Sunday, June 28, 2009

On Vacation

I've been on vacation since June 23, and won't be back till July 2nd. So there probably won't be any exciting blog entry in the world of physics till then.

Hope the world doesn't get sucked into a blackhole before then. I'd hate to miss something like that!



Monday, June 22, 2009

Work Begins on Homestake Mine

Ground breaking occurred today on the Homestake Mine as the new underground mine to study neutrinos and other things.

Scientists, politicians and other officials gathered Monday for a groundbreaking of sorts at a lab 4,850 foot below the surface of an old gold mine that was once the site of Nobel Prize-winning physics research.

The site is ideal for experiments because its location is largely shielded from cosmic rays that could interfere with efforts to prove the existence of dark matter, which is thought to make up nearly a quarter of the mass of the universe.


Sunday, June 21, 2009

Iconic Einstein Photo Sells For $74K

Just like Elvis, Einstein's memorabilia still fetches a lot of money half a century after his death.

The iconic, signed photo of Einstein sticking his tongue out was sold for more than $74,000 at an auction. In the short news article, I found out the circumstances surrounding that photo that I didn't know about.

Einstein had nine prints made. He signed the print that was auctioned on Thursday and gave it to journalist Howard K. Smith.

In his inscription, Einstein said his gesture was aimed at all of humanity. Livingston says it also was aimed at the Red Scare and the McCarthy anti-Communist hearings of the 1950s.

I guess he was defiant till the end.


Saturday, June 20, 2009

The Golden Age of Cosmology

This is a fascinating article by Nobel Laureate George Smoot on our current understanding of Cosmology.

The second reason why this is such an incredibly exciting time in cosmology is that these observations, combined with careful reasoning and an occasional brilliant insight, have allowed us to formulate an elegant and precisely quantitative model for the origin and evolution of the universe. This model reproduces to high accuracy everything that we observe over the history of the universe, images of which are displayed in the planetarium.

We now have precise observations of a very early epoch in the universe through the images made using the CMB radiation and we hope to start a newer and even more precise and illuminating effort with the launch of the Planck Mission on 14 May. However, we also have many impressive galaxy surveys and plans for even more extensive surveys using new ideas to see the relics of the acoustic oscillations in the very, very early universe, as well as the gravitational lensing caused by the more recently formed large-scale structures, such as clusters of galaxies that slightly warp the fabric of space–time by their presence. Each will give us new images and thus new information about the overall history of the universe.


Friday, June 19, 2009

Quantum Entanglement

This is a monstrous review article on quantum entanglement[1]. It is 78 pages long!

Abstract: From the point of view of quantum information science, entanglement is a resource that can be used to perform tasks that are impossible in a classical world. In a certain sense, the more entanglement we have, the better we can perform those tasks. Thus, one of the main goals in this field has been to identify under which conditions two or more systems are entangled, and how entangled they are. This paper reviews the main criteria to detect entanglement as well as entanglement measures and also discusses the role of entanglement in quantum communication and cryptography.

Even if you can't read the whole thing (who can?), at the very least, the wealth of references is more than ample reason to keep a copy of this thing.


[1] Horodecki et al., Rev. Mod. Phys. v.81, p865 (2009); the ArXiv version can be found here.

Dressing for a Job Interview

It's one of those things that isn't high on the list of things to pay attention to - dressing for an interview. Especially in academia/research, and especially in the physics profession, dressing appropriately isn't something that we pay that much emphasis on. I mean, during the summer months, I come to work in shorts, t-shirt, and sneakers. So one can already tell that I am not that "fashion conscious" (just don't anyone dare call Stacy and Clinton from "What Not To Wear"!).

Still, when one goes for a job interview, even for a job in physics/sciences, what would be appropriate to wear? Well, the Science career section this week has good tips for what to wear and what not to wear. It covers a wide enough situation, from formal to less formal, that one can buy a wardrobe to suit almost all the possible needs. And this covers for both men and women.

From the point of view of the interviewer, I would like your ability and your knowledge to stand out. This means that your outfit and how you are presented should NOT be a distraction. If you walk out of the interview and a day later, I don't remember what you wore, but I do remember exactly what you said, then you have done a good job in dressing yourself. We care more about your knowledge rather than your appearance, but your appearance can be a hindrance to our focus in deciding on what you know.

Luckily, I don't think I've ever come across an interviewee who hasn't dressed appropriately. And certainly I haven't come across anything similar to the person mentioned at the beginning of this article (it just shows lack of respect more than anything else, and that would have turned me off as an interviewer).


Students Went Into Zero-G To Do Experiment

Well, this sounds like a lot of fun.

A number of students from New Jersey went into the "Weightless Wonder", a NASA plane that can make zero-g dives, to do their experiment on plasma dust clouds.

In 2008, the first Team DPX -- comprised only of students -- boarded a DC-9. This year, NASA invited Zwicker, who was one of the mentors for both DPX teams, to join the students. The 2009 team -- including several additional students -- took aboard a second dusty plasma experiment, as well as upgraded equipment and additional cameras.

That's almost as an exotic of a "location" to do one's experiment as going to the Antarctica. Still, I wish the news report tells us a little bit more of the nature of the experiment and what exactly is being observed.


Thursday, June 18, 2009

How Does Time Travel Really Work, Sean Carroll?

Caltech's Sean Carroll took time off from his work to answer a few questions about time travel that we have seen in the movies. If nothing else, this news article gets a chuckle or two. For example:

"Superman" (1978 version)

How time travel is achieved: Superman zips into space and flies faster than the speed of light, round and round, reversing the planet's spin and reversing time.

Carroll says: "It would cause earthquakes and kill millions. And really, if you can do this, then why, if you're Superman, don't you do this all the time? He should be held to a higher standard."



Tuesday, June 16, 2009

Prototype Nokia Cell Phone Recharges Using Ambient Radio Waves?

OK, I read this and I started laughing hysterically.

Sure, I was skeptical, but I also don't doubt that this COULD work. Still it looks like they will need quite a bit of work left to do before they could harvest enough energy just from the ambient EM wave.

Nokia thinks that they have developed a cell phone that doesn't need recharging. It recharges itself from the surrounding radio waves that is almost everywhere.

While "traditional" (if there is such a thing) wireless power systems are specifically designed with a transmitter and receiver in mind, Nokia's system isn't finicky about where it gets its wireless waves. TV, radio, other mobile phone systems -- all of this stuff just bounces around the air and most of it is wasted, absorbed into the environment or scattered into the ether. Nokia picks up all the bits and pieces of these waves and uses the collected electromagnetic energy to create electrical current, then uses that to recharge the phone's battery. A huge range of frequencies can be utilized by the system (there's no other way, really, as the energy in any given wave is infinitesimal). It's the same idea that Tesla was exploring 100 years ago, just on a tiny scale.

Mind you, harvesting ambient electromagnetic energy is never going to offer enough electricity to power your whole house or office, but it just might be enough to keep a cell phone alive and kicking. Currently Nokia is able to harvest all of 5 milliwatts from the air; the goal is to increase that to 20 milliwatts in the short term and 50 milliwatts down the line. That wouldn't be enough to keep the phone alive during an active call, but would be enough to slowly recharge the cell phone battery while it's in standby mode, theoretically offering infinite power -- provided you're not stuck deep underground where radio waves can't penetrate.

Question is, how SLOW does it recharge?


The Elusive Memristor: Properties of Basic Electrical Circuits

I'm guessing that there's a flurry of activity after last year's publication of the discovery of a memristor. There is a handy article in Eur. J. Phys. describing the basics of memristor and its properties as an electrical component[1].

Abstract: We present an introduction to and a tutorial on the properties of the recently discovered ideal circuit element, a memristor. By definition, a memristor M relates the charge q and the magnetic flux phi in a circuit and complements a resistor R, a capacitor C and an inductor L as an ingredient of ideal electrical circuits. The properties of these three elements and their circuits are a part of the standard curricula. The existence of the memristor as the fourth ideal circuit element was predicted in 1971 based on symmetry arguments, but was clearly experimentally demonstrated just last year. We present the properties of a single memristor, memristors in series and parallel, as well as ideal memristor–capacitor (MC), memristor–inductor (ML) and memristor–capacitor–inductor (MCL) circuits. We find that the memristor has hysteretic current–voltage characteristics. We show that the ideal MC (ML) circuit undergoes non-exponential charge (current) decay with two time scales and that by switching the polarity of the capacitor, an ideal MCL circuit can be tuned from overdamped to underdamped. We present simple models which show that these unusual properties are closely related to the memristor's internal dynamics. This tutorial complements the pedagogy of ideal circuit elements (R, C and L) and the properties of their circuits, and is aimed at undergraduate physics and electrical engineering students.


[1] Y.N. Joglekar and S.J. Wolf, Eur. J. Phys. v.30, p.661 (2009).

High-Tc Superconductors Are Very Kinky - Update 6

Another preprint appears today on the origin of the "kink" that in ARPES spectra of high-Tc superconductors. This time, there is a careful analysis of the role of phonons in producing such an effect[1]. By making the assumption that the magnetic effects play no role at all, they calculated the possible outcome of the phonon mode as the sole source of the band kink. They concluded that for optimally-doped Bi2212, phonons contribute only 10% to this effect.

So from this work, phonons are not the dominant factor in causing the kink.

I have updated the original blog entry to contain this reference.



Monday, June 15, 2009

Another "Hoax Paper" Accepted For Publication

As much as we whine about peer-reviewed process and the prestige of certain journals that try to uphold a very rigorous acceptance process, when we read something like this, it drives home the fact that, more often than not, quality beats quantity on any given day.

A hoax paper was accepted to be published in an open access journal that I've never heard about until now {link available for free only for a limited time}.

The fake, computer-generated manuscript was submitted to The Open Information Science Journal by Philip Davis, a graduate student in communication sciences at Cornell University in Ithaca, New York, and Kent Anderson, executive director of international business and product development at The New England Journal of Medicine. They produced the paper using software that generates grammatically correct but nonsensical text, and submitted the manuscript under pseudonyms in late January.

Davis says he decided to submit the fake manuscript after receiving several unsolicited invitations by e-mail to submit papers to open-access journals published by Bentham under the author-pays-for-publication model. He wanted to test if the publisher would "accept a completely nonsensical manuscript if the authors were willing to pay".

Davis was informed by Bentham on 3 June that his manuscript was accepted for publication. The publisher requested that Davis pay US$800 to its subscriptions department, based in the United Arab Emirates, before the article was published. At this point, Davis retracted the article.

The editor of the journal is resigning from the journal in dispute with the publisher. I find it entirely VERY strange that the journal publisher is claiming that the paper has been reviewed by more than one referee, and yet, the editor in chief is not able to access or verify that such a review has taken place. Typically, the editor, of all people, are the ones assigning the referring process and has full access to all the reviews. So something is definitely fishy here.

This is reminiscent of the Alan Sokal hoax in "Social Text", even though the aim of that hoax is on an entirely different matter than this one. Still, the review process failed, and that something that is essentially garbage made it through the process and got through. This is one clear example of what would happen without proper scrutiny and review.

Of course, someone might ask "But ZapperZ, even those prestigious journals like Nature and Science are not immune to publishing such "hoaxes", as illustrate by the Hendrik Schon debacle".

Ah, but there's a difference here. When you either forge data or being unethical, it is very difficult to spot something like that, as opposed to the nonsensical paper written by Sokal and in this latest case. Any reviewer who knows the subject matter can immediately spot such "word salad" that are contained in these cases. In Schon's case, it isn't easy to spot because the deception is in THE DATA itself. It requires others to try and reproduce that experiment as a means to verify what was obtained, i.e. it requires the wheel of scientific independent verification to kick in. You'll never see such word salad manuscript getting published in Nature, Science, PRL, etc.


Sunday, June 14, 2009

Oppenheimer and Fermi: Two Developers of the First Atomic Bomb

This is the transcript of a radio broadcast (I'm assuming, on Voice of America) on a show summarizing the contribution (and brief history) of Oppenheimer and Fermi in the development of the atomic bomb.

If you haven't read or heard much about such a history, this would be a "Cliff Notes" version of it that has been highly condensed for casual consumption.


Physics Is Beauty

This is a rather good article on the journey and reason someone pursues a degree and research work in physics.

Physics is worth knowing because it is beautiful. It is the hidden secret of the scientist. We may claim to be researching some topic or other because it is "useful to society" or it will revolutionize some technology but, more often than not, we are simply fascinated by some small detail about how the world works and we can't stop thinking about it until we understand it better. We are constantly astounded by the way a few basic principles work together to explain so many different things, and sit in wonder and awe at the beauty of the world. Like an artist, I want to share this beauty with others. I want them to know what it is to see through my eyes.

Unlike crackpots, who continue to make grandiose claims of finding the "theory of everything" and solving the question of the universe, the overwhelming majority of physicists really do not have such pretentious goal. We tend to want to solve a particular problem, or work in a particular area, because these are the ones that peaked our curiosity, and we want to find the answer to their questions. We just want to add to the huge body of knowledge, even if it is just a small portion of it. Of course, some of us are more aware of the application of what we do, and that certainly can be a motivating factor in addition to the curiosity angle.


Saturday, June 13, 2009

The Physics of Nothing

This is a news article of one of the sessions that went on during this year's World Science Festival, currently running in NY City. It is essentially a dialog and Q&A involving Frank Wilczek, John Barrow, Paul Davies, and George Ellis. All they talked about was "nothing"!

“Nothing is unstable,” Frank Wilczek, a physicist and Nobel laureate from MIT, finally said to a general murmur of agreement of his colleagues on stage, John Barrow of Cambridge University in England, Paul Davies of Arizona State and George Ellis of the University of Cape Town in South Africa.

Given a chance, nature will make nothingness boil with activity.

Unfortunately, this is also a favorite topic of crackpots. I'm sure this news article will be used, somehow, to bastardize the physics of vacuum state.


Friday, June 12, 2009

To What Extent Iron-Pnictide New Superconductors Have Been Clarified: A Progress Report

It has only been a few years since the discovery of superconductivity in the iron-arsenic compound family. Yet, a lot of work, both theoretical and experimental, has been done on this material. So it is inevitable that, at some point, a review of what we know so far will appear. This is one such review.

Abstract: In this review, the authors present a summary of experimental reports on newly discovered iron-based superconductors as they were known at the end of 2008. At the same time, this paper is intended to be useful for experimenters to know the current status of these superconductors. The authors introduce experimental results that reveal basic physical properties in the normal and superconducting states. The similarities and differences between iron-pnictide superconductors and other unconventional superconductors are also discussed.

Certainly helpful to have a catalog of something like this periodically.


Speed Networking for Scientists?

No, this isn't "very fast" networking, but rather something similar to speed dating...

I'm not making this up! :)

An article in this week's Science Career section discussed something that is getting some "speed" in popularity - speed networking.

Our so-called Translational Research Bazaar, which took place in October, used a format popularized by speed dating: Two groups of people--in this case, basic scientists and clinical/translational researchers--sit on opposite sides of a table and chat for a few minutes until a bell rings, signaling that it's time to move on and strike up a new conversation. This process continues until everyone in one group has met everyone in the other group. The goal, for translational research as for dating, is to find a match.

More than 80 people registered for the event, and follow-ups with the attendees suggest it worked as planned: Eighty-five percent of participants said they met at least one potential collaborator, and seven pairs of researchers applied for internal pilot funding. Word has gotten out: Other institutions and organizations have contacted us hoping to learn how to run their own events.

Er.... yeah.

I suppose whatever works in getting to meet others. Can't see any harm in that, other than a greater risk of exposure to the H1N1 virus! :)


Thursday, June 11, 2009

Lorentz Contraction, Bell's Spaceships, and Rigid Body Motion in Special Relativity

I don't know if this manuscript has been published elsewhere, or if it has been submitted for publication. However, I found it a rather interesting reading. It explores certain "misconception" in Special Relativity, especially on the issue of "length contraction" that appears to be a standard part of physics education. Read it and see what you think.

I suppose this is another one that tries to correct certain popular misconception, or the use of inappropriate description, in SR. We already had papers dealing with issues of "relativistic mass" and why such a use is not accurate. It only serves to show the complexity in the trying to "visualize" the concept in something that has been developed for more than 100 years already, and a tribute to how revolutionary Relativity is.

Edit: This paper has now appeared in publication. Here is the complete reference:
J. Franklin, Eur. J. Phys. v.31, p.291 (2010).


Wednesday, June 10, 2009

Astronomy and the Media: a Love Story?

Another fun article to read about Astronomy. This time the article questions on whether there is ample and adequate media coverage of Astronomy, or whether the subject has been neglected in general, despite high-profiled stories about black holes, dark matter, dark energy, etc.

We can couple this with an earlier article on the public perception of astronomers throughout history. They make a rather interesting reading.


ac-Driven Atomic Quantum Motor

A very interesting and intriguing theoretical proposal.

A. V. Ponomarev et al., "ac-Driven Atomic Quantum Motor", Phys. Rev. Lett. v.102, p.230601 (2009) .

Abstract: We propose an ac-driven quantum motor consisting of two different, interacting ultracold atoms placed into a ring-shaped optical lattice and submerged in a pulsating magnetic field. While the first atom carries a current, the second one serves as a quantum starter. For fixed zero-momentum initial conditions the asymptotic carrier velocity converges to a unique nonzero value. We also demonstrate that this quantum motor performs work against a constant load.

ScienceNow has a review of this paper as well.

Now, Alexey Ponomarev, Peter Hänggi, and colleagues at the University of Augsburg, Germany, have devised the quantum-mechanical equivalent of such a motor. Their motor consists of bright spots of laser light that form a circle like so many pearls in a bracelet (see picture). The spots of laser light can trap two ultracold atoms: The first, called the carrier, is missing an electron and so is electrically charged; the second, called the starter, is uncharged. Instead of applying an oscillating current in a coil, the researchers envision applying an oscillating electric field perpendicular to the plane of the ring.

This will set the carrier into motion--but not in a simple way. Because it's a quantum particle, the carrier atom must be described by quantum waves that give the probability for finding it at one position or another. Applying an oscillating field alone will send waves of equal strength rippling around the ring in both directions, with the net result that, on average, the particle doesn't budge. To get it going, the physicists have to include the starter atom, which gives the carrier a shove whenever the two atoms happen to hop into the same light spot.

Even that is not quite enough. To make the motor turn over, the researchers find, the electric field has to oscillate in a pattern that would appear different if it were suddenly reversed--much as a song sounds different if you play it backward. Such oscillations set off quantum waves that flow predominantly either to the left or to the right, setting the motor in motion, the researchers report in a paper published online this week in Physical Review Letters.

Now let's see which experimental group will be the first to produce something similar to this! The race is on! :)


Tuesday, June 09, 2009

Lessons In Particle Physics

This appears to be lecture notes for a graduate level course in particle physics, presumably at the University of Wisconsin-Madison (Go Badgers!). It also says that this is Part 1, where the second part will be posted at the end of the Fall semester.

I do not vouch for the accuracy or validity of the notes, but still, I thought it might be useful for someone either thinking, or need a brush up on some particle physics fundamentals. It would have been nice to know what text, if any, they were using.


Sunday, June 07, 2009

Oprah Responds To Newsweek Article

Recall that I asked if Oprah Winfrey is a crackpot based on the report I read in the Newsweek article. It appears that Winfrey has responded to the Newsweek article:

"For 23 years, my show has presented thousands of topics that reflect the human experience, including doctors' medical advice and personal health stories that have prompted conversations between our audience members and their health care providers," Winfrey said in a statement. "I trust the viewers, and I know that they are smart and discerning enough to seek out medical opinions to determine what may be best for them."

Er... what?

You gave these things a highly one-sided coverage, and THEN, expect your audience to decide for themselves? This is the same audience that prefer to read some heart-wrenching novel that you peddle rather than scientific research and reading about scientific method? This is the same audience that fall into the general population that cannot tell the difference between anecdotal and scientific evidence? The SAME general population that failed miserably in the National Research Council survey on science literacy and understanding? You think they can seek out AND evaluation medical opinions AFTER you've skewered it through your show?

Yeah, right!


Accelerators and Beams - Tools For Discovery and Innovation

Anyone who has read this blog for any considerable period of time would have read several of my entries on trying to destroy the myth that "particle accelerator" only means "particle collider". This is of course patently false. People who majored in accelerators physics are not even high energy physicists. In fact, many are engineers. Still, when people hear the name "particle accelerators", they immediately associate that with particle physics.

The American Physical Society (APS) and the Division of Particle and Beams within the APS, has produced this wonderful brochure that ANYONE can read and educate him/herself on what an accelerator is, and how it is more than just something used in high energy physics particle collider. In fact, the MAJORITY of the application and use of particle accelerators are NOT for high energy physics.

This is a good brochure to read and maybe print.


Saturday, June 06, 2009

Is Oprah Winfrey A Crackpot?

The cover of June 8, 2009 issue of Newsweek shows the face of TV talk show host Oprah Winfrey with the headlines "Crazy Talk - Oprah, Wacky Cures, and You". A web version of the article can be found here. The article basically described all the weird and crazy cures, in addition to other mystic self-help advice that have occurred on Winfrey's talk show. Of course, the infamous "The Secret" gained its popularity on this show when she devoted a lot of time to it. I've already commented on the bogus physics that this thing claimed to be based on, so I won't go into it.

Still, the Newsweek article really skewered the talk show host for promoting such medically dubious cures, especially her promotion of the opinion of another "medical authority" Suzanne Somers.

I'm not going to bother to go into what has transpired. You can read it for yourself. However, I think it is safe to say that Winfrey (and many others) continue to reflect a very common characteristic of a large portion of the population. They do not understand the difference between anecdotal evidence, versus valid scientific evidence. They also are not aware of the existence of such differences, i.e. they do not know that something called "anecdotal evidence" exists, and why it isn't a solid or valid evidence. More often than not, they do not realize that correlation does not imply causation.

But such ignorance is to be expected when a talk show emphasize more on "feelings" and emotional content, rather than based on science and scientific evidence. Winfrey's book club is littered with novels exploring human emotions and well-being. You don't see books that have solid science in here book club selection. I'd die if I see her recommending Bob Park's "Voodoo Science" book, for example. Why? Because it requires a LOT of analytical thinking and requires her and her viewers to actually STUDY something carefully, rather than simply letting one's emotion and feelings take over as the major factor in reading a book. Don't get me wrong. There's nothing wrong with books exploring such emotional feelings. But shouldn't there be a balance of opinion and exploration of human capability? At what point is the scientific and analytical ability of human beings get tested and challenged in her show? It's as if that part of a human being doesn't even exist.

So is Oprah Winfrey a crackpot? Well, some of her guests may be, but she's not a crackpot. She is just ignorant of basic science facts and scientific methodology, just like a large portion of the general public. Her mix of mystical, spiritual information with valid medical opinions is what most of the public often do. They support science, but also read their horoscopes. They understand the importance of science, but still believe in ghosts and other supernatural occurrences. And there's no sign that either Winfrey or the general public is going to change that any time soon.


Friday, June 05, 2009

Building a Culture of Safety

I mentioned earlier about the tragic accident at a UCLA lab that cost the life of a researcher. I will say that this accident isn't unique, and that the culture of very lax safety concerns at universities is more of the norm rather than the exception.

Science Career section this week has an article on the culture of safety, or the lack thereof, at many educational institution. It basically reiterates what I had written. One only needs to go to many of the user facilities at various US Nat'l labs, and talk to personnel in charge of safety at these facilities. They'll tell you some of the problems they often have with users coming in from educational institutions who simply consider safety guidelines and enforcement as being nothing more than hindrance to their jobs.

Certainly the safety paranoia can be taken to an extreme. But for me, I'd rather know what I should be doing, rather than being left bumbling in the dark and not know what is the proper way of doing something, or where I can go to seek assistance when I don't know. After all, the person that has the greatest vested interest in my safety is not the safety officer, not my boss, and not the institution that I'm working for. That person is ME!


Thursday, June 04, 2009

The Physics in Disney/Pixar's "Up"


Hey, I hope you have seen Disney/Pixar's "Up". It's a gorgeous movie, especially if you see it in 3D, and a fun and even emotional storyline. So don't miss it.

One of the behind-the-scene things for "Up" is the realistic simulation of many aspect of the movie. This is especially true in the scenes involving those numerous balloons. Pixar animators are well-versed in physics, and have tried to model them according to the laws of physics.

May said that the animation department at Pixar never even considered hand-animating the balloons. But even standard computer animation wouldn't be up to the task, because of the N-squared complexity involved in the thousands of interdependent balloons. Instead, the studio's computer whizzes figured out a way to turn the problem over to a programmed physical simulator, which, employing Newtonian physics, was able to address the animation problem.

"These are relatively simple physical equations, so you program them into the computer and therefore kind of let the computer animate things for you, using those physics," said May. "So in every frame of the animation, (the computer can) literally compute the forces acting on those balloons, (so) that they're buoyant, that their strings are attached, that wind is blowing through them. And based on those forces, we can compute how the balloon should move."

Still, there's one very obvious inconsistency between the physics and what is on the screen. I'm not trying to be nitpicking here, because I love the movie, and as an animation and a movie, one should allow for a lot of artistic license in telling the story. Still, when I saw the scene in the movie, the physicist in me wanted to ask the question.

The scene involves the infamous moment when Carl's house was pulled up from the ground and floated away due to all these helium-filled balloons. Forgetting that it would probably take an unbelievable amount of balloons to do such a thing, what "bothered" me was the idea that there's no buoyancy until the balloons were "deployed". Here's what I mean.

When a couple of people from a retirement home came to pick up Carl, he handed his bags to them and told them to wait for him while he said goodbye to his house. He then went in, and then deployed all the balloons that are attached to a base in his fireplace. All these balloons then started to pull on the house, breaking it off its foundation, and the house became afloat.

But see, the balloons were already in the house. All Carl did was simply to "unleash" them so that they now float freely. But it doesn't mean that before then, they do not have the buoyancy. By simply unleashing them, it doesn't mean that the upward force suddenly got turned on. It was there all along, and Carl's house should have floated away as soon has he has filled up and attached a sufficient number of balloons.

What would have been realistic would have been some anchor that Carl would had to release to finally allow the upward force to finally overcome all the remaining part of the house and become free from the foundation. Since they are paying that much attention to the physics, this would have been more accurate. But I don't believe I saw this in the movie.

Oh well, it is still a damn fine movie. Go see it!


More is the Same; Phase Transitions and Mean Field Theories

This is a clear and concise treatise on phase transition, written by Leo Kadanoff, one of the leading figures today in condensed matter physics. Even if you don't understand the mathematics, the written description of phase transition is very well presented, so I highly recommend this for everyone to read.

Abstract: This paper Looks at the early theory of phase transitions. It considers a group of related concepts derived from condensed matter and statistical physics. The key technical ideas here go under the names of "singularity", "order parameter", "mean field theory", and "variational method".
In a less technical vein, the question here is how can matter, ordinary matter, support a diversity of forms. We see this diversity each time we observe ice in contact with liquid water or see water vapor, "steam", come up from a pot of heated water. Different phases can be qualitatively different in that walking on ice is well within human capacity, but walking on liquid water is proverbially forbidden to ordinary humans. These differences have been apparent to humankind for millennia, but only brought within the domain of scientific understanding since the 1880s.
A phase transition is a change from one behavior to another. A first order phase transition involves a discontinuous jump in a some statistical variable of the system. The discontinuous property is called the order parameter. Each phase transitions has its own order parameter that range over a tremendous variety of physical properties. These properties include the density of a liquid gas transition, the magnetization in a ferromagnet, the size of a connected cluster in a percolation transition, and a condensate wave function in a superfluid or superconductor. A continuous transition occurs when that jump approaches zero. This note is about statistical mechanics and the development of mean field theory as a basis for a partial understanding of this phenomenon.


Wednesday, June 03, 2009

FFAGs Enter Application Phase

I mentioned earlier about the unfortunate name being given to the Fixed-Field Alternating Gradient accelerator (FFAG), and the amusing possibility on how the acronym is pronounced by people working in the field. Still, it doesn't diminish the importance of the technique and why it is an active area.

This article out of CERN Courier shows where FFAG has now enters into the application phase, where it is now being constructed not simply as a research facility or a prototype, but as a facility to be used for other purposes and applications.

The Development of an Accelerator Driven Subcritical Reactor using an FFAG Proton Accelerator project, which is now reaching its goal, was initiated in 2002 under a contract with the Ministry of Education, Culture, Sports, Science and Technology (MEXT) as part of the Technology Development Project for Innovative Nuclear Energy Systems. In the experiment the FFAG accelerator provides a high-energy proton beam to a heavy-metal target in the KUCA to produce spallation neutrons, which in turn drive fission chain reactions in the KUCA-A Core.


Tuesday, June 02, 2009

A Tale of Two Curricula: The Performance of Two Thousand Students in Introductory Electromagnetism

I've only had a quick look at this report, so I can't say much about it. But still, I thought maybe someone might want to read it. It's a very interesting and quite comprehensive study of the students' response to an E&M test after going through two different curricula for intro E&M class. Not only that, they monitored this at four major universities - Purdue, North Carolina State, Georgia Tech, and Carnegie Mellon - resulting in a very extensive survey.

Abstract: The performance of over 2000 students in introductory calculus-based electromagnetism (E&M) courses at four large research universities was measured using the Brief Electricity and Magnetism Assessment (BEMA). Two different curricula were used at these universities: a traditional E&M curriculum and the Matter & Interactions (M&I) curriculum. At each university, post-instruction BEMA test averages were significantly higher for the M&I curriculum than for the traditional curriculum. The differences in post-test averages cannot be explained by differences in variables such as pre-instruction BEMA scores, grade point average, or SAT scores. BEMA performance on categories of items organized by subtopic was also compared at one of the universities; M&I averages were significantly higher in each topic. The results suggest that the M&I curriculum is more effective than the traditional curriculum at teaching E&M concepts to students, possibly because the learning progression in M&I reorganizes and augments the traditional sequence of topics, for example, by increasing early emphasis on the vector field concept and by emphasizing the effects of fields on matter at the microscopic level.

Edit 10/5/09: This exact reference to this paper is: M.A. Kohlmyer et al., Phys. Rev. ST Phys. Educ. Res. v.5, p.020105 (2009).


LHC: Status and Commissioning Plans

This is a good document which summarizes the LHC status, including the incident that caused it to be temporarily shut down, and also includes the plans in the immediate future for the facility.

Abstract: In 2008 the LHC saw a series of injection tests with beam and the start of full beam commissioning. Initial beam commissioning went well and circulating beam was quickly established. Progress was unfortunately curtailed by the sector 34 incident which caused extensive damage. The causes of the incident are recalled and the status of repairs and consolidation measures are presented. The schedule and luminosity targets for the 2009 - 2010 run are discussed.


Monday, June 01, 2009

Dark Energy Particle Spotted?

No, not dark matter, but dark energy!

A new paper[1] has thrown a wrinkle into the dark energy puzzle. A "chameleon" particle has been proposed (link open only for a limited time) that can arise out of photon traveling from distant astronomical bodies while passing through magnetic fields, very much like the proposed axions, which have yet to be detected. However, the authors of this proposed chameleon particles claim that there is a "good evidence" that they may have been detected already.

In theory, photons that travel through magnetic fields can turn into chameleons, reducing the amount of light that reaches Earth from distant sources. The amount of dimming depends on the light's frequency. By comparing light emitted across a range of frequencies from the luminous centres of 77 active galaxies, Douglas Shaw at Queen Mary University of London and his colleagues have found what they call "good evidence" that some photons have gone missing in transit.

However, these chameleon particles cannot be distinguished from those axions.

By themselves, the observations of dimmed light by Shaw and his colleagues can't distinguish between models that rely on chameleons and models in which photons turn into other 'axion-like' particles. Either "would be an interesting discovery," says Shaw.

However, only the chameleon model predicts that the photons' polarizations should be aligned with the magnetic fields they traversed. So far, the team has studied data on light from three stars in the Milky Way galaxy and in each case found the required polarization3.

Looks like there are people who are already planning on testing this in the next couple of years, so it should be interesting to see how this turns out.


[1] C. Burrage et al., Phys. Rev. Lett. v.102, p.201101 (2009).