purview of Project Exploration to include other types of science. We both think it would be fun next year to have a Dark Energy Dinner, where everyone comes dressed in black. Watch this space for updates to see if it will come to pass.

The other celebrity I got to meet at the dinner was Barak Obama, our Democratic nominee for US Senate from Illinois. In a thirty-second conversation, he came off as extremely intelligent and engaging (which is his job, I suppose). I mentioned that I had endorsed him on my blog, and he was curious about the blogging process — how much time it took, etc. It’s about time we get someone in government who has a UofC affiliation but is not a crazy neoconservative, so I’m rooting hard for him.

Nature has a feature known as “concepts essays,” in which they ask highly respected (or at least “willing”) scientists to write short reflective pieces about specific concept of importance to their field. The idea is to go slightly beyond a standard pedagogical introduction to a subject and allow for the kind of discussions that scientists might have around coffee but would never put into a journal article. (I.e. it’s an old-media version of a blog.)

I was invited to write such an essay about dark matter, which has now appeared. (That’s a pdf version on my site; there is an html version on the Nature site, but it’s not as pretty and might require registration.) I couldn’t help but mention dark energy as well, so in the final version the “concept” includes both dark matter and dark energy. (Here’s a very short intro to both subjects.)

The idiosyncratic angle I chose to take was to ask how interesting the dark sector could be — in particular, whether there could be interactions between dark matter particles (or dark matter and ordinary matter, or dark matter and dark energy) that might allow some sort of structures to form, even intelligent life. We might ask, for example, whether there could be some weakly-coupled massless abelian gauge boson that mediates interactions between dark matter particles: “dark light.”

As I say in the article, probably not. We don’t know as much as we would like about the distribution of dark matter, but we do know something, and it appears to be much more smoothly distributed than the ordinary matter in the universe. See for example this computer reconstruction of the dark matter density in a cluster of galaxies, using gravitational lensing. The simple explanation for this smoothness is that dark matter is probably collisionless. When atoms of ordinary matter bump together, they can emit light and cool, and this dissipation process allows the ordinary stuff to condense into the center of galaxies. But the interactions that give rise to dissipation are exactly those necessary for making structures and life. Of course, all we have are upper limits; it’s still possible that there is life out there in the dark matter, but characterized by much larger sizes and much longer timescales than anything in our experience. Perhaps a dark heartbeat takes millions of years to complete.

Now I am wondering whether the goofy illustration chosen by the editors to accompany the article (shown above) might feature the most dramatic decolletage ever to appear in a major scientific journal. Anyone have any other candidates?

Ed Brayton at Dispatches from the Culture Wars mentions something I should have known (and tells some gripping stories in the process): the World Series of Poker (WSOP) is going on in Las Vegas this very moment. Like lots of people, I played some five-card draw with family and friends when I was young. But I never became really interested in poker until last summer, when I read James McManus’ Positively Fifth Street. Talk about a gripping story: McManus is a writer and amateur poker player, who was given the assignment by Harper’s of writing a story about the WSOP. Being an impetuous type, he took his expense-and-advance money and used it to enter a satellite tournament (a cheaper way of trying to play your way into the main event, rather than just ponying up the $10,000 entrance fee). Remarkably, he won the satellite, and more remarkably, he kept on winning — all the way to the final table, where he finished fifth and took home over $200,000. (The book is fascinating and annoying at the same time, due to the authors self-absorption. If you want a more balanced view of the world of professional poker players, try The Biggest Game in Town by A. Alvarez.)

To gauge my ignorance, I didn’t even know that real poker players didn’t play five-card draw, but rather Texas Hold-Em. It’s a simple game at heart: everyone gets two cards dealt face-down that only they can see. Then five cards are dealt face-up in the middle of the table; each player makes the best five-card poker hand that they can, using their own cards and the five on the table. The complications only arise in the betting process, which happens after the first two cards are dealt and after each card thereafter.

Not so complicated, right? But of course it’s incredibly complex when you get into it. The secret of the allure (and challenge) of poker is that it’s a game of incomplete information, the kind game theorists love to think about. You know the cards you already have, and you (should) know the probabilities of various further cards coming your way, but you have to infer your opponents’ hands from tiny hints (their bets, their positions at the table, their personal styles, etc). Texas Hold-Em is so popular because it manages to accurately hit the mark between “enough information to devise a consistently winning strategy” and “not enough information to do much more than guess.” The charm in such games is that there is no perfect strategy, in the sense that there is no algorithm guaranteed to win in the long run against any other algorithm. The best poker players (and there are a good number of people who earn their living from poker, so it’s by no means “gambling”) are able to use different algorithms against different opponents, as the situation warrants.

I’m sure that professional game theorists have analyzed poker to death, but I haven’t ever seen any technical work on the subject myself. David Sklansky has written a book called Theory of Poker, but it doesn’t get into all the fun game-theory aspects. (For actually learning poker strategy, the acknowledged classic is Super-System by Doyle Brunson et al.)

I have played a few times in casinos, in Los Angeles and (once, late at night, in the midst of a cross-country trip from California to Chicago) at the Bellagio in Vegas. But you can play at any time online; my favorite site is ultimatebet.com, although there are several alternative sites that I haven’t looked into closely. One of the nicest features of poker is that it is a perfect meritocracy; anyone can do it, and your success depends only on your own skill, not on help from anyone else. At the casino you will sit down at a typical table with people older and younger than you, men and women, blacks, whites, and Asians, gays and straights, extroverts and introverts. Some of the world’s best players grew up as pampered bourgoisie, others were Vietnamese boat people. For some reason I haven’t been playing that much lately; I fear my poker time has been taken over by blogging. (Neither one of which is very lucrative, at my level of skill.)

An apparent rupture in the spacetime continuum has been noted over at archy and Pandagon. In one of the questions asked to President Bush on his current “bus” tour, the interlocutor referred to an apparent acausal propagation of economic hardship:

In 1998, due to the impending recession, I started living the American nightmare.

John McKay at archy wonders whether there could be a quantum-mechanical explanation for how anyone could be suffering through the effects of a recession that wouldn’t begin for another two years. But I think it is more likely that the explanation requires closed timelike curves. You see, in relativity it is impossible to move faster than the speed of light; physical particles are therefore confined to move along “timelike” trajectories that move inexorably forward in time. But in general relativity spacetime is curved; it is therefore conceivable that a timelike curve can loop back and intersect itself in the past, in a kind of time machine. Bush’s questioner had obviously found such a closed timelike curve, lived through the horrors of the recent recession, gone backwards in time, and cowered in fear as he lived once more through 1998 with the ever-present knowledge that the economy would tumble just about the time Bush was elected. Of course, it is probably necessary to violate some of the laws of physics to actually create closed timelike curves in the real world; this is the content of Hawking’s Chronology Protection Conjecture. But the administration has never let the laws of nature get in the way of their plans.

Or, I suppose, maybe the bus-tour audiences are not completely representative samples of the local population; one might even suspect that they are carefully selected to be sympathetic. But that would make me a wacky conspiracy theorist. Besides, there was one actual question, when Bush was asked about a cut in federal funding to local health services. His priceless response, as reported on NPR:

Well, that’s what happens when you’re trying to cut the deficit in half.

Such an answer cannot be explained simply by closed timelike curves; we need to invoke parallel universes.

One of the most profound experiments in physics is one you may never have heard of. It’s the torsion-balance experiment at the University of Washington (and others like it elsewhere in the world).

This group, led by Eric Adelberger, has recently garnered attention for testing Newton’s inverse-square law of gravity down to a tenth of a millimeter. This experiment is interesting because there are good (or at least plausible) reasons to suspect that Newtonian gravity actually breaks down at around a millimeter. In particular, models with large extra dimensions of space can unify the scales of quantum gravity and particle physics if there are two extra dimensions about a millimeter in size. The Washington group has placed significant constraints on this fascinating idea.

But the profound experiment I’m referring to is the one about “testing the equivalence principle.” The Equivalence Principle is Einstein’s idea that you can’t tell, if you are sitting in a sealed laboratory, whether your lab is on the surface of a gravitating body or accelerating through space at uniform acceleration. So if the EP is right, uncharged bodies should all fall at the same rate in a gravitational field, just as they would in an accelerating rocket.

So far, the UW experiments have not detected any violations of the EP. But if they did, you wouldn’t conclude that Einstein was wrong; instead you would guess that the bodies you were using weren’t really “uncharged.” In other words, you would have discovered a fifth force. The best limits right now on such fifth forces are that they are less than one-trillionth the strength of gravity, if they exist at all; that’s incredibly weak. The fact that there is no noticeable fifth force is one of the most profound facts of physics.

We know of four forces in nature: gravitation, electromagnetism, and the strong and weak nuclear forces. The latter two only operate over very short ranges (atomic scales and below), leaving only gravity and E&M as forces relevant to our daily lives. (“Electricity” and “magnetism” are two different manifestations of the same force.) This is the deep and astonishing fact: everything we directly see around us can be accounted for by some simple forms of matter (electrons, atomic nuclei) interacting through just those two forces. Fortunately for us, they can interact in extremely intricate ways.

Scientists like to talk about what they are currently doing research on, which by construction tends to be speculative ideas at the boundaries of our ignorance. What can easily get lost is an appreciation for how much we actually know beyond any reasonable doubt, and how little wriggle room there is. ESP, astrology, and other paranormal phenomena provide excellent examples of ideas that simply can’t work. When scientists criticize these ideas, they often start talking about blind tests and repeatability and so forth. All well and good, but the fact is that these ideas have no chance of being right even before we test them directly. There is no way for the human brain to send out a signal that would read a mind or bend a spoon, nor is there any way for the planet Venus to influence your love life. Any such influence would have to be communicated by one of the forces of nature, and there are only two possibilities: gravitation and electromagnetism. In either case the size of the force would be easily detectable, and we haven’t detected it.

It would be great to find a new long-range force, and there are certainly models that predict them. But even if one were found, it would be so tremendously weak that we need all of our best technology to notice its effects at all; there is no way for such a force to push around human beings (even delicate parts of their brains) in meaningful ways. This isn’t to say that there’s no room left for mysteries; figuring out how electrons and nuclei interact through two simple forces to create all of human culture and the rest of the visible world leaves more than enough unanswered questions for generations to come.

We saw a fantastic concert at the HotHouse on Friday featuring Von Freeman and Fred Anderson, two legendary Chicago tenor saxophone players. Both of them have spent their lives playing in Chicago, rather than moving to New York and doing a lot of recording; consequently, either could reasonably claim the title of “most underappreciated living saxophonist.” The occasion was Fred’s 75th birthday, making him the younger of the two, as Von is going on 82. And they can both play like nobody’s business.

Von I know very well, and it’s a surprise that I’ve gotten this far in the blog without ever mentioning him — I’ll have to rectify that at length sometime soon. But I had never heard Fred Anderson live, and it was quite an experience. Von is the consummate showman, telling stories and flirting with the crowd, and one of the most compelling features of his music is how he mixes beautifully accessible melody and harmony with exciting and challenging free-jazz explorations. Fred, in contrast, is all intensity and concentration. Listening to Von is like driving in a convertible through mountain roads where surprising vistas can suddenly appear around the corner, whereas listening to Fred is like taking the bullet train. Or maybe jumping out of an airplane.

Fred’s band is just a trio — him, bass, and drums. He stands up on stage, short and stooped to begin with, and gradually leans forward as he begins to play. Pretty soon his upper body is nearly horizontal, as he is surrounding the sax and blowing with fierce determination. The notes come quickly and relentlessly, as he spins out impossibly long lines without noticeable pause. I was talking with Michael Raynor, Von’s drummer, who was scoping out the room to see how people were reacting. We agreed that anyone could enjoy Von’s style, but you would appreciate it much more if you were really into the music; but to enjoy Fred you needed to be into it from the start. I am definitely into it, and I’ll have to make sure to drop by Fred’s club, the Velvet Lounge, more often. The only regret was that Von and Fred played separate sets, rather than jamming together; that I would have definitely loved to see.

Fred has a new CD just out; Von has one coming in July. It’s a great pleasure to listen to these two men who give so much to their music, their fellow musicians, and their city.

Brian Leiter reports on an example of absolutely shameful pettiness. He compiles a very well-known list of the best law schools, which is competitive with the famous US News rankings in influence (and noticeably superior in methodology). Now he finds out that his law school alma mater, the University of Michigan, has been “explaining” their decline in his rankings by pointing out that they denied him a faculty job. He convincingly explains why this is just ridiculous (or preposterous, as we say around here).

But it got me thinking about a potential conflict-of-interest issue — if I denigrate some institution or person, could someone assume it was just because they didn’t give me a job? Hopefully I could avoid being so shallow, but full disclosure is probably the best policy. In that spirit, here is a list of universities to which I applied for jobs but was turned down, before being offered my current position:

• UC Berkeley
• Cornell
• Penn State
• University of California-Irvine
• Duke
• Stanford
• Harvard
• Princeton
• University of Chicago
• Rutgers
• University of Kansas
• California Institute of Technology
• Brown
• University of Illinois, Urbana-Champaign
• Johns Hopkins
• University of California, Davis
• University of Pittsburgh
• University of Minnesota
• Northwestern
• University of Wisconsin, Madison
• Canadian Institute for Theoretical Astrophysics
• SLAC
• Williams College
• University of California, Santa Cruz
• University of Victoria
• State University of New York, Stony Brook
• MIT
• Swarthmore
• Yale
• Dartmouth
• University of Toronto
• University of Minnesota
• Institute for Theoretical Physics
• University of British Columbia
• University of Wisconsin, Milwaukee
• University of California, Santa Barbara
• Oxford University
• New York University
• University of Michigan (!)
• University of Texas, Austin
• UCLA
• University of Maryland
• Columbia
• University of Pennsylvania

There might be others, I forget. And that’s only including faculty jobs, I didn’t bother to include postdocs. And I only listed places once, even if they rejected me more than once. So, just to be safe, you might want to be skeptical of any disparaging remarks I might make about any of these universities or people affiliated with them.

Some of these places, like the University of Chicago, eventually saw the error of their ways and made me an offer on some later occasion. But still, a long list. Perhaps this will be heartening to some younger people on the job market today — keep plugging, for a while anyway.

Somehow I suspect this will not become a popular meme.