The myth concerning circular orbits

In this posting we will examine the myth that the Copernican revolution was hampered by its insistence that the orbits be circles.

To understand the reasons behind this we need to look at the work of an influential, but often unrecognized, player in the Copernican revolution, the astronomer Tycho Brahe (1546-1601). He is considered the greatest naked-eye astronomer. He lived just before the invention of telescopes and the accuracy, scope, and reliability of his observations had enormous impact on the field.

It is interesting that Brahe, like most astronomers at that time, rejected Copernicus’ ideas of a moving Earth. He could not accept the arguments for the Earth’s motion, seeing that as creating more problems than solving them. In fact, he developed his own system (called the Tychonic system) that was mathematically equivalent to the Copernican system, but had the Earth as a stationary center. (p. 202. Most of the material in this post is from Thomas Kuhn’s book The Copernican Revolution and page numbers are from that book.)
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Copernicus’ ideas gain support from a few astronomers

As astronomical observations became more comprehensive, and as sea-faring became more widespread, the need for better star-charts in order to have more accurate time-keeping and navigation became imperative. In order to meet this demand for increased accuracy, the method of epicycles outlined by Ptolemy became more and more complicated, and was extended in different ways by different mathematical astronomers until it became hard to say what the Ptolemaic system was. Instead there were a whole set of different calculations all based on the Ptolemaic system, all getting increasingly complicated. And none of them quite agreed with the full range of good naked-eye observations. (p. 139. Most of the material in this post is from Thomas Kuhn’s book The Copernican Revolution and page numbers are from that book.) [Read more…]

Copernicus and the laws of physics

In a previous post, we saw that the popular notion that the Copernican model of the universe was opposed because it implied a demotion for human beings is not supported by close examination of the views of the people actually living in those times. It is, instead, a revisionist version of events that gained ascendancy around 1700 or so.

In today’s post we will examine the myth that the immediate opposition to Copernicus was raised by religious people. The fact that the Copernican model was not perceived contemporaneously as a demotion already weakens the case for that story but there’s more.
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Was the Copernican model a demotion for human beings?

In this post, we will look at one particular myth surrounding the Copernican story, the one that says that Copernican ideas were opposed because they implied a demotion for human beings.

Nicolaus Copernicus (1473-1543) published De Revolutionibus Orbium Caelestium, his epic work describing a heliocentric system, in 1543 the year of his death. Until then, Ptolemy’s geocentric model described in his Almagest had been the one used for studying planetary motions. In this model, the Earth was at the center of the universe and every celestial body orbited about the center. The Almagest was the “first systematic mathematical treatise to give a complete, detailed, and quantitative account of all the celestial motions.” (Thomas Kuhn, The Copernican Revolution, p. 72) This work was so good and its methods so powerful, that it provided the framework for astronomical calculations for nearly 1500 years. It was the framework that guided Copernicus’ own work.
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Looking closely at scientific history

Since I started looking more closely into the history of science, there are two things that I have learned that I have recast into principles.

The first is that the more closely we examine important historical events in science, the less resemblance they bear to the popular condensed capsule versions that are learned in school or college or portrayed in the popular media. The earlier posting about Columbus and the flat Earth is a case in point.

The second principle is that while science textbooks are usually good for teaching the current principles of science, they tend to be bad for teaching anything about the history of science or the nature of science. In those cases, what they usually describe is better described as folklore rather than history.

Take for example one of the most famous of all scientific revolutions, the one associated with Copernicus. The popular version of this story goes as follows:

The ancient Greeks, while pretty good at mapping the stars and motion of planets, tended to create models of the universe that were strongly influenced by religious, philosophical, and aesthetic considerations, rather than on observation and experiment. Hence they came up with the idea that the Earth was the stationary center of the universe (which pleased those religious people who wanted to give pride of place to the home of God’s greatest creation – human beings) and that the stars and planets were embedded on the surface of a sphere that rotated around the Earth in circles, which pleased those philosophers with highly refined sensibilities who felt that since the circle and sphere were the most perfect geometric shapes, they had to play a central role in the cosmos.
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The myth about Columbus and the shape of the Earth

In his April 3, 2005 New York Times column called It’s a Flat World, After All, Thomas Friedman begins:

In 1492 Christopher Columbus set sail for India, going west. He had the Nina, the Pinta and the Santa Maria. He never did find India, but he called the people he met “Indians” and came home and reported to his king and queen: “The world is round.”

This is just a throwaway anecdote, to set the frame for another of Friedman’s typical banal outpourings of conventional wisdom. (Sorry to offend the many Friedman fans that are out there but I have never understood his appeal. Not only does he not seem to have any original insights but he also comes across as patronizing and condescending, especially towards the people of other countries.)
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Should college presidents take a stand on evolution?

In response to a previous post, Becky posted an interesting comment that I responded to briefly but which requires a more extended reply. (One of the unexpected pleasures of starting this blog is that it has put me in touch again with former students like Becky who was in my course about eight years ago and is now doing a PhD in Astronomy. Her own very lively blog is well worth a visit.)

Becky pointed me to an interesting article that was posted on the blog of the editors of Scientific American, entitled Cowardice, Creationism and Science Education: An Open Letter to the Universities.

At a dinner with the presidents of about a dozen private and state universities, John Rennie (one of the editors of Scientific American) and Steve Jaschik (editor of Inside Higher Education) asked the assembled presidents the following:

Suppose we have a petition here that says, “As university presidents, we affirm that evolution by means of natural selection is a demonstrated fact of science. We also assert that any failure to teach evolution, or to teach ‘intellectual design’ as an alternative theory, harms students’ educational standing.� Who here would not sign, and why?

Rennie continues: “Disappointingly, not one of the presidents in attendance was willing to go on the record as supporting such a petition. When they could finally be drawn out on why, their answers were equally unsatisfying.”

He concludes: “Let’s not tiptoe around the truth. University presidents are afraid to speak out in favor of evolution because they know that they will antagonize anti-evolution Christians.”

I think he is being too harsh. It may well be that the presidents were trying to duck the issue, knowing full well that they have to deal with a whole slew of constituencies ranging from current students and faculty, alumni, donors, legislators, etc. and any stand that they take on such an issue would be bound to cause them some grief.

But I think that there also exists a principled reason for them not taking a stand on issues such as evolution, and I was surprised that none of the college presidents present had made it.

I do not think it is the role of college presidents to take stands on this kind of specific issue. College presidents should not have to take positions on the pressing issues of the day, however clear cut they might seem to us. If they take a stand on the issue of evolution, then they would be expected to take stands on a whole range of other political and social issues and the process would never end. They would be just churning out press releases all day.

Where they should take stands is in support of the basic mission of the university, which is to provide a place for scholars and students to seek, create and disseminate knowledge, in an atmosphere of collegiality, and free from coercion or political pressure. Their goal should be to protect the right of their students and faculty to pursue knowledge in as unfettered an atmosphere as is possible, so that the university’s mission can be realized.

Thus they can, and should, be expected to take a stand on those issues that directly affect the health of universities. So for example, taking a stand on Ohio’s Senate Bill 24 is fine. Taking a stand on affirmative action in admissions is also fine. Taking a stand on issues of discrimination and harassment in universities is fine. All these issues go to the core of what universities stand for. There may be tactical reasons for not always staking out a public position on some of these, but it would be quite appropriate to do so.

But I cannot see anything special about the evolution/creationist split that requires a college president to articulate a position. While I find it bizarre that 45% of Americans can still, in this day and age (according to a Gallup poll in November 2004), believe that “God created man in present form within the last 10,000 years,” I don’t see why that should trigger a specific comment from college presidents, any more than the equally disturbing fact that 44% believe that several of the hijackers who attacked the U.S. on September 11 were Iraqis. (Here’s a question for a sociological study: Are the two groups of people actually one and the same?)

Taking a stand on specific issues that affect particular scientific or other academic struggles should be left to individual faculty members and students or their representative bodies. What college presidents should do is protect those faculty and students who do take stands on evolution or other similar issues (whichever side they support) from retribution from politicians and interest groups who try to limit the exercise of free inquiry or try to prevent the members of academic from making scholarly judgments.

So I think we should give college presidents a break on this one.

Improving the quality of our snap judgments

In a previous post, I mentioned that my Race IAT results indicated that I had no automatic preference for black or white people. This surprised me, frankly. Although I am intellectually committed to thinking of people as equal, I am still subjected to the same kinds of images and stereotypes as everyone else in society so I expected to have at least a small automatic preference for white people. But the section on Malcolm Gladwell’s book Blink on ‘priming’ experiments might give an explanation for the null result.

The priming experiments were done by psychologist John Bargh. What he did was give two randomly selected groups of undergraduate students a small test involving words. The results of the word test itself were not relevant. What was relevant was that the first set of students encountered words like “aggressively”, “bold, “rude”, “bother”, etc. in their test while the second set encountered words like “respect”, “considerate”, “patiently”, “polite”, etc.

After they had done the word test, the students were asked to go down the hall to the person running the experiment to get their next assignment. This was the real experiment because it had been arranged to have a confederate blocking the doorway, carrying on an inane and seemingly endless conversation with the experimenter. The experiment was designed to see if the set of students who had been unknowingly ‘primed’ with aggressive words would take longer to interrupt this conversation than those who had been primed with polite words. Bargh expected to see a difference, but expected that difference to be measured in milliseconds. He said “I mean, these are New Yorkers. They aren’t going to just stand there. We thought maybe a few seconds, or a minute at most.”

What he found was that the people primed to be rude eventually interrupted after an average of five minutes, but 82% of the people primed to be polite did not interrupt at all, even after ten minutes which was the cut-off time that had been pre-set for the experiment, thinking that no one would ever wait that long.

What these and other priming experiments suggest is that the kinds of experiences we have carry their effects subconsciously over to the next events, at least for some time.

This may explain my negative result because for some time now I have been studying the achievement gap between black and white students in the US. The more I looked at it, the more I became convinced that the concept of race is biologically indefensible, that it cannot be the cause of the gap, and that the reasons for the gap have to be looked for elsewhere.

Since my book on the subject (***Warning! Shameless plug coming up!***) called The Achievement Gap in US Education: Canaries in the Mine is coming out in May, I have been thinking a lot recently about these ideas and so I was probably ‘primed’ to think that there is no fundamental difference between the races, and hence my null result on the Race IAT test.

This ties in with other research that I quote in my book that deals with the role that teacher expectations of students play in student achievement. Teacher expectations are an important factor but a lot of the efforts to improve teacher expectations of low-achieving students have been along the lines “All children can learn!” sloganeering. But having teachers just saying this or plastering it on school walls may not help much, if they are not convinced of its truth. If people are conscious that they are being primed, then the priming effect disappears.

What is needed is for teachers to improve their overall expectations of students is for them to have opportunities to actually see for themselves traditionally underachieving students excelling. If they can have such experiences, then the inevitable snap judgments they make about students, and which can have an effect on student performance, may be more equitable than they are now.

I have long been in favor of diversity in our educational environments but my reasons were more social, because I felt that we all benefit from learning with, and from, those whose backgrounds and experiences differ from our own. But it seems that there is an added bonus as well. When we have a broader base of experience on which to base our judgments, our snap judgments tend to be better.

POST SCRIPT

The interesting radio program This American Life (which airs locally on WKSU 89.7 on Saturdays at 5:00pm and WCPN 90.3 on Sundays at 11:00am) also recently had an episode that featured the work of John Gottman, who has carefully analyzed the behavior of married couples and is able to ‘thin slice’ very accurately and predict, based on things that the rest of us completely miss, which couples will stay together and which ones will separate. Gottman’s studies were reported on in detail in Gladwell’s book.

To listen to this particular audio clip from the program, go to This American Life, click on “Complete Archive” and then click on the audio symbol for “The Sanctity of Marriage” that appears in the list of 2005 shows, and is dated 4/1.

Snap judgments and prejudices

In an earlier post, I described Malcolm Gladwell’s book Blink about the way we instinctively make judgments about people. The way we make snap judgments is by ‘thin-slicing’ events. We take in a small slice of the phenomena we observe and associate the information in those slices with other measures. People who make good snap judgments are those people who associate the thin-slice information with valid predictors of behavior. People who make poor or prejudicial judgments are those people who associate the thin-slice information with poor predictors.

Think about what you observe about a person immediately as that person walks into your view. Gender, ethnicity, height, weight, color, gait, dress, hair, demeanor, eyes, looks, physique, gestures, voice, the list just goes on. We sweep up all these impressions in a flash. And based on them, whether we want to or not, we make a judgment about the person. Different people will weigh different elements in the mix differently.

If someone comes into my office wearing a suit, my initial impression of the person is different than if she had come in wearing jeans. (If you were mildly surprised by my using the pronoun ‘she’ towards the end of the last sentence, it is because, like me, you implicitly associate suits with male attire, so that the first part of the sentence made you conjure up a mental image of a man.)

A personal example of snap judgments occurs when I read Physics Today which I get every month. The obituary notices in have the magazine have a standard form. There is a head-shot of the person, with the name as the header, and one or two column inches describing the person.

Almost all of the obituaries are of old white men, not surprising for physicists of the generation that is now passing away. I found myself looking at the photo and immediately identifying whether the person was of English nationality or not. And I was right a surprising number of times. And I was not reasoning it through in any conscious way. As soon as I saw the picture came into view, I’d find myself thinking “English” or “not English”. I don’t know the basis of my judgments. But as I said, I was right surprisingly often.

Gladwell describes a very successful car salesman who over the years has realized that gender, ethnicity, clothes, etc. are not good predictors of whether the person is likely to buy a car or not. Someone who his fellow salespeople might ignore or dismiss because he looks like a rustic farmer, this salesman takes seriously. And because this salesman has been able to shape his intuition to ignore superficial or irrelevant things, his senses are better attuned to pick up on those cues that really matter.

Some of the strongest associations we make are those based on ethnicity, gender, and age. We immediately associate those qualities with generalizations associated with those groupings.

People are not always comfortable talking about their attitudes on race, gender, and other controversial topics. This is why surveys on such topics are unreliable, because people can ‘psyche out’ the tests, answering in the way they think they are expected to, the ‘correct’ way, rather than what they actually feel. This is why opinion polls on such matters, or in elections where the candidates are of different races or ethnicities, are hard to rely on.

There is a website, developed by researchers at Harvard University, that recognizes this problem. They have designed a survey instrument that tries to overcome this feature by essentially (as far as I can tell) measuring the time taken to answer their questions. In other words, they are measuring the time taken for you to psyche out the test. Since we have much less control over this, the researchers believe that this survey gives a better result. They claim that you cannot change your score by simply taking the test over and over again and becoming familiar with it.

If you want to check it out for yourself, go to the test site, click on “Demonstration”, then on “Go to Demonstration Tests”, then on “I wish to proceed”. This takes you to a list of Implicit Association Tests (or IAT) and you can choose which kinds of associations you wish to check that you make.

I took the Race IAT because that was what was discussed in Gladwell’s book, and it took me less than five minutes to complete. This test looks at the role that race plays in making associations. In particular it looks at whether we instinctively associate black/white people with good/bad qualities.

It turns out that more than 80% of people who have taken this test have pro-white associations, meaning that they tend to associate good qualities with white people and bad qualities with black people. This does not mean that such people are racists. They may well be very opposed to any kind of racist thinking or policies. What these tests are measuring are unconscious associations that we pick up (from the media, the people we know, our community, etc.) without being aware of them, that we have little control over.

Gladwell himself says that the test “always leaves me feeling a bit creepy.” He found himself being rated as having a moderate automatic preference for whites although he labels himself half black because his mother is Jamaican.

I can see why this kind of test is unnerving. It may shake our image of ourselves and reveal to us the presence of prejudices that we wish we did not have. But if we are unconsciously making associations of whatever kind, isn’t it better to know this so that we can take steps to correct for them if necessary? The successful car salesman became so because he realized that people in his profession made a lot of the unconscious associations that were not valid and had to be rejected. And he used that knowledge in ways that benefited him and his customers.

Although you cannot change your Race IAT scores by simply redoing the test, there are other things that can change your score. When I took the Race IAT, the results indicated that I have no automatic preference for blacks or whites. In a later posting, I will talk about the effects that ‘priming’ might have on the test results, and how that might have affected my results.

Snap judgments

I just finished reading Malcolm Gladwell’s book Blink. It deals with how we all make snap judgments about people and things, sometimes within a couple of seconds or less. Gladwell reports on a whole slew of studies that suggest that we have the ability to ‘thin-slice’ events, to make major conclusions from just a narrow window of observations.

I first read about this as applied to teaching in an essay by Gladwell that appeared in the New Yorker (May 29, 2000) where he described research by psychologists Nalini Ambady and Robert Rosenthal who found that by showing observers silent videoclips of teachers in action, the observers (who had never met the teachers before) were able to make judgments of teacher effectiveness that correlated strongly with the evaluations of students who had taken an entire course with that teacher. (Source: Half a Minute: Predicting Teacher Evaluations From Thin Slices of Nonverbal Behavior and Physical Attractiveness, Journal of Personality and Social Psychology, 1993, vol. 64, No. 3, 431-441.)

This result is enough to give any teacher the heebie-jeebies. The thought that students have formed stable and robust judgments about you before you have even opened your mouth on the very first day of the very first class is unnerving. It seems so unfair that you are being judged before you can even begin to prove yourself. But, for good or bad, this seems to be supported by other studies, such as those done by Robert Boice in his book Advice for New Faculty Members.

The implication for this is that the cliché “You never get a second chance to make a first impression” is all too true. And what Gladwell’s New Yorker article and book seem to suggest is that this kind of thin-slicing is something that all of us do all the time. But not all of us do it well. Some people use thin-slicing to arrive at conclusions that are valid, others to arrive at completely erroneous judgments.

Those who do it well tend to be people who have considerable experience in that particular area. They have distilled that experience into some key variables that they then use to size up the situation at a glance, often without even consciously being aware of how they do it.

Seen in this way, the seemingly uncanny ability of people to identify at a glance who the good and bad teachers are might not seem that surprising. Most people have had lots of experience with many teachers in their lives, and along the way have unconsciously picked up subtle non-verbal cues that they use to correlate with good and bad teaching. They use these markers as predictors and seem to be quite good at it.

I was self-consciously reflecting on this last week when I ran two mock-seminars for visiting high-school seniors as part of “Experience Case ” days. The idea was to have a seminar class for these students so that they could see what a seminar would be like if they chose to matriculate here. I found that just by glancing around the room at the assembled students at the beginning, I could tell who was likely to be an active participant in the seminar and who would not.

It was easy for me to make these predictions and I was pretty confident that I would be proven right, and I usually was. But how did I do it? Hard to tell. But I have taught for many years and encountered thousands of students and this wealth of experience undoubtedly played a role in my ability to make snap judgments. If pressed to explain my judgments I might say that it was the way the students sat, their body language, the way they made eye contact, the expression on their faces, and other things like that.

But while I am confident about my ability to predict the students’ subsequent behavior in the seminar, I am not nearly as confident in the validity of the reasons I give. And this is consistent with what Gladwell reports in his book. Many of the experts who made good judgments did not know how they arrived at their conclusions or, when they did give reasons, the reasons could not stand up to close scrutiny.

He gives the example of veteran tennis pro and coach Vic Braden. Braden found that when watching tennis players about to make their second serve, he could predict with uncanny accuracy (close to 100%) when they would double fault. This is amazing because he was watching top players (who very rarely double fault) perform on television, and many of the players were people he had never seen play before. But what drove Braden crazy was that he could not say how he made his predictions. He just knew in a flash of insight that they would, and no amount of watching slow-motion replays enabled him to pinpoint the reasons.

But Gladwell points out that we use thin-slicing techniques even is situations where we do not have much experience or expertise and these judgments can lead us astray. In later postings, I will describe the kinds of situations where snap judgments are likely to lead us to shaky conclusions and where we should be alert.

POST SCRIPT

Last Saturday, I went with a group of students from my SAGES class to see the Eldred production of Bertholt Brecht’s play Life of Galileo The themes of the play are remarkably relevant for the present day, dealing with science-religion conflicts, politics in universities, and funding pressures. My SAGES course deals with the nature of scientific revolutions and the Copernican revolution is one of the key ones. But in addition to the scientific and political issues, the play also deals with the human side of Galileo.

There is one very minor character in the play called Clavius (described as the world’s foremost mathematician) who is being played by a different Case faculty member each night. Last Saturday it was Arts and Sciences Dean Mark Turner. Next Saturday the 16th, I will be doing the cameo spot. I have to deliver just one line so don’t blink, you might miss it!

The play is well worth seeing, See here for more details and show times.