Sunday, August 30, 2009

Nobel Laureate's Gift Creates Outcry

Some time, just because you've won the physics Nobel Prize, it doesn't mean your views on other issues will get the same level of acceptance. This is certainly true for William Shockley, the co-inventor of the transistor, and went on to win the Nobel Prize for that invention.

A gift of a piece of land after the death of Shockley's wife with the stipulation that the land be named after Shockley is creating an outcry from the community of Auburn, CA. This is due after the discovery of Shockley's belief in Eugenics later in his life.

From the late 1960s until his death, Mr. Shockley publicly pushed his belief that there was a strong genetic component to intelligence that forms along lines of race. He also suggested that some people of below-average IQ be paid if they agreed to voluntary sterilization.

During a 1974 television interview, he gave what he called his "standard statement" to a questioner who asked if he thought blacks were of inferior intelligence: "The major cause of the American Negro's intellectual and social deficits is hereditary and racially genetic in origin and thus not remediable to a major degree by practical improvements in environment." In the segment, viewable on YouTube, he denied being a racist.

For many of us physicists, and certainly, it is true in my case, we respect the work that these prominent physicists did, but we certainly do not revere them the same way the general public do with many prominent figures. One can see in many instances where the quotes from these figures are often cited as if they are biblical truths. In fact, I've had "discussions" with a few crackpots in which they try to argue about the validity of something based on nothing more than a series of out-of-context quotations from various giants in physics.

Winning the Nobel Prize certainly allows for one's opinion to not only carry a bit of weight, but also gets the notoriety. Still, this particular case clearly highlights that these people can still make silly decisions.


Saturday, August 29, 2009

Space Sciences Lab Celebrates 50 Years and 75 Satellites

Space Science lab, you say? Without reading the article or doing a search, would you know where it is? NASA? At JPL in Houston? At Goddard Space Center? Or maybe Cape Canaveral? Nope. The Space Science Lab (SSL) is in UC-Berkeley, and it is celebrating it's 50th Anniversary!

Now celebrating its 50th anniversary, UC Berkeley's Space Sciences Laboratory (SSL) has provided instruments for 75 satellites, two dozen rockets, nearly 200 balloon flights and numerous ground-based experiments. Eight of the satellites were conceived, designed, built and controlled within the lab's two hilltop buildings overlooking Berkeley and San Francisco Bay.

"The University of California at Berkeley showed its greatness when it founded the Space Sciences Laboratory at the very dawning of the space age, only a year after NASA was created," said Charles F. Kennel, former director of the Scripps Institution of Oceanography at UC San Diego and a member of the NASA committee now debating the future of human space flight. Kennel, who directed NASA's Mission to Planet Earth from 1994 to 1996, will be the keynote speaker at a banquet this Saturday (Aug. 29) celebrating the lab's anniversary.

Congratulations to an amazing facility that has made such an impact!


Physics Teachers Not up to Scratch

It appears that even in Australia, they have a problem of having teachers in high schools that have either a degree or an expertise in physics to teach the subject.

"At a time when there was lots of opportunities for young people in Australia or in engineering and in areas like that, what we're finding is that they're being turned off physics, for example, a prerequisite often to go onto a career in engineering," he said.

"The person that's teaching them might have some competence in science but just can't grab that 'aha' moment.


Thursday, August 27, 2009

Is High School AP Physics Good For All?

Should high school AP Physics be offered to all high school students, no matter how good or how weak they are in the subject? I think this physics AP teacher seems to think so.

I come from a background in nuclear engineering and "retired" to teaching about seven years ago. Having low performers in class does them a world of good. The curriculum is tough and can't be significantly watered down. I teach to the "smart" kids with the firm conviction that even the table scraps picked up by the lower-performing students are a better meal than what they're accustomed to.

While certainly "on paper", this might be true, I tend to believe that, more often than not, it depends a lot on the teacher him/herself. A good, motivated, and well-trained teacher can certainly accomplish what this physics teacher can do. However, I also think that someone who isn't that motivated might cause a backfire - the students, especially the "lower-performing ones", might learn to hate the subject after they're done with it.

My personal experience with students entering college and professed to hate physics has often been linked with them having a bad physics instruction in high school. So one can only hope that AP physics teachers are better trained, and probably are more motivated to teach the subject.


Tuesday, August 25, 2009

400 Years of Modern Astronomy

Happy 400th birthday, "modern" astronomy!

Galileo’s device was a simple telescope — two glass lenses at the ends of a leather tube that magnified objects nine times — and it would forever change our understanding of the universe. Established theories, centuries old, would fall; it would embarrass and anger the Roman Catholic Church; and it would mark the birth of modern astronomy.

But on Aug. 25, 1609, the practical Galileo focused on the telescope’s military benefits: He told the Venetian senators that it would be invaluable in war, since one could see ships sailing into Venice’s harbor a full two hours before they became visible to the naked eye. The Senate, duly impressed, doubled his salary. (The tradition perseveres: Scientists routinely tout military and other applied uses for their research in hopes of securing funding.)

.. and we will try not confuse you with "astrology"! :)


Monday, August 24, 2009

Astronomy is NOT Astrology

A rather amusing, if not sad, commentary on science illiteracy. This article highlights one recent confusion about Brian May, who finally got his Ph.D. degree in Astronomy, but some news report confused that with Astrology and calling him a "noted astrologer".

I have to confess on my paper's behalf, though, that Carlton Books aren't the only ones to have confused astrology and astronomy in recent weeks. Back in May, no less an authority than The Times itself ran a story about Sir Bernard Lovell, that described him as an "eminent astrologer".

A scientist being confused as a pseudoscience is like a liberal democrat being confused as being a conservative, right-wing republican! :)

As a physicist, I've often been referred to as "physician". I suppose it isn't as bad as being called an astrologer.


Sunday, August 23, 2009

50 Years of Anderson Localization

Physics Today has a wonderful article on the classic work by Phil Anderson which bears his name. The Anderson localization formulation has become one of the central phenomenon on condensed matter physics. 50 years after it was formulated, it is still occupying a major role in many new discoveries in this field.

The article lists all the various areas in which this phenomenon is or has been applied to successfully describe various effects.

A highly recommended article.


Friday, August 21, 2009

Embedded Video Advertisement in Print Magazine

Yes, you read it right. We now have embedded video in the print version of magazines sold on newsstands!

Supposedly (since I haven't seen the print ad) CBS bought this embedded video ad in Entertainment Weekly to advertise their show "The Big Bang Theory". And interestingly enough, the ad mentioned "Physics Today".

The video, which is activated when the magazine page is opened for more than 5 seconds, opens with Jim Parsons, the actor who plays Sheldon Cooper, a theoretical physicist on the television sitcom The Big Bang Theory, welcoming readers to "the current edition of Physics Today" before finding out he has been duped into supporting a different product.

You can find the video at the link above. Still, is this a preview of what's to come with print ads?


Thursday, August 20, 2009

Serendipity in Astronomy

This is a fun article to read. It give a historical description where serendipity, or chance, plays many different roles in advancing astronomy. But I like the point mentioned in the beginning of the article.

‘Chance favours the prepared mind’ implies both an element of luck and a prior understanding of what is normal. Making successful discoveries in astronomy is not comparable to buying a lottery ticket and then sitting back but requires a deep familiarity with the Sky, the Universe, cosmic phenomena and/or physics. It does require both sides; you don’t make discoveries without making observations and you don’t identify them as such without knowing when something is new.

This, of course, echoes what I've written earlier in one of my entries on "Imagination Without Knowledge Is Ignorance Waiting To Happen".

However, to know what is new and unexplained, one has to first make sure one knows what is known and understood! Without that, one would not know what is new even if it comes up and bites on one's rear end.

Crackpots, especially, can't stand the thought of that! :)


Argonne Open House - August 29

If you are around the Chicago area, you might want to make a trip out to the southwest suburb next weekend for the Argonne Open House. It will take place on August 29, from 9:00 am till 4:30 pm.

This will be only the 2nd open house the lab will host since Sept. 11, the last one being in 2006 for their 60th anniversary. It is a golden opportunity to see many scientific projects and facilities, and to talk to scientists working in various areas of research.


Wednesday, August 19, 2009

LIGO Detected No Gravity Waves - Yet!

A new report published in Nature this week from LIGO presents no detection of gravitational waves {Link available for free only for a limited time}. This was, in fact, expected.

Working with the Virgo Collaboration, which runs a gravitational wave detector near Pisa, Italy, the LIGO team has now analysed what their own detector saw between November 2005 and September 2007. Although LIGO did not find any waves, the teams conclude in Nature1 that the SGWB is even smaller than LIGO can currently detect. This result rules out some theoretical models of the early Universe that would generate a relatively large background of gravitational waves.

A news story on this can also be found at MSNBC website. It has a good description of LIGO and how it can measure gravitational waves. Anyone wanting more detailed description of LIGO can read one of my previous blog entry on this facility/project.


What To Do With A Soon-To-Be-Obselete Accelerator?

With the impending start of the LHC, the Tevatron days are numbered once again unless news experiments can be thought of and funded for it. This article examines the fate of the Tevatron after the LHC takes the crown as the highest energy particle collider.

Currently, the Tevatron will keep running experiments through the end of September 2010 (the end of the Department of Energy's fiscal year), and possibly through 2011, Holmes said.

After that, it will likely go into "standby mode" for about two years -- shut down but kept in working order. Holmes expects a decision by 2013 on whether to keep the Tevatron or get rid of it.

"It'll largely depend on whether somebody has some good idea for mounting a new experiment in the Tevatron," Holmes said.

I'm guessing that even Project X would not make use of the Tevatron, and even in the best case scenario that the ILC gets built at Fermilab, the Tevatron wouldn't still be needed.


Tuesday, August 18, 2009

Quantum Field Theory and Gravity

There has been plenty of speculation and general agreement that QFT and Gravity may not mix. The most prominent argument given is that QFT perturbative expansion blows up at some level when dealing with the gravitons field. That is where string theory comes in and tries to be the bridge between QFT and gravity.

There are preliminary indications that the idea that QFT's description of gravity may not produce all those infinities after all. A new paper being highlighted in APS Physics this week shows exactly just that for N=8 supergravity.

This certainly would be a significant theoretical advancement, but probably under a rather restricted condition. But still, it shows the first indication that QFT may not necessarily automatically blow up under situation.

Coincidentally enough, a new preprint by Steven Weinberg appears today on ArXiv. It is more of a description on the history and development of effective field theory as applied to the strong interaction. Here, he too argues for the possibility that effective field theory of gravitation may in fact survive at higher energies.


Monday, August 17, 2009

World's First "Spaser"

New paper out of Nature is reporting the world's smallest laser. But it turns out that this is no ordinary laser. Rather, it is a "spaser". {Link open for free only for a limited time}

Whereas a laser amplifies light, using a mirrored cavity to intensify it, a spaser amplifies surface plasmons — tiny oscillations in the density of free electrons on the surface of metals, which, in turn, produce light waves.

The article didn't actually say what "spaser" really stands for. But if we go with the acronym for "laser", then I would guess that "spaser" means "Surface Plasmon Amplified Stimulated Emission Radiation".

Very neat!


Sunday, August 16, 2009

Media Studies More Popular than Physics for A-Level Exams

Looks like things are definitely stirring up across the pond in the UK. First there were accusations that maybe the physics requirements and exams for the A-level might have been watered down considerably. Now, because of the "league tables", students are opting for "easier" subjects to take in the A-level exams, such as "Media Studies".

In 1997, only 3,000 students took media studies in state comprehensives, compared with more than 12,000 last year, according to figures published following a Parliamentary Question.

Over the last decade, the number of teenagers taking physics has fallen from 12,126 to 10,118. Numbers hit a low point in 2005, when only 9,916 took an A-level in the subject, although entries have recovered slightly.

So of course, there are top-tier universities that won't accept these "soft" subjects.


Saturday, August 15, 2009

Hans Christian Ørsted: Who He Was, and Why You Owe Him

We missed Ørsted 232nd birthday yesterday, but still it was marked by Google, and the National Geographic has a brief article on why he played a significant role in our everyday lives.

So who was Ørsted, and what did he do to deserve the Internet's ultimate accolade?

Born in 1777 in Rudkøbing, Denmark, Ørsted established in 1820 that an electrical current coursing through a wire creates a magnetic field that can deflect a compass needle.

Ørsted's seemingly simple observation was nevertheless likely the first to link electricity and magnetism, explained physicist Paul Cadden-Zimansky of the U.S. National Magnetic Field Laboratory at the University of Florida.

It has been my unwritten mission to highlight the contribution of many physicists who are not household names. Yet, these people made such important contributions to our body of knowledge, some of them more than those household names, and probably made more impact on how we live today.


Friday, August 14, 2009

A Physicist looks at "The Time Traveler's Wife"

Physicist David Goldberg takes a closer look at the new movie "Time Traveler's Wife", which opens this weekend. Strangely enough, he's quite excited about it, as opposed to other previous movies on time travel.

That's why I'm so excited about the film adaptation of Audrey Niffenegger's The Time Traveler's Wife, which tells the story of Henry DeTamble, a man with a rare genetic disorder that causes him to skip around in time while his long-suffering wife, Clare, waits for him at home. The premise is no more or less plausible than that of, say, Back to the Future, in which a tricked-out DeLorean must reach 88 mph to jump into the past. But The Time Traveler's Wife follows through on its premise in a realistic way.

So what are these realistic ways that the movie actually followed?

In a rule-abiding time-travel narrative, there are no parallel universes—just a single timeline. The Time-Traveler's Wife follows this rule to a T, and there is a significant online presence dedicated to diagramming the unique, entangled history of Henry and Clare.

The time-machine construction clause is one of the most often overlooked of the rules of time travel and is the only real mar on the otherwise exceptional Terminator (1984), which proposes a single historical line (or loop) with no alternate universes. (Subsequent movies in the series revert to the parallel-histories model.) The Time Traveler's Wife very nearly gets it right: Since Henry is the time machine, he can't visit any time before he was born. His daughter, on the other hand, bends those rules slightly: She manages to visit a time before her own birth but not so far back that her father hasn't been born, either. (We might take Henry's birth as the "invention" of time travel and the whole family as components of a single machine.)

So, try as you might, you can't kill your own grandfather, nor can you change history at all. The Terminator learned this the hard way, going back in time to prevent John Connor's birth by killing his mother. When a human travels back in time to protect her, the two fall in love—and she becomes pregnant with … John Connor. Ta-da.

There's no need for such finagling in The Time Traveler's Wife. Since Henry DeTamble serves as his own time machine, there's little chance of his preventing his own birth. Cf. rule No. 2.

In The Time Traveler's Wife, Henry and Clare enforce the (predetermined) future by giving each other instructions and hints about how things are supposed to happen. That gives them a feeling of free choice where none really exists. In a letter to Clare about their future, Henry explains, "I won't tell you any more, so you can imagine it, so you can have it unrehearsed when the time comes, as it will, as it does come."

Yes, folks. There are constraints if you want to use physics as the realistic foundation to time travel. And of course, this is assuming that what we know about General Relativity is actually perfectly valid.


Thursday, August 13, 2009

Bob Park And The Tree Limb That Fell On Him

Anyone who has read this blog for any considerable period of time would know that I adore reading Bob Park's weekly What's New column. In fact, I've called this as one of the earliest physics blog on the 'net. I don't necessarily agree with him on all issues, but I am glad that, finally, a physicist is finally going after and exposing some of the silliness that has been going on. So inevitably, he became my "hero" of some sort. I've also mentioned about one of his books "Voodoo Science" as a must read.

In any case, I was horrified back in 2000 to hear that he had this freak accident while jogging. It seems that originally, I thought that a tree fell on him or something, and he sustained a rather severe injury. I of course didn't know much more about the circumstances of the accident... till now. A news article reports that a woman jogging in the same wooded area as Bob Park's accident site was killed by a fallen tree limb! In covering the story, the news article also mentioned Bob Park's accident and interviewed him on the circumstances of the freak accident.

The freak accident in 2000 nearly killed Park, a physicist and writer who lives in College Park, Md. A pair of priests who happened upon him lying unconscious under the tree administered last rites, he later found out.

Oh, but it gets better!

Park, the 2000 tree-fall victim, understands that unlikely events will happen on occasion, such as a strange coincidence that took place the day he returned to the scene of his accident a year later.

"The story gets even more unbelievable," he said. He went to the exact place where he was struck, he said, and as he passed the broken-off trunk of the tree that nearly killed him, he passed two elderly men walking. "You know that tree fell on a guy last year," one of them said.

When Park said he was that man, one of the two began to tear up. It turned out they were the priests who found Park pinned under the tree and gave him last rites. They decided to throw him a champagne party to celebrate his survival.

What are the odds???!! :)

Still, I wonder if those two priests have had Bob Park's column and realized what his views on organized religion are! :)


Wednesday, August 12, 2009

On the Role of the Michelson-Morley Experiment: Einstein in Chicago

I came across this article and had planned on only reading just a few paragraphs since I am in the middle of doing a lot of other things. But I just couldn't pull myself away from it and ended up reading the entire article! :)

This is a treatise on the infamous question on whether Einstein was aware of the Morley-Michaelson experiment BEFORE his 1905 relativity paper, and if he was aware of it, to what degree did it influenced his 1905 paper.

The conventional thought, based on many accounts given by Einstein in his later years, is that he can't quite remember if he was aware of it, and thus, it didn't play any influential role in his formulation of the principles of relativity. This new paper, in press, reveals a slightly different version of what plausible could have happened, based on two accounts : a translation of Einstein's speech he gave in Kyoto in 1922, and a series of speeches he gave in Chicago a year earlier, and especially at the Francis W. Parker school.

The author draws up this conclusion:

What does the Parker school lecture imply for our understanding of Einstein’s relation to the Michelson-Morley experiment, and its influence on the creation of the special theory? Taking the text at face value, there can be no doubt that Einstein knew of the Michelson-Morley experiment prior to 1905. He attributed a significant role to ether drift experiments in general, and singled out the Michelson-Morley experiment for specific mention. It further suggests that Einstein had learned of the experiment before becoming convinced of the principle of relativity—contrary to his later recollections.

Einstein’s reference to his student days leads one to believe that he may have had in mind his ideas for an ether drift experiment of 1899: his comments perhaps concern the experiment that he briefly mentioned in a letter to Mileva of 10 September 1899—“A good idea occurred to me in Aarau about a way of investigating how the bodies’ relative motion with respect to the luminiferous ether affects the velocity of propagation of light in transparent bodies.”25 His next letter to Mileva, dated to 28 September 1899,26 is the letter that informed her that he had just read Wien’s article, i.e. the article containing the Michelson-Morley experiment, among a discussion of other experiments, which confirms Einstein’s usage of the plural—“experiments of this kind”—in his lecture in Chicago.

This is certainly interesting and contrary to what has been historically accepted. So then the question is, why the discrepancy?

There is an evident contradiction between Einstein’s description in Chicago of the role played by the Michelson-Morley experiment and his own words of some decades later. How is this contradiction to be understood? Did Einstein let down his guard in Chicago and allow a historical inaccuracy to slip in—perhaps to please Michelson’s home crowd? His visit was indeed a great success: soon upon his return to Berlin, Einstein received an informal inquiry as to whether he would be interested joining the University of Chicago physics faculty, an offer which he described as attractive but which he politely declined.

When weighing the different accounts that Einstein gave of his relation to the Michelson-Morley experiment, there are good reasons to accord greater credence to his earlier words, spoken in Chicago and, presumably, Kyoto. One compelling reason is that these fit in well with the contemporary evidence, as argued above. Another, less direct but equally strong reason is that recent scholarship has shown that the later Einstein’s recollections of the development of his own research—in particular with regard to the general theory of relativity—were often colored by his subsequent philosophical beliefs and the research program he was pursuing at the time; this would be the highly theoretical unified field theory program, that had virtually no exchange with empirical science.30 This circumstance coincided with his much discussed pilgrimage from an empiricist philosophical position to that of a “believing rationalist” who seeks the unification of natural forces by exclusively mathematical creativity.31 In that process, the role of experiment lost prominence in both Einstein’s practice in physics, as well as in his philosophical thought.

Oh no! You mean he was slowly evolving into a string theorist?

{Sorry, cheap shot, but I couldn't help it!}

Like I said, this was a fascinating read. Hope you find it as entertaining and informative as I did.


Tuesday, August 11, 2009

What Does One "Do" With an Undergraduate Physics Degree?

This article tries to answer the question that I get asked many times: "What Does One "Do" With an Undergraduate Physics Degree?" The writer presented this question to another physicist to get the answer.

David Saltzberg, PhD. is Professor of Physics and Astronomy at UCLA. He received his Bachelor's degree in Physics from Princeton and his doctorate from the University of Chicago. David has partially shifted his research towards neutrino astronomy, using radio detection techniques. He recently completed a scientific balloon mission looking for the electromagnetic pulses from neutrino interactions in the Antarctic Ice. He is also Science Consultant for the television sit-com: The Big Bang Theory.

While David is a scientist, he also has an undergraduate liberal arts education which made him the right person to ask: what does one "do" with a physics degree? He has not only taught many students, but has friends who chose less traditional pursuits. And he advises future educators at a leading university.

So I had high hopes that some very good answers and examples will be given here. But I'm a bit disappointed with the responses.

Why should college students consider majoring in physics?

I think there is only one reason to major in physics, and that is because you really like it. I majored in physics because I always liked my classes and wanted to learn more. Along the way, you meet some really smart people who also love physics in relatively small classes. You work together in labs and generally spend a lot of time together. It is a great way to go through college.

What have your former college classmates and students done (besides doctoral study) after earning their undergraduate degrees in physics?

It is all over the map. Various types of engineering are all possible. I even have one friend that designs robots. Others have gone into science journalism. Another friend with a physics major joined the Air Force and flies planes.

So essentially, the whole question in the topic is covered in this last paragraph. The rest of the article is about physics, funding, education, etc. There is no elaboration on the exact nature of jobs available for an undergraduate physics degree holder. So if I were such a degree holder and hoping that this article tells me a bit more on what jobs I'm qualified for, I'd say that other than some superficial information that is "... all over the map... ", I've learned nothing.

This is sad, because it is not as if such information isn't available. The AIP webpage has a wealth of statistics on the type of jobs such physics degree holders get employed in. So one could be quite specific on the type of jobs available.

But beyond that, when asked on why one should major in physics, is the best that can be answered is that "... you really like it.. "? What happened to the fact that the skills one acquire majoring in it can be quite useful in one's career, be it in science or outside of science?

I think this article missed a tremendous opportunity to produce useful information that students could have used. Instead, it had more emphasis on funding and physics education.


Monday, August 10, 2009

Canada's Nuclear Know-How in a State of Accelerated Decay?

This article presents the issues surrounding the aging Chalk River nuclear reactor facility in Canada.

With problems continuing to plague the aged Chalk River reactor, once the source of more than half the world's supply of the radioactive material vital for cancer and cardiac testing, the four-member panel has been charged with recommending a new source by Nov. 30.

It examines two important aspect of the story:

1. The fate of nuclear isotope source for the world since the facility produces close to 50% of the world supplies of isotopes for nuclear medicine

2. The possible decline of nuclear expertise in Canada if the facility shuts down with any similar replacement.

I've mentioned earlier about the alternative option of using a particle accelerator to generate the Mo99 isotopes. Certainly this is a viable, but untested, alternative.

The accelerator proposal put forth by TRIUMF, a subatomic physics lab at the University of British Columbia, uses an electron accelerator to fire a photon beam at uranium, producing moly-99. But it's an untested process creating an unfamiliar product and a whole lot of questions.

For instance, reactor-based tech-99 is "milked" from moly-99 using a device called a generator, or moly cow. But the accelerator-based moly-99 may differ from reactor-based moly-99 just enough that an entirely new model of cow would have to be manufactured, adding considerably to the startup costs.

Such option is also being considered in other parts of the world, including the US. We will see how this will turn out. I think we are still in the "proof-of-principle" stage of the development.


Saturday, August 08, 2009

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.


Wednesday, August 05, 2009

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.


[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.


Tuesday, August 04, 2009

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.


Monday, August 03, 2009

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.