Summary: The Greeks likely rejected a heliocentric theory because it would conflict with the lack of any visible stellar parallax, not for egotistical, common-sense, or aesthetic reasons.

I had always heard that the Greeks embraced a geocentric universe for common-sense, aesthetic reasons - not scientific ones. But it seems as if the real story is more complicated than that:

From Isomorphismes:

Now this is the kicker in your Popperian dirtsack. The Greeks had the right theory (heliocentric solar system) but discarded it on the basis of experimental evidence! Never preach to me about progress-in-science when all you’ve heard is a one-liner about Popper and the communal acceptance of general relativity. Especially don’t follow it up by saying that science marches toward the Truth whilst religion thwarts its progress. According to Astronomer Lisa, it’s not true that the Greeks simply thought they and their Gods were at the centre of the Universe because they were egotistical. They reasoned to the geocentric conclusion based on quantitative evidence. How? They measured parallax.(Difference in stellar appearance from spring to fall, when we’re on opposite sides of the Sun.) Given the insensitivity of their measurement tools at the time, the stars didn’t change positions at all when the Earth moved to the other side of the Sun. Based on that, they rejected the heliocentric hypothesis. If the Earth actually did move around the Sun, then the stars would logically have to appear different from one time to another. But they remain ever fixed in the same place in the Heavens, therefore the Earth must be still (geocentric).

I dug a little bit deeper, and this seems to be more or less accurate. From The Greek Heliocentric Theory and its Abandonment:

This paper then examines possible reasons for the Greek abandonment of the heliocentric theory and concludes that there is no reason to deplore its abandonment. In developing the heliocentric theory the Greeks had run the gamut of theorizing. We are indebted to the Alexandrians and Hipparchus for turning away from speculation to take up the recording of precise astronomical data. Here was laid the foundation upon which modern astronomy was built.

Let  us now suppose that Aristarchus’ theory was widely circulated and that it was given careful consideration by leading astronomers. There is one objection that immediately  arises when the earth is put in motion, the very difficulty which must  have disquieted Copernicus and which caused Tycho Brahe shortly  afterwards to renounce Copernicus’ heliocentric system and to put the earth again at rest. (Tycho reverted to a system first suggested by some ancient Greek, who made the planets revolve about the sun and the sun about the earth.) The difficulty is this. As soon as the  earth is set in motion  in an annual revolution  about the sun, the distance between any two of the earth’s positions that are six months apart will be twice as  great as the earth’s distance from the sun. Over such vast distances some displacement in the positions of the stars ought to be observed. The more accurate the astronomical instruments and the greater the estimated distance of the sun, the more reason should there be to expect stellar displacement. Now it so happened that Aristarchus reached his conclusions at the very time when interest was keen at Alexandria and elsewhere in the Greek world in accurate observations and when marked improvements were being made in precision instruments. To appreciate these developments we need only recall the careful stellar catalogues of Aristyllus and Timocharis early in the third century B.C., the work of the latter enabling Hipparchus to discover the precession of the equinoxes, and the armillary sphere of Eratosthenes by which he was able to  determine  the obliquity of the ecliptic and the circumference of the  earth. Hipparchus continued to make improvements in the next century. He, as we shall  see, had a much better appreciation of the sun’s great distance than Copernicus. Of course it was impossible to observe stellar displacement without the aid of a telescope. Inability to observe it left astronomers with only two alternatives: either the stars were so remote that it was impossible to detect displacement, or the earth would have to remain at rest.

..Heath was of  the opinion that Hipparchus was responsible for the  death of Aristarchus’ theory, that the adherence of so preeminent an astronomer to a geocentric orientation sealed the doom of the heliocentric theory. This is a reasonable conjecture. Hipparchus was  noted for his careful observations, his stellar catalogues, and the remarkable precision of his recordings of solar and  lunar  motions. According to Ptolemy he was devoted to truth above all else and  because he did not possess sufficient data, he refused to attempt to account for planetary motions as he had for those of the sun and moon. His discovery of the precession of the equinoxes attests to the keenness of his observations. He came much closer to appreciating the vast distance of the  sun than Copernicus did.

..We do not know whether or not Hipparchus ever seriously entertained  Aristarchus’ views about the earth’s motions, but from what we have seen of his cautious and accurate methods, it is likely that he would have quickly rejected the heliocentric theory in the absence of visible stellar displacement.

And from The Ancient Greek Astronomers: A Remarkable Record of Ingenuity:

Aristarchus was successful in explaining variations in brilliance and reverse courses of the planets, but planetary motions are far more complicated than that. Kepler was the first to realize that the planets do not describe circular orbits, but rather ellipses, and that the sun is not in the middle of these orbits but in the foci of the ellipses. That something was wrong might have been suspected as early as 330  B.C., for Callippus noticed that the seasons were not of the same length. He estimated their lengths between solstices and equinoxes to  be 94, 92, 89, and 90 days- figures that are very nearly correct. Or to show the irregularities that might result from combining the eccentricities of the orbits of two  planets, in  some years Mars and the earth at closest approximation are 36 million miles apart and in other years (as in 1948) may be 63 million miles apart at their nearest approach. Now the Alexandrians were pointing their precision sights at the planets and must have been disturbed by these peculiarities. Furthermore they would have been less kindly disposed towards Aristarchus’ explanation of the absence of visible stellar parallax by placing the stars at  an almost infinite distance away because they had a better appreciation of the sun’s vast distance and consequently would have stronger reason to expect to find parallax. It would seem that the more precise the  instruments, the  less  likelihood there would be of the earth’s being in motion.

A while ago when Bret Victor's amazing article Up and Down the Ladder of Abstraction was being discussed, someone mentioned that they'd like to see one made for Bayes' Theorem. I've just completed version 1.0 of my "Bayes' Theorem Ladder of Abstraction", and it can be found here: http://www.coarsegra.in/?p=111

(It uses the Canvas html5 element, so won't work with older versions of IE).

There's a few bugs in it, and it leaves out many things that I'd like to (eventually) include, but I'm reasonably satisfied with it as a first attempt. Any feedback for what works and what doesn't work, or what you think should be added, would be greatly appreciated.

Despite a glut of reading recommendation engines, I still find that I rely on personal recommendations for 90% of the books that I read. Given that, I thought it might be useful to try to compile a list of prolific recommenders - people who provide a large number of reliable book recommendations.

I'll start off with the two obvious ones, Tyler Cowen and Cosma Shalizi. The LW/OB group of Eliezer, Robin Hanson, and Michael Vassar also provide useful recommendations (though much less frequently).

Who else can reliably recommend a good book?

I'm currently about 2/3rds through Jane Jacobs' "The Death and Life of Great American Cities". This is one of the defining works of modern urban planning, and Jane Jacobs is considered one of our most important urban planning thinkers.

It's a fine book, but I found myself surprised at just how unimpressive it is for a work of such supposed importance. Her hypothesis is simple enough that I can summarize it here:

-Cities succeed by having many people using the city streets throughout the day. Large numbers of people keep the streets safe, and provide enough traffic for businesses to thrive.

-To achieve this constant stream of people, streets should have a large variety of different businesses which are utilized at different times, and should eliminate barriers that prevent the flow of people.

Jacobs' reaches this hypothesis through her own observations of various cities, along with a few bits of data concerning densities, crime rates, etc. But there's no systematic examination of data, no meticulously constructed arguments, and no addressing of criticisms or alternate explanations. Evidently, all that it takes to be a great work in urban planning is the barest rudiments of basic science. (This isn't the first time I've been critical of supposed great works in this field.)

It strikes me that, for whatever reason, Urban Planning is an underserved field* - the scholarship behind it doesn't compare to, say, the quality of work done in evolution, or cognitive psychology.

I have my theories for why this might be**, but it got me thinking - which other fields show a distinct lack of quality work done in them? What other fields are underserved?

-

*There is of course the possibility that I'm unfamiliar with more recent, higher quality urban planning literature.

**Namely, that urban planning is an offshoot of architecture, which has tended to value on aesthetic judgement and intuition over empiricism and rigorously constructed arguments.

The Wason Selection Task is the somewhat famous experimental problem that requires attempting to falsify a hypothesis in order to get the correct answer. From the wikipedia article:

You are shown a set of four cards placed on a table, each of which has a number on one side and a colored patch on the other side. The visible faces of the cards show 3, 8, red and brown. Which card(s) should you turn over in order to test the truth of the proposition that if a card shows an even number on one face, then its opposite face is red?

Aside from an illustration of the rampancy of confirmation bias (only 10-20% of people get it right), the task is interesting for another reason: when framed in terms of social interactions, people's performance dramatically improves:

For example, if the rule used is "If you are drinking alcohol then you must be over 18", and the cards have an age on one side and beverage on the other, e.g., "17", "beer", "22", "coke", most people have no difficulty in selecting the correct cards ("17" and "beer").

However, apparently psychopaths perform nearly as badly on the "social contract" versions of this experiment as they do on the normal one. From the Economist:

For problems cast as social contracts or as questions of risk avoidance, by contrast, non-psychopaths got it right about 70% of the time. Psychopaths scored much less—around 40%—and those in the middle of the psychopathy scale scored midway between the two.

The original (gated) research appears to be here.

I suspect this might interest some people here: for today only, 23andme is offering their full-package DNA testing for only 99 dollars (the normal price is $499).

23andme uses a genotyping process, which differs from a full gene-sequencing. From their website:

The DNA chip that we use genotypes hundreds of thousands of SNPs at one time. It actually reads 550,000 SNPs that are spread across your entire genome. Although this is still only a fraction of the 10 million SNPs that are estimated to be in the human genome, these 550,000 SNPs are specially selected "tag SNPs." Because many SNPs are linked to one another, we can often learn about the genotype at many SNPs at a time just by looking at one SNP that "tags" its group. This maximizes the information we can get from every SNP we analyze, while keeping the cost low.

In addition, we have hand-picked tens of thousands of additional SNPs of particular interest from the scientific literature and added their corresponding probes to the DNA chip. As a result, we can provide you personal genetic information available only through 23andMe.

I don't have any experience with 23andme (though I seem to recall them having some financial difficulties), but the price was low enough for me to order a test.

An article by Steven Pinker discussing his experience getting tested can be found here. This has also been linked on Hacker News.

Related: Fake explanation, Guessing the teachers password, Understanding your understanding, many more

The mental model concept gets used so frequently and seems so intuitively obvious that I debated whether to bother writing this. But beyond the basic value that comes from unpacking our intuitions, it turns out that the concept allows a pretty impressive integration and streamlining of a wide range of mental phenomena.

I find it interesting that when we're asleep - supposedly unconscious - we're frequently fully conscious, mired in a nonsensical dreamworld of our own creation. There's currently no universally accepted theory for the purpose of dreams - they range from cleaning up mental detritus to subconscious problem solving to cognitive accidents. On the other hand, we DO know plenty about what goes on in the brain during the dream state.

Studies show that in dreams, our thought processes are largely the same as they ones we use when we're awake. The main difference seems to be that we don't notice the insane world that we're a part of. We reason perfectly normally based on our surroundings, we're just incapable of reasoning about those surroundings - we lack metacognition when we're dreaming. The culprit behind this is a brain area known as the dorsolateral prefrontal cortex (DLPFC). It's responsible for, among other things, executive function (directing other brain functions), as well as working memory and motor planning. This combined with the fact that it's the last brain area to develop (meaning it was the last brain area to evolve) suggests that it's key in creating conscious, directed thought. And during sleep, it's shut down, cutting off our ability to question the premises we're given. So, barring entering a lucid dream state, we lack the mental hardware to recognize we're in a hallucination when we dream - it seems perfectly normal.[1]

Whenever the topic of happiness is mentioned, it's always discussed like it's the most important thing in the world. People talk about it like they would a hidden treasure or a rare beast - you have to seek it, hunt it, ensnare it and hold it tight, or it'll slip through your fingers. Perhaps it's just the contrarian in me, but this seems misguided -  happiness shouldn't be searched for like the holy grail. Not that I don't want to be happy, but is that really the purpose of my life - to have my neurons stimulated in a way that feels good, and try to keep that up until I die? Why don't I just slip myself into a Soma-coma then? Of course, anything I do boils down to a particular stimulation of neurons, but that doesn't mean there's not something better to aspire to. To pursue happiness as an end itself I think, is backwards. It wasn't built into our brains because evolution was being nice - it's there because it increases our fitness. Happiness is designed to get us somewhere, not to be a destination in itself.