Miscellany

Click the image for more. I had run across this some time ago, and was reminded of it in a post at Uncertain Principles. Consistently amusing, within even tighter self-imposed constraints than the original Law & Order series.

Another reason why living by a Great Lake is better than living by the ocean: little danger of tidal waves.

A collapsing volcano could trigger a vast tidal wave capable of wiping New York, Washington and Miami off the map, warn geologists.

They also fear southern England could be hit.

Geologists are concerned that an unstable flank of the Cumbre Vieja volcano on the island of La Palma in the Canaries is in danger of sliding into the sea.

If shaken loose by a volcanic eruption, the huge slab of rock would send a tsunami more than 150 metres high racing across the Atlantic at the speed of a jumbo jet.

Within three hours, the wave would swamp the east coast of Africa, within five hours it would reach southern England and within 12 it would hit America’s east coast.

New York, Washington, Boston and Miami would be hit by successive waves abound 20 metres high. Tens of millions of people could die.

Although the volcano could erupt any day – it has been dormant since 1971 but tends to erupt every 20 to 200 years – funding to British scientists investigating the threat has been stopped.

I like “They also fear southern England could be hit.” And this is a British scientist, in a story reported by the London Telegraph.

But there’s good news, as well: hysteria about being hit by an asteroid has somehow managed to decrease that risk from “microscopically small” to “really so miniscule that we can relax a little.” Thank goodness about that.

As Jennifer mentions in the comments, one of the instruments on the Hubble Space Telescope has apparently broken down: the Imaging Spectrograph, used to (obviously) take images with simultaneous spectral information, for example of black-hole candidates. This is too bad but not a complete catastrophe (unless you had time on the instrument); it had already lived past its expected lifespan, and there are still three instruments working on HST. Sure would be nice to have a servicing mission, though.

As far as I can tell, our track record of reaping long-term benefits from our support of repressive and authoritarian regimes is pretty dismal. Yet, we keep on doing it, mostly for short-sighted reasons. Saudi Arabia is the example that has been drawing increasing scrutiny.

The latest charming anecdote: three reformers (Ali al-Demaini, Matruk al-Faleh and Abd Allah al-Hamed) have been arrested for “calling for adopting a constitutional monarchy and using western terminology,” among other heinous offences. These are not exactly anarchists we’re talking about here — their role model is Jordan.

I wonder what Western terminology they were using? “Radical, dude”?

This weekend I had a chance to visit Chicago’s latest attraction, the somewhat-misnamed Millennium Park. This is a parcel of land just north of the Art Institute, adjacent to Grant Park, that had been languishing as a railroad yard, until the city powers decided to spruce it up as part of a celebration for the year 2000. Somewhat behind schedule and substantially over budget, the project has finally been completed, and has garnered rave reviews from visitors thus far.

Easily the most talked-about component of Millennium Park is the large reflective statue by Anish Kapoor, officially named “Cloud Gate” but universally dubbed “The Bean.” (Click for full-sized version.)

Now, I had actually seen a model for the park a couple of years ago, and had no doubt that this abstract beast was going to be a complete disaster. Let me publicly state that I was completely wrong; the full-sized bean is strangely compelling and irresistible. Reflecting the skyline and the sky itself with a gentle distortion, this simple shape grabs your attention and holds it with an eerie fascination.

You can also walk underneath the bean, where Kapoor has manipulated the reflections to produce interesting multiple images. Viewers can happily alternate between looking for images of themselves in the interior of the bean, and wondering at the ease with which their fellow visitors are entertained.

Photos don’t really do the bean justice, but you can’t help but taking many pictures when you are in its presence; I predict with confidence that within a short time this sculpture will be recognized as the most-photographed object in the world. (Note that the sculpture is actually not complete; the visible seams are to be welded to form an unbroken smooth surface.)

To be honest, the simplicity of the bean is also its limitation; it only provides perhaps fifteen minutes of contemplation before you are ready to move on to something else. Fortunately, the Art Institute is just to the south, so a pilgrimage need not be exclusively beanocentric.

The other new attractions in the park are also worth attention. An interesting, although less obviously successful, art installation is the computerized fountain designed by Barcelona artist Jaume Plensa. It consists of two rectangular towers that gently spray water in all directions, and project moving images of faces (apparently supposed to be representative citizens of Chicago). At occasional intervals the faces appear to spit water from their mouths, in a reference to more classical fountain designs.

While the fountains don’t have the immediate and universal appeal of the bean, they are a big hit with kids, who can frolic around in the water to their heart’s content. An obvious worry is the upkeep associated with the fountain systems — these would be a complete disaster if they were allowed to fall into disrepair.

Before the bean captured everyone’s heart, the centerpiece of the Millennium Park project was a new band shell designed by Frank Gehry. It brings to mind giant chocolate shavings on the top of an especially elaborately decorated cake (if chocolate shavings were made of stainless steel).

This photo isn’t a very good view of the band shell itself, because I wanted to note a cute science fact about the trellis extending out from the shell and covering a wide section of park in which visitors can relax and listen to concerts. You will notice the speakers hanging from the trellis itself; often attempts to amplify outdoor musical performances result in acoustic nightmares. To prevent this from happening, the designers calculated the time it would take sound to reach from the stage to different points in the audience, and have built in an appropriate delay in the signal sent to the speakers so that the sound reaches the listener from both sources simultaneously. Now that is good planning.

Longtime Preposterous readers know that some time ago I endorsed Barack Obama for our open Senate seat here in Illinois. At the time, I thought the alternative would be Republican Jack Ryan, who was most famous for having been previously married to an actress. But, as we all know, Ryan had to drop out after some messiness involving Paris sex clubs (always more trouble than they are worth, take my word for it). And now it looks like charismatic talk-show host Alan Keyes might be our new Republican nominee. Like everyone else, I always took Keyes for a complete nutcase. But perhaps I was wrong. According to his own website, Alan Keyes:

• Is widely considered the most formidable defender of America’s founding principles in today’s political arena.
• Is generally conceded to be the winner of the 2000 Republican Presidential Debates, due to his remarkable eloquence and persuasiveness.
• Has demonstrated exceptional ability to educate his fellow citizens about America’s founding ideals, upon which we as a people must stand if we are to survive as a free nation.
• Is capable of leading our country to widespread moral and political renewal, once all of America has a chance to see and hear, first-hand, his self-evident brilliance.
  

Pretty impressive, you have to admit. By the way, “self-evident” means “evident, apparently, only to one’s self,” right?

When it comes to quantum gravity and fundamental physics more generally, there is a lot we don’t know, and many different approaches to making progress. A top-down kind of approach attempts to figure out what the ultimate laws are, and then see what they might have to say about reality; string theory is the obvious example. But you could also take a bottom-up or phenomenological approach, in which you try to figure out what kinds of physical effects might arise due to quantum gravity and then go look for them, even if you haven’t derived them from a more complete theory. Tests of Lorentz invariance provide a good example, and the subject of my recent paper. This is the paper I mentioned writing with my (former) student Eugene; he now has a follow-up paper extending our work.

Lorentz invariance is simply the idea that there is no preferred direction in spacetime. Not only do the laws of physics not care about the direction in which you are looking (invariance under spatial rotations), it also doesn’t care about the speed at which you are moving relative to other stuff in the universe (invariance under “boosts,” as physicists would say). The idea is a cornerstone of relativity, and got a big boost (pun unintended, but accepted) when the Michelson-Morley experiment showed that the speed of light seemed to be the same in all reference frames — there was no evidence for a background “aether” with respect to which you could measure your velocity. But its roots actually go back to Galileo, who first proposed that all velocities were relative; to people on the sidewalk, the road is stationary and the cars are moving, but to people in the cars, they are stationary and the road is moving, and each perspective is perfectly valid.

Actually, this violating-Lorentz-invariance stuff is not new to me. Using cosmology to test Lorentz-violating theories was the subject of my first published paper. It was a collaboration with George Field (my Ph.D. advisor) and Roman Jackiw, both very accomplished theorists in astrophysics and field theory, respectively. My role as the meek young graduate student was largely to type in the data and make plots, but that’s how you get started in this business.

The theory we considered had a fixed timelike vector field without any independent dynamics, but it was coupled to electromagnetism in a specific way that violated parity as well as Lorentz symmetry. We showed that the coupling would cause a “twist” in the polarization of light coming from distant galaxies, and George knew that for certain radio galaxies you could determine what the polarization should be without any Lorentz-violating effect, allowing us to put a very tight limit. The data I typed in came from different sources, and consisted of the polarization information plus the distance (actually, the redshift) of the different galaxies. Years later, much to our surprise, this same data appeared on the front page of the New York Times. Two researchers had used our dataset but analyzed it in a different way, trying to constrain a vector pointing in a spacelike direction rather than a timelike one. The big difference is that they claimed to actually find a nonzero effect, which they announced in a press release before they made the paper available to other experts. Unfortunately they were just mistaken, as I recount in great detail here. But it’s still worth thinking about; indeed, some candidates for dark energy in the universe could lead to a very similar effect, so it’s worth improving the present data to put much tighter constraints (or to discover dark energy!).

What Eugene and I have done is a little different. We imagine there is a vector field through spacetime that violates Lorentz invariance (since you could, in principle, measure your speed with respect to it in an absolute sense), but we worry about its gravitational effects rather than its interactions with ordinary matter and radiation. Interestingly, we find that the vector field has no effect if there is no matter lying around, but it works to alter the strength of the gravitational field caused by matter. In other words, it changes the effective value of G, Newton’s constant of gravity. This would be an unobservable effect if it just changed Newton’s constant once and for all, since we have no experimental knowledge of what the constant was before the vector field messed with it. Fortunately, it changes it in different ways in different circumstances: making the effective value of Newton’s constant larger in the Solar System, but smaller when we consider the expansion of the entire universe.

Thus, we have an observational constraint: measure the value of G in the Solar System, use that to predict something about cosmology, and compare with the data. The most straightforward example is actually the primordial abundance of light elements such as Helium and Lithium. These were created at an early time after the Big Bang (between one second and a couple of minutes) as the universe expanded and cooled, and the precise amount of different elements you get depends sensitively on the expansion rate of the universe, and thus on Newton’s constant. We find that our vector field must be less than ten percent of the Planck scale, the fundamental unit in physics where gravity and quantum mechanics come together. The Planck scale is pretty big, so it’s not a great limit, but still an interesting one.

Everyone was (justifiably) jealous sometime back when I revealed that I had received a WMAP beach ball in the mail. WMAP, the Wilkinson Microwave Anisotropy Probe, is a NASA satellite that has taken the most precise images yet of the leftover thermal radiation from the early universe. Who wouldn’t want to have a beach ball with a snapshot of the whole universe on it?

Well, I can’t help you with the beach ball, but here’s something almost as good: a CafePress store selling all sorts of WMAP merchandise, including the boxer shorts shown at right. (Found linked from Licia Verde‘s home page.) There’s something for everyone — T-shirts, teddy bears, thongs, more than you would ever want, really.

Someday I will follow through on the idea of setting up a store for Preposterous Universe merchandise. (In the meantime, just go buy my book!) Maybe I’ll stick with coffee cups, though.

Continuing the story from yesterday, let’s say you’re an enthusiastic amateur about to go out in the field (led by one of the world’s experts) and dig up some dinosaur fossils. Your first question would of course be: what do I wear? You’ll want good hiking boots, sturdy but not too heavy. It’s beastly hot, so you’ll be tempted to wear shorts, but don’t; you’ll be tromping through cactus and sagebrush, and then spending hours kneeling on rocks and dirt, so jeans are definitely called for. Hat and sunglasses are mandatory. Some of us wore lightweight long-sleeved shirts, although I did fine with T-shirts and heavy doses of sunscreen; despite the relentless Wyoming sun, I managed to keep my healthy pale complexion largely intact.

Besides clothes, the only necessary items we were personally responsible for were our water canteens. Bug spray is a good idea, and cameras or binoculars are useful, but not required. The serious equipment was provided for us by the Project Exploration folks: GPS units, walkie-talkies, brushes, awls, hammers, gloves, shovels, pickaxe, hardener, glue, tinfoil, burlap, plaster, measuring tape. Nothing very high-tech, other than the GPS. The physicist in me was sure that there must be some X-ray-like technique to probe into the soil to distinguish fossils from the surrounding rock; but nobody knows of any good way to do it, and I didn’t have any useful ideas. (I’m a cosmologist, okay?)

Suitably equipped, we head out to the site. Let me just mention that none of the skills one develops by spending one’s days doing theoretical physics and one’s evenings at jazz clubs really come in handy out in the field. The work involves serious physical labor and tremendous patience; the good news is that, although it requires years of training and practice to be really good at it, essentially anyone can be productive after a short tutorial. It helps that Paul seems to have an endless (or at least substantial) supply of patience and confidence in his motley crew of city folks; in his shoes, I would be scared to death of what these klutzes were likely to do to my fossils, and would simply ask them to watch from a respectful distance while I did the work myself.

Our group was about fifteen people, of whom two (Paul and Bob Masek, a fossil preparator at the University of Chicago) really knew what they were doing. Of the rest of us, about half had been along the year before, and the newcomers would occasionally (in their naivete) look to us for guidance. We took two vans from the ranch where we were staying out to the site, or at least as close to the site as we could get in the vans. From there we have to lug the aforementioned equipment to the actual fossils, at which point the excitement starts.

The main fossil Paul and his students had found was a vertebra from the tail of what is likely to be a Camarasaurus, a large sauropod common in the Jurassic. (Yes I know the link says that Camarasaurus was “much smaller” than other sauropods, but when you’re 60 feet long and weigh 20 tons, you’re large in my book.) Sauropods are the hulking big four-legged herbivorous dinosaurs with long necks, like Brachiosaurus and Diplodocus; other major categories are the mostly-carnivorous theropods such as raptors and T. Rex, and ornithischians or bird-hipped dinosaurs, including most of the funky armor-plated species like Triceratops and Ankylosaurus. Just to add an element of confusion, actual birds evolved from the lizard-hipped theropods, not from the bird-hipped ornithischians.

What you typically find, of course, is a single bone sticking out of the rock. In this case, Paul had found a vertebra from the tail. The question then is, if you follow the trail into the rock, do you just find the tip of the tail, or most of the dinosaur? In other words, in which direction is the tail pointing? You just have to dig and find out.

This is where the patience and determination come in. You basically poke gingerly at the area around the fossil with an awl, then remove the dirt and stones with a brush. (Try not to use your fingers, or let the stones fall onto the fossil; a brush is gentlest.) The awl and brush are your most common tools. From the variations in texture and color, you should be able to tell the bone from the surrounding rock if you are careful, although sometimes it’s tricky even for the experts. (The experts, by the way, refer to the rock in which the fossil is embedded as “matrix,” thus adding to the science-fictiony feel of the whole enterprise.) At first you have to move extremely carefully and tentatively, as you don’t know where the rest of the bones are. Every time you uncover a little bit of bone, you pour hardener over it to help protect it from being scratched or shattered. As often as not, the bones are not “articulated” — arrayed in a nice dinosaur shape — but rather are jumbled together. But after you make a little bit of progress, you can begin to get a feeling for the way in which the skeleton is arrayed in the rock. At that point, you might decide that the three feet of rock above your fossil can be removed more rapidly than awls and brushes allow; that’s where the pickaxe and shovels come in, or even jackhammers or heavy machinery in extreme cases.

Here’s a picture of Paul hugging the part of the tail we have uncovered. He’s feeling protective because we had very good news: the fossil seems to be pretty much articulated, and even better the vertebrae are growing as we move into the rock! Which means there is an excellent chance of finding a substantial portion of Camarasaurus skeleton lying in there, undisturbed for the last 150 million years.

Our rate of progress wasn’t nearly enough to imagine actually excavating the thing; the picture here basically shows the end result of a day and a half of work. Further trips will be required before the entire fossil can be shipped to Chicago. To protect what we have uncovered, we first cover the bones with tinfoil, then with strips of burlap dipped in plaster. The plaster will not only protect the bones once we cover them with dirt again, it also will make it much easier to eventually bring the fossil home. In fact you don’t nearly dig away all the rock from the bone; you intentionally leave an inch or two of matrix surrounding the bottom half of bones, dig out from the bottom, and then plaster around the entire collection, which gets shipped back to the lab. (A ton or two of shipped materials is common.) There a real expert, working in decent conditions (presumably involving air-conditioning), can remove the rest of the matrix. Then you take appropriate pictures and measurements, and possibly think about mounting the specimen for display. If (as Paul often does) you went to Niger or Mongolia or Argentina to collect the fossils in the first place, the original country will typically want it back; you get the science out of it, and it ultimately returns home. For our Wyoming fossils, we hope to build up a collection at the University; the previous collection was short-sightedly given away.

This is the second year I’ve gone on one of these trips with PE. The first year was great fun but I was exhausted by the end; this year I wanted to stay out there and keep digging. It’s an exhilarating experience, and utterly different from being a theoretical physicist. On the other hand, dinosaurs and cosmology are two topics that readily engage the public imagination, and the folks at PE hope to extend their reach into other areas of science, so I hope I can be some help. At the end of a long day in the field I gave an informal lecture on black holes — amazingly, despite myriad other distractions and every reason to be tired (the lecture began at 9:30 p.m.), everyone on the expedition attended and asked great questions about the curvature of spacetime. Just one more reminder, as if any were needed, that most people are intrinsically fascinated by science, and it’s our duty to do a better job of sharing the excitement that professional scientists get to feel all the time.

Found over at Talking Points Memo, this amazing story from Associated Press:

Some Democrats seeking Cheney tickets had to sign oath

By RICHARD BENKE

Associated Press Writer

RIO RANCHO, N.M. (AP) — Some Democrats who signed up to hear Vice President Dick Cheney speak here Saturday were refused tickets unless they signed a pledge to endorse President Bush.

The measure was a security step designed to avoid a disruption, which Bush campaign spokesman Dan Foley alleged Democrats were planning. Democratic Party officials denied it.

Several Democrats, at least, encountered the screening measures Thursday after calling from a line that self-identified as ACT, America Coming Together, an activist group that supports Kerry, Foley said. Others attempted to give false names and were denied tickets, he said.

Two men who had sought tickets reported they were required to give name, address, phone number, e-mail address and driver’s license number, then were presented the pledge of endorsement when they arrived to pick up the tickets Thursday.

The purported explanation is that a speech by the Vice-President is a “reward” for loyal supporters, and consequently need not be open to ordinary non-supporting Americans.

Outrage fatigue. That’s the only way they can get away with this stuff.