Friday, September 22, 2017

Common Mistakes By Students In Intro Physics

Rhett Allain has listed 3 common mistakes and misunderstanding done by student in intro kinematics physics courses.

I kinda agree with all of them, and I've seen them myself. In fact, when I teach "F=ma" and try to impress upon them its validity, I will ask them that if it is true, why do you need to keep your foot on the gas pedal to keep the vehicle moving at constant speed while driving? This appears to indicate that "F" produces a constant "speed", and thus, "a=0".

Tackling this is important, because the students already have a set of understanding of how the world around the works, whether correctly or not. It needs to be tackled head-on. I tackled this also in dealing with current where we calculate the drift velocity of conduction electrons. The students discover that the drift velocity is excruciatingly slow. So then I ask them that if the conduction electrons move like molasses, why does it appear that when I turn the switch on, the light comes on almost instantaneously?

Still, if we are nitpicking here, I have a small issue with the first item on Allain's list:

What happens when you have a constant force on an object? A very common student answer is that a constant force on an object will make it move at a constant speed—which is wrong, but it sort of makes sense.

Because he's using "speed" and not "velocity", it opens up a possibility of a special case of a central force, or even a centripetal force, in a circular motion where the object has a net force acting on it, but its speed remains the same. Because the central force is always perpendicular to the motion of the particle, it imparts no increase in speed, just a change in direction. So yes, the velocity changes, but the magnitude of the velocity (the speed) does not. So the misconception here isn't always wrong.


Thursday, September 21, 2017

Gravity As A Result Of Random Quantum Fluctuation?

There are too many "buzzwords" in this entire thing, but it might still be an interesting reading for some people.

There is a new report on the possibility that gravity might not be an interaction within QFT framework, but rather as a result of quantum fluctuation.

The average of these fluctuations is a gravitational field that is consistent with Newton’s theory of gravity. In this model, gravity is born out of quantum mechanics, but is not in itself a quantum-mechanical force. It is what scientists call “semiclassical.” Until this theory is tested further, it will remain a semi-solution; while the idea does predict certain known phenomena, it doesn’t yet account for Einstein’s theory of general relativity.

This latest report is due to a preprint uploaded to ArXiv.

Now, I can understand New Scientist reporting on something like this, because they have the tendency to report on sensational and unverified science news, but for PBS/NOVA webpage to jump onto this still-unpublished work? That's surprising.

Of course, I'm complicit on this as well since I'm reporting it here. I'm going to make sure I won't highlight something like this again in the future until it has at least appear in a peer-reviewed publication, not just in New Scientist and the likes.


Tuesday, September 19, 2017

Amazon's CAPTCHA Patent Proposal Tests Your Physics Understanding

... well, more like your physics INTUITION on what should happen next.

It seems that Amazon has file a patent application that uses a physics engine to generate scenarios to see if you are a real person or a bot.

The company has filed a patent application for a new CAPTCHA method which would show you a 3D simulation of something about to happen to a person or object. That something would involve Newtonian physics — perhaps an item is about to fall on someone, or a ball is about to roll down a slope. The test would then show you several "after" scenarios and, if you pick the correct option, you've passed the test.
The idea is that, because you are a human, you have an "intuitive" understanding of what would happen next in these scenarios. But computers need much more information about the scene and "might be unable to solve the test", according to the application.

Definitely interesting, although in Fig. 3B shown in the article, both Fig (A) and Fig (B) might be possible depending on the ambiguity of the drawing.

But this brings me an important point that I've been telling my students in intro physics classes when they dealt with mechanics. We all ALREADY KNOW many of the things that will happen in cases like this. We do not need to learn physics or to be enrolled in a physics class to know the qualitative description of the dynamics of these systems. So we are not teaching you about something you are not familiar with.

What a formal physics lesson will do is to describe these things more accurately, i.e. in a QUANTITATIVE manner. We won't simply say "Oh, the ball will roll down that inclined plane." Rather, we will describe the motion of the ball mathematically, and we will be able to say how long the ball will take to each the bottom, at what speed, etc...etc. In other words, we don't just say "What goes up must come down", but we will also say "When and where it will come down". This is what separates physics (and science) from hand-waving, everyday conversation.

All of us already have an intuitive understanding of the physical systems around us. That's why Amazon can make such a CAPTCHA test for everyone. A physics lessons simply formalize that understanding in a more accurate and non-ambiguous fashion.


Friday, September 15, 2017

Bell's Theorem - The Venn Diagram Paradox

Minute Physics is tackling Bell's theorem, with limited success.

It would have been nice if they included Malus' Law description in here, because that is what we knew before QM came around, and that is what we teach students in intro physics.

In any case, I still find it difficult to follow, especially if you didn't pay that much attention to the part when they are doing the counting. They went over this a bit too quickly to let it sink in.

Maybe your brain works faster than mine and can keep up.


Sunday, September 10, 2017

Is Relativistic Mass Real?

I've mentioned about this issue several times on here. In this post, I've linked to a reference, and also a link to Lev Okun's paper in another post, that both debunked the concept of relativistic mass, and why it should not be used.

Unfortunately, as a physics instructor, I still see texts teaching this concept, and I have to work around it, telling the students the caveat on why what they should be cautious in what they are reading. It isn't easy, but I'd rather say something about it than let the students walk out of my class not knowing that this idea of "relativistic mass" is not what it has been popularly made out.

So I'm delighted that Don Lincoln has a video addressing this issue as well.

He explains it quite clearly, and also why we still sometime teach this concept to students in intro classes (unfortunately). Yes, I can understand why, but I still don't like it if it can be avoided without sacrificing the pedagogical reason for it.

It's a good video if you are still wondering what the fuss is all about.


Sunday, September 03, 2017

Rebuilding Quantum Theory

Theorists and philosophers are trying to "rebuild" quantum theory's foundation and axioms. Good luck to them!

Still, this is a rather good article on some of the issues surrounding concepts that still do not sit well with many physicists. Those of us who are in the "Shut up and calculate" camp will leave it up to them to sort things out. We are busy with doing other things.



Sunday, August 20, 2017

RIP Vern Ehlers

The first physicist ever elected to the US Congress has passed away. Vern Ehlers, a moderate Republican from Michigan, passed away at the age of 83.

Vern Ehlers, 83, a research physicist and moderate Republican who represented a western Michigan congressional district for 17 years, died late Tuesday at a Grand Rapids nursing facility, Melissa Morrison, funeral director at Zaagman Memorial Chapel, said Wednesday.

I reported on here when he decided to retire back in 2010. And of course, when he was serving Congress along with 2 other elected officials who were physicist, I cited a NY Times article that clearly demonstrated how desperate we are to have someone with science background serving as politicians.

Unfortunately, right now, the US Congress has only ONE representative who is a trained physicist (Bill Foster). It somehow reflects on the lack of rationality that is going on in Washington DC right now.


Solar Eclipse, Anyone?

It's a day before we here in Chicago will get to see a partial solar eclipse. I know of people who are already in downstate Illinois at Carbondale to view the total eclipse (they will get another total eclipse in 2024, I think).

So, any of you will be look up, hopefully with proper eye wear, to view the eclipse tomorrow? I actually will be teaching a class during the main part of the eclipse, but I may just let the students out for a few minutes just to join the crowd on campus who will be doing stuff for the eclipse. Too bad I won't be teaching optics, or this will be an excellent tie-in with the subject matter.


Tuesday, August 08, 2017

Hyperfine Splitting of Anti-Hydrogen Is Just Like Ordinary Hydrogen

More evidence that the antimatter world is practically identical to our regular matter world. The ALPHA collaboration at CERN has reported the first ever measurement of the anti-hydrogen hyperfine spectrum, and it is consistent to that measured for hydrogen.

Now, they have used microwaves to flip the spin of the positron. This resulted not only in the first precise determination of the antihydrogen hyperfine splitting, but also the first antimatter transition line shape, a plot of the spin flip probability versus the microwave frequency.

“The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting,” the researchers said.

“From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 MHz, consistent with expectations for atomic hydrogen at the level of four parts in 10,000.”

I am expecting a lot more studies on these anti-hydrogen, especially now that they have a very reliable way of sustaining these things.

The paper is an open access on Nature, so you should be able to read the entire thing for free.


Thursday, August 03, 2017

First Observation of Neutrinos Bouncing Off Atomic Nucleus

An amazing feat out of Oak Ridge.

And it’s really difficult to detect these gentle interactions. Collar’s group bombarded their detector with trillions of neutrinos per second, but over 15 months, they only caught a neutrino bumping against an atomic nucleus 134 times. To block stray particles, they put 20 feet of steel and a hundred feet of concrete and gravel between the detector and the neutrino source. The odds that the signal was random noise is less than 1 in 3.5 million—surpassing particle physicists’ usual gold standard for announcing a discovery. For the first time, they saw a neutrino nudge an entire atomic nucleus.

Currently, the entire paper is available from the Science website.


Wednesday, August 02, 2017

RHIC Sees Another First

The quark-gluon plasma created at Brookhaven's Relativistic Heavy Ion Collider (RHIC) continues to produce a rich body of information. They have now announced that the quark-gluon plasma has produced the most rapidly-spinning fluid ever produced.

Collisions with heavy ions—typically gold or lead—put lots of protons and neutrons in a small volume with lots of energy. Under these conditions, the neat boundaries of those particles break down. For a brief instant, quarks and gluons mingle freely, creating a quark-gluon plasma. This state of matter has not been seen since an instant after the Big Bang, and it has plenty of unusual properties. "It has all sorts of superlatives," Ohio State physicist Mike Lisa told Ars. "It is the most easily flowing fluid in nature. It's highly explosive, much more than a supernova. It's hotter than any fluid that's known in nature."
We can now add another superlative to the quark-gluon plasma's list of "mosts:" it can be the most rapidly spinning fluid we know of. Much of the study of the material has focused on the results of two heavy ions smacking each other head-on, since that puts the most energy into the resulting debris, and these collisions spit the most particles out. But in many collisions, the two ions don't hit each other head-on—they strike a more glancing blow.

It is a fascinating article, and you may read the significance of this study, especially in relation to how it informs us on certain aspect of QCD symmetry.

But if you know me, I never fail to try to point something out that is more general in nature, and something that the general public should take note of. I like this statement in the article very much, and I'd like to highlight it here:

But a logical "should" doesn't always equal a "does," so it's important to confirm that the resulting material is actually spinning. And that's a rather large technical challenge when you're talking about a glob of material roughly the same size as an atomic nucleus.

This is what truly distinguish science with other aspects of our lives. There are many instances, especially in politics, social policies, etc., where certain assertions are made and appear to be "obvious" or "logical", and yet, these are simply statements made without any valid evidence to support it. I can think of many ("Illegal immigrants taking away jobs", or "gay marriages undermines traditional marriages", etc...etc). Yet, no matter how "logical" these may appear to be, they are simply statements that are devoid of evidence to support them. Still, whenever they are uttered, many in the public accept them as FACTS or valid, without seeking or requiring evidence to support them. One may believe that "A should cause B", but DOES IT REALLY?

Luckily, this is NOT how it is done in science. No matter how obvious it is, or how verified something is, there are always new boundaries to push and a retesting of the ideas, even ones that are known to be true under certain conditions. And a set of experimental evidence is the ONLY standard that will settle and verify any assertion and statements.

This is why everyone should learn science, not just for the material, but to understand the methodology and technique. It is too bad they don't require politicians to have such skills.


Is QM About To Revolutionize Biochemistry?

It is an intriguing thought, and if these authors are correct, a bunch of chemical reactions, even at higher temperatures, may be explained via quantum indistinguishibility.

The worlds of chemistry and indistinguishable physics have long been thought of as entirely separate. Indistinguishability generally occurs at low temperatures while chemistry requires relatively high temperatures where objects tend to lose their quantum properties. As a result, chemists have long felt confident in ignoring the effects of quantum indistinguishability.

Today, Matthew Fisher and Leo Radzihovsky at the University of California, Santa Barbara, say that this confidence is misplaced. They show for the first time that quantum indistinguishability must play a significant role in some chemical processes even at ordinary temperatures. And they say this influence leads to an entirely new chemical phenomenon, such as isotope separation and could also explain a previously mysterious phenomenon such as the enhanced chemical activity of reactive oxygen species. 

They have uploaded their paper on arXiv.

Of course, this is still preliminary, but it provides the motivation to really explore this aspect that had not been seriously considered before. And with this latest addition, it is just another example on where physics, especially QM, are being further explored in biology and chemistry.


Sunday, July 30, 2017

Is Radiation Dangerous?

Believe it or not, there are still people out there who get scared witless and going out of their minds with their phobia about "radiation". I get questions related to this often enough that whenever I find info like this one, I want to post it here.

Don Lincoln decides to tackle this issue regarding "radiation". If you have little knowledge and idea about this, this is the video to watch.


Quantum Tunneling Time

Chad Orzel has highlighted a couple of papers (one still a preprint) on the issue of quantum tunneling time or speed. I missed these, just like him, but unlike him, I didn't have as glamorous of an excuse - I was busy finishing up teaching a summer physics class.

I'll let you read have the pleasure of reading his article, because he also gave a quick background on the quantum tunneling phenomenon, if you're not familiar with it. But as background information, I did quantum tunneling spectroscopy measurement for my PhD research and dissertation. So I'm familiar with this, but not in the sense of the detailed question on tunneling time. We simply used the phenomenon to measure the properties of the material of interest, even though in the end, I ended up looking into the detailed description of the tunneling matrix elements, which are often simplified or ignored.

Still, the issue of tunneling time has always been something in the back of my mind, and the question on whether this thing happens "very fast" or "instantaneously" (just like quantum entanglement) has always popped up now and then. It is good to see new studies on this, even though the combined conclusion out of these two results is still uncertain.


1. N. Camus et al., Phys. Rev. Lett. 119, 023201 (2017).

Tuesday, July 11, 2017

The Higgs - Five Years In

In case you've been asleep the past 5 years or so and what to catch up on our lovable Higgs, here is a quick, condensed version of the saga so far.

Where were you on 4 July 2012, the day the Higgs boson discovery was announced? Many people will be able to answer without referring to their diary. Perhaps you were among the few who had managed to secure a seat in CERN’s main auditorium, or who joined colleagues in universities and laboratories around the world to watch the webcast.

This story promises to have lots of sequels, just like the movies released so far this year.


The Universe's First Atoms Verify Big Bang Theory

The Big Bang theory makes many predictions and consequences, all of them are being thoroughly tested (unlike Intelligent Design or Creationism). These predictions and consequences are quantitative in nature, i.e. the theory predicts actual numbers.

Many of these "numbers" have been verified by experiments and observations, and they are continually being measured to higher precision. This latest one comes about from the prediction of the amount of certain gases during the early evolution of our universe.

But more data has just come in! Two new measurements, in a paper just coming out now by Signe Riemer-Sørensen and Espen Sem Jenssen, of different gas clouds lines up with a different quasar have given us our best determination of deuterium's abundance right after the Big Bang: 0.00255%. This is to be compared with the theoretical prediction from the Big Bang: 0.00246%, with an uncertainty of ±0.00006%. To within the errors, the agreement is spectacular. In fact, if you sum up all the data from deuterium measurements taken in this fashion, the agreement is indisputable.

The more they test it, the more convincing it becomes.


Wednesday, June 14, 2017

The Physics of Texting And Driving

First of all, let me be clear on this. I hate, HATE, HATE drivers who play with their mobile devices while they drive. I don't care if it is texting (stupid!) or just talking on their phones. These drivers are often driving erratically, unpredictably, and often do not use turn signals, etc. They are distracted drivers, and their stupid acts put my life and my safety in jeopardy. My nasty thought on this is that I wish Darwin would eliminate them out of the gene pool.

There! I feel better now. Coming back to the more sedate and sensible topic related to physics, Rhett Allain has a nice, short article on why physics will rationally explain to you why texting and driving is not safe, and why texting and driving ANNOYS OTHER PEOPLE!

OK, so my calmness didn't last very long.

The physics is quite elementary that even any high-school physics students can understand. And now, I am going back to my happy place.


Saturday, June 10, 2017

What Non-Scientists Can Learn From Physics

Chad Orzel has a follow-up to his earlier article on what every physics undergrad should know. This time, he tackles on what he thinks non-scientists can learn from physics.

You may read the linked article to get everything, but I have a different track in mind. Sticking to students rather than just a generic non-scientist, I'd rather focus on the value of a physics education for both scientists and non-scientists alike. After all, many non-physicists and non-scientists are "forced" to take physics classes at various levels in their undergraduate education. How can we motivate these students of the importance of these classes, and what can they learn and acquire from these classes that will be useful to them not only in their education, but also in their careers and life?

I of course tell them the relevance of physics in whatever area that they major in. But even non-scientists, such as an arts major, can acquire important skills from a physics class. With that in mind, I'd like to refer to the NACE website. They often have a poll of potential employers and what they look for in new graduates that they are considering to hire. In particular, they were asked on what type of skills they tend to look for in a candidate.

The result can be found here.

I have extracted the info in this picture:

I often show this to my students because I highlight all the skills that we will employ and honed in a physics class. I tell them that these are what they can acquire out of the class, and to be conscious of them when we either tackled a physics concept and problem, or when they are working on an experiment. In fact, often times, I often try to get them to think on how they would approach a problem in trying to solve it, with the intention of emphasizing analytical skills.

I think as physics teachers and instructors, we often neglect to show the students the non-physics benefits of a physics class. A student, whether he/she is a physics, engineering, other science, or STEM major, can ALWAYS again an advantage if he/she has those skills that I highlighted above. This is why I've often emphasize that the skills that can be acquired from a physics class often transcends the narrow boundary of a physics topic, and can often be valuable in many other areas. These skills are not subject-specific.

I often notice the irrational and puzzling argument on TV, especially from the world of politics, and I often wonder how many people could benefit from a clear, analytical ability to be able to analyze and decipher an issue or an argument. So heck yes, non-scientists can learn A LOT from physics, and from a physics class.


Friday, June 09, 2017

Host Interrupts Female Physicst Too Much, Audience Member Intervened

Hey, good for her!

The moderator of this panel interrupted physicist Veronika Hubeny of UC-Davis so much that audience member Marilee Talkington (appropriate name) got so frustrated that she intervened.

While watching a panel titled “Pondering the Imponderable: The Biggest Questions of Cosmology,” Marilee Talkington noticed that the moderator wasn’t giving physicist Veronika Hubeny, a professor at UC Davis and the only female on the panel, her fair share of speaking time.

So when the moderator, New Yorker contributor Jim Holt, finally asked Hubeny a question about her research in string theory and quantum gravity, then immediately began speaking over her to explain it himself, Talkington was furious.

Fed up with the continuous mansplaining, Talkington interrupted Holt by yelling loudly, “Let her speak, please!” The crowd applauded the request. 

You can read the rest of the story here.

Certainly, while it is awfully annoying, based on what Dr. Hubeny described, she didn't think it was a blatant sexism. Rather, she thought that the host was just overly enthusiastic. But you may judge that for yourself if the host didn't give the only female member of the panel a chance to speak.

But yeah, good for Ms. Talkington for intervening.


Friday, June 02, 2017

50 Years Of Fermilab

Don Lincoln takes you on a historical tour of Fermilab as it celebrates its 50th Anniversary this year.


Thursday, June 01, 2017

Planning For A Future Circular Collider

The future of the next circular collider to follow up the LHC is currently on the table. The Future Circular Collider (FCC) is envisioned to be 80-100 km in circumference (as compared to 27 km for the LHC) and reaching energy as high as 100 TeV (as compared to 13 TeV for the LHC).

Now you may think that this is way too early to think about such a thing, especially when the LHC is still in its prime and probably will be operating for a very long time. But planning and building one of these things take decades. As stated at the end of the article, the LHC itself took about 30 years from its planning stage all the way to its first operation. So you can't simply decide to get one of these built and hope to have it ready in a couple of years. It is the ultimate in long-term planning. No instant gratification here.

In the meantime, the next big project in high-energy physics collider is a linear collider, some form of the International Linear Collider that has been tossed around for many years. China and Japan look to still be the most likely place where this will be built. I do not foresee the US being a leading candidate during the next 4 years for any of these big, international facilities requiring multinational effort.


Tuesday, May 30, 2017

"Intersectional Quantum Physics" To Fight The Oppression of Newton?!

I've seen many crap being passed as scholarly works, but this one might take the cake.

Whitney Stark argues in support of “combining intersectionality and quantum physics” to better understand “marginalized people” and to create “safer spaces” for them, in the latest issue of The Minnesota Review.

Because traditional quantum physics theory has influenced humanity’s understanding of the world, it has also helped lend credence to the ongoing regime of racism, sexism and classism that hurts minorities, Stark writes in “Assembled Bodies: Reconfiguring Quantum Identities.”

And here's the best part:

Stark did not respond to multiple email and Facebook requests for comment from The College Fix. While she does not have any academic training in physics or quantum physics, she did complete a master’s degree in “Cyborg and Post Colonial Theory” at the University of Utrecht.

And that somehow makes her an expert in not only physics, but quantum physics and classical mechanics.

This is no different than the snake oil being peddled by the likes of Deepak Chopra. And the sad thing is, this is not new. Alan Sokal has battled this sort of thing in his attack on postmodernism philosophy. It included attacks in which the Theory of Relativity was considered to be male-biased!

But what is troubling here is that people who have only a superficial knowledge of something seem to think that they have the authority and expertise to criticize something, and all out of ignorance. And this seems to be a common practice nowadays, especially in the world of politics.


Do STEM Enrichment and Enhancement Activities Increase Study In STEM Subjects?

Well, this is a rather discouraging report.

A study of UK's secondary school students (11-16 years old) has found no significant increase in STEM participation despite involving them in STEM extra-curricula activities such as visiting labs, museum, etc. The study found that these students who were exposed to such activities are no more likely to pursue STEM subject areas and do well at the A-Levels than other students.

This longitudinal cohort study evaluated the impact of STEM enrichment and enhancement activities on continued post-16 STEM participation. A direct noticeable positive effect of engaging in these activities on pupil STEM subject choices was not found. The findings were similar for all pupils irrespective of their socio-economic status or ethnicity. Pupils who were registered by their schools for STEM enrichment and enhancement activities every year did not have any greater likelihood of continuing to study STEM subjects than their peers after compulsory education. This was true for all pupils, FSM and black ethnic minority pupils.

As someone who has participated in many outreach programs, and have been involved in providing access to various facilities to students from many schools, I always have been under the impression that such a thing might make a difference. Of course, I have no empirical evidence to back that up, other than seeing and having a feel for how excited the students were at what they were seeing and learning.  This is especially the case during my many-years of participation in Argonne's Science Careers In Search of Women program.

But I too have often wondered if these programs keep track of what the students ended up pursuing. I mean, it isn't sufficient to simply have these programs and activities. We must also evaluate how effective they are. And to be able to judge that, we have to make follow-up survey and track what these students ended up doing.

Otherwise, we will be doing all these stuff just to make us feel good without having any indication that what we did was actually beneficial or have the intended result. If this study is true, then we need to rethink how we engage with high-school students in encouraging them to be interested in STEM subjects.


Monday, May 29, 2017

Einstein and Civil Rights Activism

On tonight's episode of Antique's Roadshow on PBS, someone brought a signed photo of Albert Einstein while he was attending an honorary doctorate degree awarded to him by the historically black college of Lincoln University. This brought up the little known part of Einstein's life where he was one of the few prominent physicist who spoke about civil rights and racism in the US.

The PBS page also provided a link to an essay Einstein wrote in Pageant Magazine about racism in America at that time.

This was back in 1946. Have we changed much since then on this front?


Wednesday, May 24, 2017

What Every Physics Major Should Know?

Chad Orzel took on the silly tweet posted by Sean Carroll on what HE thinks that every physics major should  know.

Over the weekend, cosmologist and author Sean Carroll tweeted about what physics majors should know, namely that "the Standard Model is an SU(3)xSU(2)xU(1) gauge theory, and know informally what that means." My immediate reaction to this was pretty much in line with Brian Skinner's, namely that this is an awfully specific and advanced bit of material to be a key component of undergraduate physics education. (I'm assuming an undergrad context here, because you wouldn't usually talk about a "major" at the high school or graduate school levels.)

I categorize the tweet by Carroll as silly because he has no evidence to back up WHY this is such an important piece of information and knowledge for EVERY physics major. I hate to make my own silly generalization, but I'm going to here. This type of assertion sounds like it is a typical comment made by a theorist working on an esoteric subject matter. There! I've said it, and I'm sure I've offended many people already!

I would like to make another assertion, which is that there are PLENTY (even majority?) of physics majors who got their undergraduate degree without "informally" knowing the meaning of "...the Standard Model is an SU(3)xSU(2)xU(1) gauge theory...", AND..... go on to have a meaningful career in physics. Anyone care to dispute me on that?

If that is true, then Carroll's assertion is meaningless, because there appears to be NO valid reason for why a physics major needs to know that. He/she needs to know QM, CM, and E&M. That much I will give. Orzel even listed these and other subject areas that a typical undergraduate in physics is assumed to know. But a gauge symmetry in the Standard Model? Is this even in the Physics GRE?

Considering that about HALF of B.Sc degree recipients in physics do not go on to graduate school, I can think of many other, MORE IMPORTANT skills and knowledge that we should equipped physics majors. We are trying to make physics majors more "employable" in the marketplace, especially in the private sector. Comments by Carroll simply re-enforced the DISCONNECT that many physics departments have in how they train and educate their students without paying attention to their employment possibilities beyond research and academia. This is highly irresponsible!

I'm glad that Orzel took this head on, because Sean Carroll should know better... or maybe he doesn't, and that's the problem!


Thursday, May 18, 2017

"Difficult" and "Easy" Are Undefined

This post comes about because in an online forum, someone asked if it is "easier" to heat something than to cool it down. The issue for me here isn't the subject of the question, which is heating and cooling and object, but rather, that the person asking the question thinks that the "measure" here is the "easiness". I'm sure this person, and many others, didn't even think twice to realize that this is a rather vague and ambiguous question. After all, it is common to ask if something is easy or difficult. Yet, if you think about it carefully, this is really asking for something that is undefined.

First of all, the measure of something to be "easy" or "difficult" it itself is subjective. What is easy to some, can easily be difficult to others (see what I did there?). Meryl Streep can easily memorize pages and pages of dialog, something that I find difficult to do because I am awful at memorization. But yet, I'm sure I can solve many types of differential equations that she finds difficult. So already, there is a degree of "subjectiveness" to this.

But what is more important here is that, in science, for something to be considered as a valid description of something, it must be QUANTIFIABLE. In other words, a number associated with that description can be measured or obtained.

Let's apply this to an example. I can ask: How difficult or easy it is to stop a 100 kg moving mass? So, what am I actually asking here when I ask if it is "easy" or "difficult"? It is vague. However, I can specify that if I use less force to make the object come to a complete stop over a specific distance, then this is EASIER than if I have to use a larger force to do the same thing.

Now THAT is more well-defined, because I am using "easy" or "difficult" as a measure of the amount of force I have to apply. In fact, I can omit the use of the words "easy" and "difficult", and simply ask for the force needed to stop the object. That is a question that is well-defined and quantifiable, such that a quantitative comparison can be made.

Let's come back to the original question that was the impetus of this post. This person asked if it is easier to heat things rather than to cool things. So the question now is, what does it mean for it to be "easy" to heat or cool things. One measure can be that, for a constant heat transfer, how long in time does it take to heat or cool the object by the same change in temperature? So in this case, the measure of time taken to heat and cool the object by the same amount of temperature change is the measure of "easy" or "difficult". One can compare time taken to heat the object by, say, 5 Celsius, versus time taken to cool the object by the same temperature change. Now this, is a more well-defined question.

I bring this up because I often see many ordinary conversation, discussion, news reports, etc.. etc. in which statements and descriptions made appear to be clear and to make sense, when in reality, many of these are really empty statements that are ambiguous, and sometime meaningless. Describing something to be easy or difficult appears to be a "simple" and clear statement or description, but if you think about it carefully, it isn't! Ask yourself if the criteria to classify something to be easy, easier, difficult, more difficult, etc... etc. is plainly evident and universally agreed upon. Did the statement that says "such and such undermines so-and-so" is actually clear on what it is saying? What exactly does "undermines" mean in this case, and what is the measure of it?

Science/Physics education has the ability to impart this kind of analytical skills, and to impart this kind of thinking to the students, especially if they are not specializing in STEM subjects. In science, the nature of the question we ask can often be as important as the answers that we seek. This is because unless we clearly define what it is that we are asking, then we can't know where to look for the answers. This is a lesson that many people in the public need to learn and to be aware of, especially in deciphering many of the things we see in the media right now.

It is why science education is invaluable to everyone.


Thursday, May 11, 2017

Initial Employment Of US Physics Bachelors

The AIP has released the latest statistics on the initial employment of Physics Bachelors degree holders from the Class of 2013 and 2014.

Almost half of the degree holders left school to go into the workforce, with about 54% going on to graduate school. This is a significant percentage, and as educators, we need to make sure we prepare physics graduates for such a career path and not assume that they will all go on to graduate schools. This means that we design a program in which they have valuable and usable skills by the time they graduate.


Wednesday, May 10, 2017

Dad Sat In On Student's Physics Class

A dad finally had it with his son's disruptive behavior in a high school physics class, and finally made his threat came true. He sat next to his son during his physics class.

His dad explained that his son 'likes to be the life of the party, which gets him in trouble from time to time.'

'For some reason I said, "hey, if we get another call I'm going to show up in school and sit beside you in class,"' he said. 

Unfortunately for the 17-year-old, that call did come. 

The thing that these news reports didn't clarify is if this student does this in all of his classes. If so, why is the physics teacher the one one reporting? If not, why does this student only does this in his physics class?

Sometime, a lot of information is missing from a news report.


Wednesday, May 03, 2017

The US 2017 Omnibus Budget

Finally, the US Congress has a 2017 budget, and this is the time that I'm glad they didn't follow the disastrous budget proposal of Donald Trump. Both NSF and DOE Office of Science didn't fare badly, with NSF doing worse than I expected. Still, what a surprise to see an increase in funding for HEP after years of neglect and budget cuts.

The Office of Science supports six research programs, and there were winners and losers among them. On the plus side, advanced scientific computing research, which funds much of DOE's supercomputing capabilities, gets a 4.2% increase to $647 million. High energy physics gets a boost of 3.8% to $825 million. Basic energy sciences, which funds work in chemistry, material science, and condensed matter physics and runs most of DOE's large user facilities, gets a bump up of 1.2% to $1.872 billion. Nuclear physics gets a 0.8% raise to $622 million; biological and environmental research inches up 0.5% to $612 million. In contrast, the fusion energy sciences program sees its budget fall a whopping 13.2% to $380 million.

It will continue to be challenging for physics funding during the next foreseeable future, but at least this will not cause a major panic. I've been highly critical of the US Congress on many issues, but I will tip my hat to them this time for standing up to the ridiculous budget that came out of the Trump administration earlier.


Saturday, April 22, 2017

Earth Day 2017 - March For Science Day

Today is the March for Science day to coincide with Earth Day 2017.

Unfortunately, I will not be participating in it, because I'm flying off to start my vacation. However, I have the March for Science t-shirt, and will be wearing it all day. So I may not be with all of you who will be participating it in today, but I'll be there in spirit.

And yes, I have written to my elected officials in Washington DC to let them know how devastating the Trump budget proposal is to science and the economic future of this country. Unfortunately, I may be preaching to the choir, because all 3 of them (2 Senators and 1 Representative of my district) are all Democrats who I expect to oppose the Trump budget as it is anyway.

Anyhow, to those of you who will be marching, YOU GO, BOYS AND GIRLS!


Friday, April 21, 2017

"Physics For Poets" And "Poetry For Physicists"?

Chad Orzel has a very interesting and thought-provoking article that you should read.

What he is arguing is that scientists should learn the mindset of the arts and literature, while those in the humanities and the arts should learn the mindset of science. College courses should not be tailored in such a way that the mindset of the home department is lost, and that a course in math, let's say, has been devolved into something palatable to an arts major.

I especially like his summary at the end:

One of the few good reasons is that a mindset that embraces ambiguity is something useful for scientists to see and explore a bit. By the same token, though, the more rigorous and abstract scientific mindset is something that is equally worthy of being experienced and explored by the more literarily inclined. A world in which physics majors are more comfortable embracing divergent perspectives, and English majors are more comfortable with systematic problem solving would be a better world for everyone.

I think we need to differentiate between changing the mindset versus tailoring a course for a specific need. I've taught a physics class for mainly life science majors. The topics that we covered is almost identical to that offered to engineering/physics majors, with the exception that they do not contain any calculus. But other than that, it has the same rigor and coverage. The thing that made it specific to the group of students is that many of the examples that I used came out of biology and medicine. These were what I used to keep the students' interest, and to show them the relevance of what they were studying to their major area. But the systematic and analytical approach to the subject are still there. In fact, I consciously emphasized the technique and skills in analyzing and solving a problem, and made them as important as the material itself. In other words, this is the "mindset" that Chad Orzel was referring to that we should not lose when the subject is being taught to non-STEM majors.


Wednesday, April 19, 2017

The Mystery Of The Proton Spin

If you are not familiar with the issues surrounding the origin of the proton's spin quantum number, then this article might help.

It explains the reason why we don't believe that the proton spin is due just to the 3 quarks that make up the proton, and in the process, you get an idea how complicated things can be inside a proton.

There are three good reasons that these three components might not add up so simply.
  1. The quarks aren't free, but are bound together inside a small structure: the proton. Confining an object can shift its spin, and all three quarks are very much confined.
  2. There are gluons inside, and gluons spin, too. The gluon spin can effectively "screen" the quark spin over the span of the proton, reducing its effects.
  3. And finally, there are quantum effects that delocalize the quarks, preventing them from being in exactly one place like particles and requiring a more wave-like analysis. These effects can also reduce or alter the proton's overall spin.
Expect the same with a neutron.


Tuesday, April 18, 2017

Testing For The Unruh Effect

A new paper that is to appear in Phys. Rev. Lett. is already getting quite a bit of advanced publicity. In it, the authors proposed a rather simple way to test for the existence of the long-proposed Unruh effect.

Things get even weirder if one observer accelerates. Any observer traveling at a constant speed will measure the temperature of empty space as absolute zero. But an accelerated observer will find the vacuum hotter. At least that's what William Unruh, a theorist at the University British Columbia in Vancouver, Canada, argued in 1976. To a nonaccelerating observer, the vacuum is devoid of particles—so that if he holds a particle detector it will register no clicks. In contrast, Unruh argued, an accelerated observer will detect a fog of photons and other particles, as the number of quantum particles flitting about depends on an observer's motion. The greater the acceleration, the higher the temperature of that fog or "bath."

So obviously, this is a very difficult effect to detect, which explains why we haven't had any evidence for it since it was first proposed in 1976. That is why this new paper is causing heads to turn, because the authors are proposing a test using our existing technology. You may read the two links above to see what they are proposing using our current particle accelerators.

But what is a bit amusing is that there are already skeptics about this methodology of testing, but each camp is arguing it for different reasons.

Skeptics say the experiment won’t work, but they disagree on why. If the situation isproperly analyzed, there is no fog of photons in the accelerated frame, says Detlev Buchholz, a theorist at the University of Göttingen in Germany. "The Unruh gas does not exist!" he says. Nevertheless, Buchholz says, the vacuum will appear hot to an accelerated observer, but because of a kind of friction that arises through the interplay of quantum uncertainty and acceleration. So,the experiment might show the desired effect, but that wouldn't reveal the supposed fog of photons in the accelerating frame.

In contrast, Robert O'Connell, a theorist at Louisiana State University in Baton Rouge, insists that in the accelerated frame there is a fog of photons. However, he contends, it is not possible to draw energy out of that fog to produce extra radiation in the lab frame. O'Connell cites a basic bit of physics called the fluctuation-dissipation theorem, which states that a particle interacting with a heat bath will pump as much energy into the bath as it pulls out. Thus, he argues, Unruh's fog of photons exists, but the experiment should not produce the supposed signal anyway.

If there's one thing that experimenters like, it is to prove theorists wrong! :) So which ever way an experiment on this turns out, it will bound to disprove one group of theorists or another. It's a win-win situation! :)


Monday, April 17, 2017

Hot Atoms Interferometer

This work will not catch media attention because it isn't "sexy", but damn, it is astonishing nevertheless.

Quantum behavior are clearly seen at the macroscopic level because of the problem in maintaining coherence over a substantial length and time scales. One of the ways one can extend such scales is by cooling things down to extremely low temperatures so that decoherence due to thermal scattering is minimized.

So it is with great interest that I read this new paper on atoms interferometer that has been accomplished with "warm" atomic vapor[1]! You also have access to the actual paper from that link.

While the sensitivity of this technique is significantly and unsurprisingly low when compared to cold atoms, it has 2 major advantages:

However, sensitivity is not the only parameter of relevance for applications, and the new scheme offers two important advantages over cold schemes. The first is that it can acquire data at a rate of 10 kHz, in contrast to the typical 1-Hz rate of cold-atom LPAIs. The second advantage is the broader range of accelerations that can be measured with the same setup. This vapor-cell sensor remains operational over an acceleration range of 88g, several times larger than the typical range of cold LPAIs.

The large bandwidth and dynamic range of the instrument built by Biedermann and co-workers may enable applications like inertial navigation in highly vibrating environments, such as spacecraft or airplanes. What’s more, the new scheme, like all LPAIs, has an important advantage over devices like laser or electromechanical gyroscopes: it delivers acceleration measurements that are absolute, without requiring a reference signal. This opens new possibilities for drift-free inertial navigation devices that work even when signals provided by global satellite positioning systems are not available, such as in underwater navigation.

And again, let me highlight the direct and clear application of something that started out as simply appearing to be a purely academic and knowledge-driven curiosity. This really is an application of the principle of superposition in quantum mechanics, i.e. the Schrodinger Cat.

This is an amazing experimental accomplishment.


[1] G. W. Biedermann et al., Phys. Rev. Lett. 118, 163601 (2017).

Sunday, April 16, 2017

Why Is The Weak Force Weak?

Fermilab's Don Lincoln has another fun and informative video on our elementary particles and interactions.


Saturday, April 15, 2017

To Draw Or Not To Draw?

OK, this is a rather lengthy paper, and I thought I would have gotten through it by now, but I just don't have the time. So instead, I'm just going to mention it here and let you people read for yourself.

This paper seems to argue that in cases of supporting diagram that accompanies a physics question (not diagram that actually is essential to the question), this diagram can often be useless, or even a hindrance to the students' ability to solve the problem.

This isn't the same as the student having to draw a diagram in solving a problem. That is not the subject of the paper here. I'm still trying to understand what is actually categorized as "supporting diagram" that accompanies a physics question. Maybe once I have a hang of that, the rest of the paper might be more relevant.

Still, if you're bored, you might have a go at it first ahead of me.


Tuesday, April 11, 2017

Dark Energy Is Not An Illusion

This is a good intro to Dark Energy if you want to know more about it. Even if you don't buy into Ethan Siegel's argument, you at least have a good description of what we know of about Dark Energy at the moment, and why certain explanations for what have been observed have been ruled out.


Monday, April 10, 2017

"Genuine" 3-Photon Interference

I continue to be amazed at the creativity and capability of many of these experiments. This is one such example, and there were two groups that achieved this independently.

Two papers in PRL this week are reporting the first genuine observation of 3-photon interference. This is a purely quantum mechanical effect and not explained by any classical light wave description. In case you are not familiar with the background info that is needed here, the "interference" phenomenon that we are familiar with are really single-photon interference, i.e. one photon capable of making multiple paths and taking multiple slits to produce the interference pattern that we know and love. 2-photon interference has been done and is not that commonly observed. 3-photon interference is even more difficult. That is why this is such a spectacular result coming from 2 different groups.

BTW, this is another experiment that can only be described using the photon picture.


Saturday, April 08, 2017

The Search For Neutrinoless Double Beta Decay

This is a nice and simple article on why we are searching for the neutrinoless double-beta decay.

In this new study, physicists are seeking so-called neutrinoless double-beta decay. Normally, some radioactive atoms' unstable nuclei will lose a neutron via beta decay — the neutron transforms into a proton by releasing an electron and a tiny particle called an electron antineutrino. A mirror image can also occur, in which a proton turns into a neutron, releasing a positron and an electron neutrino — the normal-matter counterpart to the antineutrino. Double-beta decay happens when two electrons and two antineutrinos (the antimatter counterparts of neutrinos) are released: basically, the beta decay happens twice. Scientists have long theorized a neutrinoless version of this process — something that would suggest that the two neutrinos annihilated each other before being released from the atom. Essentially, the neutrino behaves as its own antimatter sibling.

A large portion of high-energy physics experiments around the world are done using neutrinos (Daya Bay, MINOS, NOvA, SuperK, etc...).  It won't surprise me one bit that the another major discovery will be made with these particles.


Thursday, April 06, 2017

Developing Skills Versus Developing Concepts In Undergraduate Physics Labs

This is something that is dear to my heart.

If you have followed this blog for any considerable period of time, you might have encountered a project that I started on my own years ago on here titled "Revamping Intro Physics Lab". In a series of posts (there were 7 posts and one follow-up in total), I made suggestions on the type of lab exercises that I would like to do for students in such a class. The lab experiments are more "free form" and more of a discovery-type exercises, where the students make their own self-discovery without the baggage of knowing the underlying physics before hand.

I explained the rational for wanting to do this, and the most important aspect of it is the "skill" that one might develop in trying to systematically discover the connection and correlation between two different quantities. It is the beginning of finding first the correlations, and then proceed to finding the causation. I consider such skill to be of utmost importance, even more important than trying to make the students understand the underlying physics.

Therefore, it was a pleasant bonus when I read this paper. In it, the authors studied the E-CLASS assessment of students who went through a physics lab that (i) focused on developing lab skills; (ii) focused on developing physics concepts; and (iii) focused on both. What they discovered was that the students that went through a physics lab that focused on developing lab skills ".... showed more expert-like postinstruction responses and more favorable shifts than students in either concepts-focused or both-focused course...." And what is even more interesting is the finding that ".... the
ANCOVA demonstrated that the increase in score associated with skills-focused courses was larger for women than for men, and the difference was large enough to eliminate or even reverse the typical gender gap..... "

Of course, while this is very encouraging, I won't jump up and down (yet) because one has to read their caution at the end of the paper. As with anything, this needs to be looked at and studied a lot more to see if there is a true cause-and-effect factor here, especially on why a focus on lab skills could produce such an effect.

As for me, I'm all for this. In a class where the majority of students are not physics majors, or even in a class of non-science majors, having them understand that our knowledge of the physical universe is based on how we know about the relationship between two separate quantities is very important. That is how we make sense of our world. It is why uncorrelated events, such as how one arranges one's furniture in a room somehow affects one's prosperity doesn't make much sense. None science majors do not have a lot of opportunity for a guided study of the physical world. When we get them, we need to impart as much as we can in the most effective manner. A lab when they learn how to find out how one variable affects another, and the skills the employ to do that, can be the most valuable thing they learn in a physics lesson.


Thursday, March 30, 2017

RIP Alexei Abrikosov

A Nobel Laureate and a giant in the field of theoretical condensed matter physics, Alexei Abrikosov passed away yesterday at the age of 88.

If you have been lucky enough to have met him, you'll see that this was a very gentle man who loved to sit down and chat with you about anything and everything. Once he has met you or have seen you, he never failed to acknowledge you or say hi even if he barely remembered who you are.


Wednesday, March 29, 2017

Oh, The Hypocrisy!

I just came across a bill in the US House of Representative which asked "Do EPA Regulations and Assessments Need to be Based Only on Science That's Publicly Available?" This was introduced by Rep. Lamar Smith who isn't really someone who can't be proud of his anti-science stance in many instances.

The bill passed the House with 228 Yea and 194 Nay.

On the surface, it appears to be something sound. After all, why wouldn't you base something like this on valid science?

But it turns out that it is not that simple. The EPA cannot prevent the introduction of something without any data that are available publicly that it isn't safe.

However, what is very laughable is that this very same people who voted for this bill somehow switch the rules and are the same ones who will dismiss the issue of global warming and the human cause of it, DESPITE all the available data and peer-reviewed science. So why do they accept scientific data in one, but not the other?

Thus, the hypocrisy.


Saturday, March 25, 2017

Experimental Evidence of Indefinite Causal Order

So not only do we have a superposition of observables, we also have a superposition of causality, in which the order of events happening is also in a quantum superposition.

This evidence has been experimentally observed in a new paper published in Science Advances this past week[1]. See the press release here.

What they appear to have developed is this more robust "causal witness" that allows them to sample the superposition without destroying the coherence of the system.

Now, despite the headlines of the press release and the so-called implications, this isn't a result that destroys causality. What I seem to gather here is that, in the case where there is an uncertainty on which event occurs first, i.e. the causal order itself is in a superposition, then it is only upon a measurement will we get to know which comes first, the chicken or the egg. After that, things follows as usual. This experiment shows evidence that, yes, chicken followed by egg, and egg followed by chicken, are both there before a measurement.


[1] G. Rubino et al., Sci. Adv., 3, e1602589 (2017).

Saturday, March 18, 2017

Minutephysics's "How To Teleport Schrodinger's Cat"

It used to be that Minute Physics videos are roughly.... a minute long. But that is no longer true. Here, he tackles quantum entanglement via trying an illustration of teleporting the infamous Schrodinger's Cat.

I'm sorry, but how many of you managed to follow this?

I think I'll stick to my "Quantum Entanglement for Dummies". :)


Thursday, March 16, 2017

DOE's Office Of Science Faces Disastrous Cuts

The first Trump budget proposal presents a major disaster for scientific funding and especially to DOE Office of Science budget.

President Donald Trump's first budget request to Congress, to be released at 7 a.m. Thursday, will call for cutting the 2018 budget of the National Institutes of Health (NIH) by $6 billion, or nearly 20%, according to sources familiar with the proposal. The Department of Energy's (DOE's) Office of Science would lose $900 million, or nearly 20% of its $5 billion budget. The proposal also calls for deep cuts to the research programs at the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA), and a 5% cut to NASA's earth science budget. And it would eliminate DOE's roughly $300 million Advanced Research Projects Agency-Energy.

I don't know in what sense this will make America "great again". It is certainly not in science, that's for sure.


Born Rule Confirmed To An Even Tighter Bound

I must say that I might have missed this paper if Chad Orzel didn't mention it in his article. Here, he highlighted a paper by Kauten et al. from New Journal of Physics (open access) that performed 5-slit interference test with the purpose of detecting any higher-order interference beyond that predicted by the Born rule. They found none, and imposed a tighter bound on any higher-order effects.

As Orzel reported:

That's what the NJP paper linked above is about. One of the ways you might get the Born rule from some deeper principle would be to have it be merely an approximation to some more fundamental structure. That, in turn, might very well involve a procedure other than "squaring" the wavefunction to get the probability of various measurement outcomes. In which case, you would expect to see some higher-order contributions to the probability-- the wavefunction cubed, say, or to the fourth power.
Sadly, for fans of variant models of quantum probability, what they actually do is the latter. They don't see any deviation from the ordinary Born rule, and can say with confidence that all the higher-order contributions are zero, to something like a hundredth of a percent.

Of course, this won't stop the continuation of the search, because that is what we do. But it is amazing that QM has withstood numerous challenges throughout its history.


Sunday, March 12, 2017

The Weak Nuclear Force

I'm going to highlight this latest video by Fermilab's Don Lincoln for a number of reasons. First, the video:

Second, this is one video packed with a number of very important and illuminating stuff. First he explains about the concept of "spin" in both the classical and quantum picture. This is important because to many people who do not study physics, the word "spin" conjures up a certain idea that is not correct when applied to quantum mechanics. So this video hopefully will enlighten the idea a bit.

But what is more fascinating here is his brief historical overview of the first proposal of the connection between the weak interaction and spin, and how Chien Shiung Wu should have received the Nobel Prize for this with Yang and Lee. This might be another case of gender bias that prevented a brilliant Chinese female physicist from a deserving prize. Considering the time that she lived in and the societal and cultural obstacles that she had to overcome, she simply had to be just too outstanding to be able to get to where she was.

So this is one terrific video all around, and you get to learn a bit about the weak interaction to boot!


Friday, March 10, 2017

APS Endorses March Of Science

The American Physical Society has unanimously endorsed the upcoming March for Science.

I'll be flying out of town on that exact day of the March, so I had decided a while back to simply contribute to it. I get the sentiment and the mission. However, I'm skeptical on the degree of impact that it will make. It will get publicity, and maybe focuses some of the issues, especially funding in the physical sciences, to the public.

But for it to take hold, it can't simply be a one-day event, and as much as I've involved myself in many outreach programs, I still see a lot of misinformation and ignorance among the public about science, and physics in particular.

Here's something I've always wanted to do, but never followed through and lack the resources to do it. How about we do something similar to a family tree genealogy. But instead of tracing human ancestors, we focus on technology "family tree". I've always wanted to start with the iPhone capacitive touch screen. Trace back up the technology and scientific roots of this component. I bet you there were a lot of various material science, engineering, and physics that were part of various patents, published papers, etc. that eventually gave birth to this touch screen.

What it will do is show the public that what they have so gotten used to came out of very basic research in physics and engineering. We can even list out all the funding agencies that were part of the direct line of "descendants" of the device and show them how money spent on basic science actually became a major component of our economy.

By doing this, you don't beat around the bush. You TELL the public what they can actually get out of an investment in science with a concrete example. And it may come out of areas that they never made connection before.


Thursday, March 09, 2017

Time Crystal

This is quite an astonishing feat. It was only back in 2012 that Frank Wilczek proposed the possibility of a "time crystal", where a certain symmetry repeats in time, rather than in space. This was followed soon enough by a formal proposal for such a crystal. And now, we appear to have two experimental evidence.[1,2]

Potter is part of the team led by researchers at the University of Maryland who successfully created the first time crystal from ions, or electrically charged atoms, of the element ytterbium. By applying just the right electrical field, the researchers levitated 10 of these ions above a surface like a magician’s assistant. Next, they whacked the atoms with a laser pulse, causing them to flip head over heels. Then they hit them again and again in a regular rhythm. That set up a pattern of flips that repeated in time.

Crucially, Potter noted, the pattern of atom flips repeated only half as fast as the laser pulses. This would be like pounding on a bunch of piano keys twice a second and notes coming out only once a second. This weird quantum behavior was a signature that he and his colleagues predicted, and helped confirm that the result was indeed a time crystal.

Like I said, this is quite a feat to come up with a scheme to be able to create and test this.


[1] J. Zhang et al., Nature 543, 217 (2017).
[2] S. Choi et al., Nature 543, 221 (2017).

Monday, March 06, 2017

The Race To Make Quantum Computers

We still don't quite have a truly-accepted working model, even from D-Wave. So it is interesting to see this latest news of both Google and IBM launching projects to produce and eventually sell these quantum computers.

The folks from Google's Quantum AI Laboratory wrote a comment in Nature, while IBM's intention is reported in the news.

With the Chinese company Alibaba collaborating with the Chinese Academy of Sciences to also go into this area, the next several years will be fascinating to watch.


Sunday, March 05, 2017

Raman Spectroscopy Used To Detect Skin Cancer

I found this piece of news while reading the Flash Physics section on Physics World. And if you've followed this blog for a while, you know that I will highlight this without any shame.

Chalk this up to another important application of something that came out of physics research and subsequently finds a usefulness in medical diagnostics. Many of us in Material Science/Condensed Matter Physics/Chemistry are aware of Raman spectroscopy techniques in the study of molecules and materials. It has been a common technique in these areas of study for many, many years since its first proposal in.... get this.... 1929![1]

So already it is a very useful technique in chemistry and material science. But now it has found another application, in medical diagnostics. It turns out that this same technique can be used to find hard-to-detect skin cancer.[2]

Abstract: Melanoma is the most deadly form of skin cancer with a yearly global incidence over 232,000 patients. Individuals with fair skin and red hair exhibit the highest risk for developing melanoma, with evidence suggesting the red/blond pigment known as pheomelanin may elevate melanoma risk through both UV radiation-dependent and -independent mechanisms. Although the ability to identify, characterize, and monitor pheomelanin within skin is vital for improving our understanding of the underlying biology of these lesions, no tools exist for real-time, in vivo detection of the pigment. Here we show that the distribution of pheomelanin in cells and tissues can be visually characterized non-destructively and noninvasively in vivo with coherent anti-Stokes Raman scattering (CARS) microscopy, a label-free vibrational imaging technique. We validated our CARS imaging strategy in vitro to in vivo with synthetic pheomelanin, isolated melanocytes, and the Mc1re/e, red-haired mouse model. Nests of pheomelanotic melanocytes were observed in the red-haired animals, but not in the genetically matched Mc1re/e; Tyrc/c (“albino-red-haired”) mice. Importantly, samples from human amelanotic melanomas subjected to CARS imaging exhibited strong pheomelanotic signals. This is the first time, to our knowledge, that pheomelanin has been visualized and spatially localized in melanocytes, skin, and human amelanotic melanomas.

This is another example where experimental technique in physics EVENTUALLY finds applications elsewhere. I've highlighted other examples of this, with this being the most recent one before this post. Also note the "gestation" period between when this method was first proposed, and then when it became common in physics, to when it found other applications outside of its original main use. This is not new. Look at how long between when NMR became a common technique to when it evolved into MRI. Medical technology would not have evolved and advanced without a much earlier advancement in physics and physics experiments!

What I'm trying to emphasize here is that you may not feel the pain NOW when you cut funding to basic science research. But the pain WILL be felt later, by your children and grandchildren, because it takes years for what we work on now to become a useful technique elsewhere. That physics that we used to detect some esoteric particles that you don't care about may just one day be the diagnostic tool that saves someone's life!


[1]C.V. Raman and K.S. Krishnan, The optical analog of the Compton effect, Nature 121, 711 (1928); G. Landsberg and L. Mandelstam, A novel effect of light scattering in crystals, Naturwissenschaften 16, 557 (1928); C.V. Raman and K.S. Khrishnan, The production of new radiations by light scattering, Proc. Roy. Soc. (London) 122, 23, (1929).
[2] H. Wang et al., Scientific Reports 6, Article number: 37986 (2016). Paper is open access.

Friday, March 03, 2017

The Laws Of Life

Physics Today has made the article "The Laws of Life" from the March 2017 issue available for free. In the article, astrobiologist Charles Cockell describes how the fundamental laws of physics influences the forms of life on Earth.


Thursday, March 02, 2017

Online Homework Assignment - Are They Effective?

I read this news with a bit of interest. It appears that a student at Brooklyn College is gathering petition signatures to end the use of something called "Expert TA". This sounds like an online HW assignment that has been used by the physics department at that school.

Each homework assignment has about 15 to 20 questions, but each question has multiple parts. The number of questions, attempts, and credit reductions for wrong answers is dependent on the instructor. The instructor has the option to deduct points when a student accesses hints, and feedbacks. Expert TA consists of two types of feedback: Direct and Socratic. Direct feedback let’s a student know exactly what they did wrong, while a Socratic feedback poses a question such as “Have you considered the following?” Though this may sound quite useful, students feel otherwise.

It would be a bit more informative, and more persuasive, if a specific example on how this online tool is ineffective. For example, the best complaint that I can read from the report said this:

“The problem doesn’t lie in the concepts,” said Manasherov. “It’s more like how can we navigate this website and give the right answer—the right answer meaning what the website is looking for.”
“The hints aren’t always helpful and the feedback isn’t always clear either,” said sophomore Melissa Beagle. “And they only give you a limited number of tries, which doesn’t really help.”

There types of comments are not really that informative. It is similar to you telling your doctor "I just don't feel right" without giving any specific description of what is wrong.

I have a bit of experience in dealing with such online HW assignment. I've written about it in an earlier blog post on here. In fact, I will also add that I actually worked though the online HW assignment that my students would be facing, and I can see and experience what they will have to go through. I can see good points and bad points about it. But as I've said in that earlier blog post, the biggest issue I have about online anything is the question on whether the student doing it had any external help. But that is an issue that would be present in the traditional, written HW assignment as well since the student can easily copy or had help in completing the assignment. Except for one major difference.

You see, traditional written HW assignment requires that the student show work in arriving at an answer. You normally do not see that with online assignment. From what I can gather when chatting with students, all they care about is getting the right answer to type into those answer boxes. Often time, their "work" in deriving the answer is either done haphazardly, or not as complete and clear as one that would be required in a written HW assignment that is being submitted for grading. So in some instances, these students really could not recall what they did right and what they did wrong.

I'm still divided on my opinion regarding this type of HW assignment. I see some value in it. It certainly makes the job of an instructor a bit easier. But I also see how this can make the student being lazy to really learn what is needed in solving a particular problem.

If you have gone through such online HW assignment, or if you're an instructor whose course use such a thing, I'd like to hear from you.


Wednesday, March 01, 2017

Lenz's Law Is A "Quirk" Of Physics?

I've never heard of "fidget toys" before till after I read this piece. This one is describing a fidget toy that supposedly has "antigravity" effects that simulates the low gravitational field of the moon and Mars, making the object falls slower. The toy is called Moondrop.

Based around the principle of Lenz’s law — which *deep breath* states that the current induced in a circuit due to a change or motion in a magnetic field will create a field that opposes the charge that produced it — Moondrop is a gravity-defying fidget desk toy that imitates the differential gravitational free fall on Mars and the Moon.

OK, so immediately, there are two issues here:

1. Lenz's law is not a "quirk" of physics, as stated in the title of this report. In fact, it is quite a central phenomenon in physics that is responsible for power generators to create our household electricity! So how is that a "quirk"?

2. Any physics undergraduate can spot the error in the definition given for Lenz's law. Lenz's law is the effect whereby a magnetic field is generated to oppose the CHANGE in the external magnetic field. Maybe there is a typo in the definition given, that it should have been "change" instead of "charge". That one word (or in this case, one letter) change results in an astounding difference in the physics.

If I recall correctly, there are magnetic breaks that use the same principle. I remember reading something on roller coaster rides that made use of such magnetic breaks, so that it ensure that the vehicle can still be safely stopped even when the power goes off.

So the application of Lenz's law is neither that highly unusual, nor is it a quirk of physics.

Or maybe the writer meant a "quark" of physics?


Monday, February 27, 2017

Mildred Dresselhaus In GE Commercial

So, if you did watch the 2017 Academy Awards last night and didn't run away during the commercials (at least here in the US), you may have seen the GE commercial to celebrate women in science that featured the late Millie Dresselhaus. She, of course, passed away on Feb 20, so this commercial has become a tribute to her and left a legacy to encourage women to enter science, and physics in particular.

In the commercial, GE asks what it would be like if we treated women scientists like celebrities and deserving of the accolades and recognition like any pop celebrities.

If you missed it, here's the commercial once again:


Friday, February 24, 2017

SRF Technology For Particle Accelerator

Here's a brief video on the superconducting radiofrequency (SRF) cavity for particle accelerators.

I wouldn't call it "better particle accelerator" as in the video, because SRF cavity with Nb currently have a limit of 20-30 MV/m gradient, whereas normal conducting cavity can reach 100 MV/m or even higher at 1.3 GHz.

Still, these SRF cavities have properties that are "better" in other characteristics, especially in the Q-value. And in a number of applications, these cavities are the most efficient accelerating structures.

The technology for SRF is still evolving, especially in whether there is a need for superconducting photocathode sources for SRF guns. So there's a lot more to do in this field of study, both in terms of the physics, and in engineering.


Wednesday, February 22, 2017

Dark Energy - What Is It?

I've posted many articles on Dark Energy. But here's another one aimed at the general public that actually is quite instructive. It describes not only why we think there is dark energy, but also the puzzling phenomenon of the apparent "switching" between one regime to another.

Please take note that, while it seems that this idea has been floating around for a while, the study of Dark Energy is very much still in its infancy. The general public may find it hard to understand, but we really do need a lot more experimental observations on this, and that is easier said than done. Detection of this is not easy and requires years of design and work, and not to mention, funding!


Mildred Dresselhaus

An absolute giant in physics, and especially on condensed matter physics, Mildred Dresselhaus passed away recently at the age of 86.

Besides all of her accomplishments in physics, she was truly a trail-blazer for women in science, and in physics in particular with all of her "firsts". She, along with Vera Rubin and Deborah Jin, were the strongest candidates to break the drought of women winning the Nobel Prize in physics. Now we have lost all three.


Monday, February 20, 2017

Will SMASH Be A Smash?

Here comes a new extension to the Standard Model!

A new theoretical paper in PRL has extended the Standard Model of elementary particles to include new particles, and tries to mash different ideas and theories into this new standard model called SMASH - Standard Model Axion See-saw Higgs portal inflation (yeah, it's a mouthful).

SMASH adds six new particles to the seventeen fundamental particles of the standard model. The particles are three heavy right-handed neutrinos, a color triplet fermion, a particle called rho that both gives mass to the right-handed neutrinos and drives cosmic inflation together with the Higgs boson, and an axion, which is a promising dark matter candidate. With these six particles, SMASH does five things: produces the matter–antimatter imbalance in the Universe; creates the mysterious tiny masses of the known left-handed neutrinos; explains an unusual symmetry of the strong interaction that binds quarks in nuclei; accounts for the origin of dark matter; and explains inflation.

Of course, with ANY theoretical ideas, which often has long gestation period, a lot of patient waiting and testing will have to be done to verify many of its predictions. But this seems to create quite an excitement in revamping the Standard Model.


Friday, February 10, 2017

Politics And How It Affects US Physics Research

This is a very poignant article on how politics have impacted Physics research in the US for the past decade or so. Reading this can be very disheartening, so be forewarned!

The one impact that I had mentioned a few years ago is also mentioned here, and that had to do with not only the impact of budget cuts, but also the devastating impact of a budget cut AFTER several months of continuing resolution of the US budget.

I remember one year on December first, we had a faculty meeting where we heard funding levels would be up 10% across the board — a miraculous state of affairs after multiple years of flat-flat budgets (meaning no budgetary increases for cost of living adjustments — which ultimately means it’s a 3% cut). At our next faculty meeting on December fifteenth, we heard that it was going to be a flat-flat year — par for the course. On December nineteenth, we hear the news that there was a 30% cut in funding levels.

Now losing 30% of your budget is very bad in all circumstances, but you have to remember that the fiscal year begins on October first. The only thing you can do is fire people since all the funding is salaries and to do that legally takes about six weeks and with the holiday shutdown, that meant that this was a 50% cut in that year’s funding. There was some carry-forward and other budgetary manipulations, but 30% of the lab was lost, about three or four hundred if I recall. The lab tried to shield career scientists and engineers, but still many dozens were let go.

In a post from a few years ago, I showed the simple mathematics on why this effect is devastating for science research.

Unfortunately, I don't see this changing anytime soon. As the author of this article wrote, science in general does not have a "constituent". No politician pays a political price for not funding science, or wanting funding for science to be cut, unlike cutting funding for social programs, military, or other entitlements.

Regardless of who is in office or who is in control of the US Congress, it is business as usual.


Wednesday, February 08, 2017

Gamma-Ray Imaging At Fukushima Plant

I mentioned earlier of the muon tomography imaging that was done at the damaged reactor at Fukushima, and tried to highlight this as an example of an application that came out of high energy physics. This time a gamma-ray imaging spectroscopy was performed at the same location to pin-point contamination sites.

But as with the muon tomography case, I want to highlight an important fact that many people might miss.

To address these issues of existing methods and visualize the Cs contamination, we have developed and employed an Electron-Tracking Compton Camera (ETCC). ETCCs were originally developed to observe nuclear gammas from celestial objects in MeV astronomy, but have been applied in wider  fields, including medical imaging and environmental monitoring.

So now we have an example of a device that was first developed for astronomical observation, but has found applications elsewhere.

This is extremely important to keep in mind. Experimental physics often pushes the boundaries of technology. We need better detectors, more sensitive devices, better handling of huge amount of data very quickly, etc...etc. Hardware have to be developed to do all this, and the technology from these scientific experiments often trickle down other applications. Look at all of medical technology, which practically owes everything to physics.

This impact from physics must be repeated over and over again to the public, because a significant majority of them are ignorant of it. It is why I will continue to pick out application like this and highlight it in case it is missed.


Tuesday, February 07, 2017

Being Slowly Eaten For A Decade

This is the definition of the ultimate torture.

It appears that this black hole has been slowly feasting on this dead star for at least a decade. Ouch!

"We have witnessed a star's spectacular and prolonged demise," said Dacheng Lin, a research scientist at UNH's Space Science Center and the study's lead author. "Dozens of these so-called tidal disruption events have been detected since the 1990s, but none that remained bright for nearly as long as this one."

The arXiv version of this paper can be found here.

Moral of the story: Never piss off a black hole!


Monday, February 06, 2017

Photons Steal Momentum From Sun's Surface?

We all know that photons carry momentum. But who knew that photons leaving the sun's surface actually may cause the varying rotation of the sun with its radius?

This new paper from PRL makes the confirmation that the sun's surface has a greater drag and a slower angular rotation than the deeper part of the sun. But not only that, it also proposes that this slowdown is due to the loss of momentum when photons are emitted from the plasma on the surface.
Kuhn and his colleagues also developed a model to explain their data. Photons are created in the Sun’s dense core, where the plasma behaves nearly like a solid. As they diffuse outward, they experience plasma that is less dense, faster flowing, and subject to turbulent convection. As the photons interact with the moving plasma, they exchange angular momentum with it. Inside the Sun, the photons scatter so frequently that they lose as much angular momentum as they gain. But in the photosphere, where photons escape the Sun, the plasma-photon momentum transfer results in a net loss of the plasma’s angular momentum, as photons radiate away. The effect on the plasma is a mild braking force, which slows its overall rotation. This braking is most effective at the outer edge of the Sun, where the plasma density is at its lowest.
Those photons! They can create havoc!