an autodidact meets a dilettante…

‘Rise above yourself and grasp the world’ Archimedes – attribution

Archive for the ‘science’ Category

a discussion on scientific progress and scientism

leave a comment »

Pretty funny, but not much related to this post

Scientific progress depends on an expectation of continuous innovation, on encouraging an attitude of willingness to experiment, rejecting established authority of every sort, on the assumption that new experiments will bring out new realities and force us to revise our knowledge.’
Bruno Maçães, The Dawn of Eurasia

Discuss ‘scientific progress’ in the light of this statement.

Canto: This is very interesting. As a ‘fan’ (remembering that this word comes from ‘fanatic’) of scientific progress, an evidence junky, and also a humanist, I can see, and have experienced, a collision between the scientific process, which involves a respect for evidence rather than people, and the strongly held cultural/religious beliefs of people, which they hold fast to as identifying and solidifying principles. For example, the Aboriginal belief, handed down and taught, that their people have inhabited this land for eternity, while scientists are trying to determine precisely when the first home sapiens arrived here, and how old the continent of Australia actually is, given the pre-existence of Gondwana, Pangaea and the rest. 

Jacinta: A belief probably not held by that many Aboriginal people, most of whom have been educated in institutions that treat science seriously. That’s to say, more recent generations, and this is a problem everywhere – ‘established authority’ can also mean traditional beliefs and practices, even the old established language. The tribal language, the local language, being abandoned everywhere for more global forms of communication. 

Canto: Yes I read yesterday an essay topic about the growth of English as an international language, often as a person’s second or third language – and I recognised immediately that the essay was out of date as it stated that about 900,000 used English that way. It’s well over a billion now and rising fast. 

Jacinta: And the language of science is largely English – plus mathematics. It’s funny that there are actual scientific endeavours to preserve many of the 7,000 languages that exist in the world, while scientific communication relies largely on a universal single language…

Canto: Yes, and a person can feel that contradiction, that kind of tugging both ways, within themselves. Like following Scottish or Jewish traditions at times of celebration, enjoying the fun, and then thinking – why am I doing this? I don’t believe in first-footing or plate-breaking or whatever. 

Jacinta: People follow these traditions because they work, or at least they think so, but not always in the traditional way. And many such followers are well aware of this – that these activities don’t work as lucky charms so much as social glue. But that’s the trouble with glue – you get stuck. 

Canto: You’ve heard of the missionary who tried to Christianise the Andaman Islanders and was speared to death for his efforts? Most people’s responses were of the ‘serves him right’ type. But wasn’t that because the missionary was just trying to substitute one set of myths for another? If he was trying to introduce a new fishing method, or, I don’t know, something modernising and scientific…

Jacinta: We’ll have to get onto so-called ‘scientism’ at some stage, but here’s the thing. Maçães writes about ‘rejecting established authority of every sort’, and Richard Feynman apparently described science as belief in the ignorance of experts, but when we come upon, say, the Piripkura people of Brazil’s Mato Grosso, whose continued existence in the face of western diseases and cattle-raising gunmen we’re not even sure about, converting such people into scientific modernists who should question why they’re having difficulty surviving and adapting, seems very arrogant somehow. 

Canto: This is where humanism comes in, and it’s a fraught kind of humanism. Many would say – look, all these tribes will disappear, because their way of life is outdated and ‘in the way’, which doesn’t mean the people will disappear, they’ll gradually get absorbed into the broader population, modernised, urbanised, educated and homogenised into our diverse modern world. If they’re lucky enough not to die of disease and gunshot wounds. 

Jacinta: And their expertise in traditional hunting, gathering and fishing will be found to be not so much ignorant as obsolete within the mechanised world of food production and consumption. And this is happening everywhere, from the Limi of south-western China to the Bushmen of Botswana. Could it be said that they’re the victims of scientific progress? It’s hard to distinguish science and technology from other aspects of modernism I suppose, but this is the complex other face of science’s otherwise refreshing respect for innovation, experiment and evidence rather than ‘experts’, or just plain old people. 

Canto: So what do you think of ‘scientism’, which is I think a rather vague claim about the steamrolling arrogance of science, and what about the possibly self-destructive implications of relentless scientific advancement?

Jacinta: You know there might be something in the criticism, because as I try to get my head around the complexities of, say, electromagnetism, or neurological interactions, I find myself less drawn to some of my earlier loves, literature and the visual arts. I don’t know if that means I’m arrogantly dismissing them, but I do know they’re not engaging me in the old way. I find science more exciting, and maybe that’s dangerous…

Canto: In what way? 

Jacinta: Well, the motto of this blog is ‘rise above yourself and grasp the world’, but that kind of engagement – in something so large if not abstract as ‘the world’….

Canto: The world isn’t abstract – it’s everything. Everything found in time and space. It’s absolute reality. 

Jacinta: Well maybe, but that engagement in ‘everything’, it rather detaches you from the smaller world of the people around you, and – and yourself. Rising above yourself entails escaping from yourself and you can’t really do that, can you? 

Canto: The sciences of biology, neurology, genetics and so forth are the best ways of learning about ourselves. It all comes back to us in the end, doesn’t it? Our mathematical equations, our experiments, our discoveries of black holes, the Higgs boson, gravitational waves, they’re all about us, somehow. The things we do. And it seems it helps our understanding and sympathy. Science is about finding out things, like finding out about other people. The more we find out, the less we tend to dismiss or hate, or fear. Look at those who commit acts of terror. Surely ignorance plays a major role in such acts. A refusal or inability to find out stuff about others. A lack of curiosity about why people are different in the way they look and act. Science – or the scientific impulse, which is basically curiosity – opens us up to these things, so that we no longer hate or fear mosquitos or spiders or snakes or Christians or Moslems or Jews. 

Jacinta: Hmmm, so what’s the buzz about scientism? Let’s end this post by discussing a quote from an essay on scientism written for the American Association for the Advancement of Science:

It is one thing to celebrate science for its achievements and remarkable ability to explain a wide variety of phenomena in the natural world. But to claim there is nothing knowable outside the scope of science would be similar to a successful fisherman saying that whatever he can’t catch in his nets does not exist. Once you accept that science is the only source of human knowledge, you have adopted a philosophical position (scientism) that cannot be verified, or falsified, by science itself. It is, in a word, unscientific.

Canto: Well I’m not impressed with this argument, I must say, probably because I don’t agree with the implied definition of science it presents. Science, to me, is an activity, driven by curiosity, which provides dividends in the form of a greater knowledge which raises more and more questions. I rarely worry whether it’s the only source of human knowledge, because that raises the question of what ‘knowledge’ is, and I’m not so interested in that enquiry. Much more interesting to try and work out how life came from non-life, how our planet got covered in water, whether life of any kind exists elsewhere in the solar system, how different parts of the brain interact under particular circumstances, etc etc. I don’t know or care whether you call those enquiries ‘science’ or not, I only know that you won’t get answers to those questions by just sitting around thinking about them. I mean, you can start by thinking, forming a hypothesis, but then you have to explore, gather evidence, conduct experiments, test then modify or abandon your hypothesis…

Jacinta: I thought the ‘net’ analogy used in that quote was pretty inept. Of course it’s reminiscent of the old Kantian categories, the grid or net by means of which we know things, which separates the noumenal world of things in themselves from the phenomenal world of perception/conception. But Kant’s problem was that the noumenal world was just a hypothesis that couldn’t be tested, since we only have our perceptions/conceptions – enhanced somewhat by technology – with which to test things.

Canto: Probably another reason why so many scientists, especially physicists, seem dismissive of philosophers of science. Another problem with those that go on about scientism is that they insist that there are other ways of knowing, but you can rarely pin them down on what those ways of knowing are.

Jacinta: Yes they’re often religious or new-age types, and spiritual knowledge is their stock-in-trade. And if you don’t have that spirituality, which doesn’t need to be explained, then you’ll never understand, you’ll always be a shallow materialist. There’s no response to that view.

Canto: Yes, we’re obviously on the autism spectrum, though not so far along as real scientists. Meanwhile, let’s keep exploring…

Written by stewart henderson

April 15, 2019 at 9:27 am

fish deaths in the lower Darling – interim report

leave a comment »

Jacinta: We wrote about this issue in a piece posted on February 11, so it’s time to follow up – an interim report came out on February 20, and a final report is due at the end of March, but my feeling is that the final report won’t differ much from this interim one.

Canto: Yes I get the feeling that these experts have largely known about the situation for a long time – unusual climatic conditions plus an increasing lack of water in the system, which would make the remaining water more susceptible to extremes of weather.

Jacinta: So here’s some of what they’re saying. There were three separate events; the first on December 15 involved tens of thousands of fish deaths over a 30km stretch of the Darling near Menindee, the second on Jan 6-7, over 45kms in the same area, involved hundreds of thousands of deaths, even millions according to some residents, and the third on Jan 28, with thousands of deaths. Likely effects on fish populations in the Darling will last for years.

Canto: And they warn that more deaths are likely to occur – though no major events have been reported since – due to low inflows and continued dry conditions in the catchment area. Monitoring has shown that there are problems of low dissolved oxygen and ‘high stratification’ at various points along the river. I presume ‘high stratification’ is self-explanatory, that the water isn’t mixing due to low flows?

Jacinta: Yes, but I think the issue is thermal stratification, where you have a warm surface layer sitting above a cooler, oxygen-depleted sub-surface layer. These are excellent conditions for algal blooms apparently. And the low flows are a natural feature of the Darling. It’s also very variable in flow, much more so than the Murray, due to its low relief, the more variable rainfall in the region, and the tributaries which create a large catchment area. I don’t know if that makes sense.

Canto: Neither do I. I note that they’ve been carefully critical of the NSW government’s ‘Barwon-Darling Water Sharing Plan 2012’, because between the draft and final implementation of the plan the number of high-flow Class C shares was reduced and the number of Class A (low flow) and Class B (medium flow) shares increased, which meant more extraction of water overall, and at lower flows. They recognise that there have been recent Federal moves to reverse this, but clearly they don’t consider them sufficient.

Jacinta: Yes and the problem goes back a way. They refer to an analysis from almost two decades ago:

The flow regime in the lower Darling has changed significantly since the completion of the Menindee Lakes storage scheme in 1968, and as a result of abstractions in the Barwon–Darling and its tributaries. It is estimated that the mean annual flow in the Darling River has been reduced by more than 40% as a result of abstractions in the Barwon–Darling (Gippel & Blackham, 2002). 

Presumably ‘abstractions’ means what I think it means – though elsewhere they use the term ‘extractions’ which is confusing.

Canto: We should point out the immense complexity of the system we’re dealing with, which we can see from detailed maps that accompany the report, not to mention a number of barely comprehensible charts and graphs. Anyway the effect of ‘water management’ on native vegetation has been dire in some regions. For example, reduced inundation of natural floodplains has affected the health of the river red gums, while other trees have been killed off by the creation of artificial lakes.

Jacinta: And returning to fish deaths, the report states that ‘the influence of upstream extractions on inflows to the Menindee Lakes is an important consideration when assessing the causes of fish deaths downstream’. What they point out is that the proportion of extractions is higher in times of lower inflow, which is intuitively obvious I suppose. And extractions during 2017-8 were proportionally the second highest on record. That’s in the Northern Basin, well above the Menindee Lakes.

Canto: And the extractions have been mainly out of the tributaries above the Barwon-Darling, not those principal rivers. Queenslanders!

Jacinta: No mention of Queenslanders, but let’s not get bogged down..

Canto: Easily done when there’s hardly any water…

Jacinta: Let’s go to the provisional findings and recommendations. There are 18 briefly stated findings in all, and 20 more expansive recommendations. The first two findings are about extreme weather/climatic conditions amplified by climate change, with the expectation that this will be a continuing and growing problem. Findings 3 and 4 focus on the combined effects of drought and development. There’s a lack of updated data to separate out the effects, but it’s estimated that pre-development inflows into the Menindee Lakes were two or three times what they are now. Further findings are that the impact of diversions of or extractions from flows are greater during dry years, that extractions from tributaries are more impactful than extractions from the Barwon-Darling Rivers.

Canto: The findings related directly to fish deaths – principally findings 10 through 15 – are most interesting, so I’ll try to explain. The Menindee Lakes experienced high inflows in 2012 and 2016, which caused greater connection through the river system and better conditions for fish spawning and ‘recruitment’ (I don’t know what that means). So, lots of new, young fish. Then came the bad 2017-8 period, and releases from the Menindee Lakes were less than the minimum recommended under the water sharing plan, ‘with the intent to prolong stock and domestic requests to meet critical human needs’. So by the end of 2018, the high fish biomass became trapped or restricted between weirs, unable to move upstream or downstream. As the water heated up, significant algal blooms developed in the areas where fish had accumulated. Thermal stratification also occurred, with hypoxic (low oxygen) or anoxic (no oxygen) conditions in the lower waters, and algal blooms proliferating in the surface waters, where the fish were forced to hang out. Then conditions suddenly changed, with lower air temperatures and stormy conditions causing a rapid destratification. The low oxygen water – presumably more voluminous than the oxygenated water – dominated the whole water column and the fish had no way out.

Jacinta: Yes, you can’t adapt to such sudden shifts. The final findings are about existing attempts at fish translocation and aerating water which are having some success, about stratification being an ongoing issue, and about lack of knowledge at this preliminary stage of the precise extent of the fish deaths.

Canto: So now to the 20 recommendations. They’re grouped under 3 headings; preventive and restorative measures (1-9), management arrangements (10-13), and knowledge and monitoring (14-20). The report noted a lack of recent systematic risk assessment for low oxygen, stratification and blackwater (semi-stagnant, vegetation-rich water that looks like black tea) in the areas where the fish deaths occurred. There was insufficient or zero monitoring of high-risk areas for stratification, etc, and insufficient planning to treat problems as they arose. Flow management strategies (really involving reduced extraction) need to be better applied to reduce problems in the lower Darling. Reducing barriers to fish movement should be considered, though this is functionally difficult. Apparently there’s a global movement in this direction to improve freshwater fish stocks. Short term measures such as aeration and translocation are also beneficial. Funding should be set aside for research on and implementation of ecosystem recovery – it’s not just the fish that are affected. Long-term resilience requires an understanding of interactions and movement throughout the entire basin. Fish are highly mobile and restriction is a major problem. A whole-of system approach is strongly recommended. This includes a dynamic ‘active event-based management’ approach, especially in the upper reaches and tributaries of the Barwon-Darling, where extraction has been governed by passive, long-term rules. Such reforms are in the pipeline but now need to be fast-tracked. For example, ‘quantifying the volumes of environmental water crossing the border from Queensland to NSW…. would increase transparency and would help the CEWH [Commonwealth Environmental Water Holdings] with their planning, as well as clear the path to move to active management in Queensland’.

Jacinta: Right, you’ve covered most of the issues, so I’ll finish up with monitoring, measuring and reporting. The report argues that reliable, up-to-date accounting of flows, volumes in storage, extractions and losses due to seepage and evaporation are essential to create and maintain public confidence in system management, and this is currently a problem. Of course this requires funding, and apparently the funding levels have dropped substantially over the past decade. The report cites former funding and investment through the Co-operative Research Centre, Land and Water Australia and the National Water Commission, but ‘by the early 2010s, all of these sources of funding had terminated and today aggregate levels of funding have reduced to early 1980s levels, at a time when water was far less of a public policy challenge than it is today’.

Canto: We await the government’s response to that one.

Jacinta: And on fisheries research in particular, it has been largely piecemeal except when their was a concerted co-ordinated effort under the Native Fish Strategy, but the issue right now is to know how many fish (and other organisms) of the various affected species survived the event, which involves multi-level analyses, combined with management of Basin water balances, taking into account the ongoing effects of weather events due to climate change, in order to foster and improve the growth and well-being of fish stocks and freshwater habitats in general. Connectivity of the system in particular is a major concern of the report.

Canto: Right, so this has been a bit of a journey into the unknown for us, but a worthwhile one. It suggests that governments have been a bit dozey at the wheel in recent years, that extractions, especially in the upper reaches and tributaries, haven’t been well monitored or policed, and the connectivity of the system has suffered due to extractions, droughts and climate change. Funding seems to have dried up as much as some of the rivers have, and we’ll have to wait and see if this becomes an election issue. I suspect it’ll only be a minor one.

Written by stewart henderson

March 17, 2019 at 12:01 pm

kin selection – some fascinating stuff

leave a comment »

meerkats get together for ye olde family snap

Canto: So we’ve done four blogs on Palestine and we’ve barely scratched the surface, but we’re having trouble going forward with that project because, frankly, it’s so depressing and anger-inducing that it’s affecting our well-being.

Jacinta: Yes, an undoubtedly selfish excuse, but we do plan to go on with that project – we’re definitely not abandoning it, and meanwhile we should recommend such books as Tears for Tarshiha by the Palestinian peace activist Olfat Mahmoud, and Goliath by the Jewish American journalist Max Blumenthal, which highlight the sufferings of Palestinian people in diaspora, and the major stresses of trying to exist under zionist monoculturalism. But for now, something completely different, we’re going to delve into the fascinating facts around kin selection, with thanks to Robert Sapolski’s landmark book Behave. 

Canto: The term ‘kin selection’ was first used by John Maynard Smith in the early sixties but it was first mooted by Darwin (who got it right about honey bees), and its mathematics were worked out back in the 1930s. 

Jacinta: What’s immediately interesting to me is that we humans tend to think we alone know who our kin are, especially our extended or most distant kin, because only we know about aunties, uncles and second and third cousins. We have language and writing and record-keeping, so we can keep track of those things as no other creatures can. But it’s our genes that are the key to kin selection, not our brains.

Canto: Yes, and let’s start with distinguishing between kin selection and group selection, which Sapolsky deals with well. Group selection, popularised in the sixties by the evolutionary biologist V C Wynne-Edwards and by the US TV program Wild Kingdom, which I remember well, was the view that individuals behaved, sometimes or often, for the good of the species rather than for themselves as individuals of that species. However, every case that seemed to illustrate group selection behaviour could easily be interpreted otherwise. Take the case of ‘eusocial’ insects such as ants and bees, where most individuals don’t reproduce. This was seen as a prime case of group selection, where individuals sacrifice themselves for the sake of the highly reproductive queen. However, as evolutionary biologists George Williams and W D Hamilton later showed, eusocial insects have a unique genetic system in which they are all more or less equally ‘kin’, so it’s really another form of kin selection. This eusociality exists in some mammals too, such as mole rats. 

Jacinta: The famous primatologist Sarah Hrdy dealt something of a death-blow to group selection in the seventies by observing that male langur monkeys in India commit infanticide with some regularity, and, more importantly, she worked out why. Langurs live in groups with one resident male to a bunch of females, with whom he makes babies. Meanwhile the other males tend to hang around in groups brooding instead of breeding, and infighting. Eventually, one of this male gang feels powerful enough to challenge the resident male. If he wins, he takes over the female group, and their babies. He knows they’re not his, and his time is short before he gets booted out by the next tough guy. Further, the females aren’t ovulating because they’re nursing their kids. The whole aim is to pass on his genes (this is individual rather than kin selection), so his best course of action is to kill the babs, get the females ovulating as quickly as possible, and impregnate them himself. 

Canto: Yes, but it gets more complicated, because the females have just as much interest in passing on their genes as the male, and a bird in the hand is worth two in the bush…

Jacinta: Let me see, a babe in your arms is worth a thousand erections?

Canto: More or less precisely. So they fight the male to protect their infants, and can even go into ‘fake’ estrus, and mate with the male, fooling the dumb cluck into thinking he’s a daddy. 

Jacinta: And since Hrdy’s work, infanticide of this kind has been documented in well over 100 species, even though it can sometimes threaten the species’ survival, as in the case of mountain gorillas. So much for group selection.

Canto: So now to kin selection. Here are some facts. If you have an identical twin your genome is identical with hers. If you have a full sibling you’re sharing 50% and with a half-sibling 25%. As you can see, the mathematics of genes and relatedness can be widened out to great degrees of complexity. And since this is all about passing on all, or most, or some of your genes, it means that ‘in countless species, whom you co-operate with, compete with, or mate with depends on their degree of relatedness to you’, to quote Sapolsky. 

Jacinta: Yes, so here’s a term to introduce and then fairly promptly forget about: allomothering. This is when a mother of a newborn enlists the assistance of another female in the process of child-rearing. It’s a commonplace among primate species, but also occurs in many bird species. The mother herself benefits from an occasional rest, and the allomother, more often than not a younger relation such as the mother’s kid sister, gets to practice mothering. 

Canto: So this is part of what is called ‘inclusive fitness’, where, in this case, the kid gets all-day mothering (if of varying quality) the kid sister gets to learn about mothering, thereby increasing her fitness when the time comes, and the mother gets a rest to recharge her batteries for future mothering. It’s hopefully win-win-win. 

Jacinta: Yes, there are negatives and positives to altruistic behaviour, but according to Hamilton’s Rule, r.B > C, kin selection favours altruism when the reproductive success of relatives is greater than the cost to the altruistic individual. 

Canto: To explain that rule, r equals degree of relatedness between the altruist and the beneficiary (aka coefficient of relatedness), B is the benefit (measured in offspring) to the recipient, and C is the cost to the altruist. What interests me most, though, about this kin stuff, is how other, dumb primates know who is their kin. Sapolsky describes experiments with wild vervet monkeys by Dorothy Cheney and Robert Seyfarth which show that if monkey A behaves badly to monkey B, this will adversely affect B’s behaviour towards A’s relatives, as well as B’s relatives’ behaviour to A, as well as B’s relatives’ behaviour to A’s relatives. How do they all know who those relatives are? Good question. The same researchers proved this recognition by playing a recording of a juvenile distress call to a group of monkeys hanging around. The female monkeys all looked at the mother of the owner of that distress call to see what she would do. And there were other experiments of the sort. 

Jacinta: And even when we can’t prove knowledge of kin relations (kin recognition) among the studied animals, we find their actual behaviour tends always to conform to Hamilton’s Rule. Or almost always… In any case there are probably other cues, including odours, which may be unconsciously sensed, which might aid in inclusive fitness and also avoiding inbreeding. 

Canto: Yes and It’s interesting how this closeness, this familiarity, breeds contempt in some ways. Among humans too. Well, maybe not contempt but we tend not to be sexually attracted to those we grow up with and, for example, take baths with as kids, whether or not they’re related to us. But I suppose that has nothing to do with kin selection. And yet…

Jacinta: And yet it’s more often than not siblings or kin that we have baths with. As kids. But getting back to odours, we have more detail about that, as described in Sapolski. Place a mouse in an enclosed space, then introduce two other mice, one unrelated to her, another a full sister from another litter, never encountered before. The mouse will hang out with the sister. This is called innate recognition, and it’s due to olfactory signatures. Pheromones. From proteins which come from genes in the major histocompatibility complex (MHC). 

Canto: Histowhat?

Jacinta: Okay, you know histology is the study of bodily tissues, so think of the compatibility or otherwise of tissues that come into contact. Immunology.  Recognising friend or foe, at the cellular, subcellular level. The MHC, this cluster of genes, kicks off the production of proteins which produce pheromones with a unique odour, and because your relatives have similar MHC genes, they’re treated as friends because they have a similar olfactory signature. Which doesn’t mean the other mouse in the enclosure is treated as a foe. It’s a mouse, after all. But other animals have their own olfactory signatures, and that’s another story. 

Canto: And there are other forms of kin recognition. Get this – birds recognise their parents from the songs sung to them before they were hatched. Birds have distinctive songs, passed down from father to son, since its mostly the males that do the singing. And as you get to more complex species, such as primates – though maybe they’re not all as complex as some bird species – there might even be a bit of reasoning involved, or at least consciousness of what’s going on. 

Jacinta: So that’s kin selection, but can’t we superior humans rise above that sort of thing? Australians marry Japanese, or have close friendships with Nigerians, at least sometimes. 

Canto: Sometimes, and this is the point. Kinship selection is an important factor in shaping behaviour and relations, but it’s one of a multiple of factors, and they all have differential influences in different individuals. It’s just that such influences may go below the level of awareness, and being aware of the factors shaping our behaviour is always the key, if we want to understand ourselves and everyone else, human or non-human.

Jacinta: Good to stop there. As we’ve said, much of our understanding has come from reading Sapolsky’s Behave, because we’re old-fashioned types who still read books, but I’ve just discovered that there’s a whole series of lectures by Sapolsky, about 25, on human behaviour, which employs the same structure as the book (which is clearly based on the lectures), and is available on youtube here. So all that’s highly recommended, and we’ll be watching them.

References

R Sapolski, Behave: the biology of humans at our best and worst. Bodley Head, 2017

https://www.britannica.com/science/animal-behavior/Function#ref1043131

https://en.wikipedia.org/wiki/Kin_selection

https://en.wikipedia.org/wiki/Eusociality

 

 

 

 

 

how to define a planet: the problematic case of Pluto

leave a comment »

Pluto, with its ‘heart-shaped’ area known as Sputnik Planitia, imaged by New Horizons, July 14 2015

A while back I listened to a podcast from Point of Inquiry, in which two planetary scientists, Alan Stern and David Grinspoon, involved in NASA’s New Horizons mission to Pluto, were separately interviewed, and were inevitably asked about Pluto’s demotion from planet status. Having not followed this issue, I was surprised at the response. So it’s time to take a closer look.

Of course I should be writing ecstatically about the New Horizons mission, not to mention those of Juno, Cassini, Mars’ Curiosity and so forth, and hopefully that will come, but the controversy about Pluto immediately struck me, as I thought, in my naïveté, that its demotion was a consensual thing amongst astronomers, with only the ignoroscenti (my neologism) left to mourn the fact (not that I mourned it particularly – Pluto still existed after all, and it didn’t care a jot what we thought of it).

Pluto, discovered by Clyde Tombaugh in 1930, was accepted as the ninth and final planet in our solar system for decades until the nineties, when another Kuiper belt object was discovered (besides Charon, Pluto’s large moon), and the Kuiper belt itself became a thing, in fact a massive thing, far bigger than the ‘familiar’ asteroid belt between Mars and Jupiter. We now know of more than 1000 kuiper belt objects, with at least 100,000 believed to exist. The Kuiper belt is widely spread out from the orbit of Neptune, and though Pluto is its largest and brightest object, it’s not the most massive. Presumably it’s for this reason that Pluto was demoted – what with the scattered disc and the Oort cloud there seemed to suddenly be a host of objects that could be included as planets, so it was thought better to exclude Pluto, or to demote it to dwarf planet status, presumably along with other assorted Kuiper belt objects (KBOs), rocks and iceballs that were worthy of the designation. That seemed okay to my thoughtless mind, but here’s what Alan Stern had to say on the subject:

Well, you know, we don’t really honour that classification in planetary science, that was really done by a group of different astronomers who don’t know much about planets. Let me give you a technical term, we call it BS. You know what BS stands for don’t you? Bad Science. Now you wouldn’t ask a podiatrist, a foot doctor, to help you if you had a cardiovascular problem with your heart, that’d be the wrong expertise, though they’re both doctors you’d be going for a cardiologist. And if you had a real estate problem you probably wouldn’t go to a divorce attorney, even though they’re both attorneys. In the space field we have many professions, we have engineering professions, we have many different scientific specialties, etc. Astronomers really don’t know much about planets any more than I’m an expert in black holes in faraway galaxies. They had a little meeting in 2006, they were worried that school children would have to memorise the names of too many planets, so they wrote a definition that limited the number of planets to eight. Now, right after that, Ira Flatow called me up on Science Friday and said, would you debate Mike Brown, who was one of the proponents of ‘let’s limit the planets to eight’, and I said, sure, and we got on the phone and it’s Science Friday live, and Mike Brown makes his case and says, ‘look we just can’t have 50 planets, it’s too many to remember.’ Now, I found that anti-scientific, it seems like engineering the definition, versus letting it inform you, but Ira said, Alan what’d you think, ‘can’t have 50 planets’, what d’you say back to MIke? I said, ‘well if you can’t have 50 planets then we’re probably going to have to go back to eight states, I guess’. And he was speechless…

I love that story – though no doubt Mike Brown would’ve told a different one. So let’s turn Stern’s objection into an inquiry. Was it scientifically correct/accurate/fair to reclassify Pluto as a dwarf/minor planet?

Happily I just happened to listen to a podcast of the Skeptics’ Guide a few days later, which has led me to a more detailed piece on Steven Novella’s Neurologica blog on the Pluto controversy. Apparently, in the above-mentioned 2006 meeting they decided that to be classified as a planet, a body in our solar system should meet 3 criteria:

  • it has to orbit the sun
  • it has to be spheroid (i.e. have the mass to be so, due to its gravity),
  • it must have cleared its orbit of other objects.

Now this third criteria immediately seems the dodgiest, as it sounds like it’s designed to eliminate any KBOs. And how do we know an orbit is cleared? After all, one day, a comet or asteroid may strike us, because our orbits have coincided this time around. And why is that third criterion even important?

Novella cites a recent paper by planetary scientist Phillip Metzger who argues that the third criterion is invalid and that nothing about a body’s orbit should be in the definition since orbits can alter due to external influences. Only characteristics intrinsic to the body should be included in the definition. This would essentially leave one criterion standing – that of sphericity. And even then, how sphere-like does a planet have to be? Another ‘problem’ with Metzger’s definition is that it would include moons, such as our own, and many others. Novella has his own classifying suggestion, which sounds promising to me:

We keep criteria “a” and “b” and drop “c”. However, we add that the object must not be in a subservient orbit around a larger object. What does that mean? If two objects, like the Earth and Moon, are in orbit around each other, and the center of gravity (barycenter) lies beneath the surface of one of the bodies, then the smaller object will be said to orbit the larger object, and is a moon. Therefore Europa, which is large enough by itself to be a planet, would instead be considered a moon because it orbits Jupiter.

I need to further explain the term ‘barycentre’, for my own sake. Think of two bodies in gravitational relationship to each other. Inevitably, one of them will be more massive, and will exert a greater gravitational force. An obvious case is the Earth and the Moon. Between the two there is a point, the ‘centre of gravity’, or barycentre,  around which the two bodies revolve, but because the Earth is a lot more massive that the Moon and they’re relatively close to each other, that barycentre is actually close enough to the Earth’s centre to be within the mass of the Earth, with the result that only the moon revolves. The Earth, though, is very much affected by the Moon’s gravitational field, which causes a slight wobble as well as tidal effects on the Earth’s surface. 

Interestingly, Novella’s reclassification would include Charon, Pluto’s ‘moon’, as a planet (as well as Pluto of course) because its size relative to Pluto puts the barycentre at a point between the two bodies, rather than within Pluto. So Pluto-Charon would be reclassified as a binary-planet system. It would also promote Ceres, in the asteroid belt, and Eris and Makemake, two recently discovered Kuiper belt objects, to planetary status. That takes the current eight up to thirteen, with others yet to be discovered. 

It’s unlikely of course that the astronomical overlords who reclassified Pluto would be swayed by any mere outsider’s view, however well-reasoned, but this examination of the issue is a reminder of just how dubious the reasoning of ‘experts’ can be, and how important it is to question that reasoning. Size apparently does matter to these guys, but this new category of ‘dwarf’ or ‘minor’ planet seems inherently unstable, and will probably become even more so as the number of discovered exoplanets increases. Will it be mass or volume that’s the decider, and what will be the mass or volume that decides? And does it really matter? It’s only nomenclature after all. And yet… The difference between an asteroid and a comet is important, is it not? And so is the difference between a planet and an asteroid. And so is the difference between a moon and a planet. And so… is it not? 

Written by stewart henderson

October 14, 2018 at 1:09 pm

more about ozone, and the earth’s greatest extinction event

leave a comment »

the Siberian Traps are layers of flood basalt covering an area of 2 million square kilometres

Ozone, or trioxygen (O3), an unstable molecule which is regularly produced and destroyed by the action of sunlight on O2, is a vital feature in our atmosphere. It protects life on earth from the harmful effects of too much UV radiation, which can contribute to skin cancers in humans, and genetic abnormalities in plant life. In a previous post I wrote about the discovery of the ozone shield, and the hole above Antarctica, which we seem to be reducing – a credit to human global co-operation. In this post I’m going to try and get my head around whether or not ozone depletion played a role in the so-called end-Permian extinction of some 250 mya. 

I first read of this theory in David Beerling’s 2009 book The emerald planet, but recent research appears to have backed up Beerling’s scientific speculations – though speculation is too weak a word. Beerling is a world-renowned geobiologist and expert on historical global climate change. He’s also a historian of science, and in ‘An ancient ozone catastrophe?’, chapter 4 of The emerald planet, he describes the discovery and understanding of ozone through the research of Robert Strutt, Christian Schönbein, Marie Alfred Cornu, Walter Hartley, George Dobson, Sidney Chapman and Paul Crutzen, among others. He goes on to describe the ozone hole discovery in the 70s and 80s, before focusing on research into the possible effects of previous events – the Tunguska asteroid strike of 1908, the Mount Pinatubo eruption of 1991 and others – on atmospheric ozone levels, and then homes in on the greatest extinction event in the history of our planet – the end-Permian mass extinction, ‘the Great Dying’, which wiped out some 95% of all species then existing.

According to Beerling, it was an international team of palaeontologists led by Henk Visscher at the University of Utrecht who first made the claim that stratospheric ozone had substantially reduced in the end-Permian. They hypothesised that, due to the greatest volcanic eruptions in Earth history, which created the Siberian Traps (layers of solidified basalt covering a huge area of northern Russia), huge deposits of coal and salt, the largest on Earth, were disrupted:


The widespread heating of these sediments and the action of hot groundwater dissolving the ancient salts, was a subterranean pressure cooker synthesising a class of halogenated compounds called organohalogens, reactive chemicals that can participate in ozone destruction. And in less than half a million years, this chemical reactor is envisaged to have synthesised and churned out sufficiently large amounts of organohalogens to damage the ozone layer worldwide to create an intense increased flux of UV radiation.

However, Beerling questions this hypothesis and considers that it may have been the eruptions themselves, which lasted 2 million years and occurred at the Permian-Triassic boundary 250-252 mya, rather than their impact on salt deposits, that did the damage. There’s evidence that many of the eruptions originated from as deep as 10 kilometres below the surface, injected explosively enough to reach the stratosphere, and that these plumes contained substantial amounts of chlorine. 

More recent research, published this year, has further substantiated Visscher’s team’s finding regarding genetic mutations in ancient conifers and lycopsids, and their probable connection with UV radiation enabled by ozone destruction. The mutations were global and dated to the same period. Laboratory experiments exposing related modern plants to bursts of UV radiation have produced more or less identical spore mutations.

The exact chain of events linking the eruptions to the ozone destruction have yet to be worked out, and naturally there’s a lot of scientific argy-bargy going on, but the whole story, even considering that it occurred so far in the past is a reminder of the fragility of that part of our planet that most concerns us – the biosphere. The eruptions clearly altered atmospheric chemistry and temperature. Isotopic measurements of oxygen in sea water suggest that equatorial waters reached more than 40°C. As can be imagined, this had killer effects on multiple species. 

So, we’re continuing to gain knowledge on the ozone shield and its importance, and fragility. I don’t know that there are too many ozone hole skeptics around (I don’t want to look too hard), but if we could only get the same kind of apparent near-unanimity with regard to anthropogenic global warming, that would be great progress. 

Written by stewart henderson

October 10, 2018 at 3:15 pm

about ozone, its production and depletion

with one comment

an Arctic polar stratospheric cloud, photographed in Sweden (filched from a website of NOAA’s Earth System Research Laboratory)

People will remember the ‘hole in the ozone’ issue that came up in the eighties I think, and investigators found that it was all down to CFCs, which were quite quickly banned, and then everything was hunky dory….

Or that’s how I vaguely recall it. Time to take a much closer look. 

I take my cue from ‘An ancient ozone catastrophe?’, chapter 4 of David Beerling’s The emerald planet, in which he looks at the evidence for a previous ozone disaster and its possible relation to the great Permian extinction of 252 millions years ago. I’ll probe into that matter in another post. In this post I’ll try to answer some more basic questions – what is ozone, where is the ozone layer and why does it have a hole in it?

Ozone is also known as trioxygen, which gives a handy clue to its structure. Oxygen can exist in different allotropes or molecular structures which are more or less stable. O3, ozone, is much less stable than O2 and has a very pungent chlorine-like odour and a pale blue colour. It’s present in minute quantities throughout the atmosphere but is most concentrated in the lower part of the stratosphere, 20 to 30 kilometres above the Earth’s surface. This region is called the ozone layer, or ozone shield, though it’s still not particularly dense with ozone, and that density varies geographically and seasonally. Ozone’s instability means that it doesn’t last long, and has to be replenished continually.

In 1928 chlorofluorocarbons (CFCs) were developed as a seemingly safe form of refrigerant, which, under patent as Freon, came to be used in air-conditioners, fridges, hair-sprays and a variety of other products. As it turned out, these CFCs aren’t so harmless when they reach the upper atmosphere, where the chlorine reacts with ozone to form chlorine monoxide (ClO), and regular O2. This reaction is activated by ultraviolet radiation, which then breaks up the unstable ClO, leaving the chlorine to react with more ozone in a continuing cycle.

By the eighties, it had become clear that something was going wrong with the ozone layer. Studies revealed that a gigantic hole in the layer had opened up over Antarctica, and without going into detail, CFCs were found to be largely responsible. There was the usual fight with vested business interests, but in 1987 the Montreal protocol against the use of ozone-depleting substances (ODS) was drawn up, a landmark agreement which has been successful in starting off the long and far from completed process of repair of the ozone shield.

As a very effective oxidant, ozone has many commercial applications, but the same oxidising property makes it a danger to plant and animal tissue. Much better for us to keep most of it up above the troposphere, where its ability to absorb UV radiation has made it virtually essential for maintaining healthy life on Earth’s surface. 

So here are some questions. Why does ozone proliferate particularly at the top of the troposphere, in the lower stratosphere? If it’s so reactive, how does it maintain itself at a particular rate? Has the thinning or reduction of that layer seriously influenced life on Earth in the past? From my reading, mainly of Beerling, I think I can answer the first two questions. The third question, which Beerling explores in the above-mentioned chapter of his book, is more speculative, and more interesting. 

Sidney Chapman, a brilliant geophysicist and mathematician of the early twentieth century, essentially answered the first question. He realised that ozone was both formed and destroyed by the action of sunlight, specifically UV radiation, on atmospheric oxygen. He calculated that this action would reduce and finally stop at a point approximately 15 km above sea level, because the reactions which had produced the ozone higher up had absorbed the UV radiation in the process. No activation energy to produce any more ozone. That explained the lower limit of ozone. The upper limit was explained by the lack of oxygen in the upper stratosphere to produce a stable layer – for production to exceed destruction. This was interesting confirmation of observations made earlier by the meteorologist and balloonist Léon-Phillippe Teisserenc de Bort, who noted that, contrary to his expectations, the air temperature didn’t fall gradually with altitude but reached a point of stabilisation where the air even seemed to become warmer. He named this upper layer of air the stratosphere, and the cooler more turbulent layer below he called the troposphere. It’s now known that this upper-air warming is caused by the absorption of UV radiation by ozone.

Our picture of ozone still had some holes in it, however, as it seemed there was a lot less of it around than the calculations of Chapman suggested. To quote from Beerling’s book: 

… there had to be some as-yet unappreciated means by which ozone was being destroyed. The fundamental leap required to solve the problem was taken comparatively recently, in 1970, by a then young scientist called Paul Crutzen. Crutzen showed that, remarkably, the oxides of nitrogen, produced by soil microbes, catalysed the destruction of ozone many kilometres up in the stratosphere. Few people appreciate the marvellous fact that the cycling of nitrogen by the biosphere exerts an influence on the global ozone layer: life on Earth reaches out to the chemistry of the stratosphere. 

Now to explain why the hole in the ozone shield occurred above the Antarctic. My understanding and explanation starts with reading Beerling and ends with this post from the USA’s National Oceanic and Atmospheric Administration’s Earth System Research Laboratory (NOAA/ESRL). 

The ozone hole over Antarctica varies in size, and is largest in the months of winter and early spring. During these months, due to the large and mountainous land mass there, average minimum temperatures can reach as low as −90°C, which is on average 10°C lower than Arctic winter minimums (Arctic temperatures are generally more variable than in the Antarctic). When winter minimums fall below around −78°C at the poles, polar stratospheric clouds are formed, and this happens far more often in the Antarctic – for about five months in the year. Chemical reactions between halogen gases and these clouds produce the highly reactive gases chlorine monoxide (ClO) and bromine monoxide (BrO), which are destructive to ozone. 

this graphic shows that the Antarctic stratosphere is consistently colder, and less variable in temperature, than the Arctic. Polar stratospheric clouds (PSCs) form at −78°C

Most ozone is produced in the tropical stratosphere, in reactions driven by sunlight, but a slow movement of stratospheric air, known as the Brewer-Dobson circulation, transports it over time to the poles, so that ozone ends up being more sparse in the tropics. Interestingly, although most ozone-depleting substances – mainly halogen gases – are produced in the more humanly-populated northern hemisphere, complex tropospheric convection patterns distribute the gases more or less evenly throughout the lower atmosphere. Once in the stratosphere and distributed to the poles, the air carrying the halogen-gas products becomes isolated due to strong circumpolar winds, which are at their height during winter and early spring. This isolation preserves ozone depletion reactions for many weeks or months. The polar vortex at the Antarctic, being stronger than in the Arctic, is more effective in reducing the flow of ozone from tropical regions. 

So – I’ve looked here briefly at what ozone is, where it is, and how it’s produced and destroyed, but I haven’t really touched on its importance for protecting life here on Earth. So that, and whether its depletion may have had catastrophic consequences 250 million years ago, will be the focus of my next post. 

References

The Emerald Planet, by David Beerling, Oxford Landmark Science, 2009

https://www.esrl.noaa.gov/csd/assessments/ozone/2010/twentyquestions/Q10.pdf

https://en.wikipedia.org/wiki/Ozone

https://en.wikipedia.org/wiki/Brewer–Dobson_circulation

Written by stewart henderson

October 3, 2018 at 9:24 pm

a little about the chemistry of water and its presence on Earth

leave a comment »

So I now know, following my previous post, a little more than I did about how water’s formed from molecular hydrogen and oxygen – you have to break the molecular bonds and create new ones for H2O, and that requires activation energy, I think. But I need to explore all of this further, and I want to do so in the context of a fascinating question, which I’m hoping is related – why is there so much water on Earth’s surface?

When Earth was first formed, from planetesimals energetically colliding together, generating lots of heat (which may have helped with the creation of H2O, but not in liquid form??) there just doesn’t seem to have been a place for water, which would’ve evaporated into space, wouldn’t it? Presumably the still-forming, virtually molten Earth had no atmosphere. 

The most common theory put out for Earth’s water is bombardment in the early days by meteors of a certain type, carbonaceous chondrites. These meteors were formed further out from the sun, where water would have frozen. Carbonaceous chondrites are known to contain the same ratio of heavy water to ‘normal’ water as we find on Earth. Heavy water is formed with deuterium, an isotope of hydrogen containing a neutron as well as the usual proton. Obviously there had to have been plenty of these collisions over a long period to create our oceans. Comets have been largely ruled out because, of the comets we’ve examined, the deuterium/hydrogen ratio is about double that of the chondrites, though some have argued that those comets may be atypical. Also there’s some evidence that the D/H ratio of terrestrial water has changed over time.

So there are still plenty of unknowns about the history of Earth’s water. Some argue that volcanism, along with other internal sources, was wholly or partly responsible – water vapour is one of the gases produced in eruptions, which then condensed and fell as rain. Investigation of moon rocks has revealed a D/H ratio similar to that of chondrites, and also that of Earth (yes, there’s H2O on the moon, in various forms). This suggests that, since it has become clear that the Moon and Earth are of a piece, water has been there on both from the earliest times. Water ice detected in the asteroid belt and elsewhere in the solar system provides further evidence of the abundance of this hardy little molecule, which enriches the hypotheses of researchers. 

But I’m still mystified by how water is formed from molecular, or diatomic, hydrogen and oxygen. It occurs to me, thanks to Salman Khan, that having a look at the structural formulae of these molecules, as well as investigating ‘activation energy’, might help. I’ve filched the ‘Lewis structure’ of water from Wikipedia.

It shows that hydrogen atoms are joined to oxygen by a single bond, the sharing of a pair of electrons. They’re called polar covalent bonds, as described in my last post on the topic. H2 also binds the two hydrogen atoms with a single covalent bond, while O2 is bound in a double covalent bond. (If you’re looking for a really comprehensive breakdown of the electrochemical structure of water, I recommend this site).

So, to produce water, you need enough activation energy to break the bonds of H2 and O2 and create the bonds that form H2O. Interestingly, I’m currently reading The Emerald Planet, which gives an example of the kind of activation energy required. The Tunguska event, an asteroid visitation in the Siberian tundra in 1908, was energetic enough to rip apart the bonds of molecular nitrogen and oxygen in the surrounding atmosphere, leaving atomic nitrogen and oxygen to bond into nitric oxide. But let’s have a closer look at activation energy. 

So, according to Wikipedia:

In chemistry and physics, activation energy is the energy which must be available to a chemical or nuclear system with potential reactants to result in: a chemical reaction, nuclear reaction, or various other physical phenomena.

This stuff gets complicated and mathematical very quickly, but activation energy (Ea) is measured in either joules (or kilojoules) per mole or kilocalories per mole. A mole, as I’ve learned from Khan, is the number of atoms there are in 12g of carbon-12. So what? Well, that’s just a way of translating atomic mass units (amu) to grams (one gram equals one mole of amu). 

The point is though that we can measure the activation energy, which, in the case of molecular reactions, is going to be more than the measurable change between the initial and final conditions. Activation energy destabilises the molecules, bringing about a transition state in which usually stable bonds break down, freeing the molecules to create new bonds – something that is happening throughout our bodies at every moment. When molecular oxygen is combined with molecular hydrogen in a confined space, all that’s required is the heat from a lit match to start things off. This absorption of energy is called an endothermic reaction. Molecules near the fire break down into atoms, which recombine into water molecules, a reaction which releases a lot of energy, creating a chain of reactions until all the molecules are similarly recombined. From this you can imagine how water could have been created in abundance during the fiery early period of our solar system’s evolution. 

I’ll end with more on the structure of water, for my education. 

As a liquid, water has a structure in which the H-O-H angle is about 106°. It’s a polarised molecule, with the negative charge on the oxygen being around 70% of an electron’s negative charge, which is neutralised by a corresponding positive charge shared by the two hydrogen atoms. These values can change according to energy levels and environment. As opposite charges attract, different water molecules attract each other when their H atoms are oriented to other O atoms. The British Chemistry professor Martin Chaplin puts it better than I could:

This attraction is particularly strong when the O-H bond from one water molecule points directly at a nearby oxygen atom in another water molecule, that is, when the three atoms O-H O are in a straight line. This is called ‘hydrogen bonding’ as the hydrogen atoms appear to hold on to both O atoms. This attraction between neighboring water molecules, together with the high-density of molecules due to their small size, produces a great cohesive effect within liquid water that is responsible for water’s liquid nature at ambient temperatures.

We’re all very grateful for that nature. 

Written by stewart henderson

September 24, 2018 at 10:32 am

Posted in chemistry, science, water

Tagged with , , ,