Friday, July 31, 2009

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.


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

Thursday, July 30, 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! :)


Wednesday, July 29, 2009

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.


Tuesday, July 28, 2009

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.


Monday, July 27, 2009

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?"


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.


Sunday, July 26, 2009

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.


Friday, July 24, 2009

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?



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!


Wednesday, July 22, 2009

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.


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?


Tuesday, July 21, 2009

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.


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.



Monday, July 20, 2009

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?


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).”


Sunday, July 19, 2009

Why Science Is Important?

Periodically, I read something that made me say "That's exactly what I've been trying to convery!" This Cosmic Variance post is one such thing.

The post is highlighting a video that consists of interviews of various people on why science is important. One would expect that the typical, standard response is that science allows us to progress in our knowledge, to understand the universe around us, etc... But this article (and the video) has a more important and constant message to get across.

The responses are diverse, as are, refreshingly, the participants. But if there is a common theme it isn’t that science can tell us how the universe evolved, or what describes the behavior of protons. Rather it is that science is about how to go about seeking the answers to questions, and how to evaluate the claims of others. This last point is hammered home repeatedly, not least in Shaha’s opening monologue above, where, after walking over a bed of glowing coals, he says

“You’ve just seen me walk across red hot coals, at a temperature of over five hundred degrees Celsius. I could tell you that I’m an expert in an ancient form of meditation that lets me block out pain at will. I could then tell you that you could lead a happier life if you follow my teachings. For a small fee, of course.

Or, I could tell you the truth; that walking on hot coals doesn’t require any kind of magical powers. It’s just the case that the coals are a poor conductor of heat, and I walk so quickly that there’s hardly any time for heat transfer to take place.

Separating truth from fraudulent mumbo-jumbo is just one reason why science is important.”

This is such an important point to get across. I've always tried to emphasize on HOW we arrive at a particular conclusion, and that this is something we have to do all the time in science. It is why in my effort to suggest a revamping of the undergraduate intro physics laboratory, the emphasis was always not on trying to verify some already-established physics, but rather on finding out for oneself how something behaves. The fact that many people cannot tell the difference between scientific evidence and more dubious pseudoscience clearly show why the point being made in this video is still something most people are not aware of.


Friday, July 17, 2009

The Birth of the Blues: How Physics Underlies Music

We don't see this type of article often - I certainly don't remember reading something like this before. So that in itself deserves some mention here. :)

"The birth of the blues: how physics underlies music" was written by Murray Gibson, one of the Associate Laboratory Directors at Argonne Nat'l Lab. The article appeared online on June 30, 2009, so if the IoP policy of making papers available for free during the first 30 days, you should be able to access it at the IoP website here.

Abstract: Art and science have intimate connections, although these are often underappreciated. Western music provides compelling examples. The sensation of harmony and related melodic development are rooted in physical principles that can be understood with simple mathematics. The focus of this review is not the better known acoustics of instruments, but the structure of music itself. The physical basis of the evolution of Western music in the last half millennium is discussed, culminating with the development of the 'blues'. The paper refers to a number of works which expand the connections, and introduces material specific to the development of the 'blues'. Several conclusions are made: (1) that music is axiomatic like mathematics and that to appreciate music fully listeners must learn the axioms; (2) that this learning does not require specific conscious study but relies on a linkage between the creative and quantitative brain and (3) that a key element of the musical 'blues' comes from recreating missing notes on the modern equal temperament scale. The latter is an example of 'art built on artifacts'. Finally, brief reference is made to the value of music as a tool for teaching physics, mathematics and engineering to non-scientists.

I haven't finished reading it (it's 17 pages long!).


Thursday, July 16, 2009

Bill Gates And The World of Physics Lessons

A bit more of a follow-up from yesterday's post about Bill Gates putting up a series of Feynman lectures online. CNET has an interview with Gates on the reasons for his project to put various science educational material online.

After that, I got them put onto videotape, and I got rights to make a small number of videotapes. It was VHS tape at the time, and send it around to some friends who might be interested. But I always had in the back of my mind that it was kind of a crime that there wasn't broad availability of those things, particularly for young people thinking about science.

And so I sort of had this project in mind, and (have been) making some progress in understanding who had the rights, and eventually doing deals for the rights, and then getting these things scanned, and then getting Microsoft Research agreed to host the stuff and create some innovative software around it, which Curtis (Wong) has run. It's taken a long time, but with lots of PCs and the Internet, and my willingness to spend some money, now these things are just going to be out there.

Thanks, Bill!


Wednesday, July 15, 2009

Bill Gates Puts Feynman Physics Lectures Online

I found this tidbit of information, that Microsoft has put a series of Feynman lectures online. I don't know if these are video lectures, or if they are actually online version of the infamous Feynman lecture series books. I tend to think it is the former, because this source (although I haven't had the time to check it) said that

Feynman shared the Nobel Prize for Physics in 1965, while the series of lectures were delivered at Cornell University in 1964.

The Feynman lecture series books were based on his lectures at CalTech.

It is interesting that one of the quotes attributed to Feynman (can someone verify this?) is:

You can know the name of a bird in all the languages of the world, but when you're finished you'll know absolutely nothing whatever about the bird. So let's look at the bird and see what it's doing - that's what counts. I learned very early the difference between knowing the name of something and knowing something.

This is a clear illustration of what happened, especially in quantum mechanics, where people learn about things superficially (i.e. "know the name") without understanding the in-depth physics. People bastardized things like "quantum entanglement" simply by reading pop-science articles without even realizing what it is. In addition, look, for example, at the people who kept saying that evolution is only a "theory", without understanding what the word means when it is used in the scientific context.

If anyone has tried this online software, I would welcome a review.


Tuesday, July 14, 2009

Are Iron Pnictides New Cuprates?

This is a very good review of a new PRB paper that explores a new possibility for the iron pnictides superconductors. This has become one of the hottest (notice the irony) area in condensed matter physics, not just because this is new and everyone wants to be the first to look at it from a certain angle, but because of the possibility that it provides a new insight into the cuprate superconductors.

The review provides a very good intro to the differences between the two families of superconductors, AND, of course, a free access to the paper being reviewed.


Monday, July 13, 2009

Public and Scientists View On Science

In case you may have missed this, the latest Pew Research Center survey related to science has just been published. It is very much in synch with the last Science and Engineering Indicator as far as public opinion and understanding of science goes.

It is also of no surprise that the public like science and regard it as important. However, as I've mentioned earlier, they really don't quite know what science is, why it is important, and how it operates. So the support is based on not on an understanding of science, but rather on its perceived importance. It also means that they can't distinguish between what is a scientifically valid idea versus something that isn't. Look at the glaring discrepancies in the survey on "Differences Between Scientists and Public Go Beyond Evolution".

There's very little that isn't unexpected in the result of this survey. It simply reinforces what I have mentioned all along, and that the "battle" is ongoing and far from being anywhere we can be happy with.


Friday, July 10, 2009

Arco, Idaho

What is the significance of the small town of Arco, Idaho?

It became the first place in the "free world" to be powered by "electrical energy developed from the atom."

There is an interesting and informative article by CNET reporter Daniel Terdiman not only on this small town, but also on the current ongoing research on using nuclear energy for power generation at Idaho National Laboratory. It includes a couple of videos as well.


Thursday, July 09, 2009

Science and Engineering Graduate Enrollment Increased in 2007

The National Science Foundation (NSF) has released its latest statistics on graduate school enrollment in science and engineering for 2007 academic year.

U.S. enrollment in science and engineering (S&E) graduate programs in 2007 increased by 3.3% over comparable data for 2006. This is the highest annual growth rate since 2002 and is nearly double the 1.7% growth rate seen in 2006. First-time, full-time enrollment of foreign students (the terms foreign student and temporary visa holder are equivalent in this report) eclipsed its previous high, set in 2001, and total enrollment of temporary visa holders topped its 2003 high. Despite this growth, the proportion of S&E graduate students who are temporary visa holders remained below its peak level, set in 2002, because of growth in the numbers of U.S. citizens and permanent residents pursuing graduate-level study in S&E fields.

While this looks encouraging as a whole, a closer look at the "Physical Sciences" shows that the enrollment level between 2006 and 2007 remains flat, at best. Certainly there is a slight increasing number of enrollment since 2000, but it seems have leveled off around 2005. Coincidentally, this was the period of some of the most challenging times in funding for physics, with the Bush Administration and Congress trying to out-muscle each other, with funding in physics being the victim.


Wednesday, July 08, 2009

What Is Science?


I think I'm becoming a HUGE fan of Helen Quinn.

I highlighted one of her writings in Physics Today a while back, and flat out wrote that you must read her article. That advice still stands, but now, add another one that is written by her that you MUST read.

The article is titled "What Is Science", published in the July 2009 issue of Physics Today. IT IS AN EXCELLENT ARTICLE, and practically mirrored almost 100% of my own opinion (maybe that's why I like her writings so much! :)). She wrote it in a very sensible manner, and accessible for the general public that isn't trained in science. For example, she tries to describe the process of science that is typically covered in what we normally call the "scientific method" that is taught in elementary education:

Readers of PHYSICS TODAY know that science is a process, based on interpretation of experimental or observational data using models and theories, within a tightly constrained logical structure. The constraints arise from needing a logically self-consistent explanation of multiple phenomena. Any apparent contradiction between different theories or models, between evidence and theory, or between different sources of evidence must be examined and resolved. Asking questions is a big part of doing science, and choosing to pursue answers to the more compelling and productive ones helps shape a given field. Eventually, something resembling an answer might emerge, only to be tested against further observations, models, or theories, a process that often leads to further questions. The work continues, iteratively refining both the theory or model and the questions being examined. Iterations are essential because the process is inherently messy. There are many false starts, with misinterpretations and incomplete information sometimes sending science off on a wild goose chase for a while. We scientists could well be more forthright about the fits and starts of research; after all, clearing up the inconsistencies is what confers much of the authority on the results.

But I think what is even more important is when she addressed the differences between asking WHY about something when asked by a scientist, versus that of the general public:

In everyday usage the question “Why?” can be either about the mechanism by which something occurred or about the reasons for or purposes behind an action. Thus the distinction between reason and mechanism, or between effect and purpose, is often blurred. Religion and philosophy are interested in reasons and purposes, but science cares only about mechanisms. That apparent reduction of the goal is a powerful step that separates modern science from its ancestor, natural philosophy. Modern science focuses our attention on just those questions that can have definitive answers based on observations. Where science does find a path to compare theory with observations, the theories so developed provide a powerful way to understand the world and even to make some predictions about the future. Science offers us new options that may be applied—for example, in technology and medicine—to change the way we live and extend our capabilities. However, scientists tend to forget that issues of reason and purpose are central to many people’s questioning, so the answers they get from science seem inadequate.

Excellent! If you've followed this blog for any considerable period of time, you would have seen several entries on similar topic, where the use of the same word can mean different things in science, and for the general public (example: "theory").

If you have a subscription to Physics Today, you may access it directly here. PT should really make this available for free, since this is one of those article that everyone should read.

Highly, highly, recommended reading.


Physicists In Industrial R&D

This is a report from a comprehensive 5-year study by the American Institute of Physics (AIP) on physicists working in industrial R&D.

Abstract: The halls of industry have always been peopled with physicists. For many years a bit more than a third of PhD physicists worked in industry, while almost half went into academic research and teaching. By the mid-1990s the numbers for new PhDs had reversed, with more than half going into industry and a little less than one-third going into academic institutions (see PHYSICS TODAY, April 2007, page 28). Notwithstanding the important relationship between physicists and industry, the kind of work that industrial physicists do and the way industrial R&D is organized have, until recently, been largely a matter of speculation. In 2003 the Center for History of Physics of the American Institute of Physics began a five-year study of the history of physicists in industry—the first systematic assessment of the work that physicists do in the corporate sector, how the organization and funding of industrial R&D have changed over the past several decades, and the extent to which the records of physicists in industry are being preserved for current and future researchers.

Here are the principle findings from the study:

Companies haven’t achieved a consensus on how to conduct R&D and are struggling to find the best mix of longer-term research and short-term development. That is to say, they are trying to balance the need for a stream of innovative technologies with the ongoing need to report profits.

The funding and organizational structures of corporate R&D have undergone radical changes since the 1980s. In particular, the traditional centralized R&D laboratory is an endangered species.

Many companies rely on external sources—especially physicist entrepreneurs and physics startups—for innovative technology.

No standards exist for preserving the records of corporate R&D. As a result, historically valuable records, including the once ubiquitous laboratory notebook, are being lost.


Tuesday, July 07, 2009

LIGO: the Laser Interferometer Gravitational-Wave Observatory

There is a comprehensive overview article on LIGO that just appeared. It's 25 pages long, and I think the first few pages are just the listing of all the authors alone! :)

B P Abbott et al Rep. Prog. Phys. v.72, p.076901 (2009).

Abstract: The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves (GWs) of astrophysical origin. Direct detection of GWs holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black holes and neutron stars and of uncovering unanticipated new astrophysics. LIGO, a joint Caltech–MIT project supported by the National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites in the United States. These detectors are the result of decades of worldwide technology development, design, construction and commissioning. They are now operating at their design sensitivity, and are sensitive to gravitational wave strains smaller than one part in 10^21. With this unprecedented sensitivity, the data are being analyzed to detect or place limits on GWs from a variety of potential astrophysical sources.

I can't think of a more complete and up-to-date article on LIGO than this at the present moment.



With a few minor quibbles, such as the phrase "... machine fires electronics that reach nearly the speed of light ...", this is a quick news summary of the Jefferson National Accelerator Facility, one of the DOE's National Laboratories.

The Energy Department's Thomas Jefferson National Accelerator Facility, or Jefferson Lab, was created to study nuclear physics — the most basic pieces that make up our universe.

It takes a massive machine to study the smallest particles known to man. That machine, the centerpiece of the lab's work, is the Continuous Electron Beam Accelerator Facility.

I always wonder whenever we have accounts like this, that someone eventually will get confused into wondering the difference between high energy physics and nuclear physics. For example, the Tevatron and LHC are "high energy physics" machines, while CEBAF and RHIC are "nuclear physics" machines. Most of us in physics kinda understand the energy range and even the type of studies being done in those machines that vaguely separates "nuclear" from "high energy/elementary particles". However, the general description we give to the public (see this news article, for example, doesn't have any distinguishing features that separates one from the other. I mean, saying something like:

"...created to study nuclear physics — the most basic pieces that make up our universe...."


"... a massive machine to study the smallest particles known to man... "

would be an accurate description of high energy physics endeavor as well. If I were a very astute layman, I could have easily noticed the "non-difference" and ask "OK, so how is this any different than high energy physics?"

I would have been a tremendous service to the public if news articles like this emphasize why this is specifically a "nuclear physics" facility.


Monday, July 06, 2009

Catching Relativity Violations With Atoms

A very interesting review in APS's Physics today on another paper that tries to measure any violation of a local Lorentz symmetry (the link also gives you a free copy of the PRD paper).

What makes this paper "interesting" is the list of authors. One of the author is a "Steven Chu". You may have heard of him! :)

I'm sure our current Secretary of the Dept. of Energy did this work before he was appointed. In fact, there was a similar preprint related to this work that he co-authored that appeared on arXiv the day that Chu was confirmed at the Energy Secretary. It is nice to know that he was an active physicist right to the point that he was appointed to this position.


Scientists Work on New Particle Accelerator

This news report describes the planned upgrade of the laser plasma wakefield accelerator at Berkeley Nat'l Lab.

Researchers at the Berkeley Lab plan to use microscopic waves to charge and accelerate some of the smallest particles in the universe.

The process will take place in the lab's "table-top" Berkeley Lab Laser Accelerator, a device that is planned to be built by fall 2009 and will replace the lab's current, smaller accelerator.

Not sure what the article meant as ".. some of the smallest particles in the universe.. " when they can just mention "electrons" and be done with, because that is accurately what the facility will accelerate.

The news report has some rather puzzling statements. For example:

A laser beam will then puncture the gas and cause a "wake" that will accelerate and charge the particle that follows the beam, said Paul Preuss, a member of the communications department for the lab.

The laser will cause the wake, yes, but it also "charge up" the following particle that is being accelerated? It will charge up the gas and turning it into a plasma, but the particles being accelerated, which are electrons, are already "charged"!

In this scheme, a high-powered pulsed laser passes through a cloud of neutral gas. The laser's electric field then ionizes the gas for a split second, creating a region of very high electric field gradient (what the news article kept referring to as creating "charge"). This high gradient is the accelerating gradient that will accelerate an electron bunch that trails after the laser pulse. I've highlighted this technique a while back.

This is such an amazing technique that can achieve quite high gradient. If it can be implemented, the energy ceiling for high energy physics experiments can be raised quite a bit without busting a budget. Too bad the reporting of the physics isn't that clear.


Sunday, July 05, 2009

Cooking Eggs Using Only Sunlight

This contest sounds like a lot of fun! And I suppose it helps that it is held in the desert when the midday temperature of more than 100 F.

Many contestant gathered to cook their eggs, but without using any gas, fuel, or electricity.

People of all ages and skill levels came to the 19th annual Oatman sidewalk egg fry. Contestants were given 15 minutes to fry their eggs using whatever devises they deemed necessary and that would assist the egg cooking process. The eggs were provided by the Oatman Chamber of Commerce, which sponsors the event.

I like the description of one of the setup.

Perhaps the most innovative - and certainly most effective - method of frying eggs on Saturday was that of Eric Schmidt and Xinaxiao Chou from Cibola, Ariz. Using a Frensel lens to intensify the heat, Schmidt was able to cook a perfect - and edible - sunny-side up egg in about 60 seconds.

“The Fresnel lens sequesters the carbon from the carbon dioxide. The heat coming out of the lens is about 3,800 degrees,” Schmidt said. Chou was a physics professor in Beijing and came up with the idea, he said.

The Frensel lens, named for French physicist Augustin Jean Fresnel, is a thin, optical lens of many concentric rings, which amplify light - and heat.

We could probably use this to motive students in Optics courses. :)


Saturday, July 04, 2009

The Quantum Life

Paul Davis has an intriguing article on the question if quantum mechanics can describe life.

Half a century later, the dream that quantum mechanics would somehow explain life “at a stroke” — as it had explained other states of matter so distinctively and comprehensively — has not been fulfilled. Undoubtedly, quantum mechanics is needed to explain the sizes and shapes of molecules and the details of their chemical bonding, but no clear-cut “life principle” has emerged from the quantum realm that would single out the living state as in any way special. Furthermore, classical ball-and-stick models seem adequate for most explanations in molecular biology.

Quantum mechanics is certainly relevant in biology and chemistry, which provides the fundamental building blocks of life. However, I'm not sure if QM can currently be used to explain life until both biology and chemistry have adequately describe the "transition" between "non-life" to "life".


Friday, July 03, 2009

Jury Acquits in Quantum Physics Assault

This is both jaw-dropping and amusing, all at the same time, very much like a quantum superposition of states. :)

Shortly before the incident, Fava was chatting with an acquaintance, who is also homeless, about "quantum physics and the splitting of atoms," according to prosecutors.

Authorities had said Keller joined in the conversation and, for reasons unknown, got upset. He was accused of picking up his skateboard and hitting Fava in the face with it, splitting his lip. Fava then fell and broke his ankle.

That is utterly hysterical! I've been in seminars and conferences where there were quite heated arguments that went on, but nothing like this. Come to think of it, this would have made such seminars pretty memorable! :)


Five Great Problems In Theoretical Physics

Many people, and many organinzations/publications have such list. So here's another one, done by theorist Paul Fendley. I happen to agree with most in the list, with a minor exception to "quantum computer".

Still, here is his whole list if you don't want to read the article.

1. Dark matter/dark energy
2. High Tc superconductivity
3. The Higgs
4. Quantum computer
5. Be nice! :)


Thursday, July 02, 2009

Where is the quantum critical point in the curprate superconductors?

The existence of one (or more) quantum critical point has been one of the central issue in the puzzle of the cuprate superconductors. In this article, Subir Sachdev, a world-renowned expert in this area, discusses where such quantum criticality might exist in the cuprate phase diagram based on electrical transport measurements.


Supernova Shock Wave Accelerates Cosmic Protons

This is a rather interesting report on a paper that appeared in Science last week. It describes the confirmation that the shock wave from a supernova can accelerate protons to such tremendous energy.

Astronomers have suspected for more than a decade that supernova shock waves can act like giant particle accelerators. The basic idea is this: As the remnant of a dead star hurtles through space at up to 30 million kilometers per hour, it creates a shock wave as it interacts with the so-called interstellar medium (ISM). Protons in the shock wave get trapped by the magnetic field of the ISM, which bounces the protons back toward the remnant. But the remnant has its own magnetic field, which repels the protons.

Each bounce adds more energy, and eventually the magnetic tennis match accelerates the protons to nearly the speed of light. Knocked free of the remnant and out into deep space, some of the protons finally hit Earth's atmosphere. The particles are so energetic that astronauts have reported seeing flashes of light--caused by single protons striking their retinas--even when their eyes are closed.

That last part is fascinating! I've never heard about that before. I wonder if that can do damage to one's eyesight. How do you have ample shielding to prevent that? I suppose it doesn't occur too frequently for it to be a concern. I also wonder if these protons are also the one detected by the Auger observatory?