What I Learned Today

I’d heard about the upcoming transition from analog to digital TV signals, although I hadn’t really paid attention to the date (February 17, 2009) since I don’t actually watch TV. What did pique my interest was the fact that the U.S. government is offering subsidies to households who do not procure a digital TV before the switchover date. If you still “only” have an analog TV, you can get a $40 coupon for a converter to enable you to continue getting your TV fix. No, wait: one TV per household certainly doesn’t satisfy our modern demands! That might require that the whole family watch the same show at the same time. But those clever guys at the Department of Commerce (guess who wants you watching more TV?) are one step ahead: you can now get this subsidy for two TVs per household! Now that’s America in action. We’ll show the world who’s a first-world country, and who can’t even get their constituents one TV per household.

The real point of this post, though, is about a different mandated transition that I recently discovered. By 2020, the DIRECT initiative mandates that all public and private power grids in the country be converted from AC to DC power — and by 2030, all new devices must be able to plug into this DC power bonanza without needing a converter. DIRECT stands for Development Initiative for Return to Edison Current Technology, and it’s sure to have Tesla rolling in his grave. When did this happen? Why wasn’t I told? This is a change that could have real potential for affecting my life!

I wasn’t told because apparently it’s all … an April Fool’s joke. The above link is to Lauren Weinstein’s column in the April issue of Communications of the ACM, in which it is presented without apology or caveat (although with the title “A Current Affair” and an exceedingly poor pun in the final paragraph). Googling to find out more about the “initiative” revealed its positioning as a satire piece. So what I learned today was: don’t trust the ACM! At least not in April. :)

Yesterday, I attended the first day of the Astrobiology Science Conference, or AbSciCon. The day began with a great talk by Lord Martin Rees, who is the Astronomer Royal in England. He wrote a book called “Just Six Numbers” about six parameters of our solar system and Earth that have allowed for conditions conducive to the existence of life (and human beings). He was introduced by Paul Davies, who wrote “The Goldilocks Enigma”. Both books are now candidates for inclusion in my to-read list.

I next attended some talks about the galactic habitable zone. While I’ve read about the “habitable zone” inside our solar system (largely determined by the temperature range within which water exists as a liquid), this was the first time I’d encountered its galactic counterpart. In the galaxy, the constraints relevant for habitability (specifically, the creation of planets) involve the probability of a nearby, disruptive, supernova (so you don’t want to be too close to the galactic center, where stellar density is high) and the availability of metals for forming planets, which are more available where stellar density is high since they’re created by stars (so you don’t want to be too far away from the core). Our Sun is at 8.5 kiloparsecs from the galactic center, although it apparently wobbles in and out a bit, and there’s enough uncertainty in the measurement that it’s more like 7.5 to 8.8 kpc.

The discovery of exoplanets (planets outside our solar system, orbiting other stars) is, in my opinion, one of the foremost scientific discoveries of the past decade or so. It sounds like science fiction, but it’s real (we’re up to 287 exoplanets so far!). So far we’ve predominantly found only Jupiter-sized planets that are close to their host stars (and very, very hot), but most expect that this is because those are the planets that are easiest to detect. The hunt is on for Earth-sized planets that reside in their star’s habitability zone. In particular, a five-year study is beginning to collect 100,000 observations of Alpha Centauri B in hopes of detecting terrestrial planets. No planets have yet been detected in the complex (triple star!) Alpha Centauri system. However, in planet formation simulations, 42% of the Earth-sized planets that formed fell into the habitable zone around Alpha Centauri B. Therefore, if there are planets there, they might be very interesting to study (and much closer than many of the other stellar systems with planets). There are also reasons that planets in a binary or triple star system would be less likely to exist (e.g., gravitational disruptions could prevent them from accreting), but it seems like a good place to look.

But maybe our own location isn’t always so habitable, either. It’s been observed that if you plot the number of extant species as a function of time on Earth (a biodiversity curve), there is a certain cyclicity to the peaks and troughs. Fourier analysis identifies frequencies that have a strong correlation with the signal. It was previously thought that there was a 26-27 Myr periodicity, but this is now viewed as an artifact of the sampling rate (through time) of the curve. After the recent revision of the geological time scale, a stronger signal is found with a period of 62 Myr. So, what might be happening to cause biodiversity to peak and fall every 62 Myr? There are a lot of ideas, including the Nemesis theory of a companion star repeatedly passing through and disrupting the solar system, a sharp increase in the number of mantle plumes in the Earth, solar nuclear oscillations, and, intriguingly, oscillations in the position of the solar system with respect to the galactic plane. We seem to rise up (“north”) of the galactic plane and dip down (“south”) with a period of about 64 Myr, which could be a potential match. When we head north, we move in “front” of the galaxy as it travels through the intergalactic medium, exposing us to more of the incoming cosmic rays, which are known to have negative effects on life. Three of the five known mass extinctions in history coincide with a peak of this vertical oscillation (one is already quite firmly believed to have been caused by a meteor impact and therefore need not fit with the cosmic ray periodicity). A less exotic explanation for the cyclicity is that sea level changes have affected how well fossils are preserved, therefore making it appear that there are fewer of them when preservation rates are low. In fact, strontium isotope ratios, which indicate the degree of rock weathering and erosion going on, seem to have a strong 59 My periodicity. I’d say that the jury’s still out on this one.

I recently finished reading “Unbeaten Tracks in Japan: The Firsthand Experiences of a British Woman in Outback Japan in 1878” (see my review). In addition to inspiring my awe at her fortitude and adventuresome spirit, Isabella Bird also taught me a few words and phrases:

• carbolic acid: The author requested and received permission to visit a newly constructed modern hospital, after which she wrote approvingly of the use of “carbolic acid” as a disinfectant during surgery. It is now known as phenol and no longer used for this purpose (apparently prolonged use irritates the skin), being given up in favor of aseptic techniques.
• conning their lessons: A phrase she used to describe school children studying in the evening. While the modern meaning of “con” refers to deception, an archaic meaning was “to learn by heart.”
• coolie: An “unskilled native laborer”. Ms. Bird uses this to refer to the men pulling her kuruma (wheeled cart), apparently without any sense of insult implied.
• cryptomeria: A conifer (known as ‘sugi’ in Japanese) that appears all over Japan, particularly around temples and shrines (she reports a 40-mile avenue of these trees approaching the shrine at Nikko — I’ll have to look for it myself when I visit!). The sound of the word itself appeals to me. ‘Crypto’, of course, means ‘hidden’ (Latin), but interestingly the other part of the word is from Greek ‘meros’ and means ‘part’, so named because the seeds are hidden by scales.
• Dollond: This is apparently an example of referring to an item by its brand name (like kleenex, band-aid, xerox, etc.). She wrote, “After I was mounted I was on the point of removing my Dollond from the case, which hung on the saddle horn, when a regular stampede occurred, old and young running as fast as they possibly could, children being knocked down in the haste of their elders. Ito [her guide] said that they thought I was taking out a pistol to frighten them, and I made him explain what the object really was, for they are a gentle, harmless people, whom one would not annoy without sincere regret.” She did not, of course, bother to explain to us what it was, as we must already know. Some googling suggests that she was referring to a small telescope or spyglass manufactured by Dollond.
• freshet: This word makes me think of fountains, but apparently it instead refers to a river flood caused by melting snow or rain. These appear frequently in this book, often when the author must ford the flooded streams or is stuck in one hamlet or another due to impassible fords, washed-out bridges, etc.
• plenishings: Another word for furniture or furnishings in a house.
• stretcher: Today, this word has strong invalid connotations, but the author used it to refer to the cot she brought with her in an (unsuccessful) attempt to avoid the rampant fleas (she found that laying out waxed paper around her cot improved its effectiveness significantly).

On the final day of our field trip, we headed to New York Canyon, one of the best places to see the Triassic-Jurassic boundary. We hiked up a twisting path to the top of a ridge, and then one by one began to spot fossils. On the ground. Just lying around in bits and pieces. Everywhere! These were a combination of bivalves, gastropods, and ammonites — lots of ammonites. Ammonites are commonly used for biostratigraphy, the practice of dating a particular layer by the type of ammonites it holds. They’re particularly useful for this because they were evolving so quickly that a particular shape (type of chambers, amount of ridges on the outer shell, etc.) can pinpoint dates more precisely than most other fossils can.

Most of the fossils were trace fossils, or imprints of an ancient organism (as shown at left). However, we did find some whole pieces that were undoubtedly the silicified remnants of actual ammonites. I found one about 1 cm in diameter. It would not be an exaggeration to say that the whole ridge we were on was littered with these things — so much so that we were making slower and slower progress up to the top and then down the other side. Our guides were urging us on to the next ridge over, so that we could look back at the actual boundary layer from enough distance to really see it, but it was awfully hard to press onward when everyone was oohing and ahhing over their latest finds.

At right is a beautiful slice through a gastropod fossil (also silicified). I was struck by how almost unrealistically perfect it seemed — as if it had been drawn, not real! The sparkle effect induced by the silicification makes it even more of a Hollywood fossil.

We did make it up to the other ridge, and turned around to regard the boundary layer itself. There were several holes that had been dug in and around the boundary, presumably by other researchers looking not for fossils but for evidence of a carbon isotope excursion to help pinpoint the boundary itself. As important as this is, it was somewhat less exciting than finding fossils. We never did find the smooth-shelled ammonite that is supposed to be the lowest (oldest) ammonite, appearing just after the transition to the Jurassic. An educational day nonetheless!