The Nature of Science

A rather informative video for the general public on the "Nature of Science". What is even amazing is that it was produced by a college senior as a class project.

"The Nature of Science" was Proctor's senior project as a WSU student. He finished it in April of this year, and it's regularly shown on the planetarium dome. A grant has made it possible to turn the movie into a DVD for use in local schools. The show is also being translated for use in planetariums in Argentina and Turkey, and a copy was sent to a reviewer for a magazine aimed at planetarium professionals.

It takes a bit of a simplistic route, but maybe that's the only way to go when trying to present such a topic to non-scientists. So I'm not going to nitpick over it.

Zz.

Phonon Signatures Found for "Kink" in High-Tc Superconductors?

Anyone following this blog would have seen my catalog of publications on the renormalization effect of the high-Tc cuprate band structure, resulting in the so-called "kink". We have something new to add here.

A new publication in PRL from the Stanford group[1] has reported on ARPES measurement on single and multilayer Tl cuprate family. They look at the kink for single, bilayer, and trilayer compounds and found that the kink has a momentum dependence.

Now this is significant because of two things:

1. If the coupling is electron-magnetic mode, then they argue that one should not expect any significant changes between these set of compounds.

2. But if it is electron-phonon (buckling phonon) coupling, then such changes is expected.

So the major conclusion here is that the latest ARPES data is not consistent with the magnetic spin coupling as the cause of the kink in the band dispersion. Whether this rules out such coupling as the "glue" that causes superconductivity, that remains to be seen.

Zz.

[1] W.S. Lee, Phys. Rev. Lett. v.103, p.067003 (2009).

Fermilab Getting Additional $60 Million

When it rains, it pours.

Just last year, Fermilab was laying off people, and others were forced to go on furloughs for a few days. How things have turned around dramatically.

As a part of the stimulus bill, Fermilab will be getting an additional $60 million, in addition to what it has received earlier.

More than $57 million will be used on developing new technology for a particle collider to replace Fermi's Tevatron. The new collider will use superconducting radio frequency technology to send particles hurtling at each other in experiments. Another $8 million will be spent designing an experiment involving high-intensity beams of neutrino particles.

I can't remember the last time we have this much available funds for high energy physics. It probably won't last, but at the very least, the expensive construction projects and needed infrastructure upgrade will be done, so then when the money start to diminish, the limited funds won't be channeled into these auxiliary expenses.

Zz.

The Falling Raindrop, Revisited

I was drawn to this preprint, not because I found it fascinating (it is, in some way, after I started reading it), not because I'm interesting in raindrops, and not because I've been pondering about the falling raindrops problem before it is "revisited". No, the reason why this article attracted my attention was due to the name of the author - Alan D. Sokal.

Yes, that would be the same Alan Sokal of the infamous Sokal Hoax of several years ago. I'm not going to deny that when he did that and the proverbial feces hit the ceiling fan, he automatically became my "hero". :)

So this is another opportunity to mention this "event" and to point out the link in case you have not been aware of it.

Zz.

Do Students Use and Understand Free-Body Diagrams?

A rather interesting paper on the analysis of whether students use the free-body diagrams in intro physics, and if they actually understood how and why it is used.

{I think you get get free access to all papers in PRST-PER}

Abstract: Physics education literature recommends using multiple representations to help students understand concepts and solve problems. However, there is little research concerning why students use the representations and whether those who use them are more successful. This study addresses these questions using free-body diagrams (diagrammatic representations used in problems involving forces) as a type of representation. We conducted a two-year quantitative and qualitative study of students’ use of free-body diagrams while solving physics problems. We found that when students are in a course that consistently emphasizes the use of free-body diagrams, the majority of them do use diagrams on their own to help solve exam problems even when they receive no credit for drawing the diagrams. We also found that students who draw diagrams correctly are significantly more successful in obtaining the right answer for the problem. Lastly, we interviewed students to uncover their reasons for using free-body diagrams. We found that high achieving students used the diagrams to help solve the problems and as a tool to evaluate their work while low achieving students only used representations as aids in the problem-solving process.

As a freshman, I think I wasn't consciously taught how to use the FBD, even though I end up using something similar to that, but not consistently. On, I definitely drew some diagram to help visualize and solve the problem, but again, this wasn't done consistently especially if I can visualize it in my head. I think I drew sketches in the problems that I solved more in illustrating to the grader or the instructor how I was approaching the problem, rather than in helping me to solve the problem.

It was later on, when I was a grad student and had to TA for intro physics classes that the "formal" use of using FBD, and its usefulness, were finally drilled into me. Now I can certainly see its usefulness, and will try to convey that to every student about to learn physics.

Zz.

Spin-Charge Separation Observed?

It has been predicted that in 1D Tomonaga-Luttinger liquid theory, the strong electronic correlation will cause not only the breakdown of the Fermi Liquid model, but also the phenomenon of spin-charge separation. This is where the spin and charge of the charge carrier no longer form good quantum numbers, and thus, may disperse or undergo transport separately from each other.

Tantalizing indication of this effect has been shown before. For example, the violation of the Wiedemann-Franz law has been observed in the charge and heat currents in 1D organic conductors[1]. Now comes evidence from a different type of measurement - tunneling into a 1D system[2].

Abstract: In a one-dimensional (1D) system of interacting electrons, excitations of spin and charge travel at different speeds, according to the theory of a Tomonaga-Luttinger liquid (TLL) at low energies. However, the clear observation of this spin-charge separation is an ongoing challenge experimentally. We have fabricated an electrostatically gated 1D system in which we observe spin-charge separation and also the predicted power-law suppression of tunneling into the 1D system. The spin-charge separation persists even beyond the low-energy regime where the TLL approximation should hold. TLL effects should therefore also be important in similar, but shorter, electrostatically gated wires, where interaction effects are being studied extensively worldwide.

There are certainly more evidence of this phenomenon each year. And the issue of a "particle" undergoing a "spin-charge" separation is also a fundamental issue. I wouldn't be surprised if this is another example of something that came out of condensed matter that gets "hijacked" into other fields, if it hasn't already.

Zz.

[1] T. Lorenz et al., Nature v.418, p.614 (2002).
[2] Y. Jompol et al., Science v.325. p.597 (2009).

A Springy 3D Pendulum

Somehow, this all looks very familiar.

It appears that a classical example of a "monodromy" has been demonstrated for the first time.

When a spherical pendulum is vertically upside down, even a tiny deviation will kick it out of position. This type of unstable point in a mechanical system corresponds to a singularity in the constants of motion.

Mathematicians call the study of a system as it loops around such a singularity “monodromy,” which literally means “once around.” While the effects of monodromy should appear both in classical systems, such as pendulums and spinning tops, and quantum systems, such as rotating molecules, they have only been observed experimentally (and rarely) in a quantum system. Writing in Physical Review Letters, Noah Fitch and colleagues at JILA and the University of Colorado, US, in collaboration with the University of Sydney, Australia, present the first experimental demonstration of monodromy in a classical system.

The link above also gives a free access to the PRL paper.

So what is the example of a classical monodromy? A spherical pendulum in which the arm is a spring.

This looks familiar to me because I could have sworn that I saw something like this in my qualifying exam! :)

Zz.

The Casimir Effect from a Condensed Matter Perspective

I didn't have time yet to read this paper carefully, but I thought I should still pass it along in case people missed it. It is a take on the Casimir effect but from the point of view of condensed matter physics.

Abstract: The Casimir effect, a key observable realization of vacuum fluctuations, is usually taught in graduate courses on quantum field theory. The growing importance of Casimir forces in microelectromechanical systems motivates this subject as a topic for graduate many-body physics courses. To this end, we revisit the Casimir effect using methods common in condensed matter physics. We recover previously derived results and explore the implications of the analogies implicit in this treatment.

It has been accepted for publication in AJP.

The first part is quite useful, because it covers the basics of the Casimir effect. And for those of you who can't find a use for all those complex calculus stuff you learned in math classes, such as contour integral, well here's the proof of one of their use now.

Zz.

Hybrid Linac-MRI System

This is rather fascinating.

A new medical device is being proposed that combines two existing technologies - MRI with medical linear accelerator.

A more robust way to guide radiotherapy would be to image the entire tumor continuously and adjust the radiation beams accordingly. Fallone and his colleagues are testing a prototype Linac-MR system they built to do just that.

Linacs (short for linear particle accelerators) are basically devices that use radio waves to accelerate electrons to high speeds and crash them into a solid metal target -- typically tungsten -- producing high-energy X-rays in the collision. These high-energy X-rays destroy cancerous cells by causing irreparable damage to the cells' DNA, MRIs, familiar because of their ubiquity in modern hospitals, are very good at imaging soft tissue and would be an ideal technology for combining with Linacs because most cancers occur in soft tissue.

The problem is making MRIs and Linacs work together. Normally, each one would interfere with the other. Linac systems emit radio waves, which interfere with MRI hardware -- so much so that most hospital MRIs are placed in shielded rooms that specifically block radio waves. At the same time, MRIs employ strong magnets that can interfere with Linac systems.

That's what I thought when I first read this. These are two systems that one seldom thought would be compatible with each other, since they both produces effects that the other doesn't want. I think this is more of a technical or engineering issue that needs to be carefully solved. Certainly, I don't see any showstopper that would stop the progress here. It would be an amazing and important development if one could image and perform the treatment simultaneously. In fact, if one could even detect where the x-ray is actually being deposited as the treatment is being done, that would be as important.

Zz.

2008 Nobel Lectures

If you haven't come across these already, here's a piece of info that you might find interesting. You should be able to get free access to the 2008 Nobel Prize in Physics lectures by all three recipients.

Yoichiro Nambu "Spontaneous symmetry breaking in particle physics: A case of cross fertilization"

Makoto Kobayashi "CP violation and flavor mixing"

Toshihide Maskawa "What does CP violation tell us?"

Zz.

A "Cloaking Device" for Earthquakes?

This is an amazing proposal. We now have something that could potentially be "invisible" to a broadband elastic vibrations. This includes earth's vibrations such as an earthquake.

Researchers at Aix-Marseille Université in France and at the University of Liverpool in the U.K. have now developed a barrier that keeps buildings from feeling these waves. They took a cue from stealth aircraft, which employ combinations of specially shaped and fabricated materials that absorb radar signals and deflect them off course. For earthquakes, the concept is the same: Using computers, the team modeled a device composed of layered, concentric rings of plastic, copper, and four other materials of varying flexibility and stiffness--all designed to harmlessly deflect earthquake waves.

In a series of simulations, the team bombarded the rings with the equivalent of earthquake surface waves of standard frequencies ranging from 30 to 150 hertz, or vibrations per second. The rings absorbed and redirected the waves around a central protected zone essentially without disturbing it (see illustration), the researchers report this month in Physical Review Letters. A building of the future might have such an earthquake "cloaking device" incorporated into its foundation to protect it from harmful tremors rolling across the ground.

We now need to have this thing tested beyond just simulations.

Zz.

CERN Courier Turns 50

The July/August 2009 issue of CERN Courier celebrates the publication's 50th Anniversary. Besides reproducing its first issue, it is fun to look back at all the history that the journal has covered during its lifetime.

If you've never read this publication, this might be a good time to start and catch up.

Zz.

Fermilab Stars in New Documentary

Fermilab is getting to be quite a movie star lately. This report from Symmetry indicated that it has starred in another documentary titled "The Matter of Everything".

The Matter of Everything is a feature documentary that explores quantum reality and the interconnectedness of nature from the quantum to the universe. Challenging us to see beyond our everyday sense of experience, the film reveals what we are, a billionth of a billionth of the human scale. At that level, physicists at Fermilab, one of the world’s largest particle accelerators, describe a world more unified than ever imagined.

Sounds like this is certainly more legit than that silly "What the **#()$ Do We Know?" crackpot movie. I might try to get my hands on this and see for myself.

But don't miss the last part of the Symmetry article that will give you a "scale of things" information.

Since 1985, Fermilab has produced more than nine nanograms (billionth of a gram) of antiprotons, more than any other laboratory. But even this amount is about 100 million times less than the amount that thieves steal from CERN in the Angels & Demons movie.

Movie physics, anyone?

:)

Zz.

Math Education Researchers in Demand?

Mathematics education researcher in very high demand??!! Who knew??!!!

I certainly didn't, and this must have been flying under the radar for many of us who are not in such a field. So when I saw the title of the article, my first question was "What exactly is "math education research"?"

Mathematics-education research demands a rare combination of interests and skills, says Alan Schoenfeld, a mathematics education researcher at the University of California, Berkeley. Mathematics is important, of course; but math-education researchers also use social-science tools to study teacher behavior, student reasoning, educational equity, technology, and other topics. "A lot people who are brought up in the mathematics and the sciences tend to think the social stuff is soft and therefore not as intellectually interesting or rigorous," says Schoenfeld, who holds a Ph.D. in mathematics. But "math ed., properly done, is actually more challenging than mathematics, and that's because simple systems sit still and people don't."

And they can't seem to find enough people to do this? Wow!

Zz.

Movies and Science on Collision Course at the Academy

Humm.. there seems to be a lot of news article on Science and the Movies lately. I had just posted recently on the scientific accuracy in the movies. Now, along comes this public event by the Academy of Motion Picture Arts and Sciences to be held on Aug. 6 at the Samuel Goldwyn Theater in Beverly Hills.

The "real" physics behind some of Hollywood's most famous action, science fiction and superhero scenes will be revealed when the Academy of Motion Picture Arts and Sciences presents "When Worlds Collide: The Science of Movies," on Thursday, August 6, at 7:30 p.m. at the Samuel Goldwyn Theater in Beverly Hills.

Presented by the Academy's Science and Technology Council, the program will be hosted by author Adam Weiner (DON'T TRY THIS AT HOME! THE PHYSICS OF HOLLYWOOD MOVIES) and will feature film clips and in-depth conversation with Oscar-winning visual effects artists Robert Legato ("Titanic") and Scott Stokdyk ("Spider-Man 2"), Oscar-nominated visual effects artists Shane Mahan ("Iron Man") and Matt Sweeney ("Apollo 13"), and stunt coordinator and second unit director Dan Bradley ("The Bourne Ultimatum").

It's open to the public, but you have to buy tickets for it. If you can attend, I would appreciate a report.

Zz.

Solar Eclipse Occured - No Natural Disaster Happened

So where was the "... snuffing out its life-giving light and causing food to become inedible and water undrinkable..." part during the solar eclipse yesterday? I had a bag of popcorn and settled in in front of the TV ready to watch CNN for any sign of such calamity.

So is someone going to go after these quacks and point out to them how awfully wrong those things are?

Zz.

How a Raindrop Is Like an Exploding Parachute

This has a very high cool factor, even if you only look at the high-speed video.

A bunch of physicists have look at how raindrops can behave almost like an exploding parachute as it falls through air.

The idea has been that raindrops grow as they gently bump into each other and coalesce. Meanwhile, more forceful collisions break other drops apart into a scattering of smaller droplets. All this action would explain the wide distribution of shapes and sizes. But trying to unravel how the drops crash and break up led to a tough set of equations.

The new movies, however, show a much more straightforward process. Researchers snapped 1000 pictures a second of an isolated water drop as it fell through an ascending air stream. The drop first flattens into a pancake shape, which then balloons like a parachute. The bottommost rim of this chute has a thick, irregularly corrugated rim. Pressure from the air drag eventually breaks the chute apart into numerous smaller droplets--their wide range of sizes is due to the wide range of sizes of the bumps in the rim.

While there are certainly valid reasons why important and significant research should get a lot of publicity, I still like these kinds of small and "cute" studies, simply out of curiosity for my part.

Zz.

Google Earth Physics?

I haven't had time to carefully read this preprint since I'm at a workshop, but this looks kinda fun and intriguing. The authors are using Google earth images on boats with wakes behind them to estimate the velocity of these sailing vessels.

Abstract: Google Earth photographs often show ships and their wakes in great detail. We discuss how the images can be used to calculate the velocity of these ships.

Hum....

Zz.

Solar Eclipse Pits Superstition Against Science

I read this news report on astrologers in India predicting mayhem and chaos happening due to the upcoming solar eclipse, and I could have sworn that we are back in the Dark Ages where natural phenomena somehow are supernatural events due to deliberate acts of God/s or the devil.

In Hindu mythology, the two demons Rahu and Ketu are said to "swallow" the sun during eclipses, snuffing out its life-giving light and causing food to become inedible and water undrinkable.

Pregnant women are advised to stay indoors to prevent their babies developing birth defects, while prayers, fasting and ritual bathing, particularly in holy rivers, are encouraged.

The problem with this is that, when something like this is mentioned, then any incident of any kind, whether big or small, will be used to justify the accuracy of such a prediction. This is because when you make a prediction that is VAGUE enough, something that science can't get away with to be considered to be valid, then you have enough of a wiggle room to fit anything in it. You are also inviting some crazy nut to actually commit something on that day simply to fulfill the prophecy.

Still, I want to see evidence that food becomes inedible and water undrinkable during the eclipse. If this is false, then someone needs to being these astrologers to task for the lies. But, that's not going to happen, is it?

Zz.

Scientific Accuracy In The Movies

I've posted several of this type of topic before. Still, this is another news report that examines scientific accuracy in the movies. Even if you don't learn anything new, it is still an entertaining read.

The article describes another important aspect of the "scientific accuracy", as in the movies' representation of scientists.

Cinematic shenanigans also don't do much for the public image of scientists, who are frequently portrayed as a. techno-geeks with lousy people skills, b. chronic grumps, c. power-hungry megalomaniacs or d. all of the above and worse.

Seth Shostak, senior astronomer for the SETI Institute, which scans the heavens for evidence of intelligent life, complained in a LiveScience report that “real scientists don't describe an object entering the solar system as 'notable for the fact that it was not moving in an asteroidal ellipse but moving at nearly three times 10 to the seventh meters per second.' More likely, they would say that there was 'a goddamned rock headed our way!'”

Efthimiou agreed: “The stereotyping of scientists is a problem. In the past, movies showed scientists creating problems but also scientists who came forward to solve them. These days (in the movies), scientists are creating problems, but they cannot solve them. They are closed-minded; a solution can come only from a layman who can think outside the box.

“By creating an environment of anti-scientism, younger people do not want to consider science as a possible career. And the United States is losing its dominant status (in science).”

Zz.