30 August, 2006

Two degrees of under-valuation

This week has not been a good one for a postdoc working in my lab, who has now managed to break two pieces of our equipment on consecutive days. This guy is from the 'be absurdly deferential to your superiors, trample on the dignity of your inferiors' school of academia, so both times I have been treated to barely civil demands to drop whatever it is I'm doing and get on with fixing them for him. No apologies were offered for his clumsiness, of course, which have sadly (for him) caused damage beyond my ability to repair.

I'm bristling somewhat at his brusqueness, but part of the problem is my stupid employment situation; when you're employed as a technician (even one who just happens to spend much of his time lecturing, marking, and teaching on field trips) it should hardly come as a surprise when I'm treated like one (not that such treatment is justified in any circumstances, but this person certainly wouldn't have treated me in that way if I was academic staff). However, this sort of thing actually happens so rarely that I was more than a little annoyed. I'm lucky in that most people around here react to what I do rather than my job title. They generally think that I should make more of a fuss about my current situation, but unfortunately until I get some leverage (a good job offer from somewhere else, for example) the Powers That Be merely brush off my complaints.

On a slightly more surreal note, my confused status in the building is further complicated by the fact that the computer system still thinks I'm a PhD student. This has suddenly become more than a mild annoyance (mainly because I get all the bureau-spam for the post-grads in addition to the technical and academic stuff) with the rebuilding of the departmental webpages. We're all getting a personal page, and on the draft version I'm currently listed under PhD students rather than staff. What's amusing is that my title is 'Dr.' Clearly I'm a glutton for punishment.

24 August, 2006

Pluto, king of the dwarfs

Did the IAU actually do anything useful at their General Assembly? I sincerely hope they didn’t waste the whole of their time in Prague arguing about Pluto – that would be a tragic waste with so much fine beer to be sampled.

Anyway, as Nature’s woman in the trenches reports, after a few days of wrangling and counterarguments to the original proposal, the whole thing came down to a few rounds of waving yellow cards in the air. Roundness is still a criterion, but to make it into the big league you also have to have cleared your orbit of other major bodies – if you haven’t then you’re merely a 'dwarf planet'. See the bottom of this press release for the full text of the resolutions. Phil has more at Bad Astronomy, and thinks it’s still a bit arbitrary. Josh is happy. My opinion remains unchanged.

23 August, 2006

The difference between cynicism and skepticism

I watched an interesting, if disturbing, documentary on BBC2 last night, about the case of an alleged child abuse ring in the Orkney Isles. This case highlights the problems that arise when people refuse to question their assumptions, but also illuminates a key difference between the often confused concepts of cynicism and skepticism.

The facts are provided by an accompanying article for the program on the BBC website:

In 1991, five boys and four girls, aged between eight and 15, were taken from their homes on South Ronaldsay.

The children, who could not be identified at the time, returned to their homes two months later when legal action was thrown out by a sheriff…

…The raid was organised after social workers questioned members of another family - the W family - whose father had been jailed for sexual abuse.

They became fearful there was a child sex ring and ritual abuse taking place on South Ronaldsay.

The documentary interviewed some of the children, their parents, and other Orkney locals who were involved in a public campaign for the return of the children, as well as some of the people working for the social services at the time. The behaviour of this latter group during the incident was, to say the least, somewhat questionable. Dramatised transcripts of the interviews they had with the children showed that they placed intense pressure on them, pushing the subjects to ‘remember’ abuse even in the face of strong denials that anything had happened.

The whole thing was a giant trap of self reinforcing credulity. A real case of abuse – the father of the W family – was suspected of being only the tip of the iceburg, thanks to the belief (freshly imported from America) that a large proportion of childrens’ behavioural problems had their roots in unreported physical and sexual abuse. The social workers believed that more people were involved. If the children denied it, they were just repressing the horrible memories, and needed to be pushed to remember them. If the parents denied it, well of course that’s what they’d say! At no stage was the possibility that there was, actually, nothing to uncover even briefly entertained. Even now, after the allegations were dismissed and they were strongly criticised for their handling of the case, the social workers are struggling to accept that they got it wrong. Some are even struggling to get that far: one is as fervent in her beliefs now as she ever was, saying:

"But people saying things didn't happen doesn't affect me in the slightest.

"Because that's my experience of what people always say. I'd be very surprised if they said it did."

One thing that struck me about this case was that the social workers appeared to have a very dim view of human nature, perfectly prepared to believe that large numbers of people were involved in the abuse of children. This is interesting, because a common accusation levelled at skeptics who question the effectiveness of homeopathic remedies, astrology, psychics and other woo is that we only reject these ideas because we have such a negative and suspicious worldview. ‘It’s easy for you to pick holes,’ they say, ‘why can’t you open your mind and give it a chance?’

In Orkney social services, however, we had an environment where there were suspicions of widespread abuse, and the lack of skeptical thinking meant that the optimistic scenario – that there was none – was not given air. This highlights an important point: skepticism is not negative thinking, it’s critical thinking - the rigorous examination of all ideas, particularly ideas you are predisposed to believe. Whether these ideas are positive (‘Some people can read minds’) or negative (‘most parents abuse their children’), the important question for the skeptic is always: based on the evidence, am I justified in believing that?

In fact, I’d argue that skeptical thinking is as much a guard against kneejerk cynicism as it is against unreasoning credulity. Look at my reaction to the recent terrorist arrests. My cynicism leads me to suspect some political theatre, but fortunately my skepticism prevents me from treading too far down the road of the conspiracy theorists; people who are so convinced of the murky agendas of the US that they’re prepared to believe they fabricated the whole thing (see some of the comments here, for example). Caught in a pincer movement between the cynics and the credulous, villified by both, the skeptic can only hope that one day, everyone will have read The Demon Haunted World, and joined us in the reality-based community.

21 August, 2006

Ceres – not just a ball of rock

Lab Lemming, who commented on my post about Pluto, has his own thoughts on the issue. I liked his conclusion:

If a second-grader asks if they are really planets, instead of boring him with committee recommendations and pedantic debate points, we give him a scientific answer: “We don’t know yet; we need to send a spacecraft there in order to find out.” Our planetary system deserves nothing less.

Hear, hear. Also interesting was his mention of recent research which suggested that Ceres is in fact differentiated, and therefore possibly worthy of planetary status (another interesting fact: Ceres comprises 25 percent of the asteroid belt's total mass). Hubble observations published in Nature last year [doi] by Thomas et al. indicate that Ceres is a flattened spheroid. As we all know by now, Ceres is large enough to be compressed into a spherical shape by its own gravity; however, its rotation will result in an equatorial bulge, meaning that the diameter measured across the equator is larger than the diameter measured from pole to pole. Thomas et al. measured the difference as about 32 km; however, if Ceres was a homogeneous body, we’d expect a body with its average density to have a difference closer to 40 km (just for reference, the average diameter is about 950 km). This discrepancy can be explained if Ceres is not homogeneous, but is instead differentiated with high density material (rock) concentrated at the core and lower density material (ice) on the surface. Depending on what density is assumed for the core material, modelling indicates that an icy ‘mantle’ of the order of 100 km thick would fit the observations.

These results were a rapid confirmation of a hypothesis published earlier last year by Thomas McCord and Christophe Sotin in Geophysical Research Letters [doi]. They tried to model the thermal evolution of Ceres since it formed (similar to the modelling done for Titan I’ve talked about in the past) and found that given its size and likely composition, internal heating due to radioactive decay was overwhelmingly likely to cause differentiation. They also commented that the best estimates of flattening at the time (which Thomas et al. refined but did not radically revise – it seems a little unfair that a later and less comprehensive paper probably got more publicity just because it was published in Nature) were consistent with a differentiated internal structure. They even remembered to throw in the obligatory reaction to the presence of liquid water (in the past, at least):

This suggests that chemical reactions could have existed and formed molecules of interest to exobiology studies.

More background is available here. Ceres is potentially quite interesting, people – good thing NASA decided to undo their decision to cancel the probe they’d already largely paid for; Dawn is off to visit it next year, arriving at Ceres in 2015.

18 August, 2006

Of planets and plutons

The furore over the status of Pluto – planet, “pluton”, or whatever they’ve decided to refer to it as now - is really missing the point. I can’t believe that the International Astronomical Union is wasting it’s time discussing the exact descriptive boundaries of a noun which has always been scientifically useless.

Ok, that’s a little extreme – back when ancient astronomers were restricted to observing the heavens with the naked eye, it made sense to subdivide all the points of light into those which appeared fixed relative to each other (the stars) and those which moved about (the planets). The planets move (we know now) because they’re part of our solar system, so are much closer to us than the stars are. Therefore, if we’re going by the original sense of the word, any visible body which orbits the Sun is a planet. If the Greeks had been able to observe Pluto, they would unquestionably have said that it was a planet.

We now know a lot more about those little points in the sky – enough to know that they are not at all alike. Any category that encompasses everything from little balls of silicate to gas giants is not really telling you a hell of a lot about its members beyond very broad generalities - it’s kind of like saying you can say something meaningful about life on Earth by referring to everything as a “self-replicating life-form’. For example, one thing all of these bodies do have in common is that they all coalesced out of the same gas cloud. So did Pluto, but then so did and all the other Kuiper Belt objects, and all the asteroids... forming a continuum of objects all the way from dust particles to (as our current census of extra-solar planets illustrates) virtual stars.

Let’s face it, this argument is purely aesthetic and, to a certain extent, nostalgic. People want to give the ‘classical planets’ some sort of elevated status, and are performing all sorts of descriptive gymnastics so we can include Pluto (whose discovery, thanks to one committed astronomer, was probably a few decades before its time). As a scientist, I don’t care whether it’s a planet or not, I want to know things like:

  • What’s its composition? Silicates? Ice? Gases?
  • Is it differentiated? Beyond a certain size, internal heating is enough to cause melting, causing heavier elements to separate out and migrate to the core, as iron has in our own planet. If you want to have a lower size limit, this would be my personal candidate; anything which has a clearly delineated crust, mantle and core is in. Perhaps that’s a little too difficult to definitively establish though.
  • Does it have an atmosphere? What’s it made of? Is it just a leftover or actively maintained?
  • Is it geologically active (well, it had to get in there somewhere didn’t it)?

Those are some of the interesting questions. Note that “is it large enough for its gravity to squash it into a sphere?” is not among them. Channelling my inner Trekkie, I think that eventually we’re going to have to come up with a slightly more useful classification system (not that this is in any way ideal, but conceptually it’s a good notion), especially as we discover more extrasolar planets. In that context, I suppose the proposal to classify transNeptunian objects with irregular orbits as ‘plutons’ is a vague stumble in the right direction, although I’m not a great fan of them appropriating a perfectly good geological word (pluton being the name for a large, subsurface volcanic intrusion) for their new planetary subclass.

Most commentators seem to agree with me over the silliness of the debate and are also less than impressed by the new classifications. Or both. In the long run, though, whatever Pluto is defined as, I’m still going to be waiting eagerly for the data from New Horizons, which will tell us more about what it’s like.

11 August, 2006

Evolution still OK in the UK

People over the pond (see here, here or here) are somewhat distressed by this graph:

It’s from an article in this week’s Science [doi], and combines the results of surveys in the US, 32 EU or soon to be EU countries, and Japan (the latter was in 2001, the others all last year). The participants were asked a straight yes/no/don’t know question about the validity of evolutionary theory. The USA were edged out by Turkey for bottom spot, showing that the Abrahamic faiths can at least agree on one issue.

However, there is good news for us Brits: we might not be as scientifically ignorant as the BBC poll I blogged about earlier in the year suggested. Whereas that poll suggested that only 48% of the population were convinced evolution happened, in this study it’s more like 70-75%. At the time, I hypothesised that the supposed 17% who supported Intelligent Design may have mixed it up with “some sort of ‘guided evolution/God probably had something to do with it somewhere’-type theism”. If this was the case, the two groups would combine in a a less ambiguous poll like this to give us our 70%. A slightly more nuanced 2003 survey in the supplementary material, where more than half of the 69% who err on the side of Darwin only think evolution is ‘probably true’, supports this interpretation. Likewise, only of the 15% who are creationist-leaning only 8% are True Believers. Typical Brit fence- sitting there

So, should I feel smug first, or relieved?

Lots of heat, but as yet little light

One of the frustrating things about the media nowadays their tendency, when trying to cover a breaking story in the absence of much concrete information to convey, of filling the ether with uninformed and unsubstantiated speculation, discussion and analysis – so much so that the hard facts of the case are lost in the noise.

So it has been with the current terror alert in Britain. All we really know for sure is that the police have arrested 24 people who they suspected were about to commit acts of mass terrorism; The Times claim that they included “a biochemist [and] a Heathrow airport security worker", but no-one else seems to have picked up on this. Beyond the fact that the plan involved getting explosives onto commercial airliners, most of the rampant gossip about numbers, timing and ‘liquid explosives’ is unlikely to come from reliable sources (the security services are no doubt rightly saying as little as possible about what they know until they’re sure they’ve got all of the people involved). The Independent has a good summary of what led the security services to suspect these people, and caused them to act yesterday morning.

Only a nutcase would conclude that because our leaders are worryingly prone to taking political advantage of these situations – John Reid can be strongly suspected of exploiting his foreknowledge of coming events with this particular speech, for example - that they also went the extra step of fabricating them too. But I’d be being dishonest if I said that I didn’t greet yesterday’s news with a certain amount of cynicism. I find that a distressing state of affairs; if I had trouble taking what seems to have been a credible threat seriously, it’s no surprise there’s a good degree of ambivalence in the Muslim community. Previous overhyped incidents, such as the ricin “plot” and the Forest Gate raid have significantly eroded trust in the police and intelligence services, even for people (like me) who have no reason to feel singled out or stigmatised. Those times, what we were told in the immediate aftermath did not hold up under scrutiny. This time, the claims about the planned scope and magnitude of these attacks will hopefully be promptly backed up with hard evidence.

(We apologise for the politics, your normal scientific service will be resumed shortly...)

10 August, 2006

External triggering of volcanic eruptions

Phil at Bad Astronomy has been suitably mocking about a BBC story discussing the possibility that last night’s full moon would trigger an eruption of Mount Mayon in the Phillipines (he’s now also noted that it didn’t).

We need to be careful about what this story is and isn’t about. What it’s not about is the notion that a completely inactive volcano is suddenly going to be woken up; it’s more about the potential of tidal forces as a trigger for a volcano which is already predisposed to erupt (e.g. has a full magma chamber under pressure). As the earth rotates beneath the Moon, its gravity not only pulls on the water directly beneath it, but also stretches the underlying crust. The effect is small, but it could be enough to destabilise a finely balanced system and cause an eruption.

If this is the case, we’d expect a statistical correlation between the strength of tidal forces and the frequency of volcanic eruptions, with eruptions more likely when those forces are strongest. These variations could potentially be associated with both the twice daily (diurnal) high tide-low tide cycles, and also the monthly spring-neap cycles, which is what the BBC article is referring to: spring tides occur at full and new moons (for completeness, I should point out that this latter cycle is a result of the changing relative position of the sun with respect to the moon; see here).

As Phil points out, for Mount Mayon there is no apparent correlation:

…the BBC report says that the full Moon "coincided with at least three of Mayon’s 47 eruptions, including the two most recent ones in 2000 and 2001".

…Let’s be generous and say that the time period around the full Moon is 2 days: a day before and a day after. The Moon goes through a complete cycle in roughly 29 days, so it’s full for 2/29 = 1/15th of the time. If you then look at 47 eruptions, then [if tidal forces have no effect] you expect to see 47/15 = 3 eruptions near the full Moon. And hey, that’s exactly what the report says!

In the comments someone posted a link to this article which discusses possible evidence for a link elsewhere, particularly in the eruptive pattern of Stromboli. It’s a puff piece for a documentary though, so there’s no hard data (and I can’t find any publications about it). Besides, if we want to rigorously prove a link, we don’t want to look at the eruptive history of individual volcanoes; we want to look at the global eruption record. This was done in a paper published by Mason et al. in the Journal of Geophysical Research in 2004 [doi]. Their analysis:
We found no conclusive evidence for a general correlation between volcanic activity and lunar tidal phase. This result is consistent with recent work which indicates that diurnal and fortnightly tidal stresses may be too short-lived and strain rates too high to effect a significant viscous response in partially molten regions of the Earth’s subsurface.

In other words, it appears the pressure changes induced by tidal forces are not a significant factor in triggering an eruption. However, the authors in this paper did notice a seasonal variation in global eruption rates. Their Figure 1, shown below indicates that slightly more eruptions start between November and April, compared to the period between April and October. The top subfigure is subdivided according to the eruption size according to the Volcanic Explosivity Index.

This variation appears small but is statistically significant; less clear is the mechanism which drives it. The authors suggest seasonal changes in crustal loading due to variations in sea level, atmospheric pressure, ice and snow cover, and other effects of the hydrological cycle.
Seasonality in eruptions is correlated with environmental fluctuations associated with the deformation of the Earth in response to the annual hydrological cycle, including falls in sea level, millimeter-scale motion of the Earth’s crust, and falls in regional atmospheric pressure.

This would fit in with recent speculations about the effect of melting ice sheets and glaciers on volcanic activity (pronouncements of impending doom notwithstanding).

So it seems that external sources may be able to influence the timing of volcanic eruptions; it’s just that the Moon is not one of them. But how about the other obvious potential influence: the effect of a large nearby earthquake? I’ve actually had a post in preparation for some time about this very matter, which hopefully I’ll follow up with shortly.

04 August, 2006

Crushed dreams of heroism

I usually don't bother to post these online quiz things, but I found the result of this one (via Bad Astronomy) rather apposite. We all dream of being heroes, but it seems that even the internet is insightful enough to know that is not my destiny.

Your results:
You are An Expendable Character (Redshirt)

Since your accomplishments are seldom noticed, and you are rarely thought of, you are expendable. That doesn't mean your job isn't important but if you were in Star Trek you would be killed off in the first episode you appeared in.


An Expendable Character (Redshirt) - 75%
Spock - 74%
Mr. Scott - 65%
Geordi LaForge - 65%
Leonard McCoy (Bones) - 60%
Beverly Crusher - 60%
Data - 58%
Jean-Luc Picard - 50%
Uhura - 45%
Deanna Troi - 45%
Will Riker - 45%
Worf - 40%
Chekov - 35%
Mr. Sulu - 35%
James T. Kirk (Captain) - 35%

Click here to take the Star Trek Personality Test

And in case you're wondering: yes, but not to the extent that I think learning Klingon is a good use of my time; and DS9, by some distance.