Communicating With Your PhD Supervisor

In Chapter X of my "So You Want To Be A Physicist" essay, I mentioned the process of selecting your research adviser/supervisor for your graduate work. This is possibly the most important person in your academic life and selecting someone compatible is an extremely important aspect of your education.

In last week's Science, there's a wonderful essay on the same issue that focuses on your interaction with your PhD supervisor. It deals with communicating with your supervisor no matter what style he/she adopts. This is very important especially if your supervisor is a well-known scientist that is in very high demand. So this is definitely a useful essay if you are about or just starting your graduate program.

Zz.

Science and Maths Exams are Harder Than Arts Subjects, Say Researchers

Oooh.. now this is bound to stir up a whole bunch of hornet's nests.

Researchers at Durham University in the UK think they have evidence that shows that science and math subjects are harder than arts subjects such as English, social studies, etc. They used the grading scale in the UK's A-Level examinations as their data.

They analysed the GCSE and A-level results of almost a million students who sat exams in the summer of 2006, comparing marks in traditional sciences and maths with those in arts and humanities.

There were "substantial differences in the average grades achieved by the same or comparable candidates", they found.

A-levels in physics, chemistry and biology were marked a grade lower than A-levels in drama, sociology and media studies and three-quarters of a grade harder than English, religious education and business studies, the researchers said.

Examiners were half a grade more generous when marking students of the same ability in psychology A-level, compared with biology A-level.

For many of us, this isn't really that surprising. There have been plenty of anecdotal studies on a general consensus that the science subjects are more "difficult" both in high school and in college. However, there hasn't been any kind of systematic studies on this. Furthermore, I don't know if it is a fair comparison between the two, and certainly it is comparing apples and oranges.

Still, with the UK system, it may reinforce the fact that teachers or even parents may encourage students to take the easier subjects in their A-level exams, which may explain why the number of students in the UK taking the more difficult subjects has been declining for the past several years.

Zz.

A Celebration of Learning?

I don't think so.

OK, so this is another one of those where I know that I am being overly critical here, and possibly nit-picking the issue. But still, based on my experience, the important distinction here is lost on many people who are not familiar with science and science education.

This story is reporting a group of high school and college students reading out loud various books in an effort to highlight the love of learning.

Inside the gazebo at Goettel Park was not the place Monday for anyone with a headache: Sebastian Notaro's voice boomed chapters from "College Physics" while Kate Sheldon read a cookbook. Andrea Catania recited from a Harry Potter book, and Chelsea Meredith read from the Quran.

Five others were reading aloud - all at the same time.

They even explained the reason why they are doing this silly exercise.

The event, which didn't have a name, had two purposes, including the collection of donations for a food pantry.

"It's a great way to revitalize intellectual spirit among our youth and show we are interested in learning," Miller said.

The food pantry drive thing, I have no problem with, and certainly can be effective if advertised. But the "we are interested in learning" part has a lot of things wrong with it especially as far as learning physics and mathematics are concerned.

First of all, just because someone can read something, doesn't mean he/she understands the content. Give a high school student a copy of Jackson's Classical E&M text and I can easily see that student reading it. He may stumble over a few words, but he can read it. But did he understood what he just read? I bet you cash the weight of that book that he did not. So just because someone reads off "College Physics" is meaningless as far as "learning" is concerned. That is why you never see authors of a college physics text at bookstores or coffee lounges reading chapters off their books. That would be absurd.

Secondly, one does not study physics and mathematics simply by reading it similar to what one would do when reading a novel, or a cookbook. You don't just sit in a chair with nothing else, and read Griffith's Quantum Mechanics text. While you can get some superficial knowledge out of doing something like that, you do not get the clear grasp of the content without actually working it out while reading the book. One learns and understand the material via working out the examples and following along the mathematics with pen and paper. It is also why these texts have exercise problems to test one's understanding of the material. This is the only way to really get a grasp of the physics. There are no shortcuts.

So while I can appreciate this as being nothing more than "symbolic" or a publicity stunt, the way it is done to emphasize "learning" is all wrong for understanding "College Physics". They could have done better if they read and understood the book and showed a demonstration instead. It certainly would have been a lot more exciting for the audience and may even had prevented headaches!

Zz.

Graduate Quantum Mechanics Reform

So I've written a bit on revamping the undergraduate physics laboratory. I believe that many, if not most, of the studies on better teaching and presentation methods have been directed at introductory college, undergraduates, and high school students. We don't hear much about graduate programs that need revamping. I suppose one assume that students at that advanced level can mostly learn on their own even with unequipped instructors and teaching methods that aren't well-developed.

So it is a breath of fresh air that I came across this preprint that actually talked about reforming how graduate level QM is taught.

Abstract: We address four main areas in which graduate quantum mechanics education in the U.S. can be improved: course content; textbook; teaching methods; and assessment tools. We report on a three year longitudinal study at the Colorado School of Mines using innovations in all four of these areas. In particular, we have modified the content of the course to reflect progress in the field in the last 50 years, use modern textbooks that include such content, incorporate a variety of teaching techniques based on physics education research, and used a variety of assessment tools to study the effectiveness of these reforms. We present a new assessment tool, the Graduate Quantum Mechanics Conceptual Survey, and further testing of a previously developed assessment tool, the Quantum Mechanics Conceptual Survey (QMCS). We find that graduate students respond well to research-based techniques that have previously been tested mainly in introductory courses, and that they learn a great deal of the new content introduced in each version of the course. We also find that students' ability to answer conceptual questions about graduate quantum mechanics is highly correlated with their ability to solve calculational problems on the same topics. On the other hand, we find that students' understanding of basic undergraduate quantum mechanics concepts at the modern physics level is not improved by instruction at the graduate level.

It's an interesting reading, and I've gone through it only quickly. I plan on reading it some more when I have the time. In the meantime, why don't you take a whack at it? :)

Zz.

Revamping Intro Physics Laboratory - Part 5

{{Note: If you wish to follow what has transpired so far in this series, here are Part 1, Part 2, Part 3, Part 3-Follow-up, Part 4, and Part 5}

This may be a bit misleading because it is not strictly a "laboratory exercise". In fact, I think it might be more suitable to be presented during class. Still, it involves the students doing something, so that fits in with the spirit of a laboratory.

This exercise has 2 parts to it. The first is in class where the students are asked to think about a situation, and write down what they think should occur. Then, they get to go out and test it themselves and observe the situation. They then come back and write down what they observe, and compare it to what they wrote earlier of what they THINK should occur. Finally, they get to explain their observations, especially if what they wrote earlier is different than what actually occurred.

So what is the exercise? Here goes...

You are in a stationary vehicle (a train, bus, or a large vehicle). You have a helium balloon attached at the end of a length of string, so the balloon floats freely (without being confined or rubbing against other objects), while you hold the other end of the string. The vehicle then accelerates forward. What happens to the balloon?

The whole point here is to see the effect of the acceleration in a vehicle (on earth) on an object that is less dense than air. You first give this in a class (or a lab) towards the end of the session, and then ask the students to write down what they think they will observe. They don't have to give you any reason, just what they expect to happen.

Then, give them some way to get a helium balloon. This shouldn't be too expensive, should it? Maybe they can get on a train to go downtown, let's say, with a group of their friends. That would be a great way to observe the balloon. Advice them that maybe it would be a good idea to write down there and then some notes on what they observe, and any relevant circumstances surrounding the observation (i.e. was the train packed? Did the balloon float freely? Were the windows open? Was the air conditioning blasting right at them? etc.) Then when they come back, they need to write down exactly what they observed, and compare that to what they wrote earlier before they did the "experiment".

I would then suggest that everyone discussion what they have done. Who predicted an observation that is consistent with what they actually observed? Who didn't see what they thought would happen? Why?

Now, it would be OK to tell the students before they did this that they need to make sure that there are no significant moving air, because that would ruin any effects of the acceleration. But I'm even tempted not to say that. This is because if there are students who did not consider this effect, then there could easily be a discussion on the nature of the 'experiment', and why the result that these students get doesn't quite tell you the effects of the acceleration. The "observation" isn't valid as far as finding the effect of the acceleration in a vehicle on the balloon, because other external factors have intruded into the observation. If these students acknowledged this extra factor, then they have been observant, and understands the non-validity of their observation. If the students did not realize this, then hopefully, other students will point it out during the discussion.

I'm hoping that during the discussion session is where the students start "argue" about the validity of each other's observation, such as the possibility that the wind or other factors might affect some other's observations. I'm also hoping that they might try to come up with some physics on what exactly is the most valid observation for a balloon in an accelerating vehicle that isn't affected by any other external factors. As the instructors, I would suggest you simply stay out of the way, and see how the students are thinking and reasoning their way through this. You can certainly offer some guidance, but the "thinking process" may take awhile, especially if there are many students who observe things differently from each other. They need to weed out which observation is "faulty" as far as answering the question at hand. Once they figured out the valid observation, then they need to figure out why it happened that way. It is the students that need to make their own self-discovery.

BTW, the valid observation in this case is that the balloon will tilt FORWARD, in the direction of the motion of the vehicle. This is, at first, counter-intuitive, because when a vehicle accelerates, objects tend to get pushed back in the opposite direction of motion. So the first inclination is to expect the balloon to tilt backwards. However, a floating balloon is less dense than the air surrounding it. So when the vehicle accelerates, the air surrounding the balloon gets pushed to the back of the vehicle more than the balloon, and thus displacing the balloon forward.

Strangely enough, it observation shouldn't be THAT unusual, because there's an identical situation to this that we are quite familiar with. If we apply Einstein's equivalence of gravity to acceleration, then technically, we are accelerating "upwards" at 9.8 m/s^2. Now try letting go of a helium balloon. It floats UP, in the direction of our "motion". It's the same effect we see in the accelerating vehicle. Yet, I'm sure, for many people, the observation of the balloon tilting forward is non-intuitive. If you are lucky enough to have students who actually argue using this point, then you have one heck of a student! I consider the ability to see the similarities of something "new" with something that they are familiar with as a major accomplishment. It is how we can describe many things that appear to be "different", yet share almost the same type of description or phenomena. I would suggest that if no students realize this, that you bring it up at the end of the discussion.

Zz.

Physics In Action at Theme Parks

Summer is almost here (at least here as in the northern hemisphere). With that, many theme parks are gearing for their busiest time of the year. Taking advantage of this are several schools and programs that try to marry the fun of theme park rides with physics lessons.

There are two recent examples to this. The first one is the Physics Day for area students at the Six Flags theme park in Largo.

Barnabas Adekanye, Irving Delco, Frailen Ramirez, Ludwin Romero and Johnny Wilks, all sophomores at Northwestern High School in Hyattsville who study engineering, were somewhere in the middle. They had brought a 28-page workbook of problems to solve. It was complicated stuff with a lot of formulas.

"Compare the change in potential energy to the gain in kinetic energy," went one question about the Mind Eraser. "Within experimental error, was energy conserved? Explain your answer."

Johnny, 15, had an easier explanation for what they were learning: "Like how the gravity and force relates with the loops and stuff."

The second example is a trip to Ceder Point by students from Windsor, Canada. I think it is a valid concern to look at it closely and see if the students are learning something, rather than simply using it as an excuse for a trip to a theme park. There has to be a conscious program to clearly demonstrate the physics principle to the students, and that the students actually got something. I think most of these programs try do that.

Zz.

The Extreme Deficit of Physics Undergraduates

David Harris is posting his report from the APS April Meeting going on this week in St. Louis. He is reporting on a session on physics education presented by Ted Hodapp from the APS. A listing of the issues involved in the shortage of physicists were given.

* The nuclear power industry will soon be suffering a shortage of qualified physicists to work for them. About 33 new power plants have been approved in the United States and will be starting up from 2010. That industry needs people with good science/math/problem solving abilities and physics graduates are an obvious choice.
* The medical physics industry employs about 3200 physicists, and have about 300 new jobs each year more than the current capacity for people with undergrad physics degrees. 78% of those people work in radiation oncology, and 16% in medical imaging.
* The growth of occupations requiring science and engineering undergraduate degrees has much higher growth than the civilian labor force but S&E enrollments are not growing anywhere near that fast.
* School principals rated physics and maths teachers about the hardest to recruit along with special needs teachers, primarily due to a shortage of qualified people.
* Math and computer science have about 70,000 undergraduate degrees granted each year, life science about 260,000. Physics has a mere 5000.
* Unemployment for physics graduates is very low, and for physics PhDs is an all-time low of 2.5%
* There is a need for US citizens with advanced physics degrees to work in classified areas. Hodapp says that Cherry Murray called the lack of US citizens with advanced degrees as “a national crisis.”
* The Rising Above the Gathering Storm report, the America COMPETES act, and the Tapping America’s Potential report all call for large increases in science, technology, engineering, and mathematics graduates.

Of course, there is a different viewpoint to this. You can read the comments posted to that blog entry, and also to the post that I made earlier that challenges the "Gathering Storm" report of the NAS.

Still, I have my own comments here.

1. The shortage being experienced by the nuclear industry is a direct consequences of the closing down of many nuclear engineering program in universities throughout the country during the past couple of decades. This is due to the lack of demand for nuclear engineers since the industry hasn't built a new commercial nuclear power plant at least during that time period. I don't think this can be attributed directly to the lack of physics majors.

2. While the employment may be "low", one also needs to look at what areas of physics that are more in demand than others and which areas of physics managed to get their graduates to land a job related to physics.

3. Traditional physics education needs to pay more attention to non-traditional jobs that may be available to physics graduates. I've seen school programs that are preparing their physics students to go into other areas upon graduation, rather than sticking with the traditional B.Sc-Ph.D-Post Doc-Faculty career tracks. Many smaller schools are at the forefront of that.

I still believe that a physics degree can still provide a rewarding career. However, I don't think that a lot of students are well-prepared to face the reality of employment after they graduate.

Zz.

Revamping Intro Physics Laboratory - Part 5

{Note: If you wish to follow what has transpired so far in this series, here are Part 1, Part 2, Part 3, Part 3-Follow-up, and Part 4}

I read this post in PhysicsForums and immediately realized that this is an excellent laboratory experiment and a perfect one to follow what I've described in Part 4. This was done as part of a test, but I can see this as being quite suitable for an intro undergraduate lab, especially after they had just done springs and Hooke's law.

Again, this gives them a task, rather than an explicit set of instructions on what to do. They will need to know about the elastic spring extension and also simple, basic mechanics. So this may not be that suitable to be done at the very beginning of the course, but maybe after a couple of weeks or so to make sure the students have been introduced to simple 1D kinematics. But the fact that this student could have done it, and done it well, indicates that this is certainly doable.

BTW, do most "elastic bands" obey Hooke's law rather well? I remember testing a typical rubber band one time, and it deviated from linearity rather easily. It would be a cruel thing to do to give the students such elastic bands! :)

Zz.

Sea Perch is a Fun, Hands-On Approach to Teaching Science

This Physics Today article highlights a project called Sea Perch, a hands-on approach to getting schoolchildren interested in science and technology.

For 10 weeks, Anderson will be showing the 10 students who stay after school for a couple of hours how to assemble their ROVs from kits consisting of such everyday items as PVC pipe and electrical tape. When the students are finished, they'll get to take the electrically powered vehicles to a test tank at the US Naval Academy, where they'll maneuver them by remote control. Throughout the process, the students will learn about buoyancy, displacement, and other physics principles through simple, well-crafted experiments. They also learn how to operate an electric drill and a soldering iron. Best of all, they're having fun doing it.

This is similar to my philosophy on the revamping of the undergraduate intro physics labs. Don't give some rudimentary exercise for them to do. Give them a TASK in which they have to build something or figure out something to accomplish that task. Along the way, they will need to learn certain techniques, or learn certain reason why something should be done in a certain way, just like the kids on this program:

As the children await their turn with the drill, they tested Archimedes' principle by fashioning crude model ships out of aluminum foil. Their goal was to see how many marbles they could load into the makeshift hull before it sank from the weight. By maximizing the length and width of their boats, they learned, they could increase the marble count. They recorded observations in laboratory logbooks. Asked by Anderson to explain how repeated trials are necessary in science, one savvy student explained the importance of changing a single variable at a time.

Reviewing what they had learned that day, Charlie Youngman observed, "the more weight, the more water it displaces," while Matt Rinaldi explained that if a vessel has "solid walls," it's less likely to sink. For R. J. Neal, the biggest lesson was "safety first; always use goggles when drilling."

If these are the lessons that the students learned from the program, then I would say that in my eyes, it has accomplished what many undergraduate intro physics labs have failed to accomplish or reinforce into the students. The ability to know the relationship between what we manipulate and what the corresponding outcome is one of the most important aspect of science, and certainly, experimental science. The students in this program obviously are getting that without even having to be taught of it. Why can't we do the same thing with the undergraduate intro physics labs?

Zz.

An Inquiry Into the Reproduction of Physics-Phobic Children by Physics-Phobic Teachers

I know! I was intrigued by the title as well! :)

First of all, this is a paper that was originally published in Japanese, and this English version is, what appears to be, an almost direct translation. So there will be some awkward passages here and there. If you keep that in mind, everything should be OK (just think of literal translation and you'll be fine).

The authors studied the effect of teachers who themselves have little understanding or interest in physics on students. Somehow, the teachers disinterest in physics can (surprise!) transfers itself to the students.

It is interesting to note that, with the budget crisis in physics in the US and UK, we tout the high investments in science in Europe and Asia, particularly Japan, China, and Korea. But it is obvious from this report that even in Japan, they also face, to a lesser degree, problems in getting students to do physics, not just as a career, but in terms of being educated or literate in it.

Zz.

Revamping Intro Physics Laboratory - Part 4

Continuing with this series, here's another experiment that I would propose. This would still be something that can easily be done at the beginning of the semester, which means it doesn't require that the students would have already learned any physics related to it. BTW, in case people think that all the experiments that I'm going to propose are this "simple", that is not going to be the case. These "no physics" experiments are aimed only at the beginning of the semester and where we want to introduce to the students that physics is nothing more than a systematic way of deriving what is valid and how to figure out a way to understand the relationship between things. It reinforces the idea that one doesn't need to abandon all that we already know to understand physics. In fact, we need to bringing in our "common sense" and the sense of "play" to do physics, or at least, these physics experiments. As the semester progresses and, presumably, the students' understanding gets more sophisticated, the experiments should also evolve the same way.

OK, for this experiments, we will deal with springs and masses, so again, it shouldn't be something difficult. The task this time is simple:

You will be given a "mystery" object in which you need to determine its mass. You are given a set of springs, and a set of calibrated masses. In addition, you will also have access to a ruler and a stopwatch if you need them. Figure out how you can determine, as accurately as possible, the mass of this mystery object. You must describe explicitly how you go about doing this determination.

Now, of course, in many intro physics class, this type of experiment typically requires that they find the spring constant by looking at the extension versus force or mass applied to the spring. I'm going about this the other way. Forget about the spring constant for now. The key thing here is that the student learns about the relationship between the spring extension as different masses are added to the spring. This to me would be the most obvious technique that most of the students would do. They would find the extension of the spring with different masses. Then, when given mystery mass, they may have to do some interpolation or extrapolation to estimate the mass of that object.

Now, there's also a possibility that some students may do this differently. They could, instead, let each of the known masses oscillates one at a time and find the relationship between the mass and the period of oscillation. They won't end up with a straight line, but as in the previous suggested experiment, this is OK. While we tell them they need to do this as accurately as possible, in the end, we really don't care as long as they explain what they did and how they did it. So even if they had to extrapolate/interpolate by hand, this is perfectly fine.

Now, what we can do further is this. For the students that did the first method (hanging the mass and finding the spring extension), we can ask them this:

Now, often it is difficult to get the spring to be very still - the mass tends to oscillate up and down. So maybe it might also be a good idea to see if we can make use of this property to see if there's an additional relationship here between the mass on the spring, and the period of oscillation. Can you determine the mass of the mystery object this way? Does it give the same answer? It is always more convincing when two different methods give consistent answers.

For those who did the the second method (oscillating the mass and finding the period), you then say:

Oscillating the spring doesn't allow you to read off the mass very quickly, which is something you need quite often. So is there another way to determine the mass quicker? How about looking at how much the spring extends as you hang different masses? Can this lead you to a different way to measure the mystery mass? Does this value agrees with the one you got earlier? It is always more convincing when two different methods give consistent answers.

.. and voila, you've gotten them to do this in both ways! They also learn that in science, it is always more convincing when you can show a consistent result from two different techniques (although, to be technically accurate, these are not really two different techniques, but this is a good enough demonstration at this level). Now the fun starts if they come up with very different answers. This is where they need to figure out (with the help of an instructor) on what went wrong. To me, figuring out what went wrong is as important and what went right.

After the students have done both, you then can pose an additional question such as this:

What you have now is a graph that you always need to use whenever you want to determine a mass. Is there a way to know the mass of something without having to resort to using such a graph? Can we figure out a way in which, if we know how much the spring extends, we can simply punch that number in and out comes the mass?

I think you know where I'm going with this, don't you? Considering that the students should have a background in sufficient mathematics, they would have seen a straight line equation. If not, a bit of help and hand-holding is called for, which, at this point, should be alright.

So in essence, we have done the mass-spring experiment, but done in a different manner. Rather than giving out the necessary steps that the students have to do, we instead "coerced" them into doing them by a series of questions and tasks that we want them to accomplish by themselves. Inadvertently, they "discover" Hooke's Law by themselves.

Zz.

Revamping Intro Physics Laboratory - Part 3 (Follow-Up)

OK, I got some very interesting responses to my suggestion of an experiment that can be done for an intro physics lab. I think I didn't explain myself too clearly on the premise and how I'm going to present it on here, so I should do that now.

While I tried to be explicit in describing the experiment and what would be a good way to do it, I don't actually want to reveal the whole hand. That's why I went along with the idea that there could be a dependence of the period with varying weights, because that is a very likely path that the students might attempt. If someone is thinking of actually trying to introduce this experiment in an intro lab, I don't want the possibility that some student might google it and find my blog where the whole thing has been revealed. :) That would defeat the purpose of them doing this without any kind of "previous knowledge".

So while I'm trying to be as clear and complete as possible in the experimental description, and the "philosophy" behind it, I don't really want to reveal everything either. In fact, I'm hoping that there WILL be students who decided to figure out if they can do it by changing just the weights. I consider discovering something that cannot work to be very educational. In fact, in science, knowing what doesn't work can be quite important (re: Michaelson-Morley experiment). They at least now know that changing the weights would not work. If they are curious enough, they'll try to find out WHY it doesn't work, and this is where the physics can be introduced.

Note that the experiment that I had suggested does NOT require that they have learned anything in intro physics. It is quite independent of the lesson they might have received in class. So in principle, this experiment could be done even during the first week of class. It doesn't require that they had learned about simple pendulum.

Zz.

Revamping Intro Physics Laboratory - Part 3

OK, I haven't forgotten this yet.

To me, the biggest problem with the current structure of intro physics lab is that we give students a list of things they have to do and measure, and hand-hold them into getting the result. In other words, they don't have to think too much to complete the exercise. They may have to do a bit of thinking and understanding of physics to complete the write-up, but the actual part of performing the experiment requires simply the ability to follow instructions.

I believe that we should have a more open-ended experiment to be given to the students. So I'll give an example. Note that while thing is something that I've thought about for a while, I'm still writing this off the top of my head. So there may be other problems with it that I haven't carefully considered.

Give them a problem to solve such as something like this:

Construct a pendulum clock. To make this clock useful, it would be helpful if the pendulum can swing back and forth once as close to 1 second as possible. Then each complete oscillation will take just one second. That way, this clock and measure time in increments of one second. You may use a stop watch to calibrate your pendulum to verify that it makes a one-second swing. Try to build this as accurately as possible. You must describe in detail in your lab report how you accomplish this task and why you chose to do it this way.

Now, as apparatus, give them a length of string, a set of weights, and a stop watch, plus other necessary items for them to be able to mount the pendulum on something.

Here's what I expect to occur. You'll have some students doing this by trial-and-error. They'll mount a length of string, and then start changing the weights to change the period of oscillation. Of course, there's no guarantee here that there is JUST the right weight for that length of pendulum to produce a 1-second period of oscillation. So students doing it this way may face a problem, but that's OK, because at the end when we discuss on to do such a thing, they'll discover why their technique isn't the best way.

You'll also get a bunch of student who would use a fixed weight, but tries to vary the pendulum's length. Again, they may try this simply by trial-and-error, adjusting it a little bit at a time until the period is close to 1-second interval. This technique is of course, more "refined" than the earlier one, since there's a high possibility of getting the right period.

Of course, what should be done, rather than simply doing a trial and error method, is simply to use a fixed weight, then measure a set of period corresponding to a set of pendulum lengths. Using the table, one can plot period versus lengths, and from there, interpolate (or extrapolate, depending on the range of lengths that were used) the exact length to produce a period of 1 second can be read off. So after the experiment is done and the students write their report, the lab instructor can start a discussion on the best possible technique to get the most accurate result. One can even make it a bit more complicated and ask the students how accurate is their clock as they let it swing for a length of time. This is where if they constructed a clock that swings over a large angle of oscillation, they may discover that it doesn't keep time very well.

What this type of lab forces them to do is think on the relationship between two measured variables. The first group had to figure out how the period changes as they change the weights. The second group is finding out the relationship between the period and the length of the pendulum. There may be a 3rd group that may be changing both the length and the weights simultaneous. If they do, and they're doing this by trial-and-error, god help them! :) But no matter what, the students are forced to think of what to do, and why they're doing it, to accomplish the task. They are not told how to do it. The experiment and the equipment give are familiar enough to them that this isn't something out of the ordinary. In fact, when they were kids, they probably played with something like this. The curiosity with finding how to do things is the purpose of the lab exercise. It is really playing, it is just that now, they have to think on what they are doing, why they are doing it, and how to present it in writing.

Next time, I'll try to present another possible laboratory exercise along this line.

Zz.

'Expatriates' From Physics Careers Find Funding, Fulfillment in Medicine

I think the field of Medical Physics has not been getting enough publicity among incoming students, which is too bad considering the graduates from this field continually fetch good starting salary and continue to be highly sought after.

This news article highlights the migration into Medical physics by students who suddenly face funding shortage and cutbacks. Considering the economic outlook especially in the rest of physics, these setbacks may be a blessing for these students going into this field of study.

Zz.

The Wave-Particle Duality of Light: A Demonstration Experiment

Other than the fact that I don't quite like the title, this is an excellent demonstration paper that was published recently in AJP. Very much like the J.J. Thorn et al. paper on the which-way experiment, these profound phenomena can actually be performed in an undergraduate physics lab.

First, the exact citation:

T.L. Dimitrova and A. Weis, Am. J. Phys. v.76, p.137 (2008).

They basically performed a Mach-Zehnder interferometer experiment using very low intensity light so much so that only one photon is in the apparatus at any given time. They also have a second stronger laser beam that traverse the same apparatus, but slightly displaced that exhibit the clear wave-like interference pattern.

So far, this is fine and dandy, and it would not have caught my eye because it would be a nice, undergraduate physics lab exercise. But at they end, they did something simple, yet, can be quite profound to a student. I'll quote what they said:

The demonstration, whose result is astonishing for students, is realized in the following way. First the fringe pattern is locked to a photodiode as explained in Sec. IV B, and the photomultiplier is moved to a fringe minimum, as characterized by a low photon count rate which can also be displayed acoustically. If now path A of beam 1 is blocked inside the interferometer, it is possible to hear (and see) a distinct increase of the click rate. This result demonstrates that if we give each photon the choice of taking either path A or path B, it has a low probability to appear at the detector. In contrast, if we force the photon to follow a specific path by blocking the other path, then the probability to arrive at the detector is much higher. The puzzling fact that a two-path alternative for each photon prevents it from reaching the detector, while blocking one of the paths leads to a revival of the clicks, is most intriguing for beginning students. This experiment is well suited for illustrating this remarkable quantum mechanical effect, which can be explained only if we assume that each photon simultaneously takes both paths A and B; that is, each photon, in the phrasing of Dirac, "interferes with itself."

Gorgeous!

It is something we know would happen, but the way this is demonstrated is so clear that I would say this is an experiment worth doing at every undergraduate level. Well done to the authors!!

Zz.

The Best Years of Your Life?

It may not feel that way when you're embarking on pursuing your Ph.D, but it can be. This is an article from PhysicsWorld that reviews several students in the middle of their Ph.D program in physics. It has several good advices for anyone thinking of pursuing a physics Ph.D, especially if you are in Europe. This should plug some holes in my "So You Want To Be A Physicist" essay that essentially focused mainly on the US Ph.D program. Note the important difference between the US and UK/Europe program:

Having a research topic in mind is absolutely essential when applying for PhD positions in the UK and elsewhere in Europe, since you will usually begin working on your chosen research problem straight away. In the US, however, PhD students spend two years doing coursework and exams in all areas of physics and only then begin proper research.

“Most physics students in the US start their PhDs without a specific research field in mind,” says Jayatilaka. This adds at least an extra year to the process, but it makes the US a good option for those who want to learn a bit more physics before choosing an area to specialize in, or for students who want to undertake a PhD project in an area that they do not have much experience in.

Zz.

Revamping Intro Physics Laboratory - Part 2

So what is the main purpose of intro physics laboratory?

Keep in mind that MOST students in such courses are NOT physics majors. In fact, for many, these are the only physics courses they'll ever take. So I see it as the best opportunity to introduce to the students how physics actually work. How exactly do we consider something to be valid in physics? After all, anyone and everyone can come up with some "theory" to describe something (and in the age of the internet, everyone does!). How do we select which ones are valid and which ones aren't? It all comes down to experimental verification. How we know something to be valid come from our empirical observations. Therefore, proper experimental techniques must be crucial since it can determine what is valid and what isn't. This is where the acquired skills come in.

When I say "skills", I don't just mean physical skills, such as the efficient way of using an oscilloscope, or one's agility in soldering a piece of wire. It also includes mental skill, which is the ability to think through a problem, or a nagging feeling that something isn't quite right. It also includes the ability to know what is the best and most accurate way of doing something. For example, why can't a student simply make one measurement of the restoring force of a spring, make the corresponding measurement of the spring extension, and then plug those values into the Hooke's law equation to find the spring constant? Why do we have to make a series of measurements instead? The ability to know why we need to do that is an acquired skill in proper technique to test a particular relationship of two different variables. One acquire such skill after consciously and repeatedly learning ways to make such tests. However, the students need to be told that these are the skills they are being taught, so that they are consciously aware of what they are doing and why. So often, in the usual physics labs, this awareness is lacking and not being emphasized.

What the labs can do is reveal in a very direct way how we gain and verify knowledge. What exactly is the relationship between variable x and y, and how do I test it? How do I know my result is valid? In the end, without one having to tell them point blank, they learn the difference between "scientific evidence" versus other forms of evidence, and they get a glimpse of some form of what people like to call "the scientific method". Considering that most of them will go on to do other things in life beyond just doing physics (or even science), I would think that this ability to have them understand what is involved in determining what is valid is something extremely valuable. This lack of understanding can easily be the cause of why people accept pseudoscience and other flaky ideas. That is why I consider these physics labs as extremely important not just in physics, but as part of a general education of the population.

Since I've already mentioned what is wrong with the current way of doing intro physics labs, I should put my money where my mouth is. What exactly should we do in such courses? In the next part, I will give an explicit suggestion on how to revamp these lab sessions.

Zz.

Revamping Intro Physics Laboratory - Part 1

I used to hate doing the lab in First Year college intro physics classes. It would be 2 hours of torture, and at that time, I didn't see the point. Unless things have changed, most students taking such classes would tend to feel the same way as I did. And I think this is a waste of opportunity to really get through to the students of THE most important aspect of science, and of physics in particular - the empirical testing of physical concepts, and how we arrive at our knowledge to accept something as valid. This is what separates science from pseudosciences (and even religion).

The problem here starts from the very beginning. When I was that freshman undergraduate, no instructor ever spent time explaining why the laboratory sessions are important, why it is crucial that we actually DO things, rather than just read or watch what is being done. No one was explaining to me the fact that the SKILLS that I could get out of the physics lab may turn out to be a rather important aspect of my education that transcends beyond just physics, but into other parts of my life. This means that it doesn't matter if you're a physics major or not, the physics labs can be quite beneficial as one progresses in one's education, career, and life. I strongly believe students should be made aware of this in no uncertain terms. The physics instructors must impress upon the students why doing these laboratory experiments is important, what kind of skills are being practiced, and why this is different than just sitting and reading. I would think that the students would at least become aware that there is a rational reason for forcing them to do such a thing, rather than just them being told that they need to do this for no valid reason.

When I was a lab TA years ago, I tried doing just the very thing. More than 3/4 of my students at that time were not physics majors, and I flat out told them that in the lab sessions, it was more important to pay attention to what they were doing, and reporting what they were doing, rather than the final "answer" or results that they were trying to measure. I was more interested in what they were thinking as they were doing the experiment, reporting accurately their observations, and if the results looked weird, to notice that they did look weird rather than just reporting the number and did not realize something was not quite right. In other words, I was more interesting in the doing of the experiments themselves rather than testing if the students understood the physics theory or idea that was being tested. I was more interested that the student acquire proper experimental skills. They can learn more effectively about the theory and principles in class. I wanted the lab session to be more "hands on" on how to think and conduct an experiment to measure something.

So already my philosophy in what an intro physics lab session should be was different than what I encountered during my undergraduate years. And after being in this profession for many years, and being an experimentalist, I am even more convinced that this is what such lab sessions should be.

Zz.

A Deeper Look at Student Learning of Quantum Mechanics: the Case of Tunneling

This preprint, co-authored by Nobel Laureate Carl Wieman, looks at the difficulties that students had in understanding quantum tunneling.

Abstract: We report on a qualitative study of student learning of quantum tunneling in traditional and reformed modern physics courses. In the reformed courses, which were designed to address student difficulties found in previous research, students still struggle with many of the same issues found in other courses, but the reasons for these difficulties are more subtle, and many new issues are brought to the surface. By explicitly discussing how to build models of potential energy and relate these models to real physical systems, we have opened up a floodgate of deep and difficult questions as students struggle to make sense of these models. We conclude that the difficulties found in previous research are the tip of the iceberg, and the real issue at the heart of student difficulties in learning quantum tunneling is the struggle to build the complex models that are implicit in experts' understanding but often not discussed explicitly with students.

It's a lengthy paper, and I'm still reading it. But it is interesting that you get to learn quite a bit more about quantum tunneling in here, especially on aspects that are quite subtle.

Let me know what you think...

Zz.

Maybe 'They' Should Study Some Science Instead?

I got a good chuckle and almost yell "You Go, Bill!" after reading this commentary. He is responding to the call that science and engineering students take more "liberal arts" courses as part of their education.

I am tired of the presumption that it's the engineers who need to become "well rounded." The typical engineer has broader knowledge and interests than the average non-engineer, in my experience. Then look at the abysmal understanding the public has about basic science and engineering topics; it would be funny if it wasn't so sad. These are the same people who call upon the technical community to solve every problem quickly, painlessly, and without tradeoffs. Tell me: Who needs to learn more about the other side of life?

That actually is a very strong point. Science and engineering students today have to learn a lot more than what they need to know several years ago. Our accumulation of knowledge causes students to have to know a lot more before they can graduate.

Now don't get me wrong. I think all engineering and science students should learn about other things to be effective scientists and engineers. The art of communication, be it verbally and in writing, is crucial, especially in dealing with the general public. We have already seen what can happen to science funding when the general public and our politicians are not clearly informed on why funding basic science is important.

However, I think that the liberal arts electives that these students should be exposed to should be relevant to their profession. Learning about the social, philosophical, and human aspect of science and technology, and how they are perceived by the public, would be something highly useful to them when they do become scientists and engineers. But as the commentary has mentioned, this "understanding" needs to go both ways. Many liberal arts programs do not require their students to have any working knowledge of science and engineering. So in that sense, I can fully understand the frustration of the author in this paragraph:

There are many reasons for this decline, including the sheer complexity of today's technologies, a lazy and jaded public, and the dumbing down of education (have you seen today's high-school chemistry labs?), to name a few. But the basic principles of science and engineering are still vital and unchanged (force, power, gravity, the list could go on and on). Why should our community accept the premise that it is we who need to learn more about that non-technical side, rather than the other way around?

Zz.