Friday, March 30, 2012

More Evidence Against Phonon-Origin As The Glue In Cuprate Superconductors

This latest result will not settle it, but it is another evidence against phonons as the dominant "glue" for the origin of superconductivity in the cuprate family of high-Tc superconductors. This latest work comes from fast optical measurements on the Bismuth-based cuprate superconductors[1].

The researchers measured the part-in-10-thousand changes over a few thousand femtoseconds and then plugged the numbers into a computer model to gauge which processes were most important in carrying energy through the lattice. Electron-electron interactions such as spin fluctuation should carry energy away much faster than phonons do, the researchers argued, making it possible to separate the different contributions.

The ability to study the reflectivity at different wavelengths was key, Giannetti says. That's because the ultrafast electron-electron processes were too fast to observe in the time traces. However, those processes affect the reflectivity at different wavelengths in different ways-100 femtoseconds after the pulse the material was less reflective at longer wavelengths and more reflective at shorter wavelengths. Taken all together, the data show that phonons aren't needed to explain BSCCO's superconductivity, Giannetti says. Electron-electron interactions are strong enough to do the job all by themselves.
As you can read from the article itself, while this experiment convinces people who are already in the spin-fluctuation camp, those in the phonon camps are not convinced at all due to possible issues in the analysis of the data.

In other words, this is still not the smoking gun, and the debate continues.


 [1] S. Dal Conte et al., Science v.335, p.1600 (2012).

Thursday, March 29, 2012


This is the latest version (uploaded this past weekend) of the CODATA standard.


Wednesday, March 28, 2012

Brief Biography of Emmy Noether

To celebrate her 130th birthday this month, the NY Times has an informative biography of "The Mighty Mathematician You’ve Never Heard Of" - Emmy Noether (read it quickly before it is no longer available for free online).

Of course, to many of us in physics and mathematics, her name is quite familiar, and if you need a concise reason why she is so important in physics, this description of the Noether theorem would settle the case:

What the revolutionary theorem says, in cartoon essence, is the following: Wherever you find some sort of symmetry in nature, some predictability or homogeneity of parts, you’ll find lurking in the background a corresponding conservation — of momentum, electric charge, energy or the like. If a bicycle wheel is radially symmetric, if you can spin it on its axis and it still looks the same in all directions, well, then, that symmetric translation must yield a corresponding conservation. By applying the principles and calculations embodied in Noether’s theorem, you’ll see that it is angular momentum, the Newtonian impulse that keeps bicyclists upright and on the move.
I continue to be amazed at many of these women scientists and mathematicians who, despite all they had to endure during the times that they lived in, were able to persevere and produce such profound body of work. It is amazing enough to produce these amazing work. But considering that these women had so many social obstacles that the men didn't have, one can't help be impressed by what they had accomplished.


Tuesday, March 27, 2012

Barn And Pole Paradox Revisited

Many of us (at least those of us who are/were physics majors) have come across the infamous pole-and-barn problem when dealing with Special Relativity. It truly tests one's understanding of SR's time-dilation/length contraction effects, and forces us to examine how and when we know about something that occurs.

This paper revisits that pole-and-barn paradox and tries to convey a clear explanation of all the issues surrounding this problem. It might provide a clarification for those who might still have a bit of a problem with this scenario.


Data That Outpace Theory?

There's something very wrong with the "theme" of this NY Times article. It started with the infamous Eddington's quote.

The British astrophysicist Arthur S. Eddington once wrote, “No experiment should be believed until it has been confirmed by theory.”
In this case, the issue of neutrinos moving faster than light from the OPERA experiment was  used as the poster child to illustrate the "validity" of the quote.

Eddington’s dictum is not as radical as it might sound. He made it after early measurements of the rate of expansion of the universe made it appear that our planet was older than the cosmos in which it resides — an untenable notion. “It means that science is not just a book of facts, it is understanding as well,” explained Michael S. Turner, a cosmologist at the University of Chicago, who says the Eddington saying is one of his favorites. If a “fact” cannot be understood, fitted into a conceptual framework that we have reason to believe in, or confirmed independently some other way, it risks becoming what journalists like to call a “permanent exclusive” — wrong.
People here are confusing between a valid "fact" that comes experiment, versus something that is still being debated to be valid. The OPERA result was by NO MEANS a "fact"! The validity of the result was still debated. It doesn't qualify to be a fact!

A valid fact is a valid fact. The discovery of high-Tc superconductivity came without any theory. In fact, after more than 20 years of its discovery, there is still no valid theory for this family of material. There are, however, an abundance of FACTS, ranging from the values of Tc for many of the cuprate superconductors, to the symmetry of the order parameter, etc.. etc. Does that mean that since these things are not understood in a coherent theory, that they are "permanent exclusive"?

And let's go to the other extreme - String Theory - a theory that has outpaced data! Or in this case, a theory that has ZERO data. Is this any better?

We should also not forget that phenomena such as the blackbody spectrum, photoelectric effect, atomic spectra, etc. were ALL "facts" that came first, ahead of quantum mechanics. In fact, I would say that the majority of the expansion of our knowledge came via unexpected discovery in experiments FIRST, ahead of any existing theory to describe those phenomena. CP violation, fractional quantum hall effect, superconductivity, etc.. etc. were all knowledge that got initiated via experiments first, well ahead of a theoretical understanding.

Certainly, physics involves both theory and experimental verifications. That is not the issue. For something to be considered to be "understood", there must be both. However, for experimental facts to be valid, they do  not have to require a theory to be there. We have seen enough examples of this already.


Monday, March 26, 2012

More On Driving And Saving Fuel

So I was driving along the US Interstate over the weekend, and stopped at a rest area on an Illinois interstate (we call them Oasis over here) highway. In the washroom, they have these posters placed in several places, and one of the posters has these things that tells you some "green" driving tips. One of the tips given was something that I had brought up quite a while back. It is on driving with your windows down.

The poster here said this:

Try using vents and opening windows to cool off before you turn on the air conditioner. Air conditioning increases fuel consumption.
Now, if you've read my earlier post when I asked about this, you will also have read the two comments left behind, including one on an investigation done by the Mythbusters folks. Here, it turns out that if one is driving faster than 50 mph, then rolling up the windows and turning on the air-conditioning uses LESS fuel than driving with the windows down and no air-conditioning. The drag forces above that speed causes more use of energy than the air-conditioning unit.

So this poster is not quite up-to-date on "green driving".


Largest Molecule To Show Quantum Interference

They certainly keep pushing the envelope.

A group led by Markus Arndt has now shown quantum interferences of the largest molecule to date: a derivative of phthalocyanine molecules, with 1298 AMU. Nature Nanotechnology is also right now listing the paper as available for "free" (not sure for how long)[1].

Abstract: The observation of interference patterns in double-slit experiments with massive particles is generally regarded as the ultimate demonstration of the quantum nature of these objects. Such matter–wave interference has been observed for electron, neutrons, atoms and molecules and, in contrast to classical physics, quantum interference can be observed when single particles arrive at the detector one by one. The build-up of such patterns in experiments with electrons has been described as the “most beautiful experiment in physics”. Here, we show how a combination of nanofabrication and nano-imaging allows us to record the full two-dimensional build-up of quantum interference patterns in real time for phthalocyanine molecules and for derivatives of phthalocyanine molecules, which have masses of 514 AMU and 1,298 AMU respectively. A laser-controlled micro-evaporation source was used to produce a beam of molecules with the required intensity and coherence, and the gratings were machined in 10-nm-thick silicon nitride membranes to reduce the effect of van der Waals forces. Wide-field fluorescence microscopy detected the position of each molecule with an accuracy of 10 nm and revealed the build-up of a deterministic ensemble interference pattern from single molecules that arrived stochastically at the detector. In addition to providing this particularly clear demonstration of wave–particle duality, our approach could also be used to study larger molecules and explore the boundary between quantum and classical physics.


Edit: click on this YouTube link to see the video of this. The authors, for some reason, are disabling any imbedded video.

[1] T. Juffmann et al., Nature Nanotechnology doi:10.1038/nnano.2012.34, published online March 25, 2012.

Friday, March 23, 2012


... or at least, not the way it has been envisioned.

The US Dept. of Energy has requested that LBNE be scaled down in light of flat budget for the Office of Science in the next foreseeable future.

At a projected $1.5 billion, the Long-Baseline Neutrino Experiment (LBNE) at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, is not affordable, says William Brinkman, director of DOE's Office of Science. So this week he asked physicists to come up with a cheaper way to do the same science.
This seems to be a common pattern lately. The FRIB project also initially was supposed to be twice as expensive, until it was scaled down. We shall see what kind of a plan the Fermilab/LBNE collaboration can come up with to salvage the project.


NASA Uses "Angry Birds - Space" To Teacy Microgravity

Hey, why not?

NASA is making use of the crazy popularity of Angry Birds - Space to teach about microgravity.

Angry Birds Space has provided NASA an opportunity to share a core concept of space exploration: gravity. Not only does gravity play a vital role in the game but, in general, gravity is a force that governs motion throughout the universe. It holds us to the ground, and it keeps the moon in orbit around Earth and Earth around the sun. The nature of gravity was first described by Sir Isaac Newton more than 300 years ago. Now three centuries later and more than 200 miles above our home planet on the International Space Station, astronaut Don Pettit shares the thrill of concepts like gravity and trajectories with some help from Red Bird.
 You may view the video of Don Pettit at the link above or directly below.


Thursday, March 22, 2012

Physicists Can Detect If You Are Texting While Driving

Ah, the joy of statistical analysis.

Soon, there is a way to know if you are texting while driving (and hopefully, haul your rear end off the streets). Physicists at the Pacific Northwest National Laboratory can now look at how your text output is being affected by your driving, and can accurately predict if you are texting while driving.

People who are texting "time-share" their attention between driving and texting, Watkins said. They look down briefly and then up again to check the road.

When Watkins compared the keystrokes from driving and nondriving texters, the differences were consistent and quantifiable, he said. Drivers text and pause and text again, without the rhythm of usual texting.
They didn't say where this research was published, but I think I found it with a bit of searching.

 "Autonomous detection of distracted driving by cell phone" M.L. Watkins et al.  14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011.


Read more here:

Wednesday, March 21, 2012

First Ever Neutrino-Based Communication

I continue to be amazed at some of the things that people are capable of accomplishing.

Physics World is reporting the first ever use of neutrinos to transmit information.

Stancil approached Fermilab with the proposal and, having gained agreement, the researchers encoded the word "neutrino" into binary code. This was then used to modulate the neutrino beam with a bit rate of 0.1 bits/s. The message was received with a bit error rate of just 1%, allowing the message to be decoded easily after one repetition. Nevertheless, given the short distance over which communication was achieved, the low data transmission rate and the extreme technology required to achieve it (MINERvA itself weighs several tonnes), neutrinos are clearly not a viable method of communication in the short term.

Huber, however, is excited by the work. "I think the most significant feature of this work is that somebody went out and did it," he explains, adding "it makes an enormous difference because it proves it's possible."
Certainly this falls under the "proof of concept" experiment, and I don't think we'll see anyone seriously pursuing using neutrinos for communications, at least, not within my lifetime. Still, considering how difficult it is to detect these neutrinos, I'm amazed that they are able to accomplish such a thing.

Now, if OPERA is right, then we have found a way to transmit information faster than c! :)


Tuesday, March 20, 2012

Tevatron's "Organ Donations"

I guess the Tevatron signed an "organ donation" card. Now that it is no longer around, various valuable parts of it are being donated to sites all over the world.
Fermilab’s CDF experiment is donating photomultiplier tubes, computers, electronics racks and other equipment to experiments located all over the world, said Jonathan Lewis of Fermilab’s Particle Physics Division, who is organizing the decommissioning of the detector.

“These computers are going to a lab in Korea,” Lewis said during a tour of the building. “And we’re sending those electronics racks to Italy.”
So in essence, the Tevatron will continue to live in years to come via all these various experiments.


Bad Physics In TV Commercial

There's a fun discussion on the bad physics in a TV commercial.

One can argue on what is the big deal about something like this. After all, we see bad physics in TV and movies very often. Well, this isn't a big deal at all. It is just a fun exercise, even for students, to practice their knowledge on simple kinematics. But on the other hand, considering that physics-based games such as Angry Birds, Where's My Water, etc. are trying to get as close to being physics-accurate, there's very little reason (other than pure fiction or pure fantasy) to completely blow away all kinds of reality.


Monday, March 19, 2012

You Want Us To "Consider" The Creator Hypothesis?

It seems that there's a delicious fight going on between Rabbi Lurie on Huffington Post, and U. of Chicago biologist Jerry Coyne. I will let you read it for yourself.

What I will address is the tired plea from many of these people, and also a common tactic done by crackpots. They want us to spend time and effort to "consider" their position. "Why don't you consider such-and-such?" "Why don't you try to understand my theory?" Yet, all this while, THEY refused to do the same to OUR position. If this Rabbi wants us to ".. at least consider that there could be a Designer... ", then I'd say that it is fair to ask this Rabbi to ".. at least consider that there could be NO Designer"! How about them apples, huh? Has he done it? Has he read AND UNDERSTOOD Hawking's argument? Has he read and understood Lawrence Krauss's argument?

It seems that it is always the scientists that have been asked to "disprove" of something, rather than these people showing ample validity for things they believe in. And do you want to know why? Because the physical characteristics of this "designer" can't be defined and agreed upon by all those who believe in it! There's no science that can consider testing for something that is so shifty and vague! So far, the most common argument for the "apparent" existence of one is in the form of the "god of the gaps". And we all know what happens to such a concept - the "gaps" get smaller as we know more and more about things. The anthropic principle, for example, has a lot of detractors and many arguments against such a thing. Using it as one of your supporting argument (all without knowing the intimate physics of what it is) is a risky practice and could fall right into your face.

So for this Rabbi to insist that we should "consider" such possibility is laughable, because the concept of a "designer" is unfalsifiable and "not even wrong"! If he wants us to consider the possibility, then it is only fair that he consider the opposite possibility. That is, of course, assuming that he has the ability to understand the physics with his "post-graduate level" physics courses, whatever those are.


Sunday, March 18, 2012

ICARUS Challenges OPERA's Result Again

This could be the beginning of the final nail in the coffin for OPERA's result.

ICARUS already had a very compelling result to initially challenge OPERA's superluminal neutrinos claim. Then OPERA revealed that they had some timing errors in their electronics that could sway things one way or the other. Now comes the most direct challenge so far of the OPERA's result, again from ICARUS, which not only use the neutrinos created from the same source (CERN), but also with detectors that are in almost the same location as OPERA!

THREE weeks ago the OPERA collaboration in Italy found a possible glitch that may account for its startling finding last September that elusive particles called neutrinos move faster than light, in flagrant disregard of Albert Einstein's theory of relativity. Now the first crosscheck from a rival experiment seems to vindicate the overwhelming majority of physicists who were convinced all along that some error must have crept in to OPERA's analysis. On March 16th the ICARUS collaboration posted a paper on arXiv, an online repository, which reports that neutrinos they looked at are not travelling faster than light, after all.
I'm sure the OPERA's folks will still redo their measurements (if they haven't started already considering that the LHC is back circulating protons). But so far, in terms of experimental results, there hasn't been anything to support such superluminal neutrinos.


Thursday, March 15, 2012

US Voters Have Gloomy View of US Science Future

Less than half of US voters polled think that the US will be the world's leader in science and technology by 2020.
Of the 1005 likely voters polled, 47% said they thought the United States would lead the world in health care by 2020—though the poll did not define which factors would play into that designation. More than a quarter of respondents said they weren't sure which nation would hold that title in 8 years, while 18% speculated that it would be the European Union. The rest of the responses split among China, India, and Brazil. Only 42% said they thought the United States would retain its position as the world leader in science and technology by 2020, while 26% predicted China would assume that mantle, and 23% chose India.
And yet, we are still cutting back severely on research in many fronts, especially in the physical sciences.


Tuesday, March 13, 2012

Why Don’t Americans Elect Scientists?

Holy Crap. This opinion piece almost quoted everything that I've been writing about in this blog! Do I have a twin somewhere that I don't know about? :)

For example, haven't I been saying something like this all along?

Often too interested in politics as entertainment, the media is complicit in keeping such “controversies” running. Doing so isn’t hard since vivid, just-so stories and anecdotes usually trump (or should that be Trump) dry, sometimes counterintuitive facts and statistics.
This is a damn, fine article. The only bad part here is that most of the people that should be reading this, aren't! Are the politicians themselves reading this? Do they even KNOW what it means? Or do they have staffers who read this, and then "translate" it?

Actually, the one point that the writer didn't explore is why scientists, engineers, and mathematicians MAY NOT want to be involved in American politics. One only need to look at the amount of money involved in running for office, the amount of wheeling and dealing involved in getting the party one is affiliated with to back one's candidacy, and of course, the amount of bells and whistles one has to add to one's campaign to attract the public. It is, truly, a process of turning oneself in a pseudo-celebrity and getting enough "fans". This is not something many scientists aspire to, I don't think, nor has the patience for (I certainly don't).


Matter-Antimatter Asymmetry

This is an excellent article on the matter-antimatter asymmetry. It reviews the latest paper on decay asymmetry of the charm and anticharm mesons, but in the process, provided quite a good coverage of the progress in understanding why our universe is overwhelmingly lacking of antimatter.


"Big Bang Theory" Gets Stephen Hawking

"The Big Bang Theory" TV series got its dream guest star - Stephen Hawking.

The renowned theoretical physicist will guest-star on the April 5 episode of the CBS comedy, the network said Monday. In the cameo, Hawking visits uber-geek Sheldon Cooper (Jim Parsons) at work "to share his beautiful mind with his most ardent admirer," according to CBS.
I still haven't watched this series. Most of my friends kept asking me if I have seen it, and I kept having to say that I haven't. Then they look at me funny.

Maybe one of these days, I might see it, get terribly addicted to it, and can't stop talking about it. Till that happens, I have to keep telling people that I haven't seen it.


Monday, March 12, 2012

The Physics of Angry Birds

I have seen plenty of article on the physics employed in the wildly-popular app game "Angry Birds". I came across another one here that describes the kinematics and collisions that any intro physics student can understand.

I think that the kinematics part is rather trivial, but the subsequent collisions and "destruction" that follows can be quite complicated. That would have been a more interesting part that should be discussed in depth.


Thursday, March 08, 2012

Maxwell's Demon Exorcised?

Heh, sorry. Couldn't help with the pun.

It appears that there's now experimental evidence that erasing information requires the expenditure of energy. Consequently, this energy defeats the scenario presented in the Maxwell's Demon.

The results safeguard one of the most cherished principles of physical science: the second law of thermodynamics. This law states that heat will always move from hot to cold, or equivalently, that entropy — the amount of disorder in the Universe — always increases.

In the nineteenth century, the Scottish scientist James Clerk Maxwell proposed a scenario that seemed to violate this law. In a gas, hot molecules move faster than cold ones. Maxwell imagined a microscopic intelligent being, later dubbed a 'demon', that would open and shut a trapdoor between two compartments to selectively trap hot molecules in one of them and cool ones in the other, defying the tendency for heat to spread out and entropy to increase.

Landauer’s theory offered the first compelling reason why Maxwell’s demon couldn’t do its job. The demon would need to erase (‘forget’) the information it used to select the molecules after each operation, and this would release heat and increase entropy, more than counterbalancing the entropy lost by the demon.
It is very difficult to go against the 3rd Law, I tell ya!


Invisible Mercedes-Benz

Hey, who needs all the trouble of cloaking devices using narrow-band metamaterials when you can simply use flexible LED screens!

That is what they used to make this Mercedes-Benz vehicle almost invisible.

The invisibility cloak had its tryout this week on the streets of Stuttgart, Germany. To make Q's idea of an invisible car real, Mercedes employed dozens of technicians and some $263,000 worth of flexible LED mats covering one side of the car. Using a camera mounted on the opposite side of the vehicle, the LEDs were programmed to reproduce the image from the camera at the right scale, blending the vehicle into the background from a few feet away. Doing so required power sources, computers and other gear totaling 1,100 lbs. of equipment inside the B-Class.
Not sure what this demo has got to do with promoting the "...  first production fuel-cell vehicle in Germany ... ", but ok......


Daya Bay Measures Neutrino's θ_13

The major symposium held overnight on the new Daya Bay result reveals that they have finally measured the last neutrino mixing angle, θ13.

The preprint for the paper that has been submitted to PRL for publication can be found here.


Wednesday, March 07, 2012

LHC's Higgs Gets Support From Tevatron

Well, at least they are consistent!

We are starting to see some agreement here with the various data coming out of different detectors and different facilities. A new report from ALL the data analyzed out of the now-departed Tevatron shows a hint of the Higgs in the same energy range as that reported earlier out of the LHC. It seems that both CDF and D0 might be seeing the same thing that ATLAS and CMS saw recently.

Located at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, the Tevatron smashed protons into antiprotons to blast into fleeting existence subatomic particles not ordinarily seen in nature. Those collisions occurred within two massive particle detectors, known as CDF and D0, which strived to identify new particles as they quickly decayed into combinations of more familiar ones. In their final data sets, both the CDF and D0 teams see more candidate Higgs decays than one would expect from random background processes, scientists reported today at the conference Rencontres de Moriond in La Thuile, Italy.

The excesses are in line with Higgs hints reported in December 2011 by researchers working with the LHC at the European particle physics laboratory, CERN, near Geneva, Switzerland. The LHC smashes protons into protons within two even bigger detectors that are hunting the Higgs, called ATLAS and CMS. The ATLAS and CMS teams both see excesses of candidate Higgses with a mass of about 125 giga-electron volts (GeV), or 133 times the mass of the proton. The CDF and D0 teams see candidates with roughly the same mass although with poorer mass resolution. "If you look at what ATLAS sees, at what CMS sees, and at what CDF and D0 see, it starts to look like a consistent picture," says Fermilab's Rob Roser, co-spokesperson for CDF.
While the data out of the Tevatron can't do much in terms of providing the evidence for the Higgs, it certainly can throw a huge wrench if the results aren't consistent or contradictory to that out of the LHC. So this agreement here certainly help as part of the process in gaining credibility. Ultimately, the verification for the existence of the Higgs will have to come from the upcoming LHC run that will provide a significantly more data.


Saturday, March 03, 2012

The Brain Behind "The Big Bang Theory"

I mentioned about a news article on physicist David Saltzberg a while back, who is a consultant for the "The Big Bang Theory" TV series. Now Symmetry Magazine has an interview with him on his role for that show and all the surrounding impact. It's a very good interview and covers a lot of grounds.


Most Precise Measurement of W-boson Mass

While the Tevatron at Fermilab has gone into the collider heaven in the sky, none of us expects that we won't be hearing about its legacy well into the future. And this is one such example.

The DZero collaboration has reported the most precise measurement of the W-boson mass. This should have wide-ranging ramifications, including putting more constraints on the Higgs mass.

The CDF collaboration recently measured the W boson mass to be 80387 +/- 19 MeV/c2. The DZero collaboration measured the particle’s mass to be 80375 +-23 MeV/c2. The two new measurements, along with the addition of previous data from the earliest operation of the Tevatron, combine to produce a measurement of 80387 +- 17 MeV/c2, which has a precision of 0.02 percent.

I'm sure there will be more to come out of the retired "old lady".


Friday, March 02, 2012

The Many Uses Of Electron Antineutrinos

This is a terrific Physics Today article on the applications of electron antineutrinos.

As is the case in many other examples, we should NOT lose sight of the fact that something that first appeared to be esoteric out of high energy/elementary particle physics has now become something that has important uses. Think about this next time you hear someone asks for justification in funding for these high-energy physics experiments.


Thursday, March 01, 2012

Discovery of Majorana Fermions?

The big news so far coming out of the APS March Meeting going on right now is the result from the Leo Kouwenhoven group at Delft University. They reported on their latest experiment that, in some circles, shows compelling evidence for Majorana fermions.

Kouwenhoven’s apparatus is along the latter lines. In his group’s set-up, indium antimonide nanowires are connected to a circuit with a gold contact at one end and a slice of superconductor at the other, and then exposed to a moderately strong magnetic field. Measurements of the electrical conductance of the nanowires showed a peak at zero voltage that is consistent with the formation of a pair of Majorana particles, one at either end of the region of the nanowire in contact with the superconductor. As a sanity check, the group varied the orientation of the magnetic field and checked that the peak came and went as would be expected for Majorana fermions.
If this is true and verified, my earlier bet that Majorana fermions would probably be discovered in a condensed matter system first ahead of high energy physics experiments has come true! :)

In any case, this is an astounding experiment and an amazing accomplishment. I will eagerly anticipate reading the publication of this work.