The Future of CMB Exploration

You would think that once the cosmic microwave background (CMB) has been discovered and studied, that was the end of it. That is not how science typically works, especially on something that has such a rich amount of information as the CMB.

This article reports on the next proposed major research effort in the US in further studying the CMB and refining the measurements that we currently have. The article gives you a good over view of what we currently know about the CMB, what we wish to extract out of it, and how it can be done. This appears to be a joint effort between two major science funding agencies in the US: the US Dept. of Energy and the US National Science Foundation, and will have an estimated cost of $650 million.

As someone who likes to include contemporary and most recent relevant news into my lessons, this will be another item that I will include in my Intro to Astronomy class.

Z.

My Favorite Web Applications - Part 4

Previous posts:

My favorite web applications - Part 1

My favorite web applications - Part 2

My favorite web applications - Part 3

Of course, I have to include a PhET application. How could I not? It is such an amazing collection of very useful applications and simulations.

For this one it is the demonstration on Faraday's/Lenz's law. What is interesting about this is that, if you have read one of my previous posts, I use this not so much as a virtual lab, but rather as an in-class "discovery" tool. In fact, for my f2f classes, I had an identical setup to this PhET application sitting in front of the students at the beginning of class. So the instruction that you'll see given to the students is almost identical for this application and for in-class activity.

This obviously is a lesson on Lenz's law. Instead of starting the lesson with a lecture, I give the students a series of tasks for them to do. I first tell them to set up the application or in-class apparatus to look like the picture below:

We then spend some time discussing the direction of the current in the coil if the galvanometer (in-person) or the voltmeter (PhET) has a positive or negative deflection based on being observed from the right side of the coil.

Once the students have established this, I give them a series of tasks that they have to perform and to record what they observe. The tasks are listed in the table below:

When we were doing this in-person, I asked the students to perform Task 1, to record what they observed, and then we all, as a class, discuss the observation. This exercise was helpful especially to students who were still unsure on what to do and what they should be observing. So this first tasks often clarified further what they needed to perform and what they should observe. For remote classes, this is not that easy mainly because I don't quite see what they students are doing and what they are observing. They are also doing this in their separate Zoom breakout rooms. They have a chance to discuss with members of their group, but I am not always there to double-check what they are observing. I do, however, get to see what they are recording because the table above is posted on a Google Slide document that I give them. So I can see every entry for each group and able to step in if I see something not quite right.

In any case, the students for in-person session perform the task one step at a time, and each time, we all discuss the observation. Remember that I have not told them anything about Lenz's law at all. All they are doing at this stage is performing a task and recording the corresponding observation.

By the end of this activity, both the in-person and remote students will have a set of observations for each of the tasks performed. This is where it gets interesting. I then instruct the students to discuss with their group members on how to come up with a set of rules or "laws" to accurately describe the behavior of the current in the coil in relation to what the bar magnet is doing. In other words, I want the to come up with a written description of Lenz's law.

Of course, I give them hints. The biggest hint is for them to consider the induced magnetic field in the coil. By that point, they have learned that a current in a coil or solenoid generates a magnetic field. If there is a deflection in the galvanometer/voltmeter, then there must be a current in the coil. The positive or negative deflection indicates the direction of the current in the coil, which in turn indicates the direction of the induced magnetic field in the coil.

From my experience in doing this for several semesters, only about 1/4 of the students were able to come up with a description that had a close resemblance to Lenz's law. Many of them struggled not just in understanding what they observed and what the "laws" were, but also in communicating accurately and clearly what they intended to say. The latter is a very common problem for many students trying to write scientific prose.

However, regardless of whether they managed to successfully come up with their own version of Lenz's law, I find that this exercise demonstrates this principle a lot clearer than if I just simply spew out the material in a lecture. Even if the students could not communicate clearly what they understood, most of them actually had some realization of what it is. To me, this is the biggest stumbling block in understanding Lenz's law, which was the impetus for me to present this topic in this manner.

The PhET application allowed me to do almost the same activity online as the one I do in-person. That is a very good thing!

Zz.

My Favorite Web Applications - Part 3

Previous posts:

My favorite web applications - Part 1

My favorite web applications - Part 2

Continuing with this series, here is my next favorite web application. This is a virtual experiment on measuring the specific heat of an object. The fun thing about this particular application is that (i) it is very similar to what we normally do in a real experiment and (ii) one can also use the step-by-step instruction as part of the experimental procedure, thus the name "Guided Specific Heat.... ".

Similar to the force table experiment that I cited in Part 2, this one also has randomized values for each person going through it. It randomizes the mass of the cold water, the mass of the object, and uses different specific heats. Each student doing this online will have a different answer.

When I assigned this to the students during our remote sessions, the students had to fill in all the information obtained during each step, i.e. measurement of the mass, etc. Then, during the actual measurement, once it stopped, the students had to do a screen capture of the graph of Temp. vs. time to paste in their report. They then had to show their work on how they arrived at the specific heat value of the object. If they entered the correct answer, the application acknowledges that and they should also do a screen capture of that to paste in the report. If they got it wrong, then they had the option of either submitting what they had and take the deduction for the wrong work and answer, or redo the experiment from the very beginning. They get to do this as many times as they wish until they get it right.

I also added an extra part where I asked them to think of the kind of errors and uncertainty in the experiment, especially if this were done in real life.

To double-check the students' answers, I created a spreadsheet where all I needed to do was to enter the mass of the object, mass of the cold water, and the final temperature. 

I like that each student will have a different answer. It added an extra layer where they could not just copy off each other's work directly. The experimental procedure is also almost identical to one of our experiments on specific heats anyway, so I didn't have to make huge modification to the instruction.

Now that we have gone back to f2f classes, I'm using this exercise as part of a homework assignment.

Zz.

Are Physics Papers Authored By Women Cited Less Than Those By Men?

So I'm reading this article in Physics Today of a study done on citation numbers and frequency of citation of papers where the first and/or last author is a woman. They found that papers authored by women tend to get less number of citations than men.

The number of papers authored by women in the eight physics subfields examined in the study almost doubled between 1995 and 2020, from around 17% to roughly 33%, as shown in the graph above. But those manuscripts attracted about 3% fewer citations than expected, whereas those whose first and last authors were men were cited roughly 1% more.

What’s more, the gender gap was largest in papers authored by men. According to the study, manuscripts with male authors cited recent male-authored papers about 2% more than expected and cited recent papers authored by women 6% less. Studies with a female author over-cited recent female-authored papers by 3% and under-cited recent papers by men by 1%.

Hum... But then they also say this:

One limitation of the study is that it couldn’t decipher the gender of about one-fifth of the authors, those who list only their initials instead of their first names, Bassett notes. Although Bassett says she and her team excluded those authors from their sample, McCullough thinks a significant number of them could be women. She says women in science often hide their first names to avoid discrimination.

Another problem, Bassett says, is that the software determines the chance of an author being a certain gender on the basis of his or her name, but it will be wrong at least some of the time, especially for gender-neutral names. It also cannot identify nonbinary individuals.

As someone who has read, and continues to read a lot of physics papers, the LAST thing I pay even any attention to is the gender of the authors. In fact, it is a common practice (and certainly in the groups that I have worked with) that when we publish a paper, we tend to only include first-name initials in the authors list rather than full name. It is also from my personal experiences that many of the papers that I have cited turned out to have women as first authors. No one could tell just by looking at the authors list that "K. A. Moler", "N. Trivedi", and "K. Levin" are women, for example.

Coupled with the fact that they found 3% fewer citation for women and that their study had to exclude about 20% of the authors because they couldn't tell their genders, this observation is not very convincing to me.

Zz.

Gender Differences in Test Anxiety and Self-Efficacy

It's interesting how something things come in clumps. I had just posted a paper on the effect of sharing tasks during lab work on student's interest and self-efficacy in physics. Now comes a study on gender differences in test anxiety and self-efficacy in general physics courses.

Now, to be clear, a large part of this paper clearly indicates that this is not something that physics educator can solve. This is because the issue of self-efficacy starts when a student is very young, and it has more to do with societal and cultural influences.

Performance differences between male and female students in physics courses are often due to sociocultural stereotypes and biases pertaining to who belongs in physics and who can excel in it, and insufficient efforts to counter them in order to make the learning environment more equitable and inclusive. For example, girls are less likely than boys to have parents who believe they can excel in the sciences so parents are less likely to encourage them to pursue related courses and activities from early on [5, 31]. This, combined with societal stereotypes that success in physics requires particular brilliance and brilliance is associated with men, in part explains the low numbers of women in the field [32]. Women are less likely than men to take physics in high school [10], so they are less likely to have prior experience if they are required to take physics in college. Once women are enrolled in physics courses, they tend to have lower SE, which is an important predictor of physics performance, even when controlling for prior academic preparation [19–21, 23, 24].

So already from this, this issue of test anxiety and self-efficacy among girls can't simply be swept away. Instead, this paper proposes how to handle such a thing by emphasizing more on assessment that are low-stakes (i.e. less stressful) and less on higher states assessments, such as exams.

This is definitely something to think about. It is already something that I am doing after we went remote when I consider how easily exams can be compromised. I shifted more emphasis on synchronous and asynchronous engagements that can assess a student's understanding of the material. In fact, in one of my general physics courses that ran synchronously, the total percentage of all the exams for the semester came up to less than 50% of the course grade.

Of course, I was doing this not for the reasons emphasized in this paper. I was unaware of such an effect until I came across this paper a week ago.

Zz.

Share It, Don't Split It?

This is a rather eye-opening paper on the impact of how students work together during lab work. It seems that when students divide specific tasks among themselves, there is less equitable benefits in terms of physics interest and self-efficacy. This is in comparison to the group of students (Group B) who tend to share the same tasks or take turns in doing different tasks during the experiment.

In particular, we find that Group B-style work is especially beneficial for women, a group that has historically been marginalized in physics. Thus, improving the equity of group work may be a productive step in efforts to improve equity in our field. In this context, we view equitable learning as providing equitable access to physics classes, inclusive learning environments that meet the needs of all students equitably, and learning outcomes that are not biased toward or against any groups of students. In order to improve equitable learning, we encourage educators to find ways to structure student learning to support Group B-style collaborative learning experiences for students.

Of course, this is easier said than done. The tendency here is to let the students themselves decide how they will work together. This means that if we want the students to adopt the working style of Group B, the instructor and the course structure itself has to coerce the students into it. The paper offers several suggestions on how to do this, which you may read in the paper.

This is something that I need to think about more carefully. Is there a compelling enough of evidence to support such an assertion? And if there is, have there been verified and tested methodology that accomplished the stated goals? I sometime feel that, as educators, we are being inundated with a "flavor of the month" of what we need to do for the students in the name of inclusion, equality, equity, accessibility, etc..... etc, and how to execute all that remotely even!

Still, as someone who emphasizes on experimental work quite a bit (being an experimentalist myself), I will need to read this paper a bit more and see if there are any of the recommendations that I can easily do without much modification to the current structure. I know that I have always try to limit the number of students in a group (typically 2 students per group if we have sufficient equipment), so that no one ends up just sitting there and doing nothing but watching and writing down numbers. But this paper may force me to figure out some ways to encourage each student to take turns to perform the experiment and experience every part of the work.

Something to think about, I suppose...

Zz.

My Favorite Web Applications - Part 2

 Previous posts:

My favorite web applications - Part 1

It is rather appropriate that the next web application on my list can actually make full use of the vector calculator that I mentioned in a recent post. Many of you may be familiar with the force table in a General Physics course lab. It is a contraption that looks similar to the picture below.

It actually is a rather useful apparatus to demonstrate vector addition and the powerful and convenient method of vector addition using components. Of course, when I assigned this to my students, we didn't use any vector calculator. The students had to calculate the components and find the resultant vector themselves. But this was also the situation where the students encountered the issue with knowing the correct angle that I mention in the vector calculator post. The only difference being that the visual "obviousness" here is more apparent than just looking at the numbers on an Excel spreadsheet.

When we went remote, I was lucky enough to come across this website that had a virtual version of the force table. In fact, other than not having the students struggle with knowing what weights to use, where to clamp them, and how to set up the pulleys, this exercise is quite similar to what I would normally do in class. I had to do only minor rewrite to my lab instruction to incorporate this web exercise.

The one thing I like about this app is that the situation is different for each student, i.e. the magnitudes and directions are unique to each student. Therefore, while they can consult with each other, each student still has to do his/her own calculations to get the answer. The students are given the instruction that they need to do this until they get it right, even if they exhausted all the tries and have to get the web to regenerate brand new set of forces and angles. Once they get it right, they have to do a screen capture of the acknowledgement page, and paste that in the report along with the working done to arrive at the correct answer.

The only thing I wish this web app has is the ability to specify the number of weights (or vectors) in use. In my in-person lab, I had the students start with just one vector, and they have to construct an opposing vector to get the equilibrium condition (trivial, of course, but you'd be surprised at the number of students who had to think about how to do this). Then they move on to having 2 given vectors, and finally 3 vectors, which is what we have in the web app. By doing this gradually, the students realize that they first need to find the resultant vector, and once they have that, all they need to do to get the equilibrium condition is to create another vector of equal magnitude but in opposite direction to the resultant.

Nevertheless, this is a useful web app and something that I intend to use even for in-person instruction.

Zz.

Solid State Sensors To Detect COVID Virus?

First of all, I'm not sure why this is called "Quantum sensor". Maybe it is because it is using solid-state physics principles?

This is an interesting report, and if the simulation is valid, I'm hoping that such devices will be made real soon because it has the ability to detect other types of viruses. It really is a solid state sensor that makes use of solid state physics principles.

In the presence of viral RNA, these pairs will detach from the nanodiamond surface thanks to a process called c-DNA and virus RNA hybridization. The newly formed c-DNA-Gd³⁺/RNA compound will then freely diffuse in solution, thereby increasing the distance between the magnetic Gd and the nanodiamond. As a result of this increased distance, the NV centres will sense less magnetic “noise” and thus have a longer T₁ time, which manifests itself in a larger fluorescence intensity.

By optically monitoring the change in relaxation time using a laser-based sensor, the researchers say they could identify the presence of viral RNA in a sample and even quantify the number of RNA molecules. Indeed, according to their simulations, Cappellaro, Kohandel and colleagues, who report their work in Nano Letters, say that their technique could detect as few as a few hundred strands of viral RNA and boast an FNR of less than 1%, which is much lower than RT-PCR even without the RNA amplification step. The device could also be scaled up so that it could measure many samples at once and could detect RNA viruses other than SARS-CoV-2, they add.

I find this interesting because as students in solid-state physics, one of the first thing that the students encounter in such a course is the study of solid-state crystal lattice. This includes the type of defects in a crystal lattice, such as vacancies and impurities. So this diamond NV center is exactly those two types of defect in the lattice. Imagine that something you learned during the first couple of weeks of a course in school actually has a humongous application to human well-being!

Chalk this one up as another invaluable application from condensed matter physics.

Zz.

Excel Vector Calculator - Be Careful How You Use It

I was asked to show this video to students on how to set up their own vector calculator using Excel. The calculator gives you the ability to find the sum of vectors just by entering each vector's magnitude and direction.

Is it useful? Sure it is, but this is where if you don't know what is going on, you may be using it incorrectly! I have a couple of examples to show that.

After you have set up the calculator using the example shown in the video, enter these:

Vector A: Mag=9.8; Ref. Angle=114

Vector B: Mag=16.5; Ref. Angle= -104

Vector C: Mag=11; Ref. Angle=180

If you have set up the calculator correctly, you will get the resultant vector having a magnitude of 20.2 and a direction of 20.4 degrees.

If you don't know any better and I ask you to sketch out the direction of this vector, you would have drawn an arrow that is pointing in the first quadrant of a Cartesian coordinate system, which would be WRONG! In fact, most of my students would do that. It is a natural and automatic tendency to do so since angles are measured counter clockwise relative to the positive x-axis.

If you do a quick sketch and do a "tip-to-tail" vector addition, you will end up with a vector that is actually pointing in the 3rd quadrant! In fact, the true angular direction for this vector is 200.4 degrees (180 + 20.4, the latter is the angle found from the calculator).

The reason for this is that in calculating the angle, one is dividing the y-component by the x-component. This vector has both components being negative and so the division produces a positive value, producing a positive angle. But this angle given by the calculator, if one were to sketch out the vector, is the angle measured from the NEGATIVE x-axis, not the standard positive x-axis. If one remembers lessons from trigonometry, it is why the value of the tangent of an angle is positive in both the 1st and 3rd quadrant.

So the angle given is "correct" if one knows where it is measured from.

Here's another example to try:

Vector A: Mag=12.7; Ref. Angle=45

Vector B: Mag=19.2; Ref. Angle= -171

Entering this into the calculator, you get the resultant vector having a magnitude of 11.7 and angular direction of -30.9 degrees.

Once again, if you simply go by what you get, the tendency here is to think that the vector is in the 4th quadrant, because a negative angle means that it is an angle measured from the positive x-axis but going clockwise.

This is wrong.

The vector is actually in the 2nd quadrant. A simple sketch to do the vector addition will confirm that. The angle "-30.9 degrees" is actually an angle measured clockwise from the NEGATIVE x-axis. For this vector, the x-component of the resultant is negative, and thus, the ratio of the y-component to the x-component is negative, resulting in a negative value of the tangent and the angle. Once again, from trigonometric lesson, the tangent of an angle is negative in the 2nd and 4th quadrant.

What this all means is that a positive angle value is not unique - the vector could be in the 1st or 3rd quadrant - while a negative angle value is also not unique - the vector could be in the 2nd of 4th quadrant. Either do a quick sketch to do vector addition, or look at the sign of the resulting components.

There are two important lessons here. First is that one must know what the numbers mean. Using them blindly without understanding how they come about is risky and may result in the wrong conclusion. Secondly, for this exercise, there is no substitute for doing a sketch and knowing how vectors add. A simple sketch will provide an important sanity check that your conclusion about the vector direction is not wrong.

While this video and the setting up of the calculator is useful, the producer did not go far enough to demonstrate the possible pitfalls in using it blindly. There should have been examples involving what I had presented to tell the viewers what they should be careful about. I just wonder how many people had used this and interpreted their results incorrectly.

Zz.

Whatever Happened To The LHC-Will-Destroy-The-World Nutcases?

Remember way back when the LHC was about to start up and a couple of nutcases decided to file a lawsuit in the US to stop it? If you missed the fun, read a couple of my earlier posts here and here, and the dismissal of the lawsuit here.

So now that the LHC has run for many years, had gone through an upgrade, and will probably continue to do so for the next few years, what do these wackos have to say for themselves? I know that going back and asking them will probably be fruitless because we are giving them more airtime than they deserve, but I'm always curious to see how someone like this react to the clear demonstration of how wrong he is.

But then again, if something like the Jan 6th insurrection can be called a "legitimate political discourse" despite the most obvious evidence, then there's no convincing some people of how wrong they are.

Zz.

My Favorite Web Applications - Part 1

I've used online web applications as supplement or enhancement to the class material, but during the pandemic when we went remote, I relied on them even more. In fact, I remember a couple of days where I did a lot of surfing and searching to find suitable web applications for various activities and topics, simply to catalog on the various things that are out there that I could use for my classes.

Over the months and years, I have a bunch of web applications that I consistently go to that I find to be quite useful. These can either be simulations to illustrate a physical concept, or virtual activities or experiments that mimic what students may perform in a lab.

In a series of posts, I will show what I've used and how each one was used, especially during a remote class. Maybe someone might find one or more of them useful, or might see it being used in a different way. Better yet, maybe someone has a better web application for the same task. I definitely like to hear that!

To start of, here is my most favorite web application to demonstrate the phases of the moon and why we, on Earth, see what we see. Despite the simple-looking screen, this webpage is choke-full of information. The biggest part of the screen shows the location of an observer on Earth, the location of the Moon, and the position of the Sun. You can manually click and drag the observer and the moon to get them to move to any valid position, or run the animation.

But don't ignore the two smaller animation on the right side of the screen. The top animation shows the moon phase that the observer sees at that time of the month. The lower animation shows what the observer sees at that time of the month and the time of the day. It indicates the positions of the moon and the sun at that particular time of day.

This is a very useful application to get students to understand why we see various phases of the moon, why we see the moon in a particular position in the sky at certain time of the month, etc. I tend to let the student play with the application for a while and then ask them to use the application to answer a series of questions. For example, what is the most likely day of the month for you see a full moon directly above your head at midnight? This is what the student should set up with the application to answer this question.

 

Another example was opportunistic because the Muslim's fasting month started sometime during the semester, and it was a common practice (it still is in many parts of the Muslim world) for people to look for the crescent moon at sundown to signify the start of their fasting month. So I also ask for when is it most likely to see a waxing crescent at sundown?

One of the best thing about this app is the ability to make the students realize, if they haven't already, that they should and can see the Moon during the day, i.e. when the Sun is also in the same side of the sky as the Moon! This allows use to discuss the often-mistaken idea that the phases of the Moon are due to the shadow of the Earth on the Moon from the Sun. We can also carry a more advanced discussion on why we don't see eclipses of the Sun and the Moon every month, especially if they have understood what this web application seems to convey.

I've looked at other websites demonstrating and explaining phases of the Moon, but to me, this is the best one out there so far.

Zz.

What An Experiment Can and Cannot Tell You

When classes had to go remote or online due to the pandemic, the biggest issue for general physics courses was, among other things, the labs. These courses were not designed to be done remotely, and so the labs could not simply be adopted for remote learning. This is in contrast to online general physics courses that were designed to be done remotely and have lab kits designed for such courses.

I had to resort to using virtual web applications and simulations at first, making extensive use of the PhET website, until I discovered Pivot Interactives. But this is not about that. Rather, I also had to think a little bit of actual activities that a student could do using simple, household stuff, that can either be their "experiment", or a supplement to any simulation or online labs that they did.

When we started a topic on electric charges, I used this as an in-class activity to supplement the lecture as a demonstration of static charges. When we went remote, I changed it so that it became an experiment that the students could do at home because it uses only one thing: sticky cellophane (Scotch) tape. I'm sure this is familiar to many people, but I'll describe briefly what is involved.

You take 4 strips of sticky tape, each about 6 inches long. Fold under one end of each tape so that that end doesn't stick to anything and acts as a convenient handle.

Take one tape and stick it to a flat surface such as a table or desk. Mark one end of it with a "B1" for bottom tape 1. Take another tape and stick it on top of B1. Mark that tape as "T1" for top tape 1.

Do the same for the other two tapes, but mark them as "B2" and "T2" for bottom and top tape 2, respectively. You should end up with something similar to the picture above.

Now take T1 and rip it off B1. Stick the sticky, unfolded end of T1 to the edge of the table so that most of the tape hangs freely.

Pull tape B1 off the table. Hold B1 at the folded end and let it hang down freely. Slowly, move it closer to tape T1 but don't let them touch. What do you see?

Next, attach the sticky, unfolded end of B1 to the edge of the table, very much like what was done to T1.

Rip tape T2 off B2.

Hold T2 at the folded end and let it hang down freely. Once again, slowly move it closer to T1 and observe. Repeat this by moving T2 closer to B1 and observe.

Attach T2 to the edge of the table again, the same as what you did with T1 and B1.

Pull tape B2 off the table, and repeat the process with T1, B1, and T2.

So that is the entire "experiment". The students had to describe clearly what they observed. I emphasized that this part should be just observational. I was not looking for explanation yet. The aim here is to distinguish between observations, which if valid are "facts", versus explanation which can be interpretation based on our understanding.

If the experiment was done carefully, the observation should be like this:

1. When B1 is brought closer to T1, the two tapes appear to attract each other.
2. When T2 is brought closer to T1, the two tapes appear to repel each other.
3. When T2 is brought closer to B1, the two tapes appear to attract each other.
4. When B2 is brought closer to T1, the two tapes appear to attract each other.
5. When B2 is brought closer to B1, the two tapes appear to repel each other.
6. When B2 is brought closer to T2, the two tapes appear to attract each other.
   

Those are the observations. So the next part is the explanation for the observation. Here, we invoke our understanding of the nature of forces on charges. We know that like charges repel, and unlike charges attract.

Since the two T tapes repel each other, we can conclude that they have the same type of charge. Similarly, since the two B tapes repel each other, we conclude that they have the same type of charge. Next, since the T tapes seem to attract the B tapes, then they have opposite charges. Thus, what we have in terms of the type of charge is

T1 = T2

B1 = B2

T1,T2 have opposite charge to B1,B2.

Now, if given NOTHING ELSE, this is as much as you can say about what you can get out of the experiment. But somehow, every single time I've had students do this, a few of them inevitably went a step further (or maybe a step too far?) and managed to conclude that tapes T1 and T2 have a particular type of charge (say, negative), which means that B1 and B2 tapes have positive charge. I don't quite know how they arrived at this conclusion.

Rather than just telling them that they were "wrong" in the sense that they could not deduce the nature of the charge just from the experiment alone, I decided to use this as a class discussion topic. My main question was that, to what extent can you squeeze all the information out of an experiment based on the observation, and when have you gone a bit too far?

Nothing in the observation alone tells you the type of charge on each tape. What you do get is the relative type of charge when you compare one tape against another. You can't tell which one is positive and which one is negative simply from the observation. You can only tell if two tapes have the same or opposite charges. That's it. That is the limit of the valid and verifiable conclusion that you can draw out of the observation. The experiment tells you nothing about the type of charge that each tape has.

I then asked the students if they can suggest what we can do next to actually determine the type of charge on each tape. Certainly, if we have a "reference" charge, something that we know that has a particular type of charge, then this can certainly be used to determine the type of charge. For example, rubbing wool onto a glass rod has been shown to induce a net positive charge on the rod. So the rod could be used as a reference. But I asked the students whether it is necessary to use this reference charge on ALL of the tapes, i.e. check what happens if they bring this reference charge to each individual tape. The purpose here is to use the inductive deduction, where one only needs to check with just one tape, and knowing that tape's relationship with the others, automatically determines the type of charge on all of them.

But the key thing here is that the experiment by itself can only tell you information about what is going on up to a point. Making a deduction that goes beyond that means that you are either guessing or speculating. While that is fine if you realize that that is what you are doing (we often do that in science research), it should not be confused as facts given by the experiment. They are not. The ability to know the type of charge on each tape requires a reference. Consequently, the validity of our determination of the type of charge on each tape depends on the validity of our knowledge about the reference charge. If, for some reason, our understanding of the reference charge is wrong, then our conclusion about the type of charge on each tape will also be wrong, BUT, our observations are not! The observations are facts, and they remain valid even if we wrongly assigned the type of charge on each tape.

This very simple exercise, and the lessons that can be learned from it, have huge implications to our world today. This is because a lot of people have a lot of problems deciphering and distinguishing between valid facts and conclusions/speculations. Often times, those two are intermingled until one can no longer tell which is which. I've seen people arguing about the conclusions, and somehow, that undermines the validity of the facts that they were based on, very much like wagging the dog. Even worse, when the "facts" are shown to be flawed or discredited, somehow the conclusions that were based on those facts remained alive and well!!

As science educators, we need to make a conscious effort to impress upon the students that science education is not just about learning the science. It is also learning how to think and the process of making systematic and rational deduction based on the nature of the facts.

Zz.

Making Physics Labs More Accessible

First of all, a clarification for those who are not aware of this. The term "accessible" as used here in the US within this context tends to refer to accessible to people with disabilities.

This is a report or maybe a White paper by a committee given the charge by the American Association of Physics Teachers (AAPT) to study how we can make physics labs in schools more accessible to students with various types of disabilities. I have read through it rather quickly, and I intend to read it some more when I have the chance (I've only stumbled upon it today).

Let me just say that for most physics college instructors, especially in Ph.D-granting institutions, there is very little training and awareness of the issue of accessibility of the physics courses that are taught, much less the consideration of making physics labs accessible to people with various types of disabilities. I myself was ignorant of such things until I decided to be trained as an online instructor during the COVID shutdown. It was during such training that the idea of accessibility and designing a Learning Management System (LMS) page and course material that are accessible came into my conscious awareness. So now, almost everything I post to the course's LMS page, and almost all the online material that I distribute tend to pass an accessibility evaluation, even when none of my students needed them to be.

However, those are the only things I'm capable of doing. I still struggle in trying to figure out how to make some of the more complicated figures, graphs, etc. to have the accurate alt-text to accompany them. I still am not sure how these document readers translate mathematical equations, and whether this is done accurately. And of course, the issue of how to make lab accessible to a student who can't see, can't hear, can't lift or grab something, can't walk, etc. goes way beyond my pay grade! This is not something that is easy to solve and most likely require department-wide or even institution-wide support and involvement. It will also involve quite a sizeable funding if we have to retrofit and install devices, software, etc. to existing physics lab equipment.

I'm not going to lie, I find this goal to be an exceedingly difficult task to accomplish. As an experimentalist by training, my philosophy for lab work is not just about the data-collection, but also the act of physical assembly of the equipment, following and understanding the instruction, problem-solving and making diagnostics when things don't seem to work as they should, and being creative at figuring out what causes what. I don't know how to accomplish all of this and still make the physics lab accessible to all students regardless of the type of disabilities that they have. The gist from the document that I referred to only gave superficial ideas and recommendations.

Maybe this is the lighting of the fire to start the pot to boil. I hope it is because I see a huge amount of problem-solving work to make the general physics lab more accessible and still manage to hit all the student learning goals.

Zz.

Battling The Flat-Earthers

A while ago, I read this article on battling those who believe that the Earth is flat but forgot to highlight it here. I won't say much more about it other than have you read it for yourself.

But one quote stood out with me, because it sums up not just the way it describes why flat-earthers believe in what they believe in, but also a reflection on the issues of vaccines, face masks, etc. that we have been facing with during this pandemic and these fake-news stupidity. The quote is attributed to Lee McIntyre of Boston University:

Flat-Earthers seem to have a very low standard of evidence for what they want to believe but an impossibly high standard of evidence for what they don’t want to believe.

Replace "Flat-Earthers" in the quote above with any of the conspiracy theory believers and you have the gist of why they believe in the crackpottery. 

But the question that I have is, has anyone ever mention THIS to the flat-earthers themselves? Are they self-aware that this is what they are doing?

Zz.

Media Reporting Failed Basic Central Force Motion Mechanics

This news report on The Telegraph written by Joe Pinkstone about the James Webb Space Telescope reaching its final position has a basic flaw that should be easily spotted by any intro physics student who has understood basic central force/circular motion topic.

It will stay at its current position, Lagrange 2 (L2), for its entire operational lifespan, which is expected to be around 20 years. L2 is a gravitational stable point on the other side of the Earth from the Sun, where the pull of the two bodies cancels out.

No, the pull due to the Earth and the Sun does NOT "cancels out", because if it does, then there is no centripetal force to keep the telescope to orbit around the sun! 

Rather, this is the location where the sum of the gravitational forces from the Sun and the Earth provides just the right centripetal force to keep the telescope in orbit around the Sun at the same angular speed as the Earth. It will always be on the opposite side from the Sun with respect to the Earth. You can read more explanation on what is this Lagrange2 (L2) point at the NASA website here.

This is the type of mistake that we expect to see in General Physics classes, not in major news media.

Zz.

Seeing A Single Atom With The Naked Eye?

This is not a critique of the winning photo. Rather, it is an example of a "click bait", where the news report tries to entice you to read it because the title is so astounding. I guess it worked on me.

This news report, purportedly from Popular Mechanics, is highlighting a winning science/engineering photo of a single strontium atom being held in an ion trap. But what it says is a bit misleading:

Now, we have a photograph that shows a single atom floating in an electric field, and it's large enough to see without any kind of microscope.

This is wrong. It is not "large enough" to be seen.

They corrected this somehow later in the article, but it still does not dispel the error that this has nothing to do with size, and it requires a bit of elementary knowledge of atomic energy level to realize that the earlier description is a mistake.

The strontium atom in the photo is hit by a high-powered laser, which causes the electrons orbiting the strontium atom to become more energized. Occasionally, these energized electrons will give off light. With enough energized electrons giving off enough light, it's possible for an ordinary camera to image the atom.

In other words, the strontium atom was excited and this then causes it to emit light. This process is no different than the light that you see from neon signs or your fluorescent light bulb that has mercury vapor. The unique part about this setup is that you are seeing light from a single atom, whereas in your neon signs, you are seeing the light from many, many atoms. But the process is identical! Yet, we don't go ga-ga and proclaim that we can see an atom with our naked eye.

Just be clear, you are not seeing the atom in the normal sense. You are seeing the light from an atomic transition of this strontium atom. The fact that this is made by a captured single atom is remarkable. The fact that we can detect light from this atom with our "naked eye" does not mean that we are "seeing" the atom in the normal sense that most people understand it.

Zz.

End of the Year Reflection

It has been more than 20 months since we went completely remote due to the pandemic. I still remember the chaos and panic when we started all this in March 2020. I think all of us thought that this would be short and will last only a few months. Boy were we wrong.

I had never wanted to be an online instructor, and I do not see how an effective physics instruction can be done via such a means, even when I was aware that many schools have online general physics courses. I was skeptical on how well a student can learn from such a format.

But when force to teach remotely, I had to train myself into being an online instructor. I already knew back then that I cannot simply transpose all my usual face-to-face (f2f) way of teaching and bring it online. It didn't work for the rest of the Spring 2020 semester, and I was highly unsatisfied with my own performance. I knew I had to do something, and that meant forcing myself to be trained as a certified, online instructor. I want to learn what has been know to work and effective, and what doesn't.

At the institution that I am at, the requirement to be certified as an online instructor involves passing two selected online courses offered by Quality Matters. Then, to complete the certification, an in-house courses on using our learning management system (LMS). I will admit that they were all extremely useful and gave me a different mindset on online learning. I knew that online courses is a different beast than f2f classes, but there's a lot more "psychological" consideration with online learning, both synchronous and asynchronous. It is why trying to apply f2f format to remote learning will not be very effective.

I became a certified online instructor at the end of Summer 2020. Since then I've applied many of the techniques, philosophy, and methodology of remote learning to the courses that I had taught in the subsequent semesters. I went from being uncomfortable and unfamiliar with remote teaching to actually liking it! It got my creative juices flowing as I continue to think of various ways to increase students' engagement in the course.

And that word, "engagement", became the central theme that I've learned as an remote instructor. While I used to think of "class participation" as something I want the students to be active in in f2f classes, it is now a more general concept of student engagement that is more important. Class participation is only one type of student engagement, and I learned of how I could get students to be engaged in a subject matter under remote learning modality. I realized that I spent a lot of time thinking of various things and activities that students can do or participate in, either synchronously or asynchronously, to keep that focused on the material or as means to get them to understand the material. Oh sure, it took a lot of time and effort in the beginning to come up with these things, but from the evaluation feedback that I received, they seem to be quite effective.

Technology-wise, I find that it is no longer a major issue to interact with students in answering their questions or showing them how to solve problems. I will either post my hand-written work on the course's LMS page, or if it is a synchronous session, I used my iPad and an app called AirSketch to mirror my iPad onto my computer and voila! I have a "pen and paper" capability to show my students, similar to being at a whiteboard.

For me, one of the most useful suite of online resources is the Google Office apps. I make use of Jamboard, Google Slides, and Google Documents for students to work either on their own or in a group during breakout sessions. I've even assigned graded tasks for them to solve using Google Slides where I post a problem and they have to work together to show their solution. Often, these are accompanied by a task they have to complete using PhET web applications and other simulations.

One of the most difficult part of going remote is the labs. We were not prepared for this, so unlike schools that already have established online presences, we do not have kits to give out to students so that they can continue doing physics experiments at home. We end up relying on either simulations, virtual experiments, or other means. Along this path, I discovered Pivot Interactives, which in my opinion, is one of the best alternatives to doing labs online. This is because this is not a simulation. It is an actual experiment, but done by someone else. A students is left with the tools to measure various parameters. So the result is almost like what the student would get if he/she were to perform the experiment itself, meaning that the data have all the uncertainties and errors in a typical actual measurement. I have more to say about this in an upcoming post.

During the pandemic, I upgraded many of my equipment. I replaced my old MacBook Air with the new M1 MacBook Air (so much faster!), and added a few other accessories to enhance my synchronous session, including a ring light. Here's a look at my current setup (and yes, I do have two different notebook computers that I use frequently).

I think that as far as the quality of my video during Zoom, we are good! I had students who told me that I look like one of those TV news readers. I hope they were referring to my video quality rather than how droll and dry my presentation was. 😁

While this is all well and dandy, my skepticism of online/remote learning has not gone away. This is especially true in terms of assessment. I still believe that online cheating is too easy and too rampant. I had to work extra hard in reducing (not eliminating) the chances of cheating during my exams. Forget about using questions given by the textbook publishers because those can easily be found online, especially on Chegg. All of my exams are questions that I had to formulate on my own. And it never fail to amaze me how a student who scored 20/20 on a homework will crash badly in an exam that contained questions similar to that found on that homework. And yes, I have found questions that I had formulated in an exam given just a few weeks before now appearing online verbatim, even including the sketch that I made. It means that I can't even recycle my own questions in future exams.

I am aware that there are several proctoring method that can be done with remote learning, but many of them sound rather creepy and Big-Brother-ie to me. I do not want those things installed on my computer, so why should I force my students to have them. The way I reduced the degree of cheating in my exams is to inform the students in advance that all the exams will have limited time, will open only within a certain period of time, and all the questions will be out of my head. With this, I hoped that they will realize that even if they copied from other sources to do the homework, they will at least try to understand what was done in the solution rather than doing a blind copy. I've only had limited success so far with this.

As 2021 closes, it looks like I will have to start appearing on campus. The labs will now be done f2f while the rest of the instruction will still be done remotely. I also have the option of having exams done in class rather than remotely, so maybe that will eliminate issues of cheating with the exam. What is different now than in March 2020 is that I no longer have that apprehension of teaching remotely. While I will continue with my own personal and professional development as an instructor, I think that I am now well-equipped to handle remote instructions. During these past 20 months, I've acquired both the skills and the technology to deliver lessons online effectively, even if I'd rather things go back to the way they were (don't we all?).

Happy New Year, everyone!

Zz.

You Might Get $50 Had You Read This Professor's Syllabus

The amusing story going around right now is the report on CNN about a professor hiding an information about how a student could get $50 if he/she read his course's syllabus and found the instruction on where to find the money. At the end of the semester, when the professor went back to the money's location, the $50 was still there!

The hint read: "Thus (free to the first who claims; locker one hundred forty-seven; combination fifteen, twenty-five, thirty-five), students may be ineligible to make up classes and ..."

 

This would have led students to a locker that contained a $50 bill, free to the first student to claim it.

 

But at the end of the semester, when he went to check the locker, the bill was still there.

 

Frankly, I'm not surprised (is anyone surprised by this?). I've always assumed that students do not read the syllabus given to them at the beginning of the semester. This is why (i) I go over the syllabus on the first day of class where I point out the important parts of it, and (ii) my first quiz of the semester requires that they find the answer from the syllabus itself (i.e. "What date is Exam 2?").

I put out a very detailed syllabus. Major parts of it are dictated and required by the school. But other  parts include important requirement on what they students must do. I also include a detailed calendar of when topics or chapters of the text will be covered, what are due each week, and when the exams are scheduled. Basically the entire semester has been laid out at the beginning. I find this to be extremely useful after we went remote, because it became very clear on what tasks and assignments the students have to complete each week and when they are due. They did not have to contact me for most of the questions they had about the course.

However, it isn't unusual for me to still get, in the middle of the semester, students asking when the next exam will be held, what is the weight given to homework, etc.. etc., all information that the students can find in the syllabus. I often tell them that these are all information that they could find in the syllabus, and only then do I give them the answers.

Now, to be fair to the students, because of all the stuff we have to include in the syllabus, it has gotten rather long. With the course scheduled and the course learning outcome and student learning outcome all included, my syllabus for this Fall 2021 is 13 pages long. I can certainly understand if a student just does not have the patience to read every minute detail of the document, which is why I spend that first class of the semester going over the important highlights that they must know or be aware of. I can certainly see why this professor got his $50 back if the information is buried somewhere in the many pages of information. But then again, he could also have buried it in between some very pertinent piece of information.

If you are a student, the moral of the story here is that, no matter how tedious and unimportant it seems, just spend some time readying the syllabus. It gives you an important overview of the course, and maybe even what the instructor expects out of you. Who knows, you might be lucky enough to find some lunch money!

Zz.

Impact of community masking on COVID-19

I find legislation that prevents mask mandates or requirements to be extremely irresponsible and abhorrent. These are made without regards to public safety and in contradiction to overwhelming scientific evidence that showed that wearing proper mask is one of the most effective means to reduce the risk of the spread of COVID-19.

I have presented several posts on this blog on the various scientific studies in support of this. Now comes another one that leave no doubt on the effectiveness of masking in reducing the virus transmission. This was very recently published in Science (a very prestigious and difficult journal to publish in, if you don't know this already), and is done across several villages and on a population of more than 300,000 adults in Bangladesh.

We designed our trial to encourage universal mask-wearing at the community level, rather than mask-wearing among only those with symptoms. We encouraged even healthy individuals to wear masks since a substantial share of COVID-19 transmission stems from asymptomatic or pre-symptomatic individuals, and masks may protect healthy wearers by reducing the inhalation of aerosols or droplets.

When you read this paper, keep this in mind. It is one thing to show scientifically of how masks reduces the spread of aerosols from our mouth and nose. This has been shown clearly and without any doubt base on the many publications and studies that I have highlighted so far. But it is another to show that it does have an impact STATISTICALLY when applied to large population. This latter part is more difficult because it involves a lot of variables. It is why this latest study is very important because it is one of the larger sampling of human population involved in masking (or lack thereof) to reduce the spread of the virus.

The sign of a valid idea is that the more you study it, the more convincing it becomes. Pseudosciences lack this kind of progression, where they continue to struggle getting to First base to prove that such-and-such even exists. In the case of the effectiveness of wearing proper mask to reduce COVID-19 transmission, the more we study it, the more the evidence we gather to point this to be valid, that wearing mask has been shown unequivocally to reduce the risk of the virus transmission.

Zz.

Teaching Physics Using "Anchor Equations"

 

I've only started reading this paper, so I haven't fully digest everything that was written, but I thought I should pass this on and maybe we can all read this together.

The author is presenting a way to teach intro physics lessons using a set of what are called anchor equations. 

An important step in learning to use math in science is learning to see symbolic equations not just as calculational tools, but as ways of expressing fundamental relationships among physical quantities, of coding conceptual information, and of organizing physics knowledge structures. In this paper, I propose “anchor equations” as a construct to support teaching and learning in introductory physics. I define anchor equation, provide examples, and suggest ways anchor equations can be used in instruction to support the development of students’ mathematical sense-making.

I don't know if I'm doing something similar, but I don't have what I call as "master equations", in which these are a minimal set of equations as starting points, and where other equations are derived from. Newton's 2nd law (F = ma) is certainly one of my master equations. However, I don't think my line of thought about this is as well-developed as the author's, who actually used this as a central hub in understanding the physics relevant concept.

Definitely something I need to read more carefully.

Zz.