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Calamities of Nature – Staying One Step Ahead of the Students
I’m usually not one for webcomics, but there are a select few that I do follow through my RSS feed reader. Of these, my favorite is Calamities of Nature. If you’re reading this blog (and enjoy it) then you’ll probably also like Calamities. As the author puts it, “Calamities of Nature, (is) a comic that focuses on topics of social commentary, religion, science, philosophy, and lots of bacon.” I haven’t quite figured out the bacon thing yet, but it’s still damn funny.
The latest Calamities of Nature, entitled Professors, really hit home,
I wish I was a week ahead! Instead it’s usually a race to complete a lecture before the start of class. In fact, I’m currently on break from writing tomorrow’s lecture (on free falling motion).
I often joke with my students that I have to write my lectures at the last second. It’s the only way to keep the material fresh in my mind for the lecture. In reality, time is so precious and I’m spread so thin that I often find myself squeezing in the lecture writing process at the last second. And yes, there are certain topics that I have to learn … um … I mean refresh myself on before class.
Of course, if I wasn’t spending my time writing blog entries I wouldn’t be up all night writing lectures.
[Add on note, written on Jan 26]
After sleeping on this, I realized that people may get the wrong impression about my teaching. Each original lecture I write takes six to seven hours to write (my classes are two hours long). I hope this post doesn’t give the impression that I’m rushing to write my lectures minutes before class. I do occasionally make edits at the last minute, but most of my lecture writing happens the day before the class. That’s just my poor time management skills.
For repeat classes the process is less painful. As I wrote about in Taking Notes Now For Better Teaching In The Future, by using post-lecture notes making modifications to existing lectures is so much easier. It saves time and massages the lecture into a well oiled machine.
Death by the LHC – Well not yet at Least
We are now less than two years away from our cataclysmic death. At least that would be the case if you believe the claims that the world is going to end on the 2012 winter solstice. Personally, I’m not one of them.
I’ve lost count, and don’t care to know, of all the ways we’re suppose to die. However there is one path to the afterlife that I am keeping my eye on—for nothing else but amusement—death by a black hole produced by the Large Hadronic Collider (LHC).
Credit: Maximilien Brice of CERN
Do you remember this story, Asking a Judge to Save the World, and Maybe a Whole Lot More? Back in 2008, when the LHC first came online, there were concerns from certain individuals that microscopic black holes would be produced during the highly energetic collisions the LHC would produce. Extrapolating from there, the belief is that these black holes will devour the world, sucking all of humanity in.
At this point, I feel it’s my civic duty as an astrophysicists to explain that black holes are NOT cosmic vacuum cleaners. They do not suck (where sucking here means gravitationally attracting) any more or less than another object of the same mass. Yes, it would suck (where sucking here means something bad) to fall into a black hole. The gravitational pull of a black hole is so immense that nothing can get out. Worse yet, you’re doomed to follow a path that takes you to the center of the black hole. Once there who knows what will happen to you. Seriously, nobody knows. Our current understanding of how Nature works breaks down at the extreme conditions expected near the center of a black hole.
Death by a black hole is bad, um-kay. But is this our fate? Is the LHC going to be responsible for our grisly death? The answer, in short, is no. Although there is a very small probability of the LHC producing black holes, their physical characteristics are such that they’ll be harmless.
If the LHC does produce miniature black holes their size would be much smaller than an atom (see Particle Smasher’s Black Holes Would Be Tiny). With such a small stature, their region of influence would only be slightly larger than a proton, which is freaking small (0.000000000000001 meters to not be exact). And, since atoms are mostly empty, there really wouldn’t be material to feed these subatomic black holes—black holes are NOT vacuum cleaners. To make things even more reassuring, black holes evaporate, with smaller black holes evaporating faster. So even if a subatomic black hole would form, it would mostly like evaporate before digesting any surrounding particles.
All the same, you may be wondering, has the LHC actually produced any of these black holes yet? And the answer is: no microscopic black holes yet. (The technical paper can be found here.)
If all that technical jargon doesn’t settle your nerves, there’s a website out there that answers the very important question, Has the Large Hadron Collider Destroyed the Earth Yet? Click on the link to find out. Notice the RSS feed? It’s for those that really want to stay on top of the issue.
An Astrology Interview that gets Us Nowhere
It started with a brief email from a local news reporter asking if I was interested in speaking about the recent viral news for a 13th zodiac sign. Sure, why not I thought. So I immediately replied. No kidding, within 45 minutes of receiving the initial email I found myself in front of a camera, being interviewed about something I teach every semester in my Astro 101 class. (No I don’t teach astrology, but I do teach about constellations, the zodiac, and pseudoscience so naturally astrology comes up in the discussion.)
The interview went well. Lisa Edge, the news reporter, and her camera man were very polite and asked very intelligent and directed questions. I answered them to the best of abilities and tried to avoid technical jargon. After 15 minutes or so we were done. I thought things went well. So here’s what made the cut,
Okay, first off, I had no idea that they also interviewed a christian psychic. (WTF is that anyways?) I guess that’s okay because the news is suppose to be balanced. What gets me is all that great science material I gave her was lost to the editing floor. A bit of a consolation prize is that much of what she said as the story’s wrap-up is stuff we talked about.
The one question that she did ask that I wish would have survived the cut is, “Do you think this news of a 13th zodiac sign is good for astronomy?” My answer was two sided (and probably why it got cut).
On the one hand, scientists are continually trying to educate the public about what is and is not science. On a regular bases we try to demonstrate how certain studies—and I use the term loosely—act scientific but in fact are not; astrology being one of the oldest examples. For this reason, when astronomers see astrology getting face time in the media we tend to roll our eyes and think here we go again. (For some entertaining blasting of astrology check out Astrological Sign of the Times, Astrology is Still Bullshit and the Universe Doesn’t Care About You, and This is why Horoscopes are Full of Assfog.)
However, there is the flip side. Although astrology plays the roll of a child at an adult only party, there’s still a teaching moment that we as educators can seize upon. Here we have so many people listening and interested in learning about a topic closely related to astronomy and most of the professional astronomy and science educators communities are turning their backs. Instead we should take this time to educate and to demonstrate why the 13th zodiac sign is nothing new. Why astronomers have known for ages that everyones astrological sign is off because of the Earth’s precession. Why astrology is considered a pseudoscience. Ultimately this is why I did not hesitate to give the interview. While most of the science was lost in the editorial process, and I knew it would be, I still tried to get through a little bit of scientific knowledge.
For the record, I have also posted an extensive blog entry on this whole zodiac issue: The Zodiac Shuffle According to Astronomers. This entry is meant to briefly explain the science behind the 13th zodiac sign and why most everyone’s astrological sign has shifted. For another reference, check out An Astronomer Looks at Astrology by Andrew Fraknoi.
The Zodiac Shuffle According to Astronomers
Have you heard the Earth shattering news (to be read with sarcasm)? Your zodiac sign may have changed! So if you were once a Pisces, like I was, you may now be an Aquarius. To make things worst, there’s now a thirteenth astrological sign, Ophiuchus, and it’s one that nobody can figure out how to say. I can’t imagine how many relationships are now in peril, how many new found jobs will be lost, or how many missed opportunities now exist. So what are we to make of this nonsense change? Hell, why is this happening now after thousands of years of studying the stars?
The truth is, to astronomers this is old news. Very, very, very old news. Slow shifts in astrological signs and even a thirteenth zodiac member have been known for two millennia now. To understand why this is really nothing new, let’s break down all the players in the story.
We begin with a discussion on constellations. A constellation is really nothing more than arbitrary grouping of stars that lie in close proximity to each other on the sky. The stars that make up a constellation are not necessarily—and in fact rarely are—physically connected or even related to each other. For example, the stars that make up one of the most recognizable constellations Orion (shown to the right), are at all kinds of distances. The bright red star on the top left (Betelgeuse) is 429 lightyears away while the bright blue star on the bottom right (Rigel) is 777 light-years distant. If you were to travel to another nearby star in our galaxy, then Orion would look completely different. From a historical perspective, stars found their ways into constellations because ancient cultures would relate the apparent star patterns to mythological beings and tales.
The use of constellations have not been forgotten by modern astronomers. However, their purpose has change. Today constellations play the same role as borders do on Earth. Just as political boundaries are used to identify large regions of land, constellations allow astronomers to quickly describe sections of the sky. If an astronomer says they’re observing the star Beta Orionis, it’s immediately known that the object being studied is the second brightest star in the constellation of Orion (beta being the second letter in the Greek alphabet and Orionis designating the Orion constellation).
An obvious problem with this approach is that constellations are usually identified by a small number of bright stars. What about all those dim, overlooked stars that lie in-between the constellations? To resolve this problem, in 1930 the International Astronomical Union adopted the constellation boundaries suggested by noted Belgian astronomer Eugène Delporte. The constellation boundaries were chosen such that every patch of the sky falls within the jurisdiction of one and only one constellation. Today there are 88 official constellations recognized by the astronomical community. The below figure shows the constellation boundaries in the region around Orion.
During the daytime hours stars cannot be seen because the Earth’s atmosphere spreads the Sun’s incident light across the sky. (By the way, this is why the sky is blue.) If we could remove this atmospheric effect then we would observe the Sun “in” a particular constellation. The thirteen constellations that the Sun passes through during the course of the year are collectively known as the zodiac. Yes I said thirteen. During the early part of December the Sun passes through a region of the sky assigned to Ophiuchus. The figure below represents what the sky would look like at noon on December 11, minus that atmospheric effect. Notice that the Sun is not within the official boundaries of Scorpius, which is the normal astrological designation assigned to this time of year. The unidentified region of the sky is Ophiuchus. The reason it’s unidentified is that even in Starry Night, the program I used to produce these figures, there are only twelve zodiac members.
This brings us to the recent news stories about the zodiac shuffle. In a local story, astronomer Parke Kunkle of the Minnesota Planetarium Society, told reporters that the traditional astrological signs have shifted. In reality all that has been done is that someone took the time to calculate the exact dates the Sun passes through the zodiac constellations, including Ophiuchus, and compared them to the generally accepted astrological signs. This isn’t anything new. Astronomers have know for a long time about the existence of a thirteenth zodiac sign. At a minimum, you could argue it’s been known in the astronomical community since 1930 when the official constellation boundaries were accepted. It’s not a stretch either to argue that astronomers knew of this even before 1930 because some of the bright stars of Ophiuchus do dip down into the zodiac.
But that’s just the part of the story about the thirteenth zodiac sign. There’s still the bit about the shifting of most everyone’s astrological sign. For that we have to introduce some more science.
The Earth is continually executing three major motions: it orbits the Sun in one year, it rotates about its own axis in a day, and the Earth’s rotation axis wobbles (precesses). It’s the last type of motion we’re interested in here.
Precession is a slow wobble. Think of a child’s top like the one shown to the left of the below picture. A top will spin very fast about a central axis, but that axis will move around in a circle at a much slower pace. For the Earth, the precession rate is very slow. It takes approximately 26,000 years for the Earth’s wobble to complete one circle. The planet’s precession leads to two observable outcomes. The first is that the North Star changes in time. For now Polaris is the North Star, but in the future other North Stars will come and go. In 12,000 years, the bright star Vega will be the North Star.
This image was borrowed from Astronomy Today by Chaisson & McMillan.
The other result of the Earth’s precession is that the dates in which the Sun passes through the various zodiac constellations progressively changes. Because the Earth’s precession rate is very slow, this shift is likewise slow. Recall, that astrology has been around for thousands of years which isn’t the complete 26,000 year precessional rate, but it’s enough to offset the zodiac dates by a noticeable amount. In fact, the accumulative shift over the last few thousand years is about one whole constellation. The below figure is the same as before—noontime on December 11—but now the year is 4011. Notice how the Sun is now in Libra? In the two thousands years from today, the Sun has slowly drifted over one zodiacal sign as it has done in the thousands of years since the original astrological signs had been decreed.
Much like with the thirteenth zodiac member, the Earth’s precession has been known for two thousand years. So again, the shift in your astrological sign is old news to astronomers.
Astronomers now possess such accurate models of the Earth’s motions that they can tell you, or anyone that has or will ever live, their exact astrological sign. What you do with that information is up to you. Unfortunately the reason that these recent stories on changes in astrological signs have gone so viral is that a substantial fraction of the population seems to believe that the position of heavenly bodies have some kind of influence on their daily lives. Most any newspaper in America has a daily horoscope, but not a a regular science section. Ugh.
The Science Illiteracy of Bill O’Reilly
Recently the president of the American Atheists, David Silverman, appeared on the O’Reilly Factor. Silverman was invited on the show to discuss the billboards sponsored by the American Atheists. To some, as O’Reilly is quick to point out, the messages proclaimed on the billboards can be interpreted as offensive. Before going further, I want to be clear that this posting is not about the American Atheist agenda. It’s about Bill O’Reilly’s disappointedly poor understanding of Astro 101 science, which we can see in his interview of Silverman.
So Bill O’Reilly’s argument for God appears to be simple enough, “The tide goes in, the tide goes out. Never a miscommunication.” I’m not completely sure what O’Reilly is trying to say here, especially the part about the ‘miscommunication’. If I had to conjecture I would say that he’s trying to argue that natural phenomena, such as tides, are directly the work of God. This is really one of the classical arguments for God (think Greek and Roman gods, for example). Where O’Reilly fails miserably is in his selection of which phenomena he attributes to God.
The cause of the tides is well understood and has been for hundreds of years thanks to Newton himself. They’re the result of the gravitational pull from the Moon acting on the Earth. More specifically, the ocean tides happen because the gravitational attraction between two objects depends on their separation. The closer two objects are, the stronger the gravitational attraction between them. This means that the Moon pulls harder on the near side of the Earth in comparison to the center of the Earth. Likewise the center of the Earth experiences a greater attraction to the Moon than the far side of the Earth. The difference in gravitational attractions is what is referred to as tidal force. The tidal force ultimately manifests itself as a rise in the Earth’s liquid oceans. (For a more in depth description, check out Tides, the Earth, the Moon, and why our days are getting longer.) For those thinking on a higher level, yes, the Sun likewise produces tides, but at roughly half the extent the Moon does.
So back to O’Reilly. He picks a natural occurrence that is explained by science. In fact, it’s a level of science that’s taught in most any Astro 101 course, or even more likely, in a middle school earth science class. If O’Reilly was just a little bit more educated he would have asked a deeper question like, why does Newton’s gravitational constant have the value it does? Now there’s a question not necessarily outside the realm of science, but one that’s not readily addressed with our current state of knowledge.
Regardless, it’s clear that O’Reilly lacks an understanding of the tides. What’s worst is that he challenges Silverman to explain the tides, as if an understanding of such a concept is beyond the understanding of the human mind. O’Reilly repeatedly states, “You can’t explain that.” This is where I fly off the handles.
The point of science is to construct self-consistent models that allows us to explain past observations and to make testable predictions about the future. Tides fall well within this scope. We have a model for the cause of the tides. We can predict times for future high and low tides. We can even observe tidal effects on distant worlds. It is science! But for O’Reilly he seems content to assume an explanation for the tides that appeals to a supernatural being. Moreover, he appears to even think that it cannot be explained otherwise.
What annoys the pooh out of me is that he has no apparent interest in learning about science. His religious beliefs are preventing an understanding of Nature. So what’s the harm in this? Isn’t he entitled to his own beliefs? Consider the recent story about congressman John Shimkus. According to Shimkus, “The planet won’t be destroyed by global warming because God promised Noah.” Here we have a person in political power that has a direct voice in environmental policies that may or may not lead us on a destructive path, and yet he’s outright discounting science for his own religious beliefs.
Obviously these individuals have placed a personal belief in one particular religion so high that they’re willing to discount a rational explanation based in science. To these individuals I say, Nature is going to do whatever it wants to do. We can either construct useful models in an attempt to understand how Nature works, or we can take the O’Reilly/Shimkus approach of blindly assuming the unknowable workings of a supreme being. One approach allows for progress in information sharing, extending life expectancies, knowledge about our place in the Universe, etc, etc, etc. The other approach … well I’m not sure what they expect out of it.
Of course, O’Reilly’s comments have led to many WTF’s moments on the web and on television. One of the best comes from Steven Colbert on The Colbert Report (Bill O’Reilly Proves God’s Existence – Neil deGrasse Tyson).
As usual Colbert makes insightful and whimsical remarks. His summary of O’Reilly’s argument for the existence for God is just perfect, “There must be a God because I don’t know how things work.” Most importantly, The Colbert Report attempts to educate the public about how the tides really work by having a well known astrophysicists, Neil deGrasse Tyson, describe their cause. For that I thank the show.
By the way Bill O’Reilly, here’s another argument for God, as suggested by the American Atheists, Inc Facebook page, “Food goes in… poop comes out. No miscommunication! You can’t explain that!!!”
To Attend or not to Attend Class, that is the Question
It’s that time of year again where I’m hard at work writing syllabi for the upcoming semester. This spring I’m slated to teach Astro 101 for the umpteenth time, in addition to my first go at the introductory, calculus-based physics course. As I click away at the keyboard, I’m reminded how particular I have to be in writing my syllabi. With each new semester I have to patch the many holes in my policies that students have found. One particular policy that has changed over the years is my take on attendance.
The first semester I taught I required regular attendance. For most students this wasn’t a problem, but for a few unmotivated bad eggs this was an issue. Those individuals would often come to class for nothing else but to earn their attendance points. Once in class, however, they would proceed to be a distraction. As the semester progressed the antics of these students led to lower class morale. (Admittedly I’ve also learned a lot about classroom management from this experience as well.)
Since then I’ve reversed my attendance policy. I’m now of the opinion that a student’s grade should in no way be directly based on their attendance. This isn’t because I’m avoiding the issue of in-class distractions, which I have focused on heavily, but rather in my belief that a student shouldn’t earn a grade based on their ability or inability to sit in a chair during a specified time. This isn’t elementary school after all. It’s college. I would rather assign grades based on a student’s content knowledge and/or their demonstrated ability to complete a relevant task.
This is a slight point of contention between myself a few of my colleagues. The two main counterarguments to enforcing an attendance policy is (1) there are certain assessments or activities that can only be done in a classroom setting, and (2) many students require an attendance policy to get them into the classroom where they will ultimately benefit.
I can’t argue with the first point. Activities, such as most laboratory exercises and in-class quizzes or exams, can only be completed by attending class. On these matters, my policy is simple. If a student misses class then zeros are recorded for those grades unless a prior arrangement has been made to make up the activity. Personally I feel that such a policy is only reasonable if I commit ahead of time to when those required in-class activities will occur. It’s part of the syllabus contract between the students and the instructor.
On the second counterargument, I again cannot disagree. There’s plenty of evidence demonstrating that regular class attendance explicitly improves a student’s success in a course. (see Class Attendance Article for a nice summary of these studies.) However, college students are adults and need to be responsible and attend class on their own accord. Of course, reality isn’t such. For many students, college represents the first time in which they don’t have the constant parental guidance (or more appropriately called pressure?) to attend school. Instead students make … umm, let’s just say unusual decisions, many of which lead to not attending class.
So if I don’t require attendance, why would any student attend my class? It starts with what happens in the classroom. I believe that if my teaching style is not dependent on the presence of the students, then I’m doing something wrong. Class time is a distinctive period when instructors and students come together to actively engage the material. Through a combination of lecturing, group activities, peer instruction, Q&A, etc. students are able to take advantage of a unique opportunity to learn and master the material. In short, I try to make class time an enjoyable and social journey through the material.
To convince my students of this, I ran a little experiment in my Astro 101 class last semester. As is typical, on the first day I covered the syllabus and various class policies. I told the students that their final course grade is completely dependent on their work, not on their ability to attend class. I did remind them that although class attendance is not required, it’s still expected. I then went on to explain that during the semester I was going to still take attendance. The intent was to demonstrate that even without a requirement for regular class attendance, those that attend will naturally perform better in class. In other words, a plot of Course Grade vs the Percentage of Classes Attended so should a strong correlation, which is exactly what I found. (A linear fit has an R² value of 0.67.)
This plot is for the final grade, but as the semester progressed I showed the students intermediate versions, all of which showed the same conclusion: attendance leads to better grades. (The above personalized experiment is really a verification of the results found in Park & Kerr, Determinants of Academic Performance: A Multinomial Logit Approach.)
I’ve divided the above plot into four regions. The horizontal line at 65% represents the required percentage of points students must earn to pass the class. (Instead of curving individual assignments or exams, I curve the overall course grade by 5% on day one. This is just experience telling me how to curve the class to get the desirable bell shape curve.) The vertical line at 75% is related to Coastal Carolina University catalog which states that “An instructor is permitted to impose a penalty, including assigning the grade of F, for unexcused absences in excess of 25% of the regularly scheduled class meetings”, a policy that I don’t adopt but is useful for comparison.
- The plot clearly demonstrates that for those that attend classes regularly they tend to pass with varying degrees of success, region 1.
- This particular semester two students were able to pass the class with less than 75% attendance, region 2. In each instance these were stronger students that had unusual circumstances that caused them to miss a few classes.
- Those that did not come to class regularly failed, region 3. To be fair about the reported values, three out of the four data points represent students that saw the writing on the wall and withdrew before the end of the semester. Consequentially, the low percentage of class attendance is exaggerated.
- Only one student that attended class regularly was not able to secure a grade of C or better. However, their D did allow them to satisfy the core requirement and so they won’t have to repeat the class.
So where do I go with this? At the start of this coming semester I’m going to show the new crop of students this plot as a warning. Kinda like a how the old Caribbean ports left hanging bodies to deter pirates. Ye come to class or pay thar penalty of failure.
