Tuesday, March 12, 2019

PIP-II Upgrade At Fermilab

Don Lincoln explains why the PIP-II upgrade at Fermilab will take the accelerator facility to the next level.

The video actually explains a bit about how particle accelerator works, and the type of improvement that is being planned for.


Sunday, February 24, 2019

Brian Greene on Science, Religion, Hawking, and Trump

I've only found this video recently, even though it is almost a year old already, but it is still interesting, and funny. And strangely enough, he shares my view on religion, especially the fact that people seem to ignore that there are so many of them, each claiming to be the "truth". They all can't be, and thus, the biggest threat and challenge against a religion is the existence of another religion.


Thursday, February 21, 2019

Why Does Light Slow Down In A Material?

Don Lincoln tackles one of those internet/online FAQs. This time, it is an explanation on why light slows down in water, or in matter in general.

Certainly, this is the explanation many of us know when we were in school. However, most of the questions that I get regarding this phenomenon came from people who want to know the explanation at the "quantum" level, i.e. if light is made up of photons, how does one explain this phenomenon in the photon picture? That is the origin of the two "wrong" explanations that he pointed out in the video, i.e. people wanting to use "photons" to explain what is going on here.

Actually, Don Lincoln could have gone a bit further with the explanation and included the fact that this explanation can account for why the speed of light (and index of refraction) inside a material is dependent on the frequency of the light entering the material.

Strangely enough, this actually reminded me of a puzzle that I had when I first encountered this explanation. If the electrons (or the electric dipoles) inside the material oscillate and create an additional EM wave, and the superposition of these two waves give rise to the final wave that appears to move slower in the material, then what stops this second EM wave from leaving the material? Is it only confined within the material? Do we detect "leakage" of this second or any additional wave due to things oscillating in the material? Because the second wave has a different wavelength, it will be refracted differently at the boundary, so it will no longer be aligned with the original wave after they leave the material, if they all leave the material.

Anyone knows?

Edit: Funny enough, and maybe because I watched this video, YouTube gave me an old MinutePhysics video that used the bouncing light particle explanation that Don Lincoln says isn't correct.


Sunday, February 17, 2019

Self-Propulsion of Inverse Leidenfrost Droplets Explained

I was not familiar at all with the Leidenfrost effect, even though I've heard the name. So when I read the article, I was fascinated by it. Unlike other people who want find the answers to the mysteries of the universe, etc... I went into physics because I was more curious about these small, little puzzles that, in the end, could have big impact and big outcome elsewhere. So thie Leidenfrost levitation phenomenon is right up my alley, and I'm kicking myself for not reading up on it sooner than this (or maybe they mentioned it in my advanced classical mechanics graduate course, and I overlooked it).

Anyhow, it appears that there is an inverse Leidenfrost self-propulsion, and a group of physicsts have managed to provide an explanation for it. the article describes both the Leidenfrost and inverse Leidenfrost propulsion, so you may read it for yourself. The research work[1], unfortunately, is currently available only via subscription. So you either need one for yourself, or log in to an organization that has site-wide access to it.

And look at the possible application for this seemingly mundane effect that grew out of a basic curiosity:

Gauthier’s team believe the effect could be used to develop efficient techniques for freezing and transporting biological materials including cells and proteins. With the help of simulations, they hope that this transport could occur with no risk of contamination or heat degradation to the materials.


[1] A. Gauthier et al. PNAS v.116, p.1174

Monday, February 04, 2019

When Condensed Matter Physics Became King

If you are one of those, or know one of those, who think Physics is only the LHC and high-energy physics, and String Theory, etc., you need to read this excellent article.

When I first read it in my hard-copy version of Physics Today, the first thing that came across my mind after I put it down is that this should be a must-read for the general public, but especially to high-school students and all of those bushy-tailed and bright-eyed incoming undergraduate student in physics. This is because the need to be introduced to a field of study in physics that has become the "king" in physics. Luckily, someone pointed out to me that this article is available online.

Reading the article, it was hard, but understandable, to imagine the resistance that was there in incorporating the "applied" side of physics into a physics professional organization. But it was at a time when physics was still seen as something esoteric with the grandiose idea of "understanding our world" in a very narrow sense.

Solid state’s odd constitution reflected changing attitudes about physics, especially with respect to applied and industrial research. A widespread notion in the physics community held that “physics” referred to natural phenomena and “physicist” to someone who deduced the rules governing them—making applied or industrial researchers nonphysicists almost by definition. But suspicion of that view grew around midcentury. Stanford University’s William Hansen, whose own applied work led to the development of the klystron (a microwave-amplifying vacuum tube), reacted to his colleague David Webster’s suggestion in 1943 that physics was defined by the pursuit of natural physical laws: “It would seem that your criterion sets the sights terribly high. How many physicists do you know who have discovered a law of nature? … It seems to me, this privilege is given only to a very few of us. Nevertheless the work of the rest is of value.”

Luckily, the APS did form the Division of Solid State Physics, and it quickly exploded from there.

By the early 1960s, the DSSP had become—and has remained since—the largest division of APS. By 1970, following a membership drive at APS meetings, the DSSP enrolled more than 10% of the society’s members. It would reach a maximum of just shy of 25% in 1989. Membership in the DSSP has regularly outstripped the division of particles and fields, the next largest every year since 1974, by factors of between 1.5 and 2.
This is a point that many people outside of physics do not realize. They, and the media, often make broad statements about physics and physicists based on what is happening in, say, elementary particle physics, or String, or many of those other fields, when in reality, those areas of physics are not even an valid representation of the field of physics because they are not the majority. Using, say, what is going on in high-energy physics to represent the whole field of physics is similar to using the city of Los Angeles as a valid representation of the United States. It is neither correct nor accurate!

This field, that has now morphed into Condensed Matter Physics, is vibrant, and encompassed such a huge variety of studies, that the amount of work coming out of it each week or each month is mindboggling. It is the only field of physics that has two separate section on Physical Review Letters, The Physical Review B comes out four (FOUR) times a month. Only Phys. Rev. D has more than one edition per month (twice a month). The APS March Meeting, where the Division of Condensed Matter Physics participatesin, continues to be the biggest giant of annual physics conference in the world.

Everything about this field of study is big, important, high-impact, wide-ranging, and fundamental. But of course, as I've said multiple times on here, it isn't sexy for most of the public and the media. So it never because the poster boy for physics, even if they make up the largest percentage of practicing physicist. Doug Natelson said it as much in commenting about condensed matter physics's image problem:

Condensed matter also faces a perceived shortfall in inherent excitement. Black holes sound like science fiction. The pursuit of the ultimate reductionist building blocks, whether through string theory, loop quantum gravity, or enormous particle accelerators, carries obvious profundity. Those topics are also connected historically to the birth of quantum mechanics and the revelation of the power of the atom, when physicists released primal forces that altered both our intellectual place in the world and the global balance of power.

Compared with this heady stuff, condensed matter can sound like weak sauce: “Sure, they study the first instants after the Big Bang, but we can tell you why copper is shiny.” The inferiority complex that this can engender leads to that old standby: claims of technological relevance (for example, “this advance will eventually let us make better computers”). A trajectory toward applications is fine, but that tends not to move the needle for most of the public, especially when many breathless media claims of technological advances don’t seem to pan out.

It doesn’t have to be this way. It is possible to present condensed-matter physics as interesting, compelling, and even inspiring. Emergence, universality, and symmetry are powerful, amazing ideas. The same essential physics that holds up a white dwarf star is a key ingredient in what makes solids solid, whether we’re talking about a diamond or a block of plastic. Individual electrons seem simple, but put many of them together with a magnetic field in the right 2D environment and presto: excitations with fractional charges. Want electrons to act like ultrarelativistic particles, or act like their own antiparticles, or act like spinning tops pointing in the direction of their motion, or pair up and act together coherently? No problem, with the right crystal lattice. This isn’t dirt physics, and it isn’t squalid.

It is why I keep harping to the historical fact of Phil Anderson's work on a condensed matter system that became the impetus for the Higgs mechanism in elementary particle, and how some of the most exotic consequences of QFT are found in complex material (Majorana fermions, magnetic monopoles, etc...etc.).

So if your view of physics has been just the String theory, the LHC, etc... well, keep them, but include its BIG and more influential brother, the condensed matter physics, that not only has quite a number of important, fundamental stuff, but also has a direct impact on your everyday lives. It truly is the "King" of physics.


Friday, February 01, 2019

Standing Out From The Crowd In Large Collaboration

As someone who has never been involved in these huge collaborations that we see in high energy physics, I've often wondered how a graduate student or a postdoc make a name for themselves. If you are one of dozens, even hundreds, of authors in a paper, how do you get recognized?

It seems that this issue has finally been addressed by the high energy physics community, at least in Europe. A working group has been established to look into ways for students, postdocs, and early-career researches to stand out from the crowd and have their effort recognized individually.

To fully exploit the potential of large collaborations, we need to bring every single person to maximum effectiveness by motivating and stimulating individual recognition and career choices. With this in mind, in spring 2018 the European Committee for Future Accelerators (ECFA) established a working group to investigate what the community thinks about individual recognition in large collaborations. Following an initial survey addressing leaders of several CERN and CERN-recognised experiments, a community-wide survey closed on 26 October with a total of 1347 responses. 

Still, the article does not clarify on exactly how these individual recognition can be done. I'd be interested to hear how they are going to do this.


Wednesday, January 23, 2019


Do you ever want to know about US Fermi National Accelerator Laboratory, or Fermilab?

Don Lincoln finally has made a video on everything you want to know about Fermilab, especially if you think that they don't do much anymore nowadays now that the Tevatron is long gone.

As someone who has visited there numerous times and collaborated with scientists and engineers that this facility, it is a neat place to visit if you have the chance.


Monday, January 21, 2019

Tommaso Dorigo's "False Claims In Particle Physics"

Hey, you should read this blog post by Tommaso Dorigo. It touches upon many of the myths regarding particle physics, especially the hype surrounding the name "god particle", as if that means something.

I've touched upon some of the issues he brought up. I think many of us who are active online and deal with the media and the public tend to see and observe the same thing, the same mistakes, and misinformation that are being put in print. One can only hope that by repeatedly pointing out such myths and why they are wrong, the message will slowly seep into the public consciousness.

I just wish it is seeping through faster.


Sunday, January 20, 2019

Negative Capacitance in Ferroelectric Material Finally Found

I love this sort of reports, because it is based on a material that has been discovered for a long time and rather common, it is based on a consequence of a theory, it has both direct applications and a rich physics, and finally, it has an amazing resemblance to what many physics students have seen in textbooks.

A group of researchers have finally confirmed the existence of negative capacitance in ferroelectric material haffnium zirconium oxide Hf0.5Zr0.5O2. (You may access the Nature paper here or from that news article).

Researchers led by Michael Hoffmann have now measured the double-well energy landscape in a thin layer of ferroelectric Hf0.5Zr0.5Ofor the first time and so confirmed that the material indeed has negative capacitance. To do this, they first fabricated capacitors with a thin dielectric layer on top of the ferroelectric. They then applied very short voltage pulses to the electrodes of the capacitor, while measuring both the voltage and the charge on it with an oscilloscope.

“Since we already knew the capacitance of the dielectric layer from separate experiments, we were then able to calculate the polarization and electric field in the ferroelectric layer,” Hoffmann tells Physics World. “We then calculated the double-well energy landscape by integrating the electric field with respect to the polarization.”

Of course, there are plenty of potential applications for something like this.

One of the most promising applications utilising negative capacitance are electronic circuits with much lower power dissipation that could be used to build more energy efficient devices than any that are possible today, he adds. “We are working on making such devices, but it will also be very important to design further experiments to probe the negative capacitance region in the structures we made so far to help improve our understanding of the fundamental physics of ferroelectrics.”

But the most interesting part for me is that, if you look at Fig. 1 of the Nature paper, the double-well structure is something that many of us former and current physics students may have seen. I know that I remember solving this double-well problem in my graduate level QM class. Of course, we were solving it energy-versus-space dimension, instead of the energy-versus-polarization dimension as shown in the figure.


Wednesday, January 16, 2019

Crisis? What Crisis?

Chad Orzel has posted a fun piece that really tries to clarified all the brouhaha in many circles about a "crisis" that many are presuming to be widespread. The crisis in question is the lack of "beyond the standard model" discovery in elementary particle physics, and the issue that many elementary particle theorists seem to think that a theory that is based on solid foundation and elegance are sufficient to be taken seriously.

I find this very frustrating, because physics as a whole is not in crisis. The "crisis" being described is real, but it affects only the subset of physics that deals with fundamental particles and fields, particularly on the theory side. (Experimental physicists in those areas aren't making dramatic discoveries, but they are generating data and pushing their experiments forward, so they're a little happier than their theoretical colleagues...)

The problems of theoretical high energy physics, though, do not greatly afflict physicists working in much of the rest of the discipline. While this might be a time of crisis for particle theorists, it's arguably never been a better time to be a physicist in most of the rest of the field. There are exciting discoveries being made, and new technologies pushing the frontiers of physics forward in a wide range of subfields.

This is a common frustration, because elementary particle physics is not even the biggest subfield of physics (condensed matter physics is), but yet, it makes a lot of noise, and the media+public seem to pay more attention to such noises. So whenever something rocks this field, people often tend to think that this permeates through the entire field of physics. This is utterly false!

Orzel has listed several outstanding and amazing discoveries and advancements in condensed matter. There are more! The study of topological insulators continues to be extremely hot and appear to be not only interesting for application, but also as a "playground" for exotic quantum field theory scenarios.

I've said it many times, and I'll say it again. Physics isn't just the Higgs or the LHC. It is also your iphone, your MRI, your WiFi, your CT scan, etc....etc.


Wednesday, January 09, 2019

150 Years of the Periodic Table

Hey, I'll admit it. I wouldn't have known about this 150th birthday of the periodic table if it weren't for this news article. ScienceNews has a lot more detail on the history and background of Mendeleev, who came up with the first periodic table.

Unfortunately, there might be a chance for a bit of inaccuracy here from the Miami Herald news article.

The periodic table lists the elements in order of their atomic weights, but when Mendeleev was classifying them, no one even knew what was inside these tiny things called atoms. 

While it is true that, historically, Mendeleev originally arranged the elements with respect to each atom's atomic weight (since no one knew that was inside these atoms at that time), the periodic table that we have now lists the elements in order of their atomic number, i.e. the number of protons in the element. This is because we now know that an element of a particular atomic number may have several different isotopes (atomic weights). So the atomic weight is not a unique number for an element, but atomic number is. That is why the period table is arrange in order of the element's atomic number.

In any case, Happy 150th Year, Periodic Table!


Tuesday, January 01, 2019

Rumors Emerge Following Prominent Physicist's Death

First of all, RIP Shoucheng Zhang.

It is unfortunate that my first post of the New Year is about a sad news from Dec. of 2018. Prominent Standford physicist, Shoucheng Zhang passed away in early Dec. of an apparent suicide. He was only 55, and according to his family, has been suffering from bouts of depression. But what triggers this report is the possible connection between him and US-China relation, which, btw, is purely a rumor right now.

Zhang was originally recruited in 2008 under the Thousand Talents program — a CCP effort to attract top scientists from overseas to work in China — to conduct research at Tsinghua University in Beijing. Zhang was active in helping U.S.-trained Chinese researchers return home, and expressed his desire to help “bring back the front-lines of research to China” in a recent interview with Chinese news portal Sina.  

Zhang’s venture capital firm Digital Horizon Capital (DHVC), formerly known as Danhua Capital, was recently linked to China’s “Made in China 2025” technology dominance program in a Nov. 30 U.S. Trade Representative (USTR) report. According to the report, venture capital firms like DHVC are ultimately aimed at allowing China to access vital technology from U.S. startups. Zhang’s firm lists 113 U.S. companies in its portfolio, most falling within emerging sectors that the Chinese government has identified as strategic priorities. 

The “Made in China 2025” program combines economic espionage and aggressive business acquisitions to aid China’s quest to become a tech manufacturing superpower, the USTR report continues. The program was launched in 2015 and has been cited by the Trump administration as evidence that the Chinese government is engaged in a strategic effort to steal American technological expertise. 

I have absolutely no knowledge on any of these. I can only mourn the brilliant mind that we have lost.

I first heard of "S.C. Zhang" when I was still working as a grad student in condensed matter physics, especially on the high-Tc superconductors. He published this paper in Science, authored by him alone, on the SO5 symmetry for the basis of a unified theory of superconductivity and antiferromagntism[1]. That publication created quite a shakeup in condensed matter theory world at that time.

It was a bit later that I learned that he came out of an expertise in elementary particle physics, and switched fields to go dabble into condensed matter (see, kids? I told you that various topics in physics are connected and interrelated!). Of course, his latest ground-breaking work was the initial proposal for topological insulators[2]. This was Nobel Prize-caliber work, in my opinion.

Besides that, I've often cited one of his writings when the issue of emergent phenomena comes up.[3] As someone with a training in high energy/elementary particle, he definitely had the expertise to talk about both sides of the coin: reductionism versus emergent phenomenon.

Whatever the circumstances are surrounding his death, we have lost a brilliant physicist. If topological insulators become the rich playground for physicists and engineers in the years to come, as it is expected to, I hope the world remembers his name as someone who was responsible for this advancement.


[1] S.C. Zhang, Science v.275, p.1089 (1997).
[2] H. Zhang et al., Nature Physics v.5, p.438 (2009).
[3] https://arxiv.org/abs/hep-th/0210162