Friday, July 17, 2020

Followup On Far-UVC Light Kills Airborne Coronavirus

This is a follow-up on the topic that I posted last time regarding evidence that far-UVC light can effectively reduce airborne virus transmission.

I read more about it, and found this extensive Physics World article that highlights the current development of the application of far-UVC light in virus sterilization. So obviously, this is a very active area of research right now. There are compelling evidence that far-UVC may be safe to human beings under limited exposure while still be effective in eliminating airborne viruses such as COVID-19.

But another issue that I've been trying to dig through is that, while far-UVC may be safer in terms of very short penetration depth into the skin and cornea, I haven't read much on possible ozone generation. One of the nasty effects of UVC light is that it can create ozone gas.

I sent to the International Ultraviolet Association webpage (didn't know one existed till recently), and went through their FAQs. One of them addresses the specific issue of ozone creation:
Does far UV (200 – 225 nm) generate ozone?

From a photochemical perspective, yes.

The Chapman cycle (Chapman, 1930) describes the counteractive processes of ozone formation and degradation from the interaction of light with molecular oxygen (O2) and ozone(O3). The rate of generation of ozone by far UV-C (known as the Herzberg continuum in atmospheric science) outweighs the rate of its degradation; the tipping point at which this generation/degradation balance flips is ~242 – 243 nm. (Andrew et al., 2003; Santos, Burini, and Wang, 2012), Far UVC (200-225 nm) only generates ozone in the upper atmosphere, where path lengths are very long. In a normal laboratory setting, ozone would not be generated because oxygen (O2) is a very weak absorber in the far UVC region.

As with any process, the risk of such hazards should be assessed on an application-by-application basis. A low power lamp operated in a well-ventilated area may not generate a measurable ozone concentration; a high-power system in an enclosed space may constitute a substantial risk.

Now, I don't quite understand why the "path lengths" have anything to do with ozone generation in the upper atmosphere, but it seems to imply that in a lab setting, far-UVC is not an effective ozone producer because it is a weakly absorbed by oxygen molecules. I can't get access to those articles while I'm at home, and I'm not even sure if my institution subscribes to any of those sources. So if anyone has more info on this, let's hear it.

This will be a tremendous way to reduce airborne transmission if it can be show to be effective and safe. But as with many things, it needs to be investigated carefully.

Zz.

Monday, July 13, 2020

Far-UVC Light Kills Airborne Viruses, And Safe To Humans Too?

First, let me give you the link to the paper that was published in Nature recently.

I actually have 3 separate topics to discuss here all based on this single paper.

The first is the science. UVC is used to kill viruses and sterilized stuff. We know that already. But it is also unsafe to human and we do not want to be exposed to it. But it turns out that far-UVC, having wavelengths in the range of 207-222 nm, is not totally harmful to human. In fact, ...
a regulatory limit as to the amount of 222 nm light to which the public can be exposed, which is 23 mJ/cm^2 per 8-hour exposure
means that humans can be exposed to this range of UVC for a limited amount of time. This is the basis of that research, i.e. using that wavelength and intensity of far-UVC, and see whether it can greatly "inactivate" the amount of viruses carried in airborne aerosols. They found that an exposure of just 25 minutes, very much below the regulatory limit. So there is a way to kill off viruses in airborne aerosols in the same space that human beings are around!

Certainly the implication of this research can be quite important, considering that airborne transmission of the COVID-19 virus is a strong possibility, which is why we are all wearing masks in public. There is now a way to greatly reduce such mode of transmission if this research is verified. The only thing I'm a bit weary about is the health and safety aspect. I know that they cited several sources that seems to show that the far-UVC is harmless to human, and the regulatory limits that have been imposed. Still, I'd like to have this one to be more well-established before I get really excited about it. For example, although the exposure limit is given in per 8-hour doses, how often can someone be exposed to that limit, say, in a month? Is that 8-hour dose limit per day? And certainly, long-term effect needs to be considered in anything of this sort.

But still, I find this result to be very promising, and it certainly is a new piece of information to me that far-UVC is actually not that harmful to humans.

The second aspect of this paper that I want to highlight is to the general public who often do not quite understand the nature of scientific publication. The main reason for scientists to properly publish their work is so that the rest of the community, especially those experts within the same field of study as the work, can scrutinize the work and evaluate its validity. So having something published does not automatically makes it valid. This is important to remember and understand. It requires scrutiny and verification by other experts in the field, and can sometime takes years. Think of how long of a time period from the moment the Higgs mechanism was proposed till its experimental verification at the LHC.

Therefore, it is imperative that a paper contains all the relevant information used to arrive at its conclusion or result. In this case, it is an experimental paper that produces a result. For it to be evaluated by other experts, it must contain all the necessary information. If you look closely at the end, the authors included their methodology, the exact equipment that they used, the experimental setup, the nature of the data analysis used, etc... etc. In other words, everything is as transparent as possible. It allows for someone else to repeat the experiment, and that is a crucial aspect of experimental science - REPRODUCIBILITY. It is something pseudoscience cannot do!

The third and final aspect of this paper is educational. I'm excited at the various values that they used in this paper, because I can already see myself using them in my general physics lessons. I'm already planning on using many of these numbers and asking my students to calculate (i) the amount of power per unit area based on the exposure time, (ii) the energy per photon of 222 nm light, (iii) the number of photons that impinges on a unit area during the exposure time, etc... etc. This will be perfect especially for the general physics course that I have taught that is aimed at life-science/pre-med majors. I always like taking something current, and very relevant to our times, to use as a material in our lessons. The students can immediately see first-hand that what they are learning is, in fact, very useful and has a direct effect on them beyond just wanting a good grade at the end of the semester.

So yes, I'll be holding on to this paper for quite some time.

Zz.

Friday, July 10, 2020

Simple Way To Help Your Instructor During Remote/Online Learning

Dear Student,

Many of you may continue having some form of online or remote learning this coming Fall 2020 and maybe even for the next few semesters. Even if you get back to face-to-face instruction, you may still need to communicate with your instructor electronically. So this advice that I'm going to give you will be applicable especially if you require remote assistance from your instructor.

In STEM subjects, specially math, physics, engineering, etc., face-to-face instruction has the imminent advantage over remote learning because of the simple ability to write and sketch. In physics especially, when we approach or discuss a concept or a problem, a sketch is often required to set up the situation. This is then usually followed by the writing down of mathematical equations, and then the grinding out of the math to solve the problem. In a typical class situation, these are done on paper, and it is the simplest and quickest form to do such a task.

Doing this during remote learning can be challenging. Most of you may be require to show your work, or to show what you have attempted if you need help from your instructor on a homework problem, or even during quizzes and exams. What most students end up doing is to pull out their smartphones, snap a photo of the page with their work, and then e-mailing the image file to their instructors.

I have been on the receiving end of such submission, and in at least half of the cases, it was very difficult to read and decipher the image that I received. Most students do not inspect the images for legibility. I often receive images that are dark, with poor contrast, and often having shadows that made some parts easier to read than others. In addition, the angle that the images were captured may also be rather odd, because most of these were not captured straight on.

Here, I'd like to make a suggestion on how you, as a student, can help your instructor by submitted a clearer and more legible image, using the same equipment that you already have. This is also to your advantage because in the case of a quiz or an exam, if your instructor does not understand or can't read what you wrote, you probably will not be given credit for such work if it is required.

OK, so here is what you should do. Install a scanner app on your smartphone or mobile devices that you frequently use. There are many scanner apps available on iOS and Android platform. Many of these are free or with minimal cost. Next time you need to send a snapshot of your work, use the scanner app instead or using the standard camera app. It makes a tremendous difference, and I'll prove it to you here.

I have an iPhone, and the scanner app that I have is called ClearScanner. The free version of this app has limited capability (no OCR), but it is still sufficient for what you will need it for (I have the full, paid version).

In the first image, it is a page filled with handwritten work. I took this using the iPhone standard camera app. I did not make any edits on the image quality, didn't do any cropping, etc, other than change the image file size. This is what I get.


Now, I hate to say this, but I will. Most of the submission that I received from my students were not even half as good as this. But let's go with this in any case. Now, already you can see that, as someone who has to figure out what has been written, this may not be impossible to do, but you are asking that person to do quite a bit more work here. The low lighting and the crazy angle that the image was taken present a challenge to read this accurately.

Compare this to the image of the same page but taken by the scanner app. I took it from the same angle, and under the same lighting condition. The only difference being that the scanner app asked me to confirm that correct boundary of my document in the image. In this case, the boundary is the edge of the paper. Once I confirmed that, the app took over and produced this image:


The difference is night and day. Not only is the writing clearer here, but the crazy angle is also gone. The app corrects for the angle and presents it as if you scanned it on a flat-bed scanner. And all this with hardly any more effort than taking a regular photo.

I will show another example. In the photo below, another common "feature" of images that I receive can be seen, i.e. shadowing.


Once again, it doesn't look bad in this image, but the ones that I have received were a lot worse than this. I had to do my own image editing to be able to see clearly the writing that was in the shadow.

So how does it look using the scanner app? Again, I didn't do anything to the image other than confirm the boundary of the document. This is what I get:


It looks almost identical to the previously scanned page, with the shadow removed. I assure you that this is a different image than the first scanned image above.

This is such a simple thing to do, with hardly no additional steps and effort, and yet, it produces such a remarkable difference in clarity. Which one, do you think, will your instructor prefer to receive?

Students in my class during the previous semester were told to install such apps if they have the capability. It made a tremendous difference in the quality of the document that they submitted. Many of them also told me that the app was useful to capture even written notes on whiteboard in class. So you  may find that it is one of those handy and useful app that you didn't realize you need till you have it.

Zz.

Thursday, July 09, 2020

Possible Discovery Of A New Type of Tetraquark, And Possibly Misleading Reporting Article

We have had reports of the discovery of possible tetraquarks and pentaquarks before (i.e. particles with 4 quarks and particles with 5 quarks, respectively). There is an extensive overview of the experiment and theory in this article. So the announcement out of LHCb is not that new. What is new is that this could possibly be a new type of tetraquark made up of 4 heavy quarks.

“Particles made up of four quarks are already exotic, and the one we have just discovered is the first to be made up of four heavy quarks of the same type, specifically two charm quarks and two charm antiquarks,” says the outgoing spokesperson of the LHCb collaboration, Giovanni Passaleva. “Up until now, LHCb and other experiments had only observed tetraquarks with two heavy quarks at most and none with more than two quarks of the same type.”
You may read the preprint here.

That should clear up very much of what the brouhaha is. I probably would have glanced over this had it not be the fact that I stumbled onto another news reports of this discovery, but with a different tone that could be misleading.

First of all, let's look at how CERN produced its news release. The first paragraph read like this:

The LHCb collaboration has observed a type of four-quark particle never seen before. The discovery, presented at a recent seminar at CERN and described in a paper posted today on the arXiv preprint server, is likely to be the first of a previously undiscovered class of particles.
Notice that it says "... a type of four-quark particle ...". This means that there are already other four-quark particles, and that this discover is for a new type that has not been observed before.

Now, compare that to the reporting done by two (count 'em) particle physicists on The Conversation (a place that I go to regularly) on the same discovery. Here is what they wrote:

The LHCb collaboration at CERN has announced the discovery of a new exotic particle: a so-called “tetraquark”. The paper by more than 800 authors is yet to be evaluated by other scientists in a process called “peer review”, but has been presented at a seminar. It also meets the usual statistical threshold for claiming the discovery of a new particle.

If you don't know any better, by reading the first sentence alone, you'd think that this is the first ever discovery of a tetraquark, which would be false.

Certainly, if you read the article further, you'd come across the passage that clarifies what this discovery is:

All tetraquarks and pentaquarks that have been discovered so far contain two charm quarks, which are relatively heavy, and two or three light quarks – up, down or strange. This particular configuration is indeed the easiest to discover in experiments.

But the latest tetraquark discovered by LHCb, which has been dubbed X(6900), is composed of four charm quarks. Produced in high-energy proton collisions at the Large Hadron Collider, the new tetraquark was observed via its decay into pairs of well-known particles called J/psi mesons, each made of a charm quark and a charm antiquark. This makes it particularly interesting as it is not only composed entirely of heavy quarks, but also four quarks of the same kind – making it a unique specimen to test our understanding on how quarks bind together.

So this is not the first discovery of a tetraquark, but rather a discovery of a type of tetraquark, which is what the CERN article implied.

I know I'm being picky, but I've always said that communication between scientists and the general public is extremely tedious. Often times, what you wrote is not what they understood! And once something or some impression has stuck into their heads, it is very difficult to change that. Having a misleading idea immediately imprinted at the very beginning of an article is a horrible thing to do, even if the rest of the article is accurate. At worse, the reader holds on to the original misleading idea, and at best, the reader becomes confused with conflicting understanding. In the world where a lot of people have attention deficit and all they care about are quick bites of news, the message conveyed in the very first paragraph, or even the very first line, is all that they read and get.

Zz.


Friday, July 03, 2020

Simple, Basic, COVID-19 Math

This is highly elementary for most of you. But I've learned a long time ago that what I consider to be obvious and trivial, is not the case for many members of the public. This is one such case because I've heard this uttered in the media, in print, and among some people.

There is a large increase in the number of positive COVID-19 cases being reported in many states in the US. A lot of people, who shall remain nameless, make the excuse that this is due to the increase in testing, and that it shouldn't be alarming. The more you test, the more you find, they argued.

So I'll illustrate this with simple, basic math.

Let's say you have a population of 1000 people. And let's say that 200 of them has COVID-19. This means that 20% of the population has the virus.

If you randomly test 100 people, you'll get 20 people who is positive.
If you randomly test 200 people, you'll get 40 people who is positive.
If you randomly test 300 people, you'll get 60 people who is positive.

So yes, in terms of absolute numbers, the more people you test, the more number of positive results that you will get. HOWEVER, look at the percentage of positive test. No matter how many people you test, the percentage will still be 20%. The absolute number will increase with increasing number of tests, but the percentage (some people call it positive rate) does not change considerably. This is what a lot of people appear to not fully comprehend.

Of course, in real life, the percentage won't be exact, but if we keep having these tests, it will hover around some value and not change systematically or monotonically over time if there is no change in the number of people infected. So what you need is not the absolute number but also the overall percentage of positive result per day, let's say. That is of more importance if you are trying to see if things are getting better, or worse.

The situation, of course, is more complex than this. But the point in all of this is that you simply can't dismiss the increase in numbers by claiming that it is due to an increase in the number of testing. That is not the whole picture. What if you do the above exercise again and instead, you get 50 out of 200 being positive one week, and 90 out of 300 being positive the week after that? Can you still attribute that to increase in testing only?

Zz.

Monday, June 29, 2020

Building PIP-II at Fermilab

PIP-II is being built at Fermilab as a new linear proton accelerator for its needs in years to come.



Zz.

Wednesday, June 24, 2020

Lightest Known Blackhole, Or Largest Known Neutron Star?

I tell ya, after years and years of searching for gravitational waves, and then finally discovering it several years ago, the LIGO-Virgo gravitational waves detector has become an amazing astronomical/astrophysical observatory, making one amazing discovery after another. The existence of such gravitational waves are no longer in doubt that they are now being used as a means to detect other astronomical events.

This is one such case where it appears that a 2.6 solar-mass unknown object collided with a 23 solar-mass blackhole.[1] If this 2.6 solar-mass object is a blackhole, it will be the lightest known blackhole. If it is a neutron star, it will be the heaviest known neutron star. Both scenario will require a reworking of current theories, because a blackhole that light, or a neutron star that heavy, was thought to be unlikely.

Neutron stars and stellar black holes are the final stages of evolution for large stars – with black holes being more massive than neutron stars. In theory, the maximum mass of a neutron star is about 2.1 solar masses. However, there is some indirect evidence that more massive neutron stars could exist. There is little evidence for the existence of black holes smaller than about 5 solar masses, leading to a mass gap in our observations of these compact objects.

What is intriguing about the August 2019 merger – dubbed GW190814 – is the mass of the smaller object, which appears to fall within this gap. “Whether any objects exist in the mass gap has been an ongoing mystery in astrophysics for decades,” says Charlie Hoy of the UK’s Cardiff University, who played a key role in analysing data from the detection and writing the paper that describes the observation, which has been published in The Astrophysical Journal Letters. “What we still don’t know is whether this object is the heaviest known neutron star or the lightest known black hole, but we do know that either way it breaks a record.”

The actual paper is available to be read for free here since it is an open access article.

Like I had said to the students in my astronomy classes, this is going to go down as the golden age of astronomy. Since the beginning of human history, we only had light as our only detector of the heavens. Now, we have not only neutrinos and high-energy cosmic rays, but also gravitational waves as our means to look at the heavens. We have three different and separate ways to look at our sky!

Zz.

[1] R. Abbott et al., The Astrophysical Journal Letters,896:L44(20pp), 2020.

Tuesday, June 23, 2020

The Physics Of N95 Masks

Many, if not most, of us have heard of N95 masks when the pandemic first appeared, especially when there were reports of their shortages. Why are they so in high demand? This MinutePhysics video tells you why they are the ones that front-line health care workers need to be wearing.



Zz.

Monday, June 22, 2020

Back To Remote Learning In Fall 2020

While there has been no official word yet, there are strong indications that come Fall 2020, my classes will go back to totally remote learning once more, continuing what happened during the second half of Spring 2020.

It is not surprising to me. I've been expecting it, and in some ways, I've been preparing for it. I mentioned earlier that I've enrolled in Quality Matters courses to give me formal training and credentials in running online and hybrid courses. I just finished the first workshop, and I have one more to do with them before I do the last required course with my own institution.

I must say that the one course that I've completed so far was more useful than I initially expected. There were a few "eye-opener" moments that I never realized before. It is one thing to anticipate and guess what a student needs from an online course, it is another when one actually goes through it, and are shown some of the best-practice methods of online education from the point of view of the student.

At the end of the first course, I realize that what I've learned was not only useful for the next time I have to teach a remote or online course, which will be this Fall most likely, but I'm going to take what I've learned to also improve my face-to-face courses, whenever I get to teach one. I know that many of the things I put on the Learning Management Systems can be reorganized better, because if it is suitable for online students, then it certainly is appropriate for face-to-face students.

But of course, one of the unique challenges with teaching a science course is labs, and how one can effectively do such a thing with a remote class. I've been looking at material put out by Pivot Interactives, which looks promising. I attended one of their webinars, and I like the way they show the experiments. I intend to sign up for the instructor trial version during the next week or so to check them out further. Do you have any experience with using them, either as a student or as an instructor? If you do, I'd love to hear from you.

There are more challenges unique to teaching math and science online, and I'm going to explore them during the next few weeks. I'll post them here whenever I encounter them, and maybe you might have an idea on the best-practice way to tackle them.

Zz.

Friday, June 12, 2020

More Experimental Verification of General Relativity

This is another one of those "The more they test it, the more convincing it becomes."

New "free fall" measurement in extreme high gravitational field has upheld one of the foundations of General Relativity. This time the measurement comes from a white dwarf orbiting a neutron star (a pulsar). A neutron star is a star that has huge gravitational field, so this is an amazing testing ground for GR under extreme condition.

"Above all, it is the unique configuration of that system, akin to the Earth-Moon-Sun system with the presence of a second companion (playing the role of the Sun) towards which the two other stars 'fall' (orbit) that has allowed to perform a stellar version of Galileo's famous experiment from Pisa's tower. Two bodies of different compositions fall with the same acceleration in the gravitational field of a third one."

"The pulsar emits a beam of radio waves which sweeps across space. At each turn this creates a flash of radio light which is recorded with high accuracy by Nançay's radio telescope. As the pulsar moves on its orbit, the light arrival time at Earth is shifted. It is the accurate measurement and mathematical modeling, down to a nanosecond accuracy, of these times of arrival that allows scientists to infer with exquisite precision the motion of the star," says Dr. Guillaume Voisin.

You can get free access to the actual paper here.

Zz.

Thursday, June 11, 2020

BEC In Space

 Not as amusing as Pigs In Space, but still quite impressive.

The ISS is useful after all! :) Physicists have created the first controlled Bose-Einstein condensate in low earth orbit, thus eliminating the issue of gravitational effects[1] that affects the stability of the condensate.

A review of the work can be found here.

As discussed, Bose–Einstein condensation requires low temperatures, at which atoms hardly move. However, when a BEC is released from a magnetic trap so that experiments can be carried out, repulsive interactions between the atoms cause the cloud to expand. Within a few seconds, the BEC becomes too dilute to be detected. The expansion rate can be reduced by decreasing the depth of the trap, and, thereby, the density of atoms in the trap.

On Earth, the planet’s gravitational pull restricts the shape of possible magnetic traps in such a way that a deep trap is needed to confine a BEC (Fig. 1a,b). By contrast, Aveline and colleagues found that the extremely weak gravity (microgravity) on the International Space Station allowed rubidium BECs to be created using shallow traps. As a result, the authors could study the BECs after about one second of expansion, without needing to manipulate the atoms further.

But this is more than just an achievement on the scientific level. It is also a technological feat because of the numerous requirements that are needed to be able to have an experiment on the ISS, as stated in the review:

Aveline and colleagues’ technological achievement is remarkable. Their apparatus needed to satisfy the strict mass, volume and power-consumption requirements of the International Space Station, and be robust enough to operate for years without needing to be serviced. The authors’ Earth-orbiting BECs provide new opportunities for research on quantum gases, as well as for atom interferometry, and pave the way for missions that are even more ambitious.

If you have ever designed an experiment, you know of all the issues involved, not just the scientific ones. This includes engineering, robustness, economics/costs, etc. So I can't imagine what they had to come up with to be able to send something up there and basically run this with very little to no involvement from the astronauts onboard.

Very well done indeed!

Zz.

[1] D.C. Aveline et al. Nature v.582, p.193 (2020).

Thursday, June 04, 2020

DESI Begins

A new eye on the sky is about to add to our knowledge of dark energy.



It's interesting that in the list of funding agencies, NASA is absent. This goes to show you that many of these research activities that seem to be "astronomy-related" are not the sole domain of NASA. In fact, the area of particle-astrophysics is more closely related to particle physics than astronomy.

The video didn't clarify explicitly that in looking at the "spectrum" of light from each of these celestial bodies, one gets the radial velocity of these bodies with respect to us (i.e. via the amount of redshift), not its distance from us. That last piece of information can only be "deduced" using the radial velocity and the Hubble equation, i.e. the Hubble constant, a number that is still being refined.

Still, this new telescope is going to be quite exciting in revealing more of the mysteries of dark energy.

Zz.

Thursday, May 21, 2020

Transition to Online Teaching

The June 2020 issue of Physics Today has an article on various physics instructors' effort in dealing with the migration to online teaching in physics courses. I notice a few similar issues I had to deal with, such as this:

During in-person lectures, says Greco, the instructor would pose a question every 10 minutes or so. The students would discuss the question with their neighbors for a few minutes and then submit their answers. “If most of them get the right answer, I move on,” says Greco. “If not, I adjust the live lecture.” That doesn’t work as well online: Student discussion is harder to facilitate and web-based interactions are much slower. In person, he adds, “you can tell if someone is paying attention, but that’s hard to do virtually.”

I use "clickers" in class to do a quick snapshot if the students understood the concept that was presented. And certainly, student-to-student discussion is a part of it especially if the first round of in-class question didn't produce a correct response. This can't be done during a Zoom session even though it has a Poll feature. Student discussion was almost non-existent, and we had to revert back to almost passive learning, which killed me since I'm a strong advocate for active learning.

I did resorted to giving them at-home projects as part of the material where they used simulations and virtual experiments to investigate something that was relevant to the topic of that week. But it isn't the same, obviously.

The other similar thing that I read was this:

Other instructors chose to teach asynchronously, sometimes in a flipped mode, with students watching lectures before attending virtual discussions. Some instructors, including Dubson, embed questions in their video lectures such that students can’t continue until they commit to an answer. “This allows us to require that they think,” he says.

Luckily, all my classes have these "pre-lecture" videos or documents that the students had to view or read, and then answer a few questions. These were meant to introduce to them the concepts related to the topic of that week before the come to class. So I was already doing the "flipped" mode. When we went totally remote, I expanded the pre-lecture videos and material so that the students had a bit more to view because now it became a major source of the material.

It's nice to read that many other instructors were doing the same thing, and that we could all learn from one another on how to do this better next time.

Zz.

Thursday, May 14, 2020

Goodbye Spring Semester 2020

It's been close to a week since I submitted the final grades for my students. I'm still giving my sigh of relief that the crazy semester is finally over, and I'm sure the students felt the same way too.

For someone who has had a bit of training on how to run blended or hybrid classes, it was still a huge challenge to modify an existing on-site classes to run 100% online. And as someone who is a strong advocate of active learning, it is an even bigger disappointment that all the meticulous planning and in-class activities along this line of learning had to be thrown out of the window. But as they say, life happens while you're making plans!

After this whole debacle, I'm taking the entire summer off. I was planning on going to Hawaii at the end of May and fulfill one of the items on my bucket list, which is to view a sunrise or sunset on Mauna Kea. But of course, all of that had to be cancelled.

Still, I won't be just sitting on my rear end doing nothing throughout the summer. This whole pandemic thing has force me to get more official training on the best-practice way to run online classes and lessons, especially for a course that requires labs, etc. I've signed up for several accredited training courses, with the hope of improving my online lessons and presentations. I'm very much interested in the best ways to minimize online cheating during exams, etc., because I consider that to be a major issue and why I am skeptical of the skill and understanding of students taking online classes. Other faculty members who had taken such courses mentioned that it also helped with their in-person classes, so it definitely sounds like a positive thing to do. We shall see.

I've also realized that I've been consuming more than my usual amount of wine during this stay-at-home order. Not sure if that's good or bad.... :)😁

Zz.

Friday, April 17, 2020

Simple Electric Motor Experiment

This was the last lab that my students managed to do before all in-person classes were cancelled due to the coronavirus. They had to build a simple electric motor, making use of the concept of magnetic field created by a loop of wire, the concept of magnetic moment, and magnetic torque.

The final "proof" that they had successfully built the motor is to show that it will spin continuously, which looks like this:

It's a common experiment done in many General Physics labs, but it is still a cool exercise. The students certainly had fun doing it and they felt a sense of accomplishment when they see the spinning coil in motion.

I was just glad we managed to do it just before the shutdown.

Zz.

Thursday, April 16, 2020

First Hint of CP Violation in the Neutrino Sector

The latest report on T2K results has been published[1], and it looks good for the upcoming long neutrino baseline experiment at DUNE and T2HK. The result may suggest that these two upcoming experiments may finally nail down CP violation in neutrinos, which will be a substantial advancement in our understanding on why there are more mater than antimatter in our universe.

The discovery of substantial leptonic CP violation would be groundbreaking. Its observation, together with evidence that a quantity known as lepton number has been violated (that is, not conserved), would provide strong circumstantial evidence for leptogenesis as the origin of the matter–antimatter imbalance.

Zz.

[1] T2K collaboration, Nature v.580p.339 (2020).

Tuesday, April 14, 2020

Making Physics Funny

Although Tom Gauld's cartoons do not actually focus on physics, he has included topics related to physics before. This NY Times article gives a brief interview and background on him, someone you would know if you read New Scientist frequently.

I decided to mention it here because the article included one of his cartoons that made me chuckle. I decided to include it here and make sure everyone is aware that this is credited to him. If he or his publisher object to this, I'll remove it.


It's pretty funny, though, because if you are involved in any kind of science forum or discussion online, this happens more often than you think.

And considering that our current President of the US thinks he's an expert in many different fields as well, I feel that I'm living in that Science Hell right now.

Zz.

Monday, March 30, 2020

More Geeky T-Shirts

Before all this mess with the coronavirus came up, I got the chance to wear these two t-shirts to my class when I was teaching resistance/circuits, and when I was teaching magnetic fields. These two are in addition to the other geeky t-shirt that I mentioned last time.



I'm thinking of buying more for a couple of different topics that I will be covering, but who knows when I'll get to wear them again in a class setting. I suppose I can wear them when I run my Zoom class session, but who gets to see the full effect of it when all you want to show is your face.

Zz.

Tuesday, March 24, 2020

Busy With Online Course Conversion

I'm sure everyone involved in course instruction is facing the same issue. The past 2 weeks have been rather hectic as I rush to reform the course and adapt it to a purely online course. It is certainly more daunting and more of challenge for science courses that have lab components.

I find myself not struggling as much as a few of the other faculty members that had never taught anything remotely or online. I've had some experience in teaching blended or hybrid courses, so I have had experience with conducting either asynchronous courses, synchronous courses via video-conferencing app such as WebEx. So for me, the work involves adapting my material that was meant for an on-site course into something more suitable for an online course.

As for the labs, I already have a collection of "virtual labs" that I had written previously that make use of the various online experiments such as the ones fro PhET, etc. So those actually require only minor rewrites and tweaks and they are good to go.

My main struggle and something that I still find a bit dubious, are the exams. I still do not believe that students will not cheat if they can when doing online tests and exams, no matter how much one tries. This is my main issue with any online courses, the ability to determine if the work was truly done by the student him/herself. I have heard many anecdotal cases where for the same course and same exam, students who took the online version scored significantly higher exam scores than the students who took the exam in class. So make your own conclusion there. I've written my exams in such a way that the questions are somewhat "unique" and can't be easily "googled". But there is no way to prevent the student from having someone else helping or even outright doing the exam for him/her. At the end, there is only so much one can do given the circumstances.

As of now, all I'm trying to do is survive the remainder of the semester with the new workload, and to stay healthy. I wish the same for all of you as well.

Zz.

Saturday, March 07, 2020

RIP Freeman Dyson

Freeman Dyson has died at the age of 96.

Many anti-academia often used him as an example of being able to do physics without a PhD. But really, how many people are as gifted and as brilliant as he is? He was part of academia, because that was where he worked, and using him as an example is like planning your life as if you'll win a lottery.

Dyson's legacy will go on long after he is gone.

Zz.

Wednesday, March 04, 2020

2020 APS March Meeting Cancelled

By now, I'm sure those of you involved would have heard the news of the cancellation of the APS March meeting this year due to the coronavirus issue. For those of you who don't know, the APS March meeting is the LARGEST yearly physics conference in the world, attracting more than 10,000 physicists from around the world over a week of intellectual discussion and presentations.

This cancellation is quite unprecedented, because I do not remember the last time this has happened, if it has ever happened. So this is quite a big deal. I'm sure there's a lot of people impacted by this, especially in terms of travel and accommodation cancellations and fees.

No news yet on what will happen to the APS April meeting, which is looming in the very near future.

If you are affected by it, I'd like to hear it. Luckily (or unluckily), I wasn't going this year, so I don't have to deal with the mess.

Zz.

Friday, February 14, 2020

Quantum Entanglement

I made a post quite a while back on "Quantum Entanglement for Dummies" that tried to describe what it is. I emphasized the fact that this phenomenon is different than classical physics because of one every important characteristics of quantum mechanics, which is the superposition principle that is built into the quantum wavefunction. So to be able to understand why quantum entanglement exists and why it is so "spooky", one must first understand the superposition concept.

Don Lincoln has produced a video on quantum entanglement, and if you pay attention closely, he starts off with describing the superposition concept and how that made a quantum system not "predetermined" before a measurement. He also give a good overview on a Bell-type measurement that shows how experiments agree with QM description but not the hidden variables scenario.



A good video to start you off on understanding this phenomenon.

Zz.

Monday, February 03, 2020

State of the Art of MRI

This is a very good article from Physics Today on the history and development of Magnetic Resonance Imaging, which has become ubiquitous in medical diagnostics. Of course, this came out of the discovery of the nuclear magnetic resonance phenomenon, a technique that itself came out of our understanding of quantum mechanics.

When you read this article, pay attention to how it is continuing to be developed, to evolve, and its continuing improvement. Medical physicists are still actively improving this, and other aspect of the medical field by incorporating things that physicists already know and use. Without advancement in physics, both theoretically and experimentally, there is nothing to trickle down from to the medical field.

Zz.

Monday, January 20, 2020

Charge Fluctuation at a Quantum Critical Point.

This is a fascinating paper[1] (which I'll be reading more of in the next several weeks). But for now, I'll just highlight it here.

The authors found that charge fluctuation in a "strange metal" antiferromagnetic compound exhibit a scaling of f/T (frequency over temperature) in the optical conductivity, which often indicates the presence of a quantum critical point.

If anyone has done MBE before, you'll know how tedious and difficult it is to synthesize a material such as this, and have it be pristine enough to produce these effects that can be measured, at a THz level, no less!

There are many implications here, not the least of which is that the cuprate high-Tc superconductors share the same "parent" or undoped state, being antiferromagnetic perovskites themselves. There have been experiments indicating that the cuprates superconductors are also influenced by their proximity to a quantum critical point.

This is another example where some of the most fundamental aspects of quantum mechanics, in this case the concept of quantum criticality, can often be clearly manifested in a condensed matter system, not in elementary particle physics experiment.

Zz.

[1] L. Prochaska et al., "Singular charge fluctuations at a magnetic quantum critical point." Science v.367, p.285 (2020). ArXiv version of the paper can be found here.

Wednesday, January 08, 2020

What Really Happened At The Big Bang?

Don't you want to know?

Here is a simplified explanation of what the Big Bang is, and what the Big Bang is NOT!



Zz.

Monday, January 06, 2020

Thirteen tips for engaging with physicists, as told by a biologist

This is a rather fun reading, and it has a bit of truth if we (physicists) do a bit of self-reflecting on how we operate.

I think I'm going to post the link to the LMS for the general physics course I'll be teaching this Spring for Life Science/Pre-Med majors. 😄

And then there's a reverse flow, where you get 12 tips for engaging with biologist, as told by a physicist. Even a lot more self-reflection there!

In the end, biologists and physicists gain a lot from talking to each other.

And oh, Happy New Decade, btw!

Zz.