Here’s an html version of the slides from my public lecture that I gave in Aspen last week. It’s also available as pdf, coming in at a healthy 3MB. I was pretty ambitious, explaining not just the observational situation with respect to dark matter and dark energy, but also going into fermions and bosons, and theoretical ideas of extra dimensions and supersymmetry. It was the first time I gave this particular talk; next time I’ll try to take out a couple of slides and go at a more leisurely pace.

I’m back from the annual meeting of the American Association for the Advancement of Science, which was held this year in Washington, DC. The AAAS is a useful organization whose existence is largely ignored by physicists. Their most obvious contribution is publishing Science, which (like its UK counterpart Nature) tends to deal more with biology, chemistry, medicine, and the environment than with physics. The annual meetings reflect this emphasis; physics is only a tiny part of the proceedings, although some of us would like to see it be more prominent.

The thing that separates AAAS from professional societies such as the American Physical Society or American Astronomical Society is the word advancement. The AAAS is especially concerned with the interactions between science and the outside world — through education, public policy, and media outreach. One of the main purposes of the annual meeting (maybe the main purpose) is to bring scientists in contact with interested journalists. Something that surprised me when I first realized it, but seems obvious in retrospect, is that science journalists don’t typically have the luxury of flying around to topical conferences to get a feel for what is interesting within some specialized field. Except at the very largest outlets, most science writers have to pore through press releases to find their stories; if they’re especially dedicated, they may scan Science or Nature or even the arxiv, but those are the exceptions. So the AAAS meeting provides a nice opportunity for scientists and journalists to mingle in the flesh; not coincidentally, the annual meeting of the National Association of Science Writers is usually held in conjunction with the AAAS.

(I won’t even bother to make the argument that it is good for scientists and journalists to mingle — good for science, and good for the interested public [which is most of the public]. Some scientists stay away from journalists because they think they won’t be taken seriously if they appear in the media, and some are quite explicitly disparaging of their colleagues who do. That’s a rant for another day.)

My main role this year was as the organizer of a symposium on Understanding Dark Energy. (That’s a link to the symposium web page I set up; you can also read our press release, or the symposium summary in pdf.) I thought it was successful, with maybe 150 people in the audience. We had three hours and six speakers, so the talks were short and sweet. I opened with a brief description of why we believe in dark energy, what the theoretical puzzles are that we are trying to solve, and the things we hope to learn from new experiments. Adam Riess went next; Adam was the lead author on the first of the 1998 papers that presented evidence for an accelerating universe from observations of high-redshift supernovae. He talked about the future of supernova cosmology, both from ground-based and space-based observations, and how we can simultaneously constrain the equation-of-state parameter w and its time derivative. Lenny Susskind went next, saying how happy he was to be at an AAAS meeting giving a talk on biology. That’s because he went on to compare the number of possible vacua of string theory (the “landscape”) to the number of possible biological organisms you could get by arranging base pairs in a DNA molecule — the former is perhaps 10⁵⁰⁰, while the latter is maybe 10^25000000000. So biology wins, but the lesson we are supposed to learn is that a large variety of possibilities is what enables the development of intelligent life; in the context of string theory, it is the large number of stable vacua that makes it possible to find one with a sufficiently small vacuum energy so that life can evolve. (This is the press release that Peter Woit was lamenting.)

Next up was Licia Verde, talking about what we could learn from structure in the universe, combining constraints from early times (the cosmic microwave background) and late times (galaxy surveys). She had a nice analogy with waves on the ocean, driven by wind until they become non-linear and interesting to surfers: if the ocean were made of honey, the waves would evolve quite differently. Likewise, structure in the universe evolves in a way that depends on the underlying constituents, which can be used to discover properties of dark matter and dark energy. Switching back to outlandish speculations, Gia Dvali talked about how we could get an accelerating universe even without dark energy, if gravity were modified on large scales. An important point from his talk is that you can never modify gravity only on cosmological scales — effects always leak down to smaller distances. In the case of a simple theory like mine, these effects are dramatic, and rule out the model definitively. In the case of a more subtle theory like Gia’s, the effects are less pronounced, and the model is not yet ruled out; but it is certainly testable, especially by high-precision measurements of the orbit of the Moon. We closed with a fantastic talk by John Carlstrom, who described how clusters of galaxies will be a new method to probe the expansion history of the universe. John is the world’s expert at observing the Sunyaev-Zeldovich effect, the scattering of microwave-background photons by the hot gas in galaxy clusters. Since what you observe in the SZ effect is a shadow on the CMB rather than the direct emission of light, the effect does not diminish as the clusters get farther away — they can be found at any redshift, and the rate at which they assemble as a function of time reveals a lot about the way the universe evolved. John and his collaborators are building two impressive projects to make SZ surveys: an array of eight telescopes in California, and one giant radio telescope at the South Pole (a similar project, the Atacama Cosmology Telescope, is also underway in Chile). With all these new data coming in, it won’t be surprising if theorists are once again startled by something we discover in the real world.

There are a plethora of different symposia at the AAAS, and the sexiest and most media-friendly are granted separate press conferences. For some reason, the press briefings are held before the symposia themselves; this gives reporters the feeling that they have first access to the news, but it means that they are asking questions before they’ve actually heard the talks. Still, we had a well-attended and sprightly press briefing. Since we didn’t announce any stunning new results, I think the effect will be largely in the background, helping journalists understand what is going on and preparing them for future discoveries. But there have already been a couple of stories, prompted by those wild theoretical ideas: one on the landscape, and one on modified gravity. (Update: Here’s another, from Astronomy magazine.)

Somehow I was also involved with another press conference, this one as part of the celebration of Einstein’s miraculous decade, 1905-1915. Einstein started off the decade with three spectacular papers, any one of which would be the highlight of the career of an ordinary physicist: explaining Brownian motion in terms of atoms, inventing the photon as an explanation for the photoelectric effect, and establishing special relativity. But he was just getting started, and ten years later he came out with his capstone achievement, the general theory of relativity. The other panelists for this briefing were Rolf Sinclair, Richard Wolfson, and Barry Barish. (The three of them also appeared on Science Friday with Ira Flatow, while I was busy at the dark energy symposium.) The highlight of this briefing was the unveiling of Einstein@Home, a screensaver program that uses your unwanted CPU cycles to look for signals of spinning pulsars in real data from LIGO, the Laser Interferometric Gravitational-Wave Observatory. Barry introduced Bruce Allen of the University of Wisconsin-Milwaukee, who has been instrumental in developing the Einstein@Home software. The ultimate pay-off is not quite as exciting as for SETI@Home, but the likelihood of actually finding something is much higher!

Barry Barish, by the way, is one of the most impressive physicists you will ever meet. He was trained as a particle physicist, and did some of the first experiments to discover weak neutral currents, key to the Glashow-Weinberg-Salam model of the electroweak interactions. And now, having smoothly shifted gears, he is Director of the LIGO laboratory. But Barry hasn’t forgotten about particle physics; he is extremely active in planning for future experiments, most recently as the head of the committee to decide on the basic technology for the planned International Linear Collider, the hoped-for follow-up to the Large Hadron Collider. He gave a great talk at a session on high-energy colliders, in which he explained the process by which the committee decided on the “cold” (superconducting) option rather than the “warm” option. The miracle is how quickly the worldwide community has dropped what they were doing to rally around this decision; that wasn’t so hard for the folks at DESY in Germany who had developed the superconducting technology (TESLA) in the first place, but the people in Japan and at SLAC who were pushing for the warm technology were also very quick to get on board once the decision had been made. Now all that remains is to figure out where to build it (outside Fermilab would make sense), and who will pay. (For info on the current climate, see comments at Peter’s blog.) The total cost is estimated to come in around five to eight billion dollars, which for comparison purposes is about one percent the cost of a manned mission to Mars.

My final event at AAAS was a TV interview with ScienCentral. This is an interesting outfit that makes short science stories, then sells them to other media outlets (like your local news program). They interview you on tape for half an hour or so, and then will chop it up into TV-sized morsels afterwards. (After some practice, I’m pretty comfortable on radio and TV by now, but I still need work on speaking in sound bites instead of elaborate paragraphs.) The woman interviewing me, Joyce Gramza, was initially skeptical about the whole cosmology thing, since she had just finished a bunch of interviews with scientists whose work actually had a tangible impact, like getting flu shots to people. Of course science does have an important impact on our daily lives, but that’s not the whole point of it — there’s also the straightforward human pleasure of learning about the universe around us. Most people will accept that if you tell it to them honestly, rather than trying to pretend that we really study dark energy because it will someday lead to a cure for cancer. Joyce seemed to buy my argument, and by the end was saying that I should get my own show, which was nice of her. She also complained that she was interested in mathematics and physics as a student, but was consistently discouraged from studying them because she was a girl. I guess she just wasn’t honest enough with herself to admit that she probably didn’t have the intrinsic aptitude that us boys are blessed with.

One of the pleasures of combining a big meeting like the AAAS with a power center like DC is that you keep bumping into celebrities. I ran into Shirley Ann Jackson, who is President of the AAAS and also of Rensselaer Polytechnic Institute (I guess she hasn’t been honest with herself either). And I went to a panel discussion on how to write and sell popular-level science books, which featured none other than John Derbyshire. Okay, he’s not really a celebrity outside the blogosphere, but still. He was generally charming in an English-public-school sort of way; but no mention of LSD trips, and I didn’t have the heart to ask. Finally, as I was heading out of my hotel I noticed Ralph Nader in the lobby chatting with some people. He’s taller than he seems on TV.

I almost didn’t write this post because I thought there wasn’t that much to say. But I see I’ve gone on at unseemly length. This is what you get when I have an hour to kill in the airport before my flight back to Chicago.

Seems like everyone on the left-hand side of the blogosphere is having great fun with David Horowitz’s latest misadventure, DiscoverTheNetwork: A Guide to the Political Left. (See e.g. Michael Bérubé, Pharyngula, Crooked Timber.) The website tracks the many connections between the vast left-wing conspiracy that has been so effective at keeping conservatives out of power in this country. It’s pure comedy gold, I have to admit. I mean, consider the following set of people:

Quite a motley crew, wouldn’t you say? Anyone who thinks that these folks are part of some common “network” is just a fruitcake. To any right-wingers out there who might harbor suspicions, trust me on this: Bruce Springsteen is not lunching with Abu Musab al-Zarqawi, nor is Howard Dean planning on bringing Fidel Castro to help him on the Democratic National Committee. Look, guys: the Ayatollah Khomeini was not a leftist, okay?

But beyond the laughs, there is something ugly and offensive going on. Look at the last paragraph of the entry for Barack Obama:

Who and what is the real Barack Obama? “I am a Christian,” he told the Chicago Sun-Times last April to assuage all those who had asked if he had any religion at all. “I have a deep faith.” The mother that a decade ago he described in his book as a “lonely witness for secular humanism” he now describes as “a Christian.” It is here we are told that his stepfather in Indonesia, where Barack spent two years in a Muslim Madrassah, was a “non-practicing Muslim.” Obama and his wife and two young daughters now attend Chicago’s liberal Trinity United Church of Christ. “Obama doesn’t believe he, or anyone else, will go to hell,” wrote Sun-Times reporter Cathleen Falsani, “But he’s not sure if he’’ll be going to heaven, either.”

I presume the insinuation here isn’t too subtle for anyone to decode. Sure, this guy with the funny name “Obama” claims to be a Christian, and apparently is devious enough to actually attend church (albeit a “liberal” one). But don’t let that fool you: his stepfather was a Muslim, and he spend two years in a Madrassah. In Horowitz’s crazed world, this is tantamount to an al-Qaeda membership card. As Matthew Yglesias says: What’s wrong with you people?

Michael Chabon (author of The Amazing Adventures of Kavalier and Clay), writing in the New York Review of Books, discusses The New Annotated Sherlock Holmes. He quotes Holmes in The Sign of Four:

Holmes remarks to Watson, referring to A Study in Scarlet, and continues:

Honestly, I cannot congratulate you upon it. Detection is, or ought to be, an exact science, and should be treated in the same cold and unemotional manner. You have attempted to tinge it with romanticism, which produces much the same effect as if you worked a love-story or an elopement into the fifth proposition of Euclid.

Some of us feel, of course, that the fifth proposition of Euclid would only be improved by a nice juicy elopement.

What? I hope not too many people believe that. Juicy elopements are all well and good, but they would not improve Euclid’s Fifth Postulate:

If a straight line crossing two straight lines makes the interior angles on the same side less than two right angles, the two straight lines, if extended indefinitely, meet on that side on which are the angles less than the two right angles.

The postulate is already cumbersome enough! Mixing elopements into the act would only degrade an already-confusing situation. What would you want, the two indefinitely-extended straight lines to exchange secret vows of eternal love on the side on which the angles are less than right angles? Madness.

Of course, the Fifth Postulate (or Parallel Postulate) is not necessarily “true”; by relaxing this assumption, we are led to non-Euclidean geometry, which ultimately provides the basis for the geometric understanding of spacetime achieved by Einstein in general relativity. Everyone knew that the parallel postulate was suspiciously ugly, but it took quite a while to gather up the courage to simply discard it and see what happens.

Likewise, of course, I doubt that many elopements would be improved by Euclid’s Fifth Postulate. Like it or not, the beauty of mathematics springs from its rigorous austerity; it’s a different kind of beauty than we might find in a clandestine marriage, but no less compelling for that.

Greetings from Aspen, where tonight I’ll be giving a public talk on Dark Matter and Dark Energy: From the Universe to the Laboratory. It’s at 8:00 pm, any blog readers in the neighborhood are encouraged to drop by. The talk is part of the Aspen Winter Conference on The Highest Energy Physics, which is in turn part of a sequence of annual conferences held at the Aspen Center for Physics. Physicists know how to live, I tell you.

Right now the highest-energy physics we have here on earth is being conducted at Fermilab, a short drive from Chicago. The Tevatron accelerator is crashing protons into antiprotons to see what comes out. The hope is that we see something good like the Higgs boson, or supersymmetry, or large extra dimensions of space. If not, the Large Hadron Collider at CERN in Switzerland is scheduled to turn on in 2007, and will be operating at notably higher energies. There’s almost a guarantee that the LHC will see something interesting, although of course you never know what until you look.

In the meantime, you are welcome to go look at the actual events at the Tevatron in real time! The two main experiments, CDF and D0, both have displays where you can see live events. I wish there was a little more explanation about what the displays actually mean; right now it’s more gee-whiz than really being informative. But still, pretty gee-whiz; this is a schematic of the cylindrical volume of the CDF detector, with all those curly lines representing particles produced by a collision.

Of course, there are much higher-energy particles that are not made on Earth, namely ultra-high-energy cosmic rays. These are being observed by the new Pierre Auger observatory, which has a facility in Argentina and hopes to build another in the U.S. The analogy I will use tonight is that particle astrophysics and collider physics are like eavesdropping and interrogation. When you eavesdrop on someone, they might reveal things that they would never tell you outright; similarly, the ultra-high-energy cosmic rays could teach us something about particle physics that we couldn’t get to by accelerating particles ourselves. But the problem with eavesdropping is that you can’t just ask the questions you want to; besides, most of the time the conversations you overhear are just boring. If you are interrogating someone, perhaps they will clam up about some interesting questions, but at least you can be precise about what you are asking. And who knows, they might just tell you the answer.

TigerHawk points to another one of those 0nly-on-the-internet cool things: the NameVoyager, which allows you to find out the relative popularity of different names given to children since the year 1900. Even better, it plots the frequencies of all names that begin with the letters you’ve entered, so that you can see which first letters are most popular. The amount of fluctuation in names is really quite impressive. One interesting thing his how we’ve recently become infatuated with exotic-sounding names, as evidenced by the zoom in popularity of names beginning with letters like “Q”, “X”, and “Z”:

Of course, the Z demographic is dominated by Zachary, which points to another trend towards solid Old Testament names: Joshua, Isaiah, and Hannah have all seen surges in popularity. No sign of Jezebel or Baal, though.

Daniel Wallechinsky, writing for Parade magazine (that high-powered foreign policy journal), has consulted with Human Rights Watch, Freedom House, Amnesty International and Reporters Without Borders to construct a list of the World’s Ten Worst Dictators. Since we are now told, somewhat belatedly, that our invasion of Iraq was actually a humanitarian venture designed to spread democracy throughout the world (and the bits about weapons of mass destruction and ties to al-Qaeda were just honest mistakes), this list will serve as a helpful finding-chart for our future foreign policy objectives. I figure we’ll be invading each in turn, from the worst at the top down to the not-quite-so-evil at the bottom. By the time we get through them all, the ineluctable logic of the Bush Doctrine will no doubt convince all remaining dictators to abdicate in a hurry.

1. Omar al-Bashir, Sudan.
2. Kim Jong Il, North Korea.
3. Than Shwe, Burma.
4. Hu Jintao, China.
5. Crown Prince Abdullah, Saudi Arabia.
6. Muammar al-Qaddafi, Libya.
7. Pervez Musharraf, Pakistan.
8. Saparmurat Niyazov, Turkmenistan.
9. Robert Mugabe, Zimbabwe.
10. Teodoro Obiang Nguema, Equatorial Guinea.

We can quibble about the list, but the top three are consensus picks to be sure. al-Bashir and Shwe will likely fold like a cheap suit after the first hundred cruise missiles, so they shouldn’t be any problem. Kim Jong Il is trickier, with those nuclear weapons and all. Fortunately he doesn’t yet have the capability to launch them all the way to California, so South Korea and Japan will likely take the brunt of the carnage. (Maybe they can borrow our missile defense system?) China will be tougher yet, what with a substantial military and over a billion people. Might have to call up more of the Guard. But we know about their nefarious plans to put an Asian person on the Moon, and we have to act swiftly before the Chinese flag is flapping in the Lunar breeze overhead.

Saudi Arabia will be awkward, since they’re our close allies and all, but frankly we could use the oil, and our armed forces are already in the area. (The fact that al-Qaeda actually has support there is just a bonus.) I’m surprised to see Qaddafi so high on the list; I thought he had lost the will to be a really brutal dictator, but apparently he’s rebounded in the last year, punishing entire towns for “collective guilt.” Pakistan — again, awkward, and heavily armed. But perhaps we could take out bin Laden in the process, which would be a PR coup. Personally I think Niyazov should be ranked even higher; he has quite a fondness for erecting statues of himself, which will make for great visuals after Turkmenistan is liberated. Mugabe and Nguema have slipped in the rankings over the last year, but that’s as much a reflection of the tough competition as it is their own faults. Fact is, both regimes condone the use of torture against their suspected enemies, and that’s a no-no in this new era of enforced Enlightenment values. Freedom is on the march!

Brad DeLong has a nice post about receiving a challenging undergraduate education. He was prompted by an article by Ross Douthat in the Atlantic Monthly, which apparently whines about how it is possible to skate through Harvard without working very hard or learning very much. DeLong points out that it was, and still is, also possible to receive an extraordinarily rewarding education at a place like Harvard — it’s in the hands of the student to go out and get it.

I would just point out that this lesson is completely universal, not specific to Harvard. At almost any university in the United States, it’s possible to graduate without being challenged very much, if that’s your major goal (perhaps places like MIT and CalTech are exceptions). And at the same time, any halfway-decent institution of higher learning can provide a fantastic education to a student who makes the effort to get it. In my experience, students consistently underestimate the extent to which the quality of their education depends much more on themselves than on the place they are studying. The same is even true, albeit to a lesser extent, in graduate school: students who go beyond their coursework, who go to seminars and try to catch on with what is being discussed, who knock on professors’ doors to talk about research, who speak up in meetings to politely ask questions — these students will learn a tremendous amount no matter where they are.

I was an undergraduate at Villanova, a middle-class Catholic school most notable for winning the NCAA men’s basketball championship my first year. While many of my classmates were biding time until the weekend, I was being constantly challenged and amazed by faculty in astronomy, physics, mathematics, biology, philosophy, English, sociology, religious studies, political science, history, and elsewhere. So, to Edward Guinan, Frank Maloney, Mike Burke, Jack Doody, Colleen Sheehan, Peter Knapp, Felix Beiduk, Tony Godzieba, Bill Werpehowski, Earl Bader, John Caputo, Bill Marks, Bill Fleishman, and many others who inspired me to be a better thinker and person — thanks.

In the comments to the post about Easterbrook’s nonsense, the question arises about the practical usefulness of fields like particle physics. This deserves a more careful response, but I think the basic idea is straightforward: There are parts of science that are worth doing just because we want to know the answer, not because they will lead to tangible results. And we shouldn’t be reluctant to admit it — the “we” who want to know the answer isn’t just professional scientists, it’s a healthy fraction of people in all professions.

(And by the way — does anyone other than me detect irony here? I mean, a complaint that society spends too much of its resources on the frivolous pursuit of high-energy physics is contained in a column about football?)

Matt McIrvin points to a very nice post of his about neutrino astrophysics. But I agree with the spirit of the response by CapitalistImperialistPig, which I take to be that this really isn’t the point. Pure science is worth doing for its own reasons, not because of hypothetical future spin-offs (even though such spin-offs have been remarkably important).

But CIP’s comment contains one very bad idea: that we should require some sort of outreach from every professional scientist. The crucially important job of explaining ourselves to our fellow humans is a duty that inheres in the field as a whole, not in each individual. Outreach is a crucial part of the scientific enterprise, along with things like “theory” and “experiment” and “mentoring students” and “writing grant proposals.” But there’s no reason to require that every single scientist participate in experiments, for example (and thank goodness). What we need to do is to recognize the importance of outreach (not to mention education) for the continued health of science, and identify the best ways to get it done. Perhaps, as budgets are squeezed and money is diverted from real science to Bushian wild-goose chases, the scientific community will overcome its reluctance to give outreach the credit it is due.

Photographs by Chicago artist Nate Larson.

Update: Obviously he hasn’t read my post on Life and the forces of nature.