Econstudentlog

Galaxies

I have added some observations from the book below, as well as some links covering people/ideas/stuff discussed/mentioned in the book.

“On average, out of every 100 newly born star systems, 60 are binaries and 40 are triples. Solitary stars like the Sun are later ejected from triple systems formed in this way.”

“…any object will become a black hole if it is sufficiently compressed. For any mass, there is a critical radius, called the Schwarzschild radius, for which this occurs. For the Sun, the Schwarzschild radius is just under 3 km; for the Earth, it is just under 1 cm. In either case, if the entire mass of the object were squeezed within the appropriate Schwarzschild radius it would become a black hole.”

“It only became possible to study the centre of our Galaxy when radio telescopes and other instruments that do not rely on visible light became available. There is a great deal of dust in the plane of the Milky Way […] This blocks out visible light. But longer wavelengths penetrate the dust more easily. That is why sunsets are red – short wavelength (blue) light is scattered out of the line of sight by dust in the atmosphere, while the longer wavelength red light gets through to your eyes. So our understanding of the galactic centre is largely based on infrared and radio observations.”

“there is strong evidence that the Milky Way Galaxy is a completely ordinary disc galaxy, a typical representative of its class. Since that is the case, it means that we can confidently use our inside knowledge of the structure and evolution of our own Galaxy, based on close-up observations, to help our understanding of the origin and nature of disc galaxies in general. We do not occupy a special place in the Universe; but this was only finally established at the end of the 20th century. […] in the decades following Hubble’s first measurements of the cosmological distance scale, the Milky Way still seemed like a special place. Hubble’s calculation of the distance scale implied that other galaxies are relatively close to our Galaxy, and so they would not have to be very big to appear as large as they do on the sky; the Milky Way seemed to be by far the largest galaxy in the Universe. We now know that Hubble was wrong. […] the value he initially found for the Hubble Constant was about seven times bigger than the value accepted today. In other words, all the extragalactic distances Hubble inferred were seven times too small. But this was not realized overnight. The cosmological distance scale was only revised slowly, over many decades, as observations improved and one error after another was corrected. […] The importance of determining the cosmological distance scale accurately, more than half a century after Hubble’s pioneering work, was still so great that it was a primary justification for the existence of the Hubble Space Telescope (HST).”

“The key point to grasp […] is that the expansion described by [Einstein’s] equations is an expansion of space as time passes. The cosmological redshift is not a Doppler effect caused by galaxies moving outward through space, as if fleeing from the site of some great explosion, but occurs because the space between the galaxies is stretching. So the spaces between galaxies increase while light is on its way from one galaxy to another. This stretches the light waves to longer wavelengths, which means shifting them towards the red end of the spectrum. […] The second key point about the universal expansion is that it does not have a centre. There is nothing special about the fact that we observe galaxies receding with redshifts proportional to their distances from the Milky Way. […] whichever galaxy you happen to be sitting in, you will see the same thing – redshift proportional to distance.”

“The age of the Universe is determined by studying some of the largest things in the Universe, clusters of galaxies, and analysing their behaviour using the general theory of relativity. Our understanding of how stars work, from which we calculate their ages, comes from studying some of the smallest things in the Universe, the nuclei of atoms, and using the other great theory of 20th-century physics, quantum mechanics, to calculate how nuclei fuse with one another to release the energy that keeps stars shining. The fact that the two ages agree with one another, and that the ages of the oldest stars are just a little bit less than the age of the Universe, is one of the most compelling reasons to think that the whole of 20th-century physics works and provides a good description of the world around us, from the very small scale to the very large scale.”

“Planets are small objects orbiting a large central mass, and the gravity of the Sun dominates their motion. Because of this, the speed with which a planet moves […] is inversely proportional to the square of its distance from the centre of the Solar System. Jupiter is farther from the Sun than we are, so it moves more slowly in its orbit than the Earth, as well as having a larger orbit. But all the stars in the disc of a galaxy move at the same speed. Stars farther out from the centre still have bigger orbits, so they still take longer to complete one circuit of the galaxy. But they are all travelling at essentially the same orbital speed through space.”

“The importance of studying objects at great distances across the Universe is that when we look at an object that is, say, 10 billion light years away, we see it by light which left it 10 billion years ago. This is the ‘look back time’, and it means that telescopes are in a sense time machines, showing us what the Universe was like when it was younger. The light from a distant galaxy is old, in the sense that it has been a long time on its journey; but the galaxy we see using that light is a young galaxy. […] For distant objects, because light has taken a long time on its journey to us, the Universe has expanded significantly while the light was on its way. […] This raises problems defining exactly what you mean by the ‘present distance’ to a remote galaxy”

“Among the many advantages that photographic and electronic recording methods have over the human eye, the most fundamental is that the longer they look, the more they see. Human eyes essentially give us a real-time view of our surroundings, and allow us to see things – such as stars – that are brighter than a certain limit. If an object is too faint to see, once your eyes have adapted to the dark no amount of staring in its direction will make it visible. But the detectors attached to modern telescopes keep on adding up the light from faint sources as long as they are pointing at them. A longer exposure will reveal fainter objects than a short exposure does, as the photons (particles of light) from the source fall on the detector one by one and the total gradually grows.”

“Nobody can be quite sure where the supermassive black holes at the hearts of galaxies today came from, but it seems at least possible that […] merging of black holes left over from the first generation of stars [in the universe] began the process by which supermassive black holes, feeding off the matter surrounding them, formed. […] It seems very unlikely that supermassive black holes formed first and then galaxies grew around them; they must have formed together, in a process sometimes referred to as co-evolution, from the seeds provided by the original black holes of a few hundred solar masses and the raw materials of the dense clouds of baryons in the knots in the filamentary structure. […] About one in a hundred of the galaxies seen at low redshifts are actively involved in the late stages of mergers, but these processes take so little time, compared with the age of the Universe, that the statistics imply that about half of all the galaxies visible nearby are the result of mergers between similarly sized galaxies in the past seven or eight billion years. Disc galaxies like the Milky Way seem themselves to have been built up from smaller sub-units, starting out with the spheroid and adding bits and pieces as time passed. […] there were many more small galaxies when the Universe was young than we see around us today. This is exactly what we would expect if many of the small galaxies have either grown larger through mergers or been swallowed up by larger galaxies.”

Links of interest:

Galaxy (‘featured article’).
Leonard Digges.
Thomas Wright.
William Herschel.
William Parsons.
The Great Debate.
Parallax.
Extinction (astronomy).
Henrietta Swan Leavitt (‘good article’).
Cepheid variable.
Ejnar Hertzsprung. (Before reading this book, I had no idea one of the people behind the famous Hertzsprung–Russell diagram was a Dane. I blame my physics teachers. I was probably told this by one of them, but if the guy in question had been a better teacher, I’d have listened, and I’d have known this.).
Globular cluster (‘featured article’).
Vesto Slipher.
Redshift (‘featured article’).
Refracting telescope/Reflecting telescope.
Disc galaxy.
Edwin Hubble.
Milton Humason.
Doppler effect.
Milky Way.
Orion Arm.
Stellar population.
Sagittarius A*.
Minkowski space.
General relativity (featured).
The Big Bang theory (featured).
Age of the universe.
Malmquist bias.
Type Ia supernova.
Dark energy.
Baryons/leptons.
Cosmic microwave background.
Cold dark matter.
Lambda-CDM model.
Lenticular galaxy.
Active galactic nucleus.
Quasar.
Hubble Ultra-Deep Field.
Stellar evolution.
Velocity dispersion.
Hawking radiation.
Ultimate fate of the universe.

 

February 5, 2017 Posted by | astronomy, books, cosmology, Physics | Leave a comment

Random Stuff

i. On the youtube channel of the Institute for Advanced Studies there has been a lot of activity over the last week or two (far more than 100 new lectures have been uploaded, and it seems new uploads are still being added at this point), and I’ve been watching a few of the recently uploaded astrophysics lectures. They’re quite technical, but you can watch them and follow enough of the content to have an enjoyable time despite not understanding everything:


This is a good lecture, very interesting. One major point made early on: “the take-away message is that the most common planet in the galaxy, at least at shorter periods, are planets for which there is no analogue in the solar system. The most common kind of planet in the galaxy is a planet with a radius of two Earth radii.” Another big take-away message is that small planets seem to be quite common (as noted in the conclusions, “16% of Sun-like stars have an Earth-sized planet”).


Of the lectures included in this post this was the one I liked the least; there are too many (‘obstructive’) questions/interactions between lecturer and attendants along the way, and the interactions/questions are difficult to hear/understand. If you consider watching both this lecture and the lecture below, I would say that it would probably be wise to watch the lecture below this one before you watch this one; I concluded that in retrospect some of the observations made early on in the lecture below would have been useful to know about before watching this lecture. (The first half of the lecture below was incidentally to me somewhat easier to follow than was the second half, but especially the first half hour of it is really quite good, despite the bad start (which one can always blame on Microsoft…)).

ii. Words I’ve encountered recently (…or ‘recently’ – it’s been a while since I last posted one of these lists): Divagationsperiphrasis, reedy, architravesettpedipalp, tout, togs, edentulous, moue, tatty, tearaway, prorogue, piscine, fillip, sop, panniers, auxology, roister, prepossessing, cantle, catamite, couth, ordure, biddy, recrudescence, parvenu, scupper, husting, hackle, expatiate, affray, tatterdemalion, eructation, coppice, dekko, scull, fulmination, pollarding, grotty, secateurs, bumf (I must admit that I like this word – it seems fitting, somehow, to use that word for this concept…), durophagy, randy, (brief note to self: Advise people having children who ask me about suggestions for how to name them against using this name (or variants such as Randi), it does not seem like a great idea), effete, apricity, sororal, bint, coition, abaft, eaves, gadabout, lugubriously, retroussé, landlubber, deliquescence, antimacassar, inanition.

iii. “The point of rigour is not to destroy all intuition; instead, it should be used to destroy bad intuition while clarifying and elevating good intuition. It is only with a combination of both rigorous formalism and good intuition that one can tackle complex mathematical problems; one needs the former to correctly deal with the fine details, and the latter to correctly deal with the big picture. Without one or the other, you will spend a lot of time blundering around in the dark (which can be instructive, but is highly inefficient). So once you are fully comfortable with rigorous mathematical thinking, you should revisit your intuitions on the subject and use your new thinking skills to test and refine these intuitions rather than discard them. One way to do this is to ask yourself dumb questions; another is to relearn your field.” (Terry Tao, There’s more to mathematics than rigour and proofs)

iv. A century of trends in adult human height. A figure from the paper (Figure 3 – Change in adult height between the 1896 and 1996 birth cohorts):

elife-13410-fig3-v1

(Click to view full size. WordPress seems to have changed the way you add images to a blog post – if this one is even so annoyingly large, I apologize, I have tried to minimize it while still retaining detail, but the original file is huge). An observation from the paper:

“Men were taller than women in every country, on average by ~11 cm in the 1896 birth cohort and ~12 cm in the 1996 birth cohort […]. In the 1896 birth cohort, the male-female height gap in countries where average height was low was slightly larger than in taller nations. In other words, at the turn of the 20th century, men seem to have had a relative advantage over women in undernourished compared to better-nourished populations.”

I haven’t studied the paper in any detail but intend to do so at a later point in time.

v. I found this paper, on Exercise and Glucose Metabolism in Persons with Diabetes Mellitus, interesting in part because I’ve been very surprised a few times by offhand online statements made by diabetic athletes, who had observed that their blood glucose really didn’t drop all that fast during exercise. Rapid and annoyingly large drops in blood glucose during exercise have been a really consistent feature of my own life with diabetes during adulthood. It seems that there may be big inter-individual differences in terms of the effects of exercise on glucose in diabetics. From the paper:

“Typically, prolonged moderate-intensity aerobic exercise (i.e., 30–70% of one’s VO2max) causes a reduction in glucose concentrations because of a failure in circulating insulin levels to decrease at the onset of exercise.12 During this type of physical activity, glucose utilization may be as high as 1.5 g/min in adolescents with type 1 diabetes13 and exceed 2.0 g/min in adults with type 1 diabetes,14 an amount that quickly lowers circulating glucose levels. Persons with type 1 diabetes have large interindividual differences in blood glucose responses to exercise, although some intraindividual reproducibility exists.15 The wide ranging glycemic responses among individuals appears to be related to differences in pre-exercise blood glucose concentrations, the level of circulating counterregulatory hormones and the type/duration of the activity.2

August 13, 2016 Posted by | astronomy, demographics, diabetes, language, Lectures, mathematics, Physics, random stuff | Leave a comment

Random stuff

I find it difficult to find the motivation to finish the half-finished drafts I have lying around, so this will have to do. Some random stuff below.

i.

(15.000 views… In some sense that seems really ‘unfair’ to me, but on the other hand I doubt neither Beethoven nor Gilels care; they’re both long dead, after all…)

ii. New/newish words I’ve encountered in books, on vocabulary.com or elsewhere:

Agleyperipeteia, disseverhalidom, replevinsocage, organdie, pouffe, dyarchy, tauricide, temerarious, acharnement, cadger, gravamen, aspersion, marronage, adumbrate, succotash, deuteragonist, declivity, marquetry, machicolation, recusal.

iii. A lecture:

It’s been a long time since I watched it so I don’t have anything intelligent to say about it now, but I figured it might be of interest to one or two of the people who still subscribe to the blog despite the infrequent updates.

iv. A few wikipedia articles (I won’t comment much on the contents or quote extensively from the articles the way I’ve done in previous wikipedia posts – the links shall have to suffice for now):

Duverger’s law.

Far side of the moon.

Preference falsification.

Russian political jokes. Some of those made me laugh (e.g. this one: “A judge walks out of his chambers laughing his head off. A colleague approaches him and asks why he is laughing. “I just heard the funniest joke in the world!” “Well, go ahead, tell me!” says the other judge. “I can’t – I just gave someone ten years for it!”).

Political mutilation in Byzantine culture.

v. World War 2, if you think of it as a movie, has a highly unrealistic and implausible plot, according to this amusing post by Scott Alexander. Having recently read a rather long book about these topics, one aspect I’d have added had I written the piece myself would be that an additional factor making the setting seem even more implausible is how so many presumably quite smart people were so – what at least in retrospect seems – unbelievably stupid when it came to Hitler’s ideas and intentions before the war. Going back to Churchill’s own life I’d also add that if you were to make a movie about Churchill’s life during the war, which you could probably relatively easily do if you were to just base it upon his own copious and widely shared notes, then it could probably be made into a quite decent movie. His own comments, remarks, and observations certainly made for a great book.

May 15, 2016 Posted by | astronomy, Computer science, history, language, Lectures, mathematics, music, random stuff, Russia, wikipedia | Leave a comment

A few lectures

I was debating whether to post this, but considering how long it’s been since my last post I decided to do it. A large number of lectures have recently been uploaded by the Institute for Advanced Studies, and despite the fact that most of my ‘blogging-related activities’ these days relate to book reading I have watched a few of those lectures, and so I decided to post a couple of the lectures here:

I liked this lecture. Part II of the lecture in particular, starting around the 38 minute mark, dealt with stuff reasonably closely related to things I’d read about before (‘relatively’…) recently, back when I read Lammer’s text (blog coverage here); so although I didn’t remember the stuff covered in Lammer’s text in too much detail, it was definitely helpful to have worked with this stuff before. However I do believe you can watch the lecture and sort of understand what she’s talking about without knowing a great deal about these topics, at least if you don’t care too much about understanding all the details (I’d note that there are a lot of things going on ‘behind the scenes’ here, and that you can say a lot of stuff about topics closely related to this talk, like outgassing processes and how they relate to things like volcanism as well as e.g. the dynamic interactions between atmospheric molecules and the solar wind taking place in the early stages of stellar evolution). As is always the case for IAS lectures it’s really hard to hear the questions being asked and that’s annoying, but actually I think miss Schilchting is reasonably good at repeating the question or sort of answer them in a way that enables you to gather what’s ‘going on’; at least the fact that you can’t hear the questions is in my opinion a somewhat bigger problem in the lecture below (relatedly you can actually also see where the laser pointer is pointing in this lecture, at least some of the time – you can’t in the lecture below).

As mentioned this one was harder to follow, at least for me.

I hope to find time to blog a bit more in the days to come. One of several reasons why I’ve not blogged more than I have during the last weeks is that I recently realized that if I put in a bit of effort I’d be able to reach 150 books this year (I’m currently at 143 books, but very close to 144), with 50 non-fiction books (I think going for 52 would be a bit too much, but I’m not ruling it out yet – I’m currently at 47 non-fiction books (…but very close to 48)). I should note that I update the book post to which I link above much more often than I update ‘the blog’ in general with new posts. The reason why the ‘read 150 books this year goal’ is relevant is of course that every time I blog a book here on the blog, this takes away a substantial amount of time which I can’t spend actually reading books. Goodreads incidentally have recently made a nice ‘book of the year’ profile where you can see more details about the books I’ve read etc. From that profile I realized that my implicit working goal of reading 100 pages/day over the year has already been met (I’m currently at ~42.000 pages).

December 18, 2015 Posted by | astronomy, books, Lectures, Physics | Leave a comment

A couple of lectures and a little bit of random stuff

i. Two lectures from the Institute for Advanced Studies:

The IAS has recently uploaded a large number of lectures on youtube, and the ones I blog here are a few of those where you can actually tell from the title what the lecture is about; I find it outright weird that these people don’t include the topic covered in the lecture in their lecture titles.

As for the video above, as usual for the IAS videos it’s annoying that you can’t hear the questions asked by the audience, but the sound quality of this video is at least quite a bit better than the sound quality of the video below (which has a couple of really annoying sequences, in particular around the 15-16 minutes mark (it gets better), where the image is also causing problems, and in the last couple of minutes of the Q&A things are also not exactly optimal as the lecturer leaves the area covered by the camera in order to write something on the blackboard – but you don’t know what he’s writing and you can’t see the lecturer, because the camera isn’t following him). I found most of the above lecture easier to follow than I did the lecture posted below, though in either case you’ll probably not understand all of it unless you’re an astrophysicist – you definitely won’t in case of the latter lecture. I found it helpful to look up a few topics along the way, e.g. the wiki articles about the virial theorem (/also dealing with virial mass/radius), active galactic nucleus (this is the ‘AGN’ she refers to repeatedly), and the Tully–Fisher relation.

Given how many questions are asked along the way it’s really annoying that you in most cases can’t hear what people are asking about – this is definitely an area where there’s room for improvement in the context of the IAS videos. The lecture was not easy to follow but I figured along the way that I understood enough of it to make it worth watching the lecture to the end (though I’d say you’ll not miss much if you stop after the lecture – around the 1.05 hours mark – and skip the subsequent Q&A). I’ve relatively recently read about related topics, e.g. pulsar formation and wave- and fluid dynamics, and if I had not I probably would not have watched this lecture to the end.

ii. A vocabulary.com update. I’m slowly working my way up to the ‘Running Dictionary’ rank (I’m only a walking dictionary at this point); here’s some stuff from my progress page:

Vocab
I recently learned from a note added to a list that I’ve actually learned a very large proportion of all words available on vocabulary.com, which probably also means that I may have been too harsh on the word selection algorithm in past posts here on the blog; if there aren’t (/m)any new words left to learn it should not be surprising that the algorithm presents me with words I’ve already mastered, and it’s not the algorithm’s fault that there aren’t more words available for me to learn (well, it is to the extent that you’re of the opinion that questions should be automatically created by the algorithm as well, but I don’t think we’re quite there yet at this point). The aforementioned note was added in June, and here’s the important part: “there are words on your list that Vocabulary.com can’t teach yet. Vocabulary.com can teach over 12,000 words, but sadly, these aren’t among them”. ‘Over 12.000’ – and I’ve mastered 11.300. When the proportion of mastered words is this high, not only will the default random word algorithm mostly present you with questions related to words you’ve already mastered; but it actually also starts to get hard to find lists with many words you’ve not already mastered – I’ll often load lists with one hundred words and then realize that I’ve mastered every word on the list. This is annoying if you have a desire to continually be presented with both new words as well as old ones. Unless vocabulary.com increases the rate with which they add new words I’ll run out of new words to learn, and if that happens I’m sure it’ll be much more difficult for me to find motivation to use the site.

With all that stuff out of the way, if you’re not a regular user of the site I should note – again – that it’s an excellent resource if you desire to increase your vocabulary. Below is a list of words I’ve encountered on the site in recent weeks(/months?):

Copaceticfrumpyelisiontermagantharridanquondam, funambulist, phantasmagoriaeyelet, cachinnate, wilt, quidnunc, flocculent, galoot, frangible, prevaricate, clarion, trivet, noisome, revenant, myrmidon (I have included this word once before in a post of this type, but it is in my opinion a very nice word with which more people should be familiar…), debenture, teeter, tart, satiny, romp, auricular, terpsichorean, poultice, ululation, fusty, tangy, honorarium, eyas, bumptious, muckraker, bayou, hobble, omphaloskepsis, extemporize, virago, rarefaction, flibbertigibbet, finagle, emollient.

iii. I don’t think I’d do things exactly the way she’s suggesting here, but the general idea/approach seems to me appealing enough for it to be worth at least keeping in mind if I ever decide to start dating/looking for a partner.

iv. Some wikipedia links:

Tarrare (featured). A man with odd eating habits and an interesting employment history (“Dr. Courville was keen to continue his investigations into Tarrare’s eating habits and digestive system, and approached General Alexandre de Beauharnais with a suggestion that Tarrare’s unusual abilities and behaviour could be put to military use.[9] A document was placed inside a wooden box which was in turn fed to Tarrare. Two days later, the box was retrieved from his excrement, with the document still in legible condition.[9][17] Courville proposed to de Beauharnais that Tarrare could thus serve as a military courier, carrying documents securely through enemy territory with no risk of their being found if he were searched.” Yeah…).

Cauda equina syndromeCastleman’s disease, Astereognosis, Familial dysautonomia, Homonymous hemianopsia, Amaurosis fugax. All of these are of course related to content covered in the Handbook.

1740 Batavia massacre (featured).

v. I am also fun.

October 30, 2015 Posted by | astronomy, history, language, Lectures, medicine, personal, Physics, random stuff, wikipedia | Leave a comment

A few lectures

The Institute for Advanced Studies recently released a number of new lectures on youtube and I’ve watched a few of them.

Both this lecture and the one below start abruptly with no introduction, but I don’t think much stuff was covered before the beginning of this recording. The stuff in both lectures is ‘reasonably’ closely related to content covered in the book on pulsars/supernovae/neutron stars by McNamara which I recently finished (goodreads link) (…for some definitions of ‘reasonably’ I should perhaps add – it’s not that closely related, and for example Ramirez’ comment around the 50 minute mark that they’re disregarding magnetic fields seemed weird to me in the context of McNamara’s coverage). The first lecture was definitely much easier for me to follow than was the last one. The fact that you can’t hear the questions being asked I found annoying, but there aren’t that many questions being asked along the way. I was surprised to learn via google that Ramirez seems to be affiliated with the Niels Bohr Institute of Copenhagen (link).

Here’s a third lecture from the IAS:

I really didn’t think much of this lecture, but some of you might like it. It’s very non-technical compared to the first two lectures above, and unlike them the video recording did not start abruptly in the ‘middle’ of the lecture – which in this case on the other hand also means that you can actually easily skip the first 6-7 minutes without missing out on anything. Given the stuff he talks about in roughly the last 10 minutes of the lecture (aside from the concluding remarks) this is probably a reasonable place to remind you that Feynman’s lectures on the character of physical law are available on youtube and uploaded on this blog (see the link). If you have not watched those lectures, I actually think you should probably do that before watching a lecture like the one above – it’s in all likelihood a better use of your time. If you’re curious about things like cosmological scales and haven’t watched any of videos in the Khan Academy cosmology and astronomy lecture series, this is incidentally a good place to go have a look; the first few videos in the lecture series are really nice. Tegmark talks in his lecture about how we’ve underestimated how large the universe is, but I don’t really think the lecture adequately conveys just how mindbogglingly large the universe is, and I think Salman Khan’s lectures are much better if you want to get ‘a proper perspective’ of these things, to the extent that obtaining a ‘proper perspective’ is even possible given the limitations of the human mind.

Lastly, a couple more lectures from khanacademymedicine:

This is a neat little overview, especially if you’re unfamiliar with the topic.

July 24, 2015 Posted by | astronomy, Lectures, medicine, Physics, Psychology | Leave a comment

A few lectures

This one is not quite new, but I have never seen it or blogged it before. The sound is not completely optimal and as is so often the case for lectures like these it’s at times slightly annoying that you can’t tell what she’s pointing at when she’s talking about the slides, but these issues are relatively minor and should not keep you from watching the lecture.

This is a really nice introduction to some main ideas in the Nimzo Indian defence.

June 10, 2015 Posted by | astronomy, Chess, Lectures | Leave a comment

Stuff

i. World Happiness Report 2013. A few figures from the publication:

Fig 2.2

Fig 2.4

Fig 2.5

ii. Searching for Explanations: How the Internet Inflates Estimates of Internal Knowledge.

“As the Internet has become a nearly ubiquitous resource for acquiring knowledge about the world, questions have arisen about its potential effects on cognition. Here we show that searching the Internet for explanatory knowledge creates an illusion whereby people mistake access to information for their own personal understanding of the information. Evidence from 9 experiments shows that searching for information online leads to an increase in self-assessed knowledge as people mistakenly think they have more knowledge “in the head,” even seeing their own brains as more active as depicted by functional MRI (fMRI) images.”

A little more from the paper:

“If we go to the library to find a fact or call a friend to recall a memory, it is quite clear that the information we seek is not accessible within our own minds. When we go to the Internet in search of an answer, it seems quite clear that we are we consciously seeking outside knowledge. In contrast to other external sources, however, the Internet often provides much more immediate and reliable access to a broad array of expert information. Might the Internet’s unique accessibility, speed, and expertise cause us to lose track of our reliance upon it, distorting how we view our own abilities? One consequence of an inability to monitor one’s reliance on the Internet may be that users become miscalibrated regarding their personal knowledge. Self-assessments can be highly inaccurate, often occurring as inflated self-ratings of competence, with most people seeing themselves as above average [here’s a related link] […] For example, people overestimate their own ability to offer a quality explanation even in familiar domains […]. Similar illusions of competence may emerge as individuals become immersed in transactive memory networks. They may overestimate the amount of information contained in their network, producing a “feeling of knowing,” even when the content is inaccessible […]. In other words, they may conflate the knowledge for which their partner is responsible with the knowledge that they themselves possess (Wegner, 1987). And in the case of the Internet, an especially immediate and ubiquitous memory partner, there may be especially large knowledge overestimations. As people underestimate how much they are relying on the Internet, success at finding information on the Internet may be conflated with personally mastered information, leading Internet users to erroneously include knowledge stored outside their own heads as their own. That is, when participants access outside knowledge sources, they may become systematically miscalibrated regarding the extent to which they rely on their transactive memory partner. It is not that they misattribute the source of their knowledge, they could know full well where it came from, but rather they may inflate the sense of how much of the sum total of knowledge is stored internally.

We present evidence from nine experiments that searching the Internet leads people to conflate information that can be found online with knowledge “in the head.” […] The effect derives from a true misattribution of the sources of knowledge, not a change in understanding of what counts as internal knowledge (Experiment 2a and b) and is not driven by a “halo effect” or general overconfidence (Experiment 3). We provide evidence that this effect occurs specifically because information online can so easily be accessed through search (Experiment 4a–c).”

iii. Some words I’ve recently encountered on vocabulary.com: hortatory, adduce, obsequious, enunciate, ineluctable, guerdon, chthonic, condignphilippic, coruscate, exceptionable, colophon, lapidary, rubicund, frumpish, raiment, prorogue, sonorous, metonymy.

iv.

v. I have no idea how accurate this test of chess strength is, (some people in this thread argue that there are probably some calibration issues at the low end) but I thought I should link to it anyway. I’d be very cautious about drawing strong conclusions about over-the-board strength without knowing how they’ve validated the tool. In over-the-board chess you have at minimum a couple of minutes/move on average and this tool never gives you more than 30 seconds, so some slow players will probably suffer using this tool (I’d imagine this is why u/ViktorVamos got such a low estimate). For what it’s worth my Elo estimate was 2039 (95% CI: 1859, 2220).

In related news, I recently defeated my first IM – Pablo Garcia Castro – in a blitz (3 minutes/player) game. It actually felt a bit like an anticlimax and afterwards I was thinking that it would probably have felt like a bigger deal if I’d not lately been getting used to winning the occasional bullet game against IMs on the ICC. Actually I think my two wins against WIM Shiqun Ni during the same bullet session at the time felt like a bigger accomplishment, because that specific session was played during the Women’s World Chess Championship and I realized while looking up my opponent that this woman was actually stronger than one of the contestants who made it to the quarter-finals in that event (Meri Arabidze). On the other hand bullet isn’t really chess, so…

April 15, 2015 Posted by | astronomy, Chess, Lectures, papers, Psychology | 2 Comments

Some links (Open Thread?)

It’s been quite a while since the last time I posted a ‘here’s some interesting stuff I’ve found online’-post, so I’ll do that now even though I actually don’t spend much time randomly looking around for interesting stuff online these days. I added some wikipedia links I’d saved for a ‘wikipedia articles of interest’-post because it usually takes quite a bit of time to write a standard wikipedia post (as it takes time to figure out what to include and what not to include in the coverage) and I figured that if I didn’t add those links here I’d never get around to blogging them.

i. Battle of Dyrrhachium. Found via this link, which has a lot of stuff.

ii. An AMA by someone who claims to have succeeded in faking his own death.

iii. I found this article about the so-called “Einstellung” effect in chess interesting. I’m however not sure how important this stuff really is. I don’t think it’s sub-optimal for a player to spend a significant amount of time in positions like the ones they analyzed on ideas that don’t work, because usually you’ll only have to spot one idea that does to win the game. It’s obvious that one can argue people spend ‘too much’ time looking for a winning combination in positions where by design no winning combinations exist, but the fact of the matter is that in positions where ‘familiar patterns’ pop up winning resources often do exist, and you don’t win games by overlooking those or by failing to spend time looking for them; occasional suboptimal moves in some contexts may be a reasonable price to pay for increasing your likelihood of finding/playing the best/winning moves when those do exist. Here’s a slightly related link dealing with the question of the potential number of games/moves in chess. Here’s a good wiki article about pawn structures, and here’s one about swindles in chess. I incidentally very recently became a member of the ICC, and I’m frankly impressed with the player pool – which is huge and includes some really strong players (players like Morozevich and Tomashevsky seem to play there regularly). Since I started out on the site I’ve already beaten 3 IMs in bullet and lost a game against Islandic GM Henrik Danielsen. The IMs I’ve beaten were far from the strongest players in the player pool, but in my experience you don’t get to play titled players nearly as often as that on other sites if you’re at my level.

iv. A picture of the Andromeda galaxy. A really big picture. Related link here.

v. You may already have seen this one, but in case you have not: A Philosopher Walks Into A Coffee Shop. More than one of these made me laugh out loud. If you like the post you should take a look at the comments as well, there are some brilliant ones there as well.

vi. Amdahl’s law.

vii. Eigendecomposition of a matrix. On a related note I’m currently reading Imboden and Pfenninger’s Introduction to Systems Analysis (which goodreads for some reason has listed under a wrong title, as the goodreads book title is really the subtitle of the book), and today I had a look at the wiki article on Jacobian matrices and determinants for that reason (the book is about as technical as you’d expect from a book with a title like that).

viii. If you’ve been wondering how I’ve found the quotes I’ve posted here on this blog (I’ve posted roughly 150 posts with quotes so far), links like these are very useful.

ix. Geology of the Yosemite area.

February 7, 2015 Posted by | astronomy, Chess, Geology, history, mathematics, Open Thread, random stuff, wikipedia | Leave a comment

Wikipedia articles of interest

i. Pendle witches.

“The trials of the Pendle witches in 1612 are among the most famous witch trials in English history, and some of the best recorded of the 17th century. The twelve accused lived in the area around Pendle Hill in Lancashire, and were charged with the murders of ten people by the use of witchcraft. All but two were tried at Lancaster Assizes on 18–19 August 1612, along with the Samlesbury witches and others, in a series of trials that have become known as the Lancashire witch trials. One was tried at York Assizes on 27 July 1612, and another died in prison. Of the eleven who went to trial – nine women and two men – ten were found guilty and executed by hanging; one was found not guilty.

The official publication of the proceedings by the clerk to the court, Thomas Potts, in his The Wonderfull Discoverie of Witches in the Countie of Lancaster, and the number of witches hanged together – nine at Lancaster and one at York – make the trials unusual for England at that time. It has been estimated that all the English witch trials between the early 15th and early 18th centuries resulted in fewer than 500 executions; this series of trials accounts for more than two per cent of that total.”

“One of the accused, Demdike, had been regarded in the area as a witch for fifty years, and some of the deaths the witches were accused of had happened many years before Roger Nowell started to take an interest in 1612.[13] The event that seems to have triggered Nowell’s investigation, culminating in the Pendle witch trials, occurred on 21 March 1612.[14]

On her way to Trawden Forest, Demdike’s granddaughter, Alizon Device, encountered John Law, a pedlar from Halifax, and asked him for some pins.[15] Seventeenth-century metal pins were handmade and relatively expensive, but they were frequently needed for magical purposes, such as in healing – particularly for treating warts – divination, and for love magic, which may have been why Alizon was so keen to get hold of them and why Law was so reluctant to sell them to her.[16] Whether she meant to buy them, as she claimed, and Law refused to undo his pack for such a small transaction, or whether she had no money and was begging for them, as Law’s son Abraham claimed, is unclear.[17] A few minutes after their encounter Alizon saw Law stumble and fall, perhaps because he suffered a stroke; he managed to regain his feet and reach a nearby inn.[18] Initially Law made no accusations against Alizon,[19] but she appears to have been convinced of her own powers; when Abraham Law took her to visit his father a few days after the incident, she reportedly confessed and asked for his forgiveness.[20]

Alizon Device, her mother Elizabeth, and her brother James were summoned to appear before Nowell on 30 March 1612. Alizon confessed that she had sold her soul to the Devil, and that she had told him to lame John Law after he had called her a thief. Her brother, James, stated that his sister had also confessed to bewitching a local child. Elizabeth was more reticent, admitting only that her mother, Demdike, had a mark on her body, something that many, including Nowell, would have regarded as having been left by the Devil after he had sucked her blood.”

“The Pendle witches were tried in a group that also included the Samlesbury witches, Jane Southworth, Jennet Brierley, and Ellen Brierley, the charges against whom included child murder and cannibalism; Margaret Pearson, the so-called Padiham witch, who was facing her third trial for witchcraft, this time for killing a horse; and Isobel Robey from Windle, accused of using witchcraft to cause sickness.[33]

Some of the accused Pendle witches, such as Alizon Device, seem to have genuinely believed in their guilt, but others protested their innocence to the end.”

“Nine-year-old Jennet Device was a key witness for the prosecution, something that would not have been permitted in many other 17th-century criminal trials. However, King James had made a case for suspending the normal rules of evidence for witchcraft trials in his Daemonologie.[42] As well as identifying those who had attended the Malkin Tower meeting, Jennet also gave evidence against her mother, brother, and sister. […] When Jennet was asked to stand up and give evidence against her mother, Elizabeth began to scream and curse her daughter, forcing the judges to have her removed from the courtroom before the evidence could be heard.[48] Jennet was placed on a table and stated that she believed her mother had been a witch for three or four years. She also said her mother had a familiar called Ball, who appeared in the shape of a brown dog. Jennet claimed to have witnessed conversations between Ball and her mother, in which Ball had been asked to help with various murders. James Device also gave evidence against his mother, saying he had seen her making a clay figure of one of her victims, John Robinson.[49] Elizabeth Device was found guilty.[47]

James Device pleaded not guilty to the murders by witchcraft of Anne Townley and John Duckworth. However he, like Chattox, had earlier made a confession to Nowell, which was read out in court. That, and the evidence presented against him by his sister Jennet, who said that she had seen her brother asking a black dog he had conjured up to help him kill Townley, was sufficient to persuade the jury to find him guilty.[50][51]

“Many of the allegations made in the Pendle witch trials resulted from members of the Demdike and Chattox families making accusations against each other. Historian John Swain has said that the outbreaks of witchcraft in and around Pendle demonstrate the extent to which people could make a living either by posing as a witch, or by accusing or threatening to accuse others of being a witch.[17] Although it is implicit in much of the literature on witchcraft that the accused were victims, often mentally or physically abnormal, for some at least, it may have been a trade like any other, albeit one with significant risks.[74] There may have been bad blood between the Demdike and Chattox families because they were in competition with each other, trying to make a living from healing, begging, and extortion.”

ii. Kullback–Leibler divergence.

This article is the only one of the five ‘main articles’ in this post which is not a featured article. I looked this one up because the Burnham & Anderson book I’m currently reading talks about this stuff quite a bit. The book will probably be one of the most technical books I’ll read this year, and I’m not sure how much of it I’ll end up covering here. Basically most of the book deals with the stuff ‘covered’ in the (very short) ‘Relationship between models and reality’ section of the wiki article. There are a lot of details the article left out… The same could be said about the related wiki article about AIC (both articles incidentally include the book in their references).

iii Atmosphere of Jupiter.

The first thing that would spring to mind if someone asked me what I knew about it would probably be something along the lines of: “…well, it’s huge…”

Jupiter-Earth-Spot_comparison

…and it is. But we know a lot more than that – some observations from the article:

“The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System. It is mostly made of molecular hydrogen and helium in roughly solar proportions; other chemical compounds are present only in small amounts […] The atmosphere of Jupiter lacks a clear lower boundary and gradually transitions into the liquid interior of the planet. […] The Jovian atmosphere shows a wide range of active phenomena, including band instabilities, vortices (cyclones and anticyclones), storms and lightning. […] Jupiter has powerful storms, always accompanied by lightning strikes. The storms are a result of moist convection in the atmosphere connected to the evaporation and condensation of water. They are sites of strong upward motion of the air, which leads to the formation of bright and dense clouds. The storms form mainly in belt regions. The lightning strikes on Jupiter are hundreds of times more powerful than those seen on Earth.” [However do note that later on in the article it is stated that: “On Jupiter lighting strikes are on average a few times more powerful than those on Earth.”]

“The composition of Jupiter’s atmosphere is similar to that of the planet as a whole.[1] Jupiter’s atmosphere is the most comprehensively understood of those of all the gas giants because it was observed directly by the Galileo atmospheric probe when it entered the Jovian atmosphere on December 7, 1995.[26] Other sources of information about Jupiter’s atmospheric composition include the Infrared Space Observatory (ISO),[27] the Galileo and Cassini orbiters,[28] and Earth-based observations.”

“The visible surface of Jupiter is divided into several bands parallel to the equator. There are two types of bands: lightly colored zones and relatively dark belts. […] The alternating pattern of belts and zones continues until the polar regions at approximately 50 degrees latitude, where their visible appearance becomes somewhat muted.[30] The basic belt-zone structure probably extends well towards the poles, reaching at least to 80° North or South.[5]

The difference in the appearance between zones and belts is caused by differences in the opacity of the clouds. Ammonia concentration is higher in zones, which leads to the appearance of denser clouds of ammonia ice at higher altitudes, which in turn leads to their lighter color.[15] On the other hand, in belts clouds are thinner and are located at lower altitudes.[15] The upper troposphere is colder in zones and warmer in belts.[5] […] The Jovian bands are bounded by zonal atmospheric flows (winds), called jets. […] The location and width of bands, speed and location of jets on Jupiter are remarkably stable, having changed only slightly between 1980 and 2000. […] However bands vary in coloration and intensity over time […] These variations were first observed in the early seventeenth century.”

“Jupiter radiates much more heat than it receives from the Sun. It is estimated that the ratio between the power emitted by the planet and that absorbed from the Sun is 1.67 ± 0.09.”

iv. Wife selling (English custom).

Wife selling in England was a way of ending an unsatisfactory marriage by mutual agreement that probably began in the late 17th century, when divorce was a practical impossibility for all but the very wealthiest. After parading his wife with a halter around her neck, arm, or waist, a husband would publicly auction her to the highest bidder. […] Although the custom had no basis in law and frequently resulted in prosecution, particularly from the mid-19th century onwards, the attitude of the authorities was equivocal. At least one early 19th-century magistrate is on record as stating that he did not believe he had the right to prevent wife sales, and there were cases of local Poor Law Commissioners forcing husbands to sell their wives, rather than having to maintain the family in workhouses.”

“Until the passing of the Marriage Act of 1753, a formal ceremony of marriage before a clergyman was not a legal requirement in England, and marriages were unregistered. All that was required was for both parties to agree to the union, so long as each had reached the legal age of consent,[8] which was 12 for girls and 14 for boys.[9] Women were completely subordinated to their husbands after marriage, the husband and wife becoming one legal entity, a legal status known as coverture. […] Married women could not own property in their own right, and were indeed themselves the property of their husbands. […] Five distinct methods of breaking up a marriage existed in the early modern period of English history. One was to sue in the ecclesiastical courts for separation from bed and board (a mensa et thoro), on the grounds of adultery or life-threatening cruelty, but it did not allow a remarriage.[11] From the 1550s, until the Matrimonial Causes Act became law in 1857, divorce in England was only possible, if at all, by the complex and costly procedure of a private Act of Parliament.[12] Although the divorce courts set up in the wake of the 1857 Act made the procedure considerably cheaper, divorce remained prohibitively expensive for the poorer members of society.[13][nb 1] An alternative was to obtain a “private separation”, an agreement negotiated between both spouses, embodied in a deed of separation drawn up by a conveyancer. Desertion or elopement was also possible, whereby the wife was forced out of the family home, or the husband simply set up a new home with his mistress.[11] Finally, the less popular notion of wife selling was an alternative but illegitimate method of ending a marriage.”

“Although some 19th-century wives objected, records of 18th-century women resisting their sales are non-existent. With no financial resources, and no skills on which to trade, for many women a sale was the only way out of an unhappy marriage.[17] Indeed the wife is sometimes reported as having insisted on the sale. […] Although the initiative was usually the husband’s, the wife had to agree to the sale. An 1824 report from Manchester says that “after several biddings she [the wife] was knocked down for 5s; but not liking the purchaser, she was put up again for 3s and a quart of ale”.[27] Frequently the wife was already living with her new partner.[28] In one case in 1804 a London shopkeeper found his wife in bed with a stranger to him, who, following an altercation, offered to purchase the wife. The shopkeeper agreed, and in this instance the sale may have been an acceptable method of resolving the situation. However, the sale was sometimes spontaneous, and the wife could find herself the subject of bids from total strangers.[29] In March 1766, a carpenter from Southwark sold his wife “in a fit of conjugal indifference at the alehouse”. Once sober, the man asked his wife to return, and after she refused he hanged himself. A domestic fight might sometimes precede the sale of a wife, but in most recorded cases the intent was to end a marriage in a way that gave it the legitimacy of a divorce.”

“Prices paid for wives varied considerably, from a high of £100 plus £25 each for her two children in a sale of 1865 (equivalent to about £12,500 in 2015)[34] to a low of a glass of ale, or even free. […] According to authors Wade Mansell and Belinda Meteyard, money seems usually to have been a secondary consideration;[4] the more important factor was that the sale was seen by many as legally binding, despite it having no basis in law. […] In Sussex, inns and public houses were a regular venue for wife-selling, and alcohol often formed part of the payment. […] in Ninfield in 1790, a man who swapped his wife at the village inn for half a pint of gin changed his mind and bought her back later.[42] […] Estimates of the frequency of the ritual usually number about 300 between 1780 and 1850, relatively insignificant compared to the instances of desertion, which in the Victorian era numbered in the tens of thousands.[43]

“In 1825 a man named Johnson was charged with “having sung a song in the streets describing the merits of his wife, for the purpose of selling her to the highest bidder at Smithfield.” Such songs were not unique; in about 1842 John Ashton wrote “Sale of a Wife”.[nb 6][58] The arresting officer claimed that the man had gathered a “crowd of all sorts of vagabonds together, who appeared to listen to his ditty, but were in fact, collected to pick pockets.” The defendant, however, replied that he had “not the most distant idea of selling his wife, who was, poor creature, at home with her hungry children, while he was endeavouring to earn a bit of bread for them by the strength of his lungs.” He had also printed copies of the song, and the story of a wife sale, to earn money. Before releasing him, the Lord Mayor, judging the case, cautioned Johnson that the practice could not be allowed, and must not be repeated.[59] In 1833 the sale of a woman was reported at Epping. She was sold for 2s. 6d., with a duty of 6d. Once sober, and placed before the Justices of the Peace, the husband claimed that he had been forced into marriage by the parish authorities, and had “never since lived with her, and that she had lived in open adultery with the man Bradley, by whom she had been purchased”. He was imprisoned for “having deserted his wife”.[60]

v. Bog turtle.

Baby_bog_turtle_in_palm_(cropped)

“The bog turtle (Glyptemys muhlenbergii) is a semiaquatic turtle endemic to the eastern United States. […] It is the smallest North American turtle, measuring about 10 centimeters (4 in) long when fully grown. […] The bog turtle can be found from Vermont in the north, south to Georgia, and west to Ohio. Diurnal and secretive, it spends most of its time buried in mud and – during the winter months – in hibernation. The bog turtle is omnivorous, feeding mainly on small invertebrates.”

“The bog turtle is native only to the eastern United States,[nb 1] congregating in colonies that often consist of fewer than 20 individuals.[23] […] densities can range from 5 to 125 individuals per 0.81 hectares (2.0 acres). […] The bog turtle spends its life almost exclusively in the wetland where it hatched. In its natural environment, it has a maximum lifespan of perhaps 50 years or more,[47] and the average lifespan is 20–30 years.”

“The bog turtle is primarily diurnal, active during the day and sleeping at night. It wakes in the early morning, basks until fully warm, then begins its search for food.[31] It is a seclusive species, making it challenging to observe in its natural habitat.[11] During colder days, the bog turtle will spend much of its time in dense underbrush, underwater, or buried in mud. […] Day-to-day, the bog turtle moves very little, typically basking in the sun and waiting for prey. […] Various studies have found different rates of daily movement in bog turtles, varying from 2.1 to 23 meters (6.9 to 75.5 ft) in males and 1.1 to 18 meters (3.6 to 59.1 ft) in females.”

“Changes to the bog turtle’s habitat have resulted in the disappearance of 80 percent of the colonies that existed 30 years ago.[7] Because of the turtle’s rarity, it is also in danger of illegal collection, often for the worldwide pet trade. […] The bog turtle was listed as critically endangered in the 2011 IUCN Red List.[53]

January 3, 2015 Posted by | astronomy, biology, history, statistics, wikipedia, Zoology | Leave a comment

A few lectures

 

 

December 14, 2014 Posted by | astronomy, Lectures, Physics | Leave a comment

Origin and Evolution of Planetary Atmospheres – Implications for Habitability

I recently finished this book. I gave the book two stars on goodreads, however I also added this comment to the information about the book on my 2014 book list: “Close to three stars, but the poor language of the publication made it difficult for me to justify giving it that rating.” I liked reading the book, but I do not condone sloppy and/or unclear language and this is something I’ll usually punish.

When I started reading the book I’d assumed there might be some overlap with Gale’s book, which I haven’t covered here, but that actually turned out not really to be the case; the two books focus on different things even if a few of the questions they ask are quite similar, and so the coverage of the two books actually don’t much overlap. Most of this was new stuff, which was nice. The book is in my opinion more technical and harder to read than was Gale’s book, but again, they deal with different stuff so I’m not sure how much sense it makes to compare them. Lammer doesn’t shy away from covering relevant math formulas where they might be helpful to improve understanding, and/but some of these are not easy to understand if you do not have a background in physics; you need to know some stuff about things like electromagnetism, thermodynamics, and plasma physics to understand all of the stuff in this book. I didn’t – I certainly didn’t know ‘enough’ – but his coverage is fortunately such that even if you mentally skip a few formulas without really understanding the details of the dynamics they model, you’ll usually still be able to figure out roughly how they work wrt. the specific issue at hand because he also talks about how they work and which conclusions to draw; though you’ll likely still need to look up some unfamiliar terms along the way in order not to be completely confused.

I should make clear that although it may sound from the above as if this is really a rather dull book about mathematical formulas and complicated physics, one thing I find it really hard to term this book is ‘boring’. The book talks about what the Earth was like back when Earth was covered by magma oceans. Freaking magma oceans! It talks about how the Earth was quite likely early on in its ‘lifetime’ (before life on the planet, it should perhaps be noted) covered by a huge hydrogen atmosphere, and how that early atmosphere was blown away by a Sun which was spinning much faster than it does today, bombarding the early proto-atmospheres of the newly formed planets with huge numbers of highly charged particles despite the sun shining ‘less brightly’ back then than it does now. It talks about how a slightly different atmospheric composition back then, with more hydrogen, might have lead to the Earth being unable to get rid of all that hydrogen, most likely leading to the Earth having ended up as a ‘waterworld’ without continents, completely covered by water. It talks about how the Sun slowed down after what was most likely just a few million years, and how it has since then been doing things quite differently from the way it did things in the beginning. Phenomena such as outgassing and impact events are discussed. The book talks about how conditions were different on Mars and Venus from the way they were on Earth, and what role various factors might have played in terms of explaining how the atmospheres got to be the way they are now, and why those planets turned out quite different. The role of gravity, the role of a magnetosphere, which concrete processes lead to loss of (/which) atmospheric components. There’s a lot of stuff in this book, and much of it I found really quite interesting. But it is also hard to read, sometimes hard to understand, and certainly far from always particularly well-written. The topics covered I found quite interesting though.

I was wondering how to cover this book, but I decided early on that given how many things I was looking up along the way it would make a lot of sense to bookmark some relevant links and add them to this post; so below I have added a list of terms and concepts covered in the book. Some of the concepts are much better covered in the book than in the links (the wiki article on atmospheric escape for example has very little stuff on this topic compared to the stuff included in the book about this topic), but in other cases there’s a lot of stuff in the wiki article which was not included in the book (naturally, or it would not have made sense for me to look up stuff there). So the stuff in the links don’t add up to the material covered in the book, but the articles should give you a clue what kind of book this is. Below the list I have added a few quotes from the book. As should be obvious from the number of links, the book has a lot of content despite the relatively low page-count.

Atmosphere of Earth.
Troposphere.
Atmospheric escape.
Hydrodynamic escape.
Maxwell–Boltzmann distribution.
Noachian.
Exosphere.
Outflow channels.
Scale height.
Larmor radius.
Adiabatic process.
Energetic neutral atom.
Magnetopause.
Bow shock.
Lyman series.
Heliosphere.
Roche lobe.
Plasma (physics).
Astrophysical plasma.
Photoionization.
Nebular hypothesis.
Stellar evolution.
Protostar.
Protoplanetary disk
.
Solar wind.
Hydrostatic equilibrium.
Kelvin–Helmholtz instability.
Polar wind.

“As contrasted to meteorology which studies the properties and behavior of the lower atmosphere between the surface and the tropopause where the weather phenomena are generated, aeronomy is a division of atmospheric science that studies physics and chemistry of the upper atmosphere that extends from above the troposphere up to the altitudes where it is modified by the solar wind plasma. […] The central part of [this] monograph presents a detailed discussion of the atmospheric loss mechanisms due to the action of various thermal and non-thermal escape processes for the neutral and ionized particles from a hot, extended atmospheric corona. Scenarios for the formation and evolution of the atmospheres of Earth, Venus, and Mars, that is, the planets orbiting within the habitable zone around the Sun, are considered. A crucial role of the magnetosphere of a planet in protecting its hot, extended, and partially ionized corona from the solar wind erosion is discussed. […] The book presents a brief review of the present state of knowledge of the aeronomy of planetary atmospheres and of their evolution during the lifetime of their host stars by taking into account conventionally accepted concepts, as well as recent observational and theoretical results.”

“the classical concept of the habitable zone and its related questions of what makes a planet habitable is much more complex than having a big rocky body located at the right distance from its host star. […] A careful study of various astrophysical and geophysical aspects indicate that Earth-analogue class I habitats have to be located at the right distance of the habitable zone from their host stars, must lose their protoatmospheres during the right time period, should maintain plate tectonics over the planet’s lifetime, should have nitrogen as the main atmospheric species after the stellar activity decreased to moderate values and finally, the planet’s interior should have developed conditions that an intrinsic strong global magnetic field could evolve.” [I should probably add here that this specific stuff is covered extensively in Gale’s book, but doesn’t make up too much of the coverage of this book].

“The mantle solidification of a magma ocean is a fast process and ends at ∼105 years for Earth-size planets with low volatile contents and at ≤3Myr [million years, US] for planets with higher volatile contents and magma ocean depths of ≤2,000km […] During the magma ocean solidification process, H2O and CO2 molecules can enter the solidifying minerals in relative low quantities [8, 9]. As a result the H2O/CO2 volatiles will degas into dense steam atmospheres […] If the early Earth would have obtained slightly more material from water-rich planetesimals, its CO2 content would have been much higher and Earth’s oceans could have been tens to hundreds of kilometers deep […]. Such environmental conditions would have resulted in a globally covered water world [43, 44] which is surrounded by a Venus-type dense CO2 atmosphere and a hydrogen envelope.” [I tried while reading this to imagine a magma ocean which was something like 2000 kilometers deep, but I failed to do so. Just think about this…]

“There is observational evidence from solar proxies with younger age compared to the present Sun, that during the early history of the Solar System the EUV flux was up to∼100 times larger as it is today […] The evolution of planetary atmospheres can only be understood if one considers that the radiation and particle environment of the Sun or a planet’s host star changed during their life time. The magnetic activity of solar-type stars declines steadily during their evolution on the Zero-Age-Main-Sequence (ZAMS). According to the solar standard model, the Sun’s photospheric luminosity was ∼30 % lower ∼4.5 Gyr ago […] when the Sun arrived on the ZAMS compared to present levels. The observed faster rotation of young stars is responsible for an enhanced magnetic activity and related heating processes in the chromosphere, X-ray emissions are ≥1,000, and EUV, and UV ∼100 and ∼10 times higher compared to today’s solar values. Moreover, the production rate of high-energy particles is orders of magnitude higher at young stars, and from observable stellar mass loss-activity relations one can also expect a much stronger solar/stellar wind during the active stellar phase.”

“The nuclear evolution of the Sun is well known from stellar evolutionary theory and backed by helioseismological observations of the internal solar structure [10]. The results of these evolutionary solar models, indicate that the young Sun was ∼10% cooler and ∼15% smaller compared to the modern Sun ∼4.6Gyr ago. According to the solar standard model, due to accelerating nuclear reactions in the Sun’s core, the Sun is a slowly evolving variable G-type star that has undergone an ∼30% increase in luminosity over the past ∼4.5Gyr. […] the outward flowing plasma carries away angular momentum from the star [which explains] the observed spin-down to slower rotation of young stars after their arrival at the ZAMS [the book mentions elsewhere that it’s been estimated based on observations of other star systems that the young sun was rotating more than 10 times as fast as it does now]. […] the early Earth may have lost during [the first 100 million years] an amount of hydrogen equivalent of ∼20EOs [Earth Oceans] thermally […] after the loss of [a large amount of the original steam atmosphere,] the Earth’s atmosphere environment near the surface reached the critical temperature of ∼650 K. After reaching this temperature the remaining H2O-vapor of ∼1EO could condense and collapsed into the liquid water ocean [84]. Additional amount[s] of water could have been delivered also continuously via impacts, but the bulk of the early Earth’s initial water inventory is most likely a by-product of a condensed fraction of the catastrophically outgassed steam atmosphere. […] One should […] note that in the case of the early Earth due to the Moon forming impact a fraction of ≤30% of atmosphere could have also been lost to space [113].”

“The present average atmospheric mass loss of hydrogen, oxygen, and nitrogen ions from the Earth is ∼ 1.3 × 103 g s-1

“The first protoatmosphere will be captured and accumulated hydrogen- and helium-rich gas envelopes from the nebula. Depending on the planetary formation time, the nebula dissipation time, the numbers of additional planets including gas giants in the system, the protoplanet’s gravity, its orbit location, and the host star’s radiation and plasma environment terrestrial planets may capture tens or even several hundreds of the Earth ocean equivalent amounts of hydrogen around its rocky core.
The second protoatmosphere depends on the initial volatile content of the protoplanet when accretion finished. During the magma ocean solidification […] steam atmospheres with surface pressures ranging from∼100 to several 104 bar can be catastrophically outgassed.
Finally, secondary atmospheres will be produced by tectonic activity such as volcanos and by the delivery of volatiles via large impacts. The origin and initial state of a planet’s protoatmosphere, therefore, determines a planet’s atmospheric evolution and finally if the planet will evolve to an Earth-analog class I habitat or not. […] The efficiency of the solar/stellar forcing is essentially inversely proportional to the square of the distance to the planet’s host star. From that, it follows that the closer a planet orbits around its host star, the more efficient are the atmospheric escape processes. The main effects caused by the stellar radiation and plasma environment on the atmospheres of an effected planet are to ionize, chemically modify, heated, expand, and slowly erode the upper atmosphere throughout the lifetime of a planet. The highest thermal and non-thermal atmospheric escape rates are obtained during the early active phase of the planet’s host star […] Besides the orbital location, a planet’s gravity constitutes an additional major protection mechanism especially for thermal escape of its atmosphere, while the nonthermal escape processes are affected on a weaker scale.”

December 11, 2014 Posted by | astronomy, books, Physics | Leave a comment

Wikipedia articles of interest

(A minor note: These days when I’m randomly browsing wikipedia and not just looking up concepts or terms found in the books I read, I’m mostly browsing the featured content on wikipedia. There’s a lot of featured stuff, and on average such articles more interesting than random articles. As a result of this approach, all articles covered in the post below are featured articles. A related consequence of this shift may be that I may cover fewer articles in future wikipedia posts than I have in the past; this post only contains five articles, which I believe is slightly less than usual for these posts – a big reason for this being that it sometimes takes a lot of time to read a featured article.)

i. Woolly mammoth.

Ice_age_fauna_of_northern_Spain_-_Mauricio_Antón

“The woolly mammoth (Mammuthus primigenius) was a species of mammoth, the common name for the extinct elephant genus Mammuthus. The woolly mammoth was one of the last in a line of mammoth species, beginning with Mammuthus subplanifrons in the early Pliocene. M. primigenius diverged from the steppe mammoth, M. trogontherii, about 200,000 years ago in eastern Asia. Its closest extant relative is the Asian elephant. […] The earliest known proboscideans, the clade which contains elephants, existed about 55 million years ago around the Tethys Sea. […] The family Elephantidae existed six million years ago in Africa and includes the modern elephants and the mammoths. Among many now extinct clades, the mastodon is only a distant relative of the mammoths, and part of the separate Mammutidae family, which diverged 25 million years before the mammoths evolved.[12] […] The woolly mammoth coexisted with early humans, who used its bones and tusks for making art, tools, and dwellings, and the species was also hunted for food.[1] It disappeared from its mainland range at the end of the Pleistocene 10,000 years ago, most likely through a combination of climate change, consequent disappearance of its habitat, and hunting by humans, though the significance of these factors is disputed. Isolated populations survived on Wrangel Island until 4,000 years ago, and on St. Paul Island until 6,400 years ago.”

“The appearance and behaviour of this species are among the best studied of any prehistoric animal due to the discovery of frozen carcasses in Siberia and Alaska, as well as skeletons, teeth, stomach contents, dung, and depiction from life in prehistoric cave paintings. […] Fully grown males reached shoulder heights between 2.7 and 3.4 m (9 and 11 ft) and weighed up to 6 tonnes (6.6 short tons). This is almost as large as extant male African elephants, which commonly reach 3–3.4 m (9.8–11.2 ft), and is less than the size of the earlier mammoth species M. meridionalis and M. trogontherii, and the contemporary M. columbi. […] Woolly mammoths had several adaptations to the cold, most noticeably the layer of fur covering all parts of the body. Other adaptations to cold weather include ears that are far smaller than those of modern elephants […] The small ears reduced heat loss and frostbite, and the tail was short for the same reason […] They had a layer of fat up to 10 cm (3.9 in) thick under the skin, which helped to keep them warm. […] The coat consisted of an outer layer of long, coarse “guard hair”, which was 30 cm (12 in) on the upper part of the body, up to 90 cm (35 in) in length on the flanks and underside, and 0.5 mm (0.020 in) in diameter, and a denser inner layer of shorter, slightly curly under-wool, up to 8 cm (3.1 in) long and 0.05 mm (0.0020 in) in diameter. The hairs on the upper leg were up to 38 cm (15 in) long, and those of the feet were 15 cm (5.9 in) long, reaching the toes. The hairs on the head were relatively short, but longer on the underside and the sides of the trunk. The tail was extended by coarse hairs up to 60 cm (24 in) long, which were thicker than the guard hairs. It is likely that the woolly mammoth moulted seasonally, and that the heaviest fur was shed during spring.”

“Woolly mammoths had very long tusks, which were more curved than those of modern elephants. The largest known male tusk is 4.2 m (14 ft) long and weighs 91 kg (201 lb), but 2.4–2.7 m (7.9–8.9 ft) and 45 kg (99 lb) was a more typical size. Female tusks averaged at 1.5–1.8 m (4.9–5.9 ft) and weighed 9 kg (20 lb). About a quarter of the length was inside the sockets. The tusks grew spirally in opposite directions from the base and continued in a curve until the tips pointed towards each other. In this way, most of the weight would have been close to the skull, and there would be less torque than with straight tusks. The tusks were usually asymmetrical and showed considerable variation, with some tusks curving down instead of outwards and some being shorter due to breakage.”

“Woolly mammoths needed a varied diet to support their growth, like modern elephants. An adult of six tonnes would need to eat 180 kg (397 lb) daily, and may have foraged as long as twenty hours every day. […] Woolly mammoths continued growing past adulthood, like other elephants. Unfused limb bones show that males grew until they reached the age of 40, and females grew until they were 25. The frozen calf “Dima” was 90 cm (35 in) tall when it died at the age of 6–12 months. At this age, the second set of molars would be in the process of erupting, and the first set would be worn out at 18 months of age. The third set of molars lasted for ten years, and this process was repeated until the final, sixth set emerged when the animal was 30 years old. A woolly mammoth could probably reach the age of 60, like modern elephants of the same size. By then the last set of molars would be worn out, the animal would be unable to chew and feed, and it would die of starvation.[53]

“The habitat of the woolly mammoth is known as “mammoth steppe” or “tundra steppe”. This environment stretched across northern Asia, many parts of Europe, and the northern part of North America during the last ice age. It was similar to the grassy steppes of modern Russia, but the flora was more diverse, abundant, and grew faster. Grasses, sedges, shrubs, and herbaceous plants were present, and scattered trees were mainly found in southern regions. This habitat was not dominated by ice and snow, as is popularly believed, since these regions are thought to have been high-pressure areas at the time. The habitat of the woolly mammoth also supported other grazing herbivores such as the woolly rhinoceros, wild horses and bison. […] A 2008 study estimated that changes in climate shrank suitable mammoth habitat from 7,700,000 km2 (3,000,000 sq mi) 42,000 years ago to 800,000 km2 (310,000 sq mi) 6,000 years ago.[81][82] Woolly mammoths survived an even greater loss of habitat at the end of the Saale glaciation 125,000 years ago, and it is likely that humans hunted the remaining populations to extinction at the end of the last glacial period.[83][84] […] Several woolly mammoth specimens show evidence of being butchered by humans, which is indicated by breaks, cut-marks, and associated stone tools. It is not known how much prehistoric humans relied on woolly mammoth meat, since there were many other large herbivores available. Many mammoth carcasses may have been scavenged by humans rather than hunted. Some cave paintings show woolly mammoths in structures interpreted as pitfall traps. Few specimens show direct, unambiguous evidence of having been hunted by humans.”

“While frozen woolly mammoth carcasses had been excavated by Europeans as early as 1728, the first fully documented specimen was discovered near the delta of the Lena River in 1799 by Ossip Schumachov, a Siberian hunter.[90] Schumachov let it thaw until he could retrieve the tusks for sale to the ivory trade. [Aargh!] […] The 1901 excavation of the “Berezovka mammoth” is the best documented of the early finds. It was discovered by the Berezovka River, and the Russian authorities financed its excavation. Its head was exposed, and the flesh had been scavenged. The animal still had grass between its teeth and on the tongue, showing that it had died suddenly. […] By 1929, the remains of 34 mammoths with frozen soft tissues (skin, flesh, or organs) had been documented. Only four of them were relatively complete. Since then, about that many more have been found.”

ii. Daniel Lambert.

Daniel Lambert (13 March 1770 – 21 June 1809) was a gaol keeper[n 1] and animal breeder from Leicester, England, famous for his unusually large size. After serving four years as an apprentice at an engraving and die casting works in Birmingham, he returned to Leicester around 1788 and succeeded his father as keeper of Leicester’s gaol. […] At the time of Lambert’s return to Leicester, his weight began to increase steadily, even though he was athletically active and, by his own account, abstained from drinking alcohol and did not eat unusual amounts of food. In 1805, Lambert’s gaol closed. By this time, he weighed 50 stone (700 lb; 318 kg), and had become the heaviest authenticated person up to that point in recorded history. Unemployable and sensitive about his bulk, Lambert became a recluse.

In 1806, poverty forced Lambert to put himself on exhibition to raise money. In April 1806, he took up residence in London, charging spectators to enter his apartments to meet him. Visitors were impressed by his intelligence and personality, and visiting him became highly fashionable. After some months on public display, Lambert grew tired of exhibiting himself, and in September 1806, he returned, wealthy, to Leicester, where he bred sporting dogs and regularly attended sporting events. Between 1806 and 1809, he made a further series of short fundraising tours.

In June 1809, he died suddenly in Stamford. At the time of his death, he weighed 52 stone 11 lb (739 lb; 335 kg), and his coffin required 112 square feet (10.4 m2) of wood. Despite the coffin being built with wheels to allow easy transport, and a sloping approach being dug to the grave, it took 20 men almost half an hour to drag his casket into the trench, in a newly opened burial ground to the rear of St Martin’s Church.”

“Sensitive about his weight, Daniel Lambert refused to allow himself to be weighed, but sometime around 1805, some friends persuaded him to come with them to a cock fight in Loughborough. Once he had squeezed his way into their carriage, the rest of the party drove the carriage onto a large scale and jumped out. After deducting the weight of the (previously weighed) empty carriage, they calculated that Lambert’s weight was now 50 stone (700 lb; 318 kg), and that he had thus overtaken Edward Bright, the 616-pound (279 kg) “Fat Man of Maldon”,[23] as the heaviest authenticated person in recorded history.[20][24]

Despite his shyness, Lambert badly needed to earn money, and saw no alternative to putting himself on display, and charging his spectators.[20] On 4 April 1806, he boarded a specially built carriage and travelled from Leicester[26] to his new home at 53 Piccadilly, then near the western edge of London.[20] For five hours each day, he welcomed visitors into his home, charging each a shilling (about £3.5 as of 2014).[18][25] […] Lambert shared his interests and knowledge of sports, dogs and animal husbandry with London’s middle and upper classes,[27] and it soon became highly fashionable to visit him, or become his friend.[27] Many called repeatedly; one banker made 20 visits, paying the admission fee on each occasion.[17] […] His business venture was immediately successful, drawing around 400 paying visitors per day. […] People would travel long distances to see him (on one occasion, a party of 14 travelled to London from Guernsey),[n 5] and many would spend hours speaking with him on animal breeding.”

“After some months in London, Lambert was visited by Józef Boruwłaski, a 3-foot 3-inch (99 cm) dwarf then in his seventies.[44] Born in 1739 to a poor family in rural Pokuttya,[45] Boruwłaski was generally considered to be the last of Europe’s court dwarfs.[46] He was introduced to the Empress Maria Theresa in 1754,[47] and after a short time residing with deposed Polish king Stanisław Leszczyński,[44] he exhibited himself around Europe, thus becoming a wealthy man.[48] At age 60, he retired to Durham,[49] where he became such a popular figure that the City of Durham paid him to live there[50] and he became one of its most prominent citizens […] The meeting of Lambert and Boruwłaski, the largest and smallest men in the country,[51] was the subject of enormous public interest”

“There was no autopsy, and the cause of Lambert’s death is unknown.[65] While many sources say that he died of a fatty degeneration of the heart or of stress on his heart caused by his bulk, his behaviour in the period leading to his death does not match that of someone suffering from cardiac insufficiency; witnesses agree that on the morning of his death he appeared well, before he became short of breath and collapsed.[65] Bondeson (2006) speculates that the most consistent explanation of his death, given his symptoms and medical history, is that he had a sudden pulmonary embolism.[65]

iii. Geology of the Capitol Reef area.

Waterpocket_Fold_-_Looking_south_from_the_Strike_Valley_Overlook

“The exposed geology of the Capitol Reef area presents a record of mostly Mesozoic-aged sedimentation in an area of North America in and around Capitol Reef National Park, on the Colorado Plateau in southeastern Utah.

Nearly 10,000 feet (3,000 m) of sedimentary strata are found in the Capitol Reef area, representing nearly 200 million years of geologic history of the south-central part of the U.S. state of Utah. These rocks range in age from Permian (as old as 270 million years old) to Cretaceous (as young as 80 million years old.)[1] Rock layers in the area reveal ancient climates as varied as rivers and swamps (Chinle Formation), Sahara-like deserts (Navajo Sandstone), and shallow ocean (Mancos Shale).

The area’s first known sediments were laid down as a shallow sea invaded the land in the Permian. At first sandstone was deposited but limestone followed as the sea deepened. After the sea retreated in the Triassic, streams deposited silt before the area was uplifted and underwent erosion. Conglomerate followed by logs, sand, mud and wind-transported volcanic ash were later added. Mid to Late Triassic time saw increasing aridity, during which vast amounts of sandstone were laid down along with some deposits from slow-moving streams. As another sea started to return it periodically flooded the area and left evaporite deposits. Barrier islands, sand bars and later, tidal flats, contributed sand for sandstone, followed by cobbles for conglomerate and mud for shale. The sea retreated, leaving streams, lakes and swampy plains to become the resting place for sediments. Another sea, the Western Interior Seaway, returned in the Cretaceous and left more sandstone and shale only to disappear in the early Cenozoic.”

“The Laramide orogeny compacted the region from about 70 million to 50 million years ago and in the process created the Rocky Mountains. Many monoclines (a type of gentle upward fold in rock strata) were also formed by the deep compressive forces of the Laramide. One of those monoclines, called the Waterpocket Fold, is the major geographic feature of the park. The 100 mile (160 km) long fold has a north-south alignment with a steeply east-dipping side. The rock layers on the west side of the Waterpocket Fold have been lifted more than 7,000 feet (2,100 m) higher than the layers on the east.[23] Thus older rocks are exposed on the western part of the fold and younger rocks on the eastern part. This particular fold may have been created due to movement along a fault in the Precambrian basement rocks hidden well below any exposed formations. Small earthquakes centered below the fold in 1979 may be from such a fault.[24] […] Ten to fifteen million years ago the entire region was uplifted several thousand feet (well over a kilometer) by the creation of the Colorado Plateaus. This time the uplift was more even, leaving the overall orientation of the formations mostly intact. Most of the erosion that carved today’s landscape occurred after the uplift of the Colorado Plateau with much of the major canyon cutting probably occurring between 1 and 6 million years ago.”

iv. Problem of Apollonius.

“In Euclidean plane geometry, Apollonius’s problem is to construct circles that are tangent to three given circles in a plane (Figure 1).

396px-Apollonius_problem_typical_solution.svg

Apollonius of Perga (ca. 262 BC – ca. 190 BC) posed and solved this famous problem in his work Ἐπαφαί (Epaphaí, “Tangencies”); this work has been lost, but a 4th-century report of his results by Pappus of Alexandria has survived. Three given circles generically have eight different circles that are tangent to them […] and each solution circle encloses or excludes the three given circles in a different way […] The general statement of Apollonius’ problem is to construct one or more circles that are tangent to three given objects in a plane, where an object may be a line, a point or a circle of any size.[1][2][3][4] These objects may be arranged in any way and may cross one another; however, they are usually taken to be distinct, meaning that they do not coincide. Solutions to Apollonius’ problem are sometimes called Apollonius circles, although the term is also used for other types of circles associated with Apollonius. […] A rich repertoire of geometrical and algebraic methods have been developed to solve Apollonius’ problem,[9][10] which has been called “the most famous of all” geometry problems.[3]

v. Globular cluster.

“A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin globulus—a small sphere. A globular cluster is sometimes known more simply as a globular.

Globular clusters, which are found in the halo of a galaxy, contain considerably more stars and are much older than the less dense galactic, or open clusters, which are found in the disk. Globular clusters are fairly common; there are about 150[2] to 158[3] currently known globular clusters in the Milky Way, with perhaps 10 to 20 more still undiscovered.[4] Large galaxies can have more: Andromeda, for instance, may have as many as 500. […]

Every galaxy of sufficient mass in the Local Group has an associated group of globular clusters, and almost every large galaxy surveyed has been found to possess a system of globular clusters.[8] The Sagittarius Dwarf galaxy and the disputed Canis Major Dwarf galaxy appear to be in the process of donating their associated globular clusters (such as Palomar 12) to the Milky Way.[9] This demonstrates how many of this galaxy’s globular clusters might have been acquired in the past.

Although it appears that globular clusters contain some of the first stars to be produced in the galaxy, their origins and their role in galactic evolution are still unclear.”

October 23, 2014 Posted by | astronomy, biology, Geography, Geology, history, mathematics, Paleontology, wikipedia, Zoology | Leave a comment

Wikipedia articles of interest

i. Dodo (featured article).

“The dodo (Raphus cucullatus) is an extinct flightless bird that was endemic to the island of Mauritius, east of Madagascar in the Indian Ocean. Its closest genetic relative was the also extinct Rodrigues solitaire, the two forming the subfamily Raphinae of the family of pigeons and doves. […] Subfossil remains show the dodo was about 1 metre (3.3 feet) tall and may have weighed 10–18 kg (22–40 lb) in the wild. The dodo’s appearance in life is evidenced only by drawings, paintings and written accounts from the 17th century. Because these vary considerably, and because only some illustrations are known to have been drawn from live specimens, its exact appearance in life remains unresolved. Similarly, little is known with certainty about its habitat and behaviour.”

“The first recorded mention of the dodo was by Dutch sailors in 1598. In the following years, the bird was hunted by sailors, their domesticated animals, and invasive species introduced during that time. The last widely accepted sighting of a dodo was in 1662. Its extinction was not immediately noticed, and some considered it to be a mythical creature. In the 19th century, research was conducted on a small quantity of remains of four specimens that had been brought to Europe in the early 17th century. Among these is a dried head, the only soft tissue of the dodo that remains today. Since then, a large amount of subfossil material has been collected from Mauritius […] The dodo was anatomically similar to pigeons in many features. […] The dodo differed from other pigeons mainly in the small size of the wings and the large size of the beak in proportion to the rest of the cranium. […] Many of the skeletal features that distinguish the dodo and the Rodrigues solitaire, its closest relative, from pigeons have been attributed to their flightlessness. […] The lack of mammalian herbivores competing for resources on these islands allowed the solitaire and the dodo to attain very large sizes.[19]” [If the last sentence sparked your interest and/or might be something about which you’d like to know more, I have previously covered a great book on related topics here on the blog]

“The etymology of the word dodo is unclear. Some ascribe it to the Dutch word dodoor for “sluggard”, but it is more probably related to Dodaars, which means either “fat-arse” or “knot-arse”, referring to the knot of feathers on the hind end. […] The traditional image of the dodo is of a very fat and clumsy bird, but this view may be exaggerated. The general opinion of scientists today is that many old European depictions were based on overfed captive birds or crudely stuffed specimens.[44]

“Like many animals that evolved in isolation from significant predators, the dodo was entirely fearless of humans. This fearlessness and its inability to fly made the dodo easy prey for sailors.[79] Although some scattered reports describe mass killings of dodos for ships’ provisions, archaeological investigations have found scant evidence of human predation. […] The human population on Mauritius (an area of 1,860 km2 or 720 sq mi) never exceeded 50 people in the 17th century, but they introduced other animals, including dogs, pigs, cats, rats, and crab-eating macaques, which plundered dodo nests and competed for the limited food resources.[37] At the same time, humans destroyed the dodo’s forest habitat. The impact of these introduced animals, especially the pigs and macaques, on the dodo population is currently considered more severe than that of hunting. […] Even though the rareness of the dodo was reported already in the 17th century, its extinction was not recognised until the 19th century. This was partly because, for religious reasons, extinction was not believed possible until later proved so by Georges Cuvier, and partly because many scientists doubted that the dodo had ever existed. It seemed altogether too strange a creature, and many believed it a myth.”

Some of the contemporary accounts and illustrations included in the article, from which behavioural patterns etc. have been inferred, I found quite depressing. Two illustrative quotes and a contemporary engraving are included below:

“Blue parrots are very numerous there, as well as other birds; among which are a kind, conspicuous for their size, larger than our swans, with huge heads only half covered with skin as if clothed with a hood. […] These we used to call ‘Walghvogel’, for the reason that the longer and oftener they were cooked, the less soft and more insipid eating they became. Nevertheless their belly and breast were of a pleasant flavour and easily masticated.[40]

“I have seen in Mauritius birds bigger than a Swan, without feathers on the body, which is covered with a black down; the hinder part is round, the rump adorned with curled feathers as many in number as the bird is years old. […] We call them Oiseaux de Nazaret. The fat is excellent to give ease to the muscles and nerves.[7]

640px-Jacht_op_dodo's_door_Willem_van_West-Zanen_uit_1602

ii. Armero tragedy (featured).

“The Armero tragedy […] was one of the major consequences of the eruption of the Nevado del Ruiz stratovolcano in Tolima, Colombia, on November 13, 1985. After 69 years of dormancy, the volcano’s eruption caught nearby towns unaware, even though the government had received warnings from multiple volcanological organizations to evacuate the area when volcanic activity had been detected in September 1985.[1]

As pyroclastic flows erupted from the volcano’s crater, they melted the mountain’s glaciers, sending four enormous lahars (volcanically induced mudslides, landslides, and debris flows) down its slopes at 50 kilometers per hour (30 miles per hour). The lahars picked up speed in gullies and coursed into the six major rivers at the base of the volcano; they engulfed the town of Armero, killing more than 20,000 of its almost 29,000 inhabitants.[2] Casualties in other towns, particularly Chinchiná, brought the overall death toll to 23,000. […] The relief efforts were hindered by the composition of the mud, which made it nearly impossible to move through without becoming stuck. By the time relief workers reached Armero twelve hours after the eruption, many of the victims with serious injuries were dead. The relief workers were horrified by the landscape of fallen trees, disfigured human bodies, and piles of debris from entire houses. […] The event was a foreseeable catastrophe exacerbated by the populace’s unawareness of the volcano’s destructive history; geologists and other experts had warned authorities and media outlets about the danger over the weeks and days leading up to the eruption.”

“The day of the eruption, black ash columns erupted from the volcano at approximately 3:00 pm local time. The local Civil Defense director was promptly alerted to the situation. He contacted INGEOMINAS, which ruled that the area should be evacuated; he was then told to contact the Civil Defense directors in Bogotá and Tolima. Between 5:00 and 7:00 pm, the ash stopped falling, and local officials instructed people to “stay calm” and go inside. Around 5:00 pm an emergency committee meeting was called, and when it ended at 7:00 pm, several members contacted the regional Red Cross over the intended evacuation efforts at Armero, Mariquita, and Honda. The Ibagué Red Cross contacted Armero’s officials and ordered an evacuation, which was not carried out because of electrical problems caused by a storm. The storm’s heavy rain and constant thunder may have overpowered the noise of the volcano, and with no systematic warning efforts, the residents of Armero were completely unaware of the continuing activity at Ruiz. At 9:45 pm, after the volcano had erupted, Civil Defense officials from Ibagué and Murillo tried to warn Armero’s officials, but could not make contact. Later they overheard conversations between individual officials of Armero and others; famously, a few heard the Mayor of Armero speaking on a ham radio, saying “that he did not think there was much danger”, when he was overtaken by the lahar.[20]

“The lahars, formed of water, ice, pumice, and other rocks,[25] incorporated clay from eroding soil as they traveled down the volcano’s flanks.[26] They ran down the volcano’s sides at an average speed of 60 kilometers (40 mi) per hour, dislodging rock and destroying vegetation. After descending thousands of meters down the side of the volcano, the lahars followed the six river valleys leading from the volcano, where they grew to almost four times their original volume. In the Gualí River, a lahar reached a maximum width of 50 meters (160 ft).[25]

Survivors in Armero described the night as “quiet”. Volcanic ash had been falling throughout the day, but residents were informed it was nothing to worry about. Later in the afternoon, ash began falling again after a long period of quiet. Local radio stations reported that residents should remain calm and ignore the material. One survivor reported going to the fire department to be informed that the ash was “nothing”.[27] […] At 11:30 pm, the first lahar hit, followed shortly by the others.[28] One of the lahars virtually erased Armero; three-quarters of its 28,700 inhabitants were killed.[25] Proceeding in three major waves, this lahar was 30 meters (100 ft) deep, moved at 12 meters per second (39 ft/s), and lasted ten to twenty minutes. Traveling at about 6 meters (20 ft) per second, the second lahar lasted thirty minutes and was followed by smaller pulses. A third major pulse brought the lahar’s duration to roughly two hours; by that point, 85 percent of Armero was enveloped in mud. Survivors described people holding on to debris from their homes in attempts to stay above the mud. Buildings collapsed, crushing people and raining down debris. The front of the lahar contained boulders and cobbles which would have crushed anyone in their path, while the slower parts were dotted by fine, sharp stones which caused lacerations. Mud moved into open wounds and other open body parts – the eyes, ears, and mouth – and placed pressure capable of inducing traumatic asphyxia in one or two minutes upon people buried in it.”

“The volcano continues to pose a serious threat to nearby towns and villages. Of the threats, the one with the most potential for danger is that of small-volume eruptions, which can destabilize glaciers and trigger lahars.[51] Although much of the volcano’s glacier mass has retreated, a significant volume of ice still sits atop Nevado del Ruiz and other volcanoes in the Ruiz–Tolima massif. Melting just 10 percent of the ice would produce lahars with a volume of up to 200 million cubic meters – similar to the lahar that destroyed Armero in 1985. In just hours, these lahars can travel up to 100 km along river valleys.[33] Estimates show that up to 500,000 people living in the Combeima, Chinchina, Coello-Toche, and Guali valleys are at risk, with 100,000 individuals being considered to be at high risk.”

iii. Asteroid belt (featured).

“The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt is also termed the main asteroid belt or main belt to distinguish its members from other asteroids in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids, Ceres, Vesta, Pallas, and Hygiea. Vesta, Pallas, and Hygiea have mean diameters of more than 400 km, whereas Ceres, the asteroid belt’s only dwarf planet, is about 950 km in diameter.[1][2][3][4] The remaining bodies range down to the size of a dust particle.”

“The asteroid belt formed from the primordial solar nebula as a group of planetesimals, the smaller precursors of the planets, which in turn formed protoplanets. Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to accrete into a planet. Collisions became too violent, and instead of fusing together, the planetesimals and most of the protoplanets shattered. As a result, 99.9% of the asteroid belt’s original mass was lost in the first 100 million years of the Solar System’s history.[5]

“In an anonymous footnote to his 1766 translation of Charles Bonnet‘s Contemplation de la Nature,[8] the astronomer Johann Daniel Titius of Wittenberg[9][10] noted an apparent pattern in the layout of the planets. If one began a numerical sequence at 0, then included 3, 6, 12, 24, 48, etc., doubling each time, and added four to each number and divided by 10, this produced a remarkably close approximation to the radii of the orbits of the known planets as measured in astronomical units. This pattern, now known as the Titius–Bode law, predicted the semi-major axes of the six planets of the time (Mercury, Venus, Earth, Mars, Jupiter and Saturn) provided one allowed for a “gap” between the orbits of Mars and Jupiter. […] On January 1, 1801, Giuseppe Piazzi, Chair of Astronomy at the University of Palermo, Sicily, found a tiny moving object in an orbit with exactly the radius predicted by the Titius–Bode law. He dubbed it Ceres, after the Roman goddess of the harvest and patron of Sicily. Piazzi initially believed it a comet, but its lack of a coma suggested it was a planet.[12] Fifteen months later, Heinrich Wilhelm Olbers discovered a second object in the same region, Pallas. Unlike the other known planets, the objects remained points of light even under the highest telescope magnifications instead of resolving into discs. Apart from their rapid movement, they appeared indistinguishable from stars. Accordingly, in 1802 William Herschel suggested they be placed into a separate category, named asteroids, after the Greek asteroeides, meaning “star-like”. […] The discovery of Neptune in 1846 led to the discrediting of the Titius–Bode law in the eyes of scientists, because its orbit was nowhere near the predicted position. […] One hundred asteroids had been located by mid-1868, and in 1891 the introduction of astrophotography by Max Wolf accelerated the rate of discovery still further.[22] A total of 1,000 asteroids had been found by 1921,[23] 10,000 by 1981,[24] and 100,000 by 2000.[25] Modern asteroid survey systems now use automated means to locate new minor planets in ever-increasing quantities.”

“In 1802, shortly after discovering Pallas, Heinrich Olbers suggested to William Herschel that Ceres and Pallas were fragments of a much larger planet that once occupied the Mars–Jupiter region, this planet having suffered an internal explosion or a cometary impact many million years before.[26] Over time, however, this hypothesis has fallen from favor. […] Today, most scientists accept that, rather than fragmenting from a progenitor planet, the asteroids never formed a planet at all. […] The asteroids are not samples of the primordial Solar System. They have undergone considerable evolution since their formation, including internal heating (in the first few tens of millions of years), surface melting from impacts, space weathering from radiation, and bombardment by micrometeorites.[34] […] collisions between asteroids occur frequently (on astronomical time scales). Collisions between main-belt bodies with a mean radius of 10 km are expected to occur about once every 10 million years.[63] A collision may fragment an asteroid into numerous smaller pieces (leading to the formation of a new asteroid family). Conversely, collisions that occur at low relative speeds may also join two asteroids. After more than 4 billion years of such processes, the members of the asteroid belt now bear little resemblance to the original population. […] The current asteroid belt is believed to contain only a small fraction of the mass of the primordial belt. Computer simulations suggest that the original asteroid belt may have contained mass equivalent to the Earth.[37] Primarily because of gravitational perturbations, most of the material was ejected from the belt within about a million years of formation, leaving behind less than 0.1% of the original mass.[29] Since their formation, the size distribution of the asteroid belt has remained relatively stable: there has been no significant increase or decrease in the typical dimensions of the main-belt asteroids.[38]

“Contrary to popular imagery, the asteroid belt is mostly empty. The asteroids are spread over such a large volume that it would be improbable to reach an asteroid without aiming carefully. Nonetheless, hundreds of thousands of asteroids are currently known, and the total number ranges in the millions or more, depending on the lower size cutoff. Over 200 asteroids are known to be larger than 100 km,[44] and a survey in the infrared wavelengths has shown that the asteroid belt has 0.7–1.7 million asteroids with a diameter of 1 km or more. […] The total mass of the asteroid belt is estimated to be 2.8×1021 to 3.2×1021 kilograms, which is just 4% of the mass of the Moon.[2] […] Several otherwise unremarkable bodies in the outer belt show cometary activity. Because their orbits cannot be explained through capture of classical comets, it is thought that many of the outer asteroids may be icy, with the ice occasionally exposed to sublimation through small impacts. Main-belt comets may have been a major source of the Earth’s oceans, because the deuterium–hydrogen ratio is too low for classical comets to have been the principal source.[56] […] Of the 50,000 meteorites found on Earth to date, 99.8 percent are believed to have originated in the asteroid belt.[67]

iv. Series (mathematics). This article has a lot of stuff, including lots of links to other stuff.

v. Occupation of Japan. Interesting article, I haven’t really read very much about this before. Some quotes:

“At the head of the Occupation administration was General MacArthur who was technically supposed to defer to an advisory council set up by the Allied powers, but in practice did everything himself. As a result, this period was one of significant American influence […] MacArthur’s first priority was to set up a food distribution network; following the collapse of the ruling government and the wholesale destruction of most major cities, virtually everyone was starving. Even with these measures, millions of people were still on the brink of starvation for several years after the surrender.”

“By the end of 1945, more than 350,000 U.S. personnel were stationed throughout Japan. By the beginning of 1946, replacement troops began to arrive in the country in large numbers and were assigned to MacArthur’s Eighth Army, headquartered in Tokyo’s Dai-Ichi building. Of the main Japanese islands, Kyūshū was occupied by the 24th Infantry Division, with some responsibility for Shikoku. Honshū was occupied by the First Cavalry Division. Hokkaido was occupied by the 11th Airborne Division.

By June 1950, all these army units had suffered extensive troop reductions and their combat effectiveness was seriously weakened. When North Korea invaded South Korea (see Korean War), elements of the 24th Division were flown into South Korea to try to stem the massive invasion force there, but the green occupation troops, while acquitting themselves well when suddenly thrown into combat almost overnight, suffered heavy casualties and were forced into retreat until other Japan occupation troops could be sent to assist.”

“During the Occupation, GHQ/SCAP mostly abolished many of the financial coalitions known as the Zaibatsu, which had previously monopolized industry.[20] […] A major land reform was also conducted […] Between 1947 and 1949, approximately 5,800,000 acres (23,000 km2) of land (approximately 38% of Japan’s cultivated land) were purchased from the landlords under the government’s reform program and resold at extremely low prices (after inflation) to the farmers who worked them. By 1950, three million peasants had acquired land, dismantling a power structure that the landlords had long dominated.[22]

“There are allegations that during the three months in 1945 when Okinawa was gradually occupied there were rapes committed by U.S. troops. According to some accounts, US troops committed thousands of rapes during the campaign.[36][37]

Many Japanese civilians in the Japanese mainland feared that the Allied occupation troops were likely to rape Japanese women. The Japanese authorities set up a large system of prostitution facilities (RAA) in order to protect the population. […] However, there was a resulting large rise in venereal disease among the soldiers, which led MacArthur to close down the prostitution in early 1946.[39] The incidence of rape increased after the closure of the brothels, possibly eight-fold; […] “According to one calculation the number of rapes and assaults on Japanese women amounted to around 40 daily while the RAA was in operation, and then rose to an average of 330 a day after it was terminated in early 1946.”[40] Michael S. Molasky states that while rape and other violent crime was widespread in naval ports like Yokosuka and Yokohama during the first few weeks of occupation, according to Japanese police reports and journalistic studies, the number of incidents declined shortly after and were not common on mainland Japan throughout the rest of occupation.[41] Two weeks into the occupation, the Occupation administration began censoring all media. This included any mention of rape or other sensitive social issues.”

“Post-war Japan was chaotic. The air raids on Japan’s urban centers left millions displaced and food shortages, created by bad harvests and the demands of the war, worsened when the seizure of food from Korea, Taiwan, and China ceased.[58] Repatriation of Japanese living in other parts of Asia only aggravated the problems in Japan as these displaced people put more strain on already scarce resources. Over 5.1 million Japanese returned to Japan in the fifteen months following October 1, 1945.[59] Alcohol and drug abuse became major problems. Deep exhaustion, declining morale and despair were so widespread that it was termed the “kyodatsu condition” (虚脱状態 kyodatsujoutai?, lit. “state of lethargy”).[60] Inflation was rampant and many people turned to the black market for even the most basic goods. These black markets in turn were often places of turf wars between rival gangs, like the Shibuya incident in 1946.”

August 16, 2014 Posted by | astronomy, biology, Geology, history, mathematics, wikipedia, Zoology | Leave a comment

Open Thread

This is where you share interesting stuff you’ve come across since the last time I posted one of these.

I figured I should post a bit of content as well, so here we go:

i.

(Chichen Itza is not located in ‘Southern America’, but aside from that I don’t have a lot of stuff to complain about in relation to that lecture. As I’ve mentioned before I generally like Crawford’s lectures.)

ii. I haven’t read this (yet? Maybe I won’t – I hate when articles are gated; even if I can usually get around that, I take this sort of approach to matters as a strong signal that the authors don’t really want me to read it in the first place (if they wanted me to read it, why would they make it so difficult for me to do so?)), but as it sort of conceptually relates to some of the work Boyd & Richerson talk about in their book, which I read some chapters of yesterday, I figured I should link to it anyway: Third-party punishment increases cooperation in children through (misaligned) expectations and conditional cooperation. Here’s the abstract:

“The human ability to establish cooperation, even in large groups of genetically unrelated strangers, depends upon the enforcement of cooperation norms. Third-party punishment is one important factor to explain high levels of cooperation among humans, although it is still somewhat disputed whether other animal species also use this mechanism for promoting cooperation. We study the effectiveness of third-party punishment to increase children’s cooperative behavior in a large-scale cooperation game. Based on an experiment with 1,120 children, aged 7 to 11 y, we find that the threat of third-party punishment more than doubles cooperation rates, despite the fact that children are rarely willing to execute costly punishment. We can show that the higher cooperation levels with third-party punishment are driven by two components. First, cooperation is a rational (expected payoff-maximizing) response to incorrect beliefs about the punishment behavior of third parties. Second, cooperation is a conditionally cooperative reaction to correct beliefs that third party punishment will increase a partner’s level of cooperation.”

I should note that I yesterday also started reading a book on conflict resolution which covers the behavioural patterns of social animals in some detail, and which actually also ‘sort of relate, a bit’ to this type of stuff. A lot of stuff that people do they do for different reasons than the ones they usually apply themselves to explain their behaviours (if they even bother to do that at all..), but scientists in many different areas of research are making progress in terms of finding out ‘what’s really going on’, and there are probably a lot more potentially useful approaches to these types of problems than most people usually imagine. Many smart people seem at this point to me to be familiar with some of the results of the heuristics-and-biases literature/approach to human behaviour because that stuff’s been popularized a lot over the last decade or two, and they probably have a tendency to interpret human behaviour using that sort of contextual framework, perhaps combined with the usual genes/environment-type conceptual approaches. Perhaps they combine that stuff with the approaches that are most common among people with their educational backgrounds (people with a medical degree may be prone to using biological models, an economist might perhaps apply game theory, and an evolutionary biologist might ask what a chimpanzee would have done). This isn’t a problem as such, but many people might do well to try to keep in mind every now and then that there are a lot other theoretical frameworks one might decide to apply in order to make sense of what humans do than the one(s) they usually apply themselves, and that some of these may actually add a lot information even if they’re much less well-known. Some of the methodological differences relate to levels of analysis (are we trying to understand one individual or a group of individuals?), but that’s far from the whole story. To take a different kind of example, it has turned out that animal models are actually really nice tools if you want to understand some of the details involved in addictive behaviours, and they seem to be useful if you want to deal with conflict resolution stuff as well, at least judging from the stuff I’ve read in that new book so far (one could of course consider animal models to be a subset of the genetic modeling framework, but in an applied context it makes a lot of sense to keep them separate from each other and to consider them to be distinct subfields…). I have a nagging suspicion that animal models may also be very useful when it comes to explaining various forms of what people usually refer to as ’emotional behaviours’, and that despite the fact that a lot of people tend to consider that kind of stuff ‘unanalyzable’, it probably isn’t if you use the right tools and ask the right questions. You don’t need to be a doctor or a biologist to see why hard-to-observe purely ‘biological effects’ having behavioural effects may be important, but are these sorts of dynamics taken sufficiently into account when people interact with each other? I’m not sure. Mathematical modeling approaches like the one above are other ways (of course various approaches can be combined, making this stuff even more complicated…) to proceed and they seem to me to be, certainly when they generate testable predictions, potentially useful a well – not necessarily always only because we learn whether the predictions are correct or not, but also because mathematical thinking in general allows/requires you to think more carefully about stuff  and identify relevant variables and pathways (but I’ve talked about this before).

I should point out that I wrote the passage above in part because very occasionally I encounter a Fan of The Hard Sciences (on the internet) who seems to think that rejecting all kinds of human behavioural theory/-research (‘Social Science’) on account of it not being Hard Enough to generate trustworthy inferences is a good way to go – I actually had a brief encounter with one of those not too long ago, which was part of what motivated me to write the stuff above (and the stuff below). That guy expressed the opinion that you’d learn more about human nature by reading a Dostoyevsky novel than you would by reading e.g. Leary & Hoyle’s textbook. I’m perhaps now being rather more blunt than I usually am, but I thought I should make it clear here, so that there are no misunderstandings, that I tend to consider people with that kind of approach to things to be clueless fools who don’t have any idea what they’re talking about. Perhaps I should also mention that I have in fact read both so I feel qualified to judge on the matter, but this is probably arguably besides the point; the disagreement goes much deeper than just the truth content of the specific statement in question, as the much bigger problem is the methodological divide. Some skepticism is often required in behavioural sciences, among other things because establishing causal inference is really hard in many areas, but if you want your skepticism to make sense and be taken seriously you need to know enough about the topic and potential problems to actually formulate a relevant and cogent criticism. In that context I emphasize that ‘unbundling’ is really important – if you’re speaking to someone who’s familiar with at least some part of ‘the field of social science’, criticizing ‘The Social Sciences’ in general terms will probably just make you look stupid unless you add a lot of caveats. That’s because it’s not one field. Do the same sort of problems arise when people evaluate genetic models of human behavioural variance and ‘sociological approaches’? Applied microeconomics? Attachment theory? Evolutionary biology? All of these areas, and many others, play some role and provide part of the picture as to why people behave the way they do. Quantum physics and cell biology are arguably closer connected than are some of the various subfields which might be categorized as belonging to ‘the field’ of ‘social science’. Disregarding this heterogeneity seems to be more common than I’d wish it was, as is ‘indiscriminatory skepticism’ (‘all SS is BS’). A problem with indiscriminatory skepticism of this sort is incidentally that it’s sort of self-perpetuating in a way; that approach to matters pretty much precludes you from ever learning anything about the topic, because anyone who has anything to teach you will think you’re a fool whom it’s not worth spending time talking to (certainly if they’re in a bad mood on account of having slept badly last night…). This dynamic may not seem problematic at all to people who think all SS is BS, but of course it might be worth pointing out to those kinds of people that by maintaining that sort of approach to the subject matter they’re probably also cutting themselves off from learning about research taking place in areas they hadn’t even considered to belong to the field of social science in the first place. Symptom analyses of medical problems are usually not considered to be research belonging to the social sciences, but that’s mostly just the result of a categorization convention; medical problems, or the absence of them, impact our social behaviours in all kinds of ways we’re often not aware of. Is it medical science when a doctor performs the analysis, but social science when the psychologist analyzes the same data? Is what that guy is doing social science or statistics? Sometimes the lines seem to get really blurry to me. Discriminatory skepticism is better (and probably justified, given methodological differences across areas), but contains its own host of problems. Often discriminatory skepticism seems to imply that you disregard certain levels of analysis completely – instead of ‘all SS i BS’, it becomes ‘all SS belonging to this level of analysis is BS’. Maybe that’s better than the most sensible alternative (‘perhaps it’s not all BS’) if the science is really bad, but even in those situations you’ll have contagion effects as well which may cause problems (‘culture? That’s the sort of crap cultural anthropologists deal with, isn’t it? Those people are full of crap. I’m not going to spend time on that stuff.’ So you disregard those aspects of behaviour completely, even if perhaps they do matter and can be subject to scientific analysis of a different type than the one the Assigned Bad Guys (‘Cultural Anthropologists’) usually apply).

I don’t think we’ll ever get to the point where we have a Big All-Encompassing Theory of How Humans Work because there are too many variables, but that does not mean that the analysis of specific behaviours and specific variables is without merit. Understanding that I may feel argumentative right now because I’ve misjudged my insulin requirements (or didn’t sleep enough, or haven’t had enough to eat, or had a fight with my mother yesterday, or…) is important knowledge to take into account, and you can add a lot of other similarly-useful observations to your toolbox if you spend some time on this type of stuff. A big problem with not doing the research is that not doing the research does not protect you from adopting faulty models – rather it seems to me that it almost guarantees that you do. Humans need explanations for why things happen, and ‘things that happen’ include social behaviours; they/we need causal models to make sense of the world, and having no good information will not stop them from coming up with theories about why people behave the way they do (social scientists realized that a while back..). And as a result of this, people might end up using a novel written 150 years ago to obtain insights into why humans behave the way they do, instead of perhaps relying on a textbook written last year containing the combined insights of hundreds of researchers who looked at these things in a lot of detail. The researchers might be wrong, sure, but even so this approach still seems … stupid. ‘I don’t trust the social scientists, so instead I’ll rely on the life lessons and social rules taught to me by my illiterate grandmother when I was a child.’ Or whatever. You can easily end up doing stuff like this, without ever even suspecting, much less realizing, that that’s what you’re doing.

Comments on the topics covered above are welcome, but I must admit that I didn’t really write this stuff to start a dicussion about these things – it was more of a, ‘this is where I’m coming from and these are some thoughts on this topic which I’ve had, and now you know’-posting.

iii. Enough lecturing. Let’s have a chess video. International Master Christof Sielecki recently played a tournament in Mallorca, and he’s made some excellent videos talking about his games. Here’s one of those videos:

I incidentally think I have learned quite a bit from watching his material on youtube. I may have talked about his youtube channel here on the blog before, but even if I have I don’t mind repeating myself as you should know about it if you’re interested in chess. He is one of the strongest players online providing this sort of content, and he provides a lot of content. If you’re a beginner some of his material may be beyond you, but not all of it; I don’t think his opening videos for example are particularly difficult to understand or follow, even if you’re not a very strong player. And if you’re a ‘strong club player’ I think this is the best chess channel on youtube.

May 25, 2014 Posted by | astronomy, Chess, Lectures, Open Thread, Physics | 7 Comments

A few lectures

It is occasionally slightly annoying that you can’t tell what she’s pointing at (a recurring problem in these lectures), but aside from this it’s a nice lecture – and this is a rather minor problem.

Most of this stuff was review to me, but it’s a nice overview lecture in case you have never had a closer look at this topic. There are some sound issues along the way, but otherwise the coverage is quite nice.

This one is technically not a lecture as much as a conversation, but I figured I should cover it somewhere and this may be as good a place as any. If you’re going to watch both this one and the lecture above, you should know that the order I posted them in is not random – the lectures overlap a little (Ed Copeland is one of those “lots of people [who] are playing with that idea” which Crawford mentions towards the end of her lecture) and I think it makes most sense to watch Crawford’s lecture before you watch Brady and Ed Copeland’s discussion if you’re going to watch both.
Incidentally the fact that this is not a lecture does not in my opinion subtract from the coverage provided in the video – if anything I think it may well add. Instead of a lecturer talking to hundreds of people simply following a script without really knowing whether they understand what he’s talking about due to lack of feedback, here you have one expert talking to a very curious individual who asks quite a few questions along the way and makes sure the ideas presented are explained and clarified whenever explanation or clarification is needed. Of course the standard lecture does have its merits as well, but I really like these ‘longer-than-average’ Sixty Symbols conversation videos.

Again I’m not sure I’d categorize this as a lecture, but it’s close enough for me to include it here. Unfortunately if you’re not an at least reasonably strong player who knows some basic concepts I assume some of the stuff covered may well be beyond you – I’ve seen it remarked before in the comments to some of Sielecki’s videos that there are other channels which are better suited for new/weak players – and I’m not sure how many people might find the video interesting, but I figured I might as well include it anyway. If comments like “this move is terrible because black loses control over the f5 square – which means his position is basically lost” (he doesn’t actually say this in the video, but it’s the kind of thing he might say) would be hard for you to understand (‘why would I care about the f5 square?’ ‘Why is it lost? What are you talking about? The position looks fine to me!’ …or perhaps even: ‘the f5 square? What’s that?’), this video may not be for you (in the latter case it most certainly isn’t).

April 5, 2014 Posted by | astronomy, Chess, Lectures, Physics | Leave a comment

A few lectures

I love Crawford’s lectures, and this one is great as usual. Much of this will presumably be review if you’ve explored wikipedia a bit (lots of good astronomy stuff there), but there’ll probably be some new stuff as well and her delivery is really good.

I’m very skeptical about some of the numbers presented in this lecture, and this kind of stuff – insufficiently sourced (/unsourced) numbers which are hard to look up, also on account of other information being constantly added to the mix – is an aspect of lectures which I really don’t like. Not a great lecture in my opinion, but I figured I might as well post it anyway.

I’ve linked to e.g. this article before, so some of the stuff covered in this lecture should be well known to those readers who’ve read along for a long time and follow all my links… (Ha!)

As usual it’s annoying that you can’t see where the lecturer is pointing when talking about stuff on a given slide, but the lecture has some interesting stuff and it’s worth watching it despite this problem.

March 2, 2014 Posted by | astronomy, Lectures, mathematics, Physics | Leave a comment

A few lectures

I think I liked Carolin Crawford’s lectures better, but anyway here are a few of Ian Morison’s lectures from Gresham College:

January 3, 2014 Posted by | astronomy, Lectures, Physics | Leave a comment

Open Thread

i. A while back I promised an update on the clinical trial I’ve been enrolled in, but I forgot about that stuff. Anyway I have learned that I was one of the patients who got the active drug, and they’d like me to continue taking the drug for another two years. I’ve decided to stay in the trial (technically I’m enrolling in a new trial, but…) and keep taking the drug.

ii. Given that the World Chess Championship has just started, this paper about chess ratings seems timely. Here’s incidentally the World Chess Championship main site. It’s started out with two draws, the last of them lasting only one hour and fifteen minutes or so – really disappointing but perhaps not that surprising; most championship match games tend in my opinion to be rather boring.

iii. This weekend I went to a Mensa ‘Game Day’ meetup – basically we got together and played various games (mostly board-games in my case, but no chess..) the entire day. This is one of the few ways I’m currently trying to step outside my comfort zone. It was sort of an okay experience and I’m glad I gave it a shot. But I did get bored towards the end and I felt very drained afterwards. I learned that this kind of thing is an inefficient way to get to know people. I was reminded that when you feel socially isolated and lonely you tend to think of social interaction with other people as much nicer than it actually often is in real life.

iv.

Sorry for the infrequent updates. What have you been up to? Read something interesting? Watched a good movie?

November 12, 2013 Posted by | astronomy, Chess, Open Thread, papers, personal | 6 Comments

A few lectures

I’ve posted a few of Carolin Crawford’s astronomy lectures before – in this post I’ve added a few more:

i.

If you want a more detailed account, Rory Barnes’ Formation and Evolution of Exoplanets is probably a good try, even though it’s a couple of years old and things are – as Crawford points out – changing rather fast in this field of exploration. I read the first couple of chapters of that book a while back and browsed a few of the other chapters a bit later on, but I decided against finishing it because it was too much work – the mathematics gets a bit ugly along the way, and if you don’t happen to have a rather strong foundation in physics and(/or?) maths it’s probably not worth your time as you’ll not understand much of what’s going on.

ii.

It’s sometimes a bit annoying that you can’t tell what she’s pointing at when she’s explaining what going on in a given picture or illustration (I find that this is a very common problem when it comes to online lectures, and it’s also sometimes an issue during the other lectures in this series), but it’s still a great lecture.

iii.

This one is actually the most recent one I’ve watched, even though it turns out it’s her first Gresham lecture. The sound quality of this lecture is a bit worse than that of the ones above, especially during the first minutes (perhaps I just got used to it? I don’t know…) but it’s pretty awesome anyway:

I think Crawford’s doing a splendid job and that’s she’s given some very interesting and educational videos. Please don’t skip/ignore these videos just because they’re somewhat longer than ‘the standard youtube video‘ – there’s some really awesome stuff here (the same thing applies, I think, to the various medical lectures I’ve posted recently as well – you can go back to those posts now and have a look if you skipped them the first time around; they’re all still there…). Wikipedia incidentally has great coverage of many astronomy-related topics and I’m sure (because I’ve read some of them before, e.g. the article about Enceladus) that there are some featured articles about stuff covered in these lectures waiting for you if you want to learn more. You don’t need to start at the Enceladus article if you want to learn more about Saturn’s moons – a better place to start would probably be this article.

As Razib Khan put it recently, this is truly a golden age of the mind, if you want it. As some of the readers who read my most recent post (I pulled it later, and there wasn’t much to read, really – so the rest of you didn’t miss out on anything..) might have inferred, I often have doubts about if this will keep being ‘enough’ for me, for some rather narrow definitions of ‘enough’ – but I should point out that I do derive (…/and so it is possible to derive…) a great deal of pleasure from living in an age where you at least in theory (but to a greater and greater extent also in practise) have the option of exploring and learning (/trying to learn..) stuff about almost any topic you’d care to have a go at. Even though I from time to time find myself depressed on account of wanting/desiring much more from life than what such a life of the mind on its own can possibly give me, I do think that most people do not take enough advantage of the opportunities they have today in this area of life.

October 14, 2013 Posted by | astronomy, Lectures, Physics, science | Leave a comment