Thursday, November 30, 2006

Animals Levitated By Sound

Here's another physical demonstration of levitation - this time, using sound.

I wonder how many crackpots will latch on to this?


Physicists Argue on the Authenticity of a Painting

File this one as something I haven't come across before. Two groups of physicists are battling it out on whether fractal analysis can actually be used to autenticate a group of possible Jackson Pollock painting.


High Energy Physics Goes Euro

A news report indicating what most physicists have known already. The high energy physics experiments will soon migrate out of the US completely and into Europe. This will certainly be true when the Tevatron ends its funding and the LHC goes online.

The fight for the ILC is still hazy. No definitive decision yet on building it, and where to build it. I know that Fermilab is making a major push to host it, and those of us here at Argonne are certainly supporting it. If the ILC goes elsewhere, then the US has ZILCH large scale high energy physics facility for the first time in the history of high energy physics experiments (SLAC is already being retooled into a light source with the building of the LCLS).


Wednesday, November 29, 2006

Hawking Awarded Copley Medal

The British Royal Society is awarding the Copley Medal to Stephen Hawking on Nov. 30. The unique aspect of this is that the medal was flown on the Space Shuttle Discovery last July.

Don't you just wish that the Shuttle can actually do some actual, publishable science, rather than just various publicity stunts such as this? Not that I have anything against publicity stunts all the time, but this is one very expensive publicity stunt to maintain this long.


Physics In Dance?

OK, this is where I risk offending some people. However, I think this is a load of crap, almost as bad as the movie "What the *&#(*%! Do We Know?". String theory and Relativity in Dance? Can we say pop science gone wild?

I'm all for introducing physics to the public, but sometime one simply has got to draw the line on quality versus quantity.


Science Journal Committee Issues Report on Hwang Debacle

A committee appointed by the journal Science on its handling of the disgraced Korean geneticist Woo Suk Hwang et al. has issued its report. This report affect everyone that intends to not only submit a manuscript to Science, but possibly also to Nature. It addresses the handling of high-impact publication such as this and also similar work that would include the Hendrik Schon retracted work from a few years ago.


Single Photon Sources

I'm adding this info here just so I can look up the reference easily since I seem to need it pretty often. We seem to continually have people having an uproar over the "photon picture" of light [Notice that in all of the complaints, NONE of them have ever done ANY of the experiments they criticize, and that in none of them can they prove that the photon picture FAILS to also account for the effect being displayed].

Anyway, as of now, this is almost the DEFINITIVE reference to single photon sources being created almost ON DEMAND. This is a very comprehensive review of all available single-photon sources so far. I strongly recommend anyone interested to get a copy of this review paper.

B. Lounis and M. Orrit, Rep. Prog. Phys. v. 68, p.1129 (2005).

There is a HUGE difference between reading about an experiment, and DOING it yourself where you can really oberve something. Not only that, you are also able to tweak and modify some parameters and see how such things affect others. There isn't anything more convincing. But then again, I'm bias.


Tuesday, November 28, 2006

Nov. 28, 2006 is Argonne Day

The Governor of Illinois declared that today, Nov. 28 2006 is Argonne National Laboratory Day! Hooray! Now do we get a holiday on this day every year?


Argonne is celebrating its 60th Anniversary this year as the oldest US National Laboratory. Still, many people still mistaken it for Fermilab.


Physics Demo Caught Fire

Wow! We have plenty of news all of the sudden on physics classroom demonstration gone wrong. This time it came from the University of Utah. A physics demo using the Reicke tube caught fire, causing the classroom to be evacuated.

Who said that physics isn't dangerous? :)


University of Chicago to be APS Historic Site

The American Physical Society will designate the University of Chicago as a physics historic site on Nov. 30, for the work done by Millikan.

I'm not sure why U. of Chicago hasn't been designated as such already, considering all the work done by Fermi. Maybe it was because the building Fermi worked in no longer exist?


Newton's 3rd Law Produced Unexpected Reaction

Be very careful in doing a classroom physics demonstration. If you do it wrong, you could get accused of sexual harrassment! Oy vey!

The best quote I found in this article was this one:

Assuming I wasn't moral and ethical, I'm not stupid, Do they think I'd be stupid enough to molest a girl in front of 34 witnesses? To me, this is absolutely insane.

I hope they publish the outcome of this thing.


Monday, November 27, 2006

The Sherwood Boehlert Interview

In last week's issue of Science (24 November 2006), there is an interview with Serwood Boehlert, the current Chairman of the US Congress Science Committee who, after 24 years, is retiring at the end of this year.

I think every scientist, especially young, new scientists, should read this interview and read it carefully. There are profound points and observations that was made. For instance, note this point:

"I'll bet you that if you look at all the new freshmen (respresentatives), you won't find a single one, from either party, who campaigned on something like the American Competitiveness Initiative, or more resources for NSF [National Science Foundation], or greater investment in science and math education. I'll bet you won't find one. And that's a failure by the scientific community."

There are many smack-in-your-face-and-wake-up points like that. So do NOT miss it!


Sunday, November 26, 2006

Dinner Theater Classroom for Physics

University of Michigan has a novel way of teaching physics beyond the standard, passive learning method. This looks rather interesting. However, we have seen any different methodology in the teaching of physics. I'm all for using new and modern methods. But at some point, we have to go beyond the novelty act and figure out how effective these things are and whether such a thing can be sustained with our limited resources.


The Premier and I

OK, so it will not make a very good movie or Broadway musical like The King and I, but this is still a fascinating account of the friendship between the Premier of China and a physics Nobel laureat.

Of course, since this is a state run news source, one should read something like this with that in mind.


Drop in the Number of New Zealand Students Taking Physics Exams

It appears that the US and UK are not the only places experiencing a drop in the number of students going into physics (although there appears to be a recovery in the US with the recent increase in the number of physics undergraduates). New Zealand is reporting a drop in the number of students sitting for NCEA physics and mathematics.

Have we not sold the profession as well as we should?


Saturday, November 25, 2006

All About Snowflakes

Since it is almost that time of the year (at least in the Northern Hemisphere), I thought it is appropriate to point out this website. It contains everything (or almost everything) you wanted to know about snowflakes and snow crystals, but was afraid to ask. It was created by Kenneth Libbrecht, a physicist at Caltech. In addition to the physics of snowflakes, there are also a lot of amazing pictures.


Thursday, November 23, 2006

Silicon Becomes a Superconductor?

A rather unexpected discovery reported in Nature this week. Silicon, when overdoped with Boron, becomes a superconductor at 0.35K. This, of course, will require verification and confirmation. Still, it might add to the family of known superconductors.


String Theory Deconstructed

As if String Theory needs any more critique.

Bert Schroer has an article addressing string theory to commemorate Phil Anderson's 83rd birthday. Phil Anderson, along with Bob Laughlin, has been a critique of String Theory and the fallacy of the "Theory of Everything". This article by Schroer actually addresses something that is even more fundamentally wrong with String Theory and not just from its practice. If these claims are true, it may mean that there's a fatal flaw in its foundation.


Wednesday, November 22, 2006

Happy Thanksgiving

To all those who celebrates it, Happy Thanksgiving!


The End for Mars Global Surveyor?

The Mars Global Surveyor has not been heard from. Have we heard the last from this workshorse?

I find it rather puzzling that NASA is now concentrating on "manned" mission, when space craft such as this and the Mars rovers are capable of doing more for less.


Fusion Deal Signed

Reported by Nature News and Science Daily News update today, the cost of building ITER was finalized and signed yesterday.

It is now time to build!


Physics at Universal Studios

A group of high school students learn about physics at Universal Studios in Orlando. While I applaud efforts like this to related what kids learn in school with some "real life" example, I still don't know if there's any meticulous study on the effectiveness of class outings like this. I mean, did the kids actually learn something useful, or were they just pretending they did just so they can spend a day at a theme park or outside the classroom?

I wonder...


Tuesday, November 21, 2006

Bob Park - Physics Strikes Back!

It is very seldom that physics and/or physicists are in the popular media to strike back at all the nonsense that are constantly reported and taken as "facts". This range from reports of "perpetual motion" machines, machines that can generate energy more than it consumes, various claims of faster-than-light illusion, politicians making science decisions not based on science, etc. It is sad to see a lot of the general public are taken in by such quacks, fraud'sters, and charlatans simply because they have colorful personalities and lots of bells and whistles. Science, including physics, has taken quite a beating with even attempting to fight back.

The exception to this, however, is a physicist by the name of Robert Park of the University of Maryland. Starting off while he was with the American Physical Society, he started a weekly column called What's New. This soon became a hit among physicists who subscribed and read his column religiously. This was, to me, the original "blogger" before it became a household word. Bob Park began addressing all the absurdity and abuse of science done by everyone ranging from some Joe Newman who claimed to have physics-defying inventions, to the brain-dead decisions of various politicians and govermental bodies. He was very instrumental, at least for me, in exposing the unbelievable patent of The Blacklight Co. for the "hydrino", attributed to various members (now deposed) of the US Patent Office having some affinity for "free energy".

This, and other embarrasing misteps in physics can be hilariously read at the What's New webpage.

His new column are posted and e-mail to subscribers every Friday. While I don't necessarily agree with everything he says, I applaud his courage for being one of the few physicists who dare to expose these quacks for what they are and reminding people that in the end, Nature always wins.

Related to this, he also has a book that I highly recommend, titled "Voodoo Science". In it he relates everthing from the Cold Fusion debacle, to astrology, to medical fallacies. Throughout the book, he tries to convey the distinct difference between "scientific evidence" and "anectdotal evidence", and why the latter is not acceptable. A science major, especially, should read this book. An essay from that book on "magnetic therapy" can be read here:


Monday, November 20, 2006

Physics at a Bar

Why not? It appears that in Toronto, they have a scientific conversations at a bar with prominent physicists, organized by the Ontario Science Center. Not a bad idea, really.


Saturday, November 18, 2006

Physicists on the Money

A rather amusing website that lists all the physicists that have appeared on currencies from various parts of the world. It's good to know that in some parts of the world, some of us are considered as important as King, Queens, and Presidents.



Friday, November 17, 2006

Happy 20th Birthday, High-Tc Superconductors!

Gosh, has it been 20 years since Bednorz and Muller published their landmark discovery?

This past Sept. marked the 20th anniversary of the discovery of High-Tc superconductors. It was a discovery that turns physics, and especially condensed matter physics, upside down. A subject area that was thought to be 'dead' and fully matured, where we thought we knew everything that we were supposed to know, suddenly started revealing a whole new side that were never thought to be possible before. Certainly, there were no theoretical insights into what were to come next during the following years. Certainly, there probably would never again be (at least in my lifetime) the "Physics Woodstock" as the one that happened during the APS March Meeting in NY right after the discovery (although something similar did happen in 2001 in Seattle after the discovery of superconductivity in MgB2 - we called that Physics Woodstock West).

The revolution in the condensed matter that started out by this discovery affected ALL aspects of that field of study. Suddenly, strongly-correlated electron system, which permeates all of condensed matter, has a very prominent poster child in the form of high-Tc superconductors. The understanding that we got out of this material provided insights into a bunch of areas, some even beyond condensed matter.

This week's issue of Science (Science, 17 November, 2006) has a terrific recount of the history, difficulties, and future of High-Tc superconductors. Don't miss it if you have access to the journal.


Dark Energy Goes WAAAAAA Back!

A new news report seems to indicate that dark energy was present in our universe at least as far back as 9 billion years ago. That makes it, what, our great, great, great, great.... granddaddy?

Edit: there's also a report in Nature's daily news update. However, I believe this is available for free only for a limited time, so read it now while you can.


I'm sure there's plenty more to be said on this issue.

More edit: you can read a review of the report at the PhysicsWeb site also.


Thursday, November 16, 2006

Misconception of the Heisenberg Uncertainty Principle

One of the common misconception about the Heisenberg Uncertainty Principle (HUP) is that it is the fault of our measurement accuracy. A descripton that is often used is the fact that to observe the position of an electron, for example, one needs a probe, such as a photon, with very short wavelength to get any reliable accuracy. But a very short wavelength photon has a very high energy, and thus, the act of position measurement will simply destroy the accurate information of that electron's momentum. Hence, this is an example of the HUP.

While this is true, it isn't really a manifestation of the HUP. The HUP isn't about a single measurement and what can be obtained out of that single measurement. It is about how well we can predict subsequent measurements given the identical conditions. In classical mechanics, if you are given a set of identical conditions, the dynamics of a particle will be well defined. The more you know the initial position, the better you will be able to predict it's momentum, and vice versa.

The most direct way to illustrate this is using a single-slit measurement. Let's first consider the classical case so that we know what we normally expect to happen. I suggest you sketch the setup along (since I'm unable to show sketches on here, but will try to make an effort to clearly explain the orientation of things).

Let's say you have a source of classical particle that emits this particle one at a time on demand, and emits it with a constant velocity and kinetic energy. At some distance from this source is a single slit. For clarity sake let's say the slit is alligned along the x-direction, so that the width of the slit is along the y-direction. The orientation of the x and y coordinate axes is in such a way that (using the right-handed coordinate system) the z-axis is along the direction of propagation of the particles. So the direction of the z-axis is from the source to the slit, and beyond.

Beyond the slit is a screen of detectors (could be a photographic plate, a CCD, etc.) This detector records where the particle hits after it passes through the slit. Let's say this screen is a distance L after the slit.

Now, let's get some basics out of the way:

1.If a particle gets through the slit, then I can say that my knowledge of the position of the particle at the slit has an uncertainty equal to the width of the slit. Thus, the width of the slit Delta(y) is the uncertainty in the postion of the particle when it passes through the slit.

2. The y-component of the momentum of the particle can be found by looking at how far the particle drifts along the y-direction when it hits the screen. This makes the explicit assumption that no external forces acts on the particle at and after it passes through the slit, so that it's momentum remains constant from the slit to the screen (which is a reasonable assumption). Let's say the particle drifts from the center, straight-through line and hits the screen at a distance Y. If it takes the particle a time T to reach the screen (which we can assume to be a constant if screen distance from the slit is much larger than the width of the slit (i.e. L >> Delta(y)), then the y-component of the momentum is p_y prop. Y/T. Now, there is a measurement uncertainty here in determining where exactly the particle hits the detector. This measurement uncertainty depends on the resolution of the detector, how fine is the "mesh", etc. But this is NOT the "uncertainty" that is meant in the HUP. We haven't gotten to the uncertainty of the momentum YET. All we have is a measurement of the y-component of the momentum of the particle.

Now, let's do the experiment with the classical particles. You shoot the particles one at a time and record where it hits on the screen. Ideally, what you will end up on the screen is only one spot where the particles that pass through the slit hit. However, closer to reality is that you end up with a gaussian distribution at the slit, where the peak lies directly along the straight-through direction that has zero y-component of momentum. The uncertainty in the momentum then corresponds to the width of the gaussian distribution (full width at half maximum). Now THIS is Delta(p_x) as refered to in the HUP!

Let's make the width of the slit smaller. This means Delta(y) is smaller. You are now letting a smaller possible angle of incidence of the particle from the source to get through the slit. This means that there will be a smaller spread that is detected on the screen. The gaussian distribution will be thinner. So classically, what we expect is that as Delta(y) gets smaller, Delta(p_y) also correspondingly becomes smaller.

This is what we expect in classical mechanics. If all the initial conditions remans identical (I have the same source), then the more I know where the object is at any given instant, the more I can predict its subsequent properties. I can say what its y-momentum will be with increasing accuracy as I increase my certainty of its position by decreasing the width of the slit. I can easily predict where the next particle is going to hit since I will know what its momentum is going to be after it passes through a very narrow slit. My ability to predict such things increases with decreasing slit width.

Fine, but what happens with a quantum particle such as a photon, electron, neutron, etc.?

We need to consider two different cases. If the slit width is considerably larger than the deBroglie wavelength (or in the case of a photon, its wavelength) of the particle, then what you have is simply the image of the slit itself. The ideal situation would give you simply a "square" or gaussian distribution at the screen of the intensity of particles hitting the detector. This is no different than the classical case.

It gets interesting as you decrease the slit. By the time the width of the slit is comparable to the deBroglie wavelength, something strange happens. On the screen, the spread of the particles being detected start expanding! In fact, the smaller you make the slit width, the larger the range of values for Y that you detect. The "gaussian spread" now is becoming fatter and fatter. This is the single-slit diffraction pattern that everyone is familiar with.

Now THIS is the uncertainty principle at work. The slit width, and thus Delta(y) is getting smaller. This implies that Delta(p_y) is getting larger. Take note that the measurement uncertainty in a single is still the same as in the classical case. If I shoot the particle one at a time, I still see a distinct, accurate "dot" on the screen to tell me that this is where the particle hits the detector. However, unlike the classical case, my ability to predict where the NEXT one is going to hit becomes worse as I make the slit smaller. As the slit and Delta(y) becomes smaller and smaller, I know less and less where the particle is going to hit the screen. Thus, my knowledge of its y-component of the momentum correspondingly becomes more uncertain.

What I am trying to get across is that the HUP isn't about the knowledge of the conjugate observables of a single particle in a single measurement. I have shown that there's nothing to prevent anyone from knowing both the position and momentum of a particle in a single mesurement with arbitrary accuracy that is limited only by our technology. However, physics involves the ability to make a dynamical model that allows us to predict when and where things are going to occur in the future. While classical mechanics does not prohibit us from making as accurate of a prediction as we want, QM does! It is this predictive ability that is contained in the HUP. It is an intrinsic part of the QM formulation and not just simply a "measurement" uncertainty, as often misunderstood by many.


Wednesday, November 15, 2006

Protest Against Reading Physics Closure

The Physics Department at Reading University in the UK is certainly getting a huge amount of support against its closure.

Let's hope this whole thing is a wake-up call for UK academics and politicians to do something about promoting physics not just to students, but to the population in general.


I have made repeated mention of synchrotron centers. If people are curious on what they are (and if you want my opinion, you SHOULD know what they are because there's a good chance your tax money is being used to build one), then you should go to this link:

This site list all the activities related to synchrotron centers, and has a comprehensive listing of ALL the synchrotron centers (and other light source centers) all over the world. Eventually, if it hasn't already, it will include all the FEL (free electron laser) centers since these are also light sources that promises to be of great use in the future.

The National Synchrotron Light Source (NSLS) that I had mentioned in my earlier entry where I made my 1 1/2 second worth of fame, is one such center. If you are in the New York City/Long Island area over the summer, you may want to keep an eye on the Brookhaven Lab (where the NSLS is located) website for their yearly Summer Sunday Tours. One of these tours will focus on the NSLS, which along with the RHIC tour, is one of the most popular places to visit during this event.

So, go familiarize yourself with this thing. See what have been done and can be done at such a center. You could be finding out about something that you didn't know before!


Alum Sues School Over Accident in a Physics Lab

Wow! Today is just a day about reports of accidents/incidents in a physics laboratory.

A Univeristy of Iowa alumus is suing the university over an accident that occured during an undergraduate physics laboratory. We can only wait to see how this will come out.


Radiation Leak at Princeton

First of all, I don't intend to blow this out of proportion. This is a MINOR incident and it is not even worth mentioning if we simply consider the amount. But since it in the news, I'll report it here.

Having seen previously how the hysterics of something like this can create a public relations nightmare (see Brookhaven's High Flux Beam Reactor), I hope that this doesn't get the same type of attention. If this were to happen at a US National Lab, it would have been a major pain in the rear end for all those involved.


Tuesday, November 14, 2006

APS New Webpage

The American Physical Society (APS) has a new re-designed webpage. Check it out! It looks sleek!

If you have not checked out this APS website, go browse around. It has a wealth of information, not just about physics, but about the profession itself. As the largest physics organization in the world, it has 45,000 members from N. America and around the world.


Videogames Turn Physics Into Fun?

This may be a free advertisement for this company, but claims to be producing video games that are "physics focus".

I suppose "real life" isn't interesting enough to get people fascinated in physics. I'm always curious to know if such "enhancement" actually works in getting people either to learn physics, or have an appreciation for it in certain situation.


Monday, November 13, 2006

Purdue FunFest

I reported earlier about the Purdue FunFest that was about to take place. So now this is the report on what did occur.

It sounds like it was almost as much fun as our Argonne Open House that we had here a month ago. Hey, anything that gets the public to understand and see a lot more of what we do, and what physics is, is always a plus in my book.


Hands On Physics

More reports of high school teachers trying to make a difference and make physics more interesting. Teachers like this are one of our most valuable resources. They DON'T have to be good in a system that rewards mere competence, not brilliance. Yet, some of them go the extra mile or two to inspire.

Cheers to all of them!


Blackholes at RHIC?

This is old news, but still.....

I read with a bit of a glee at news like this - not to mention the fact that there's nothing remotely "blackhollish" being created at RHIC.

I have a bit of a personal interest in this thing, thanks to the Comedy Central. Several years ago, after Frank Wilczek's "blackhole" scenario in RHIC's collision made it into the news media all over the world, the Comedy Central channel decided to join in the fun and did a piece on it. This was supposed to be an "investigative report" by Steve Carell to appear in The Daily Show with Jon Stewart.

Now rumor has it that Brookhaven's PR people wasn't amused by this and did not give them permission to come in an do the report. However, again as a rumor, someone from the show knew of someone from Brookhaven, and managed to arrange for access to the lab. So they got on site, but could not gain access to RHIC, which is central to their piece. However, they did manage to gain access (via their contact) to a different facility within Brookhaven - the National Synchrotron Light Source (NSLS). So, instead of RHIC, they toured and filmed around the NSLS instead.

This is where *I* came in. I was working as a postdoc during that time, and happen to be doing experimental work at the NSLS. Now you have to keep in mind that Brookhaven has done promotional work now and then, so it is not an unusual sight to see someone video taping some part of the lab every now and then. So when I was in the middle of doing work and see a film crew wondering around the facility, I thought nothing of it. I also do not watch the Comedy Central channel often (other than for South Park), and I certainly was not a frequent viewer of the Daily Show. So I had no clue who these people were, even though I nodded at Steve Carell at that time (I was oblivious on who he was then).

Anyway, several weeks passed by and one morning, while I was in my office, one of the staff physicist on my floor came in and started telling people that Brookhaven appeared on the Comedy Central's Daily Show the night before, and it was hilarious. They did a piece on RHIC but filmed everything at the NSLS... etc.. etc... So we all went into the hallway to listen to the whole thing. And in the middle of it, he turned around towards me, pointed his finger at me and said "... and you were in it!"

I swear, the first words out of my mouth were "I did WHAT?"

Luckily, he made a tape copy of the show. So a bunch of us filed into a small conference room and watched the tape. Of course, it was hysterically funny, especially for us since we knew that they were interviewing the wrong people and filming at the wrong place, both of which had nothing to do with RHIC. And yes, I did appear in the piece for about 1 1/2 seconds. They filmed me while I was fiddling with the gasflow meter.

Needless to say, I made a copy of the tape. I've been showing it to friends at every opportunity I get to accumulate my 15-minute worth of fame. So whenever I hear stories about blackholes at RHIC, I chuckle at the fond memories. :)


Sunday, November 12, 2006

More on Schrodinger Cat

I pointed out earlier of several references regarding the new development and results related to the Schrodinger Cat-type phenomenon. I left out Leggett's article in Physics World from a while back after the Stony Brook/Delft experiments were reported. So if you haven't read it yet, here it is.


Saturday, November 11, 2006

Physics is Fun Demonstration

More report on physicist trying to read to students and kindle interest in physics. Kudos to all of these efforts and all of these people in their efforts to make physics more attractive to these young students.


Physics? Or Did You Mean Psychics?

I am a regular in one of the Internet Relay Chat (IRC) physics group. Now and then, we get someone coming into our discussion group asking for a "reading". This is such a common occurrence that most of us are used to this. Being a "smartass", I usually go along with such a question. I usually respond with

"Let me see... I already of a vision of you in school... and I'm seeing that you were not very good with spelling, were you?"

Somehow, they're always amazed that I can be see them that well! :)

Isn't it ironic that physics, which is the antithesis of psychic, can have such similar spelling, and that people can make one mistake while aiming for the other?

Lest we all think that only people on internet chats only make such a mistake, look at this very puzzling press release. It's titled "Healers and Physics"! I kid you not. Of course, is a "conference" of healers and psychics. They misspell "psychics" twice in that article. Even more puzzling, this appears to be an advertisement for people to learn something about real estate! I didn't realize that RE/MAX have booths at these things. Don't they know that the attendees to such an event can ALREADY FORSEE what the real estate market is going to be in the future? Get with the program already!


OK, I shouldn't be having this much fun at 5:00 am in the morning. :)


Friday, November 10, 2006

The Fate of Science With the New US Congress

The the recent US election into power by the Democratic Party to take over the US Congress, what will be the future of science and science funding?

The Science journal take a preliminary guess at the direction of science under a new Congress.


Purdue's FunFest

This Saturday, Nov. 11, Purdue University Physics Dept. will be presenting a FunFest to promote interest in physics. Try to attend it if you're in the neighborhood!


Thursday, November 09, 2006

Working Alone

It's 4:30 pm here in this building. I'm the only one left and I still have several hours to go with my experimental work.

One of the things one has to learn when working at a US National Lab is the plethora of safety issues. We get trained for many different safety issues based on the job hazzards that we are expected to face. One of the things we are instructed is the Working Alone policy.

When one has to do experimental, one inevitably could be dealing with hazzard such as radiation, high-powered lasers, electrical equipment, etc.. While in many instance, one isn't the only person in the building, there are some cases (such as me where most of the regular occupant of the building leaves by 3:30 pm) where one is the only person alone in the building. When that occurs, the Work Alone policy kicks in automatically.

This policy instructs the person who is alone to call a specified phone number. Then he/she talks to a security personnel and gives his/her name, location, phone number, etc. Then an arrangement is made whereby a phone call will be made every designated interval. If the person doesn't answer that phone call, a security personnel will be sent to check up on that person.

The person also has to call back before leaving work to cancel this, of course, or else they'll continue to look for you and it'll be a mess the next day.

So guess who's going to be calling for this in a few mins? I think I'll have them call me every hour.


CERN Pushes for Open Access

CERN is trying to push for open access to all high energy physics papers.

More and more institutions and journals are trying to include some form of open access to published papers. Many established journals such as the Physical Review series, have now included a one-time fee that authors can pay to have their papers available for free by all readers and not just subscribers. CERN's push for the entire field of high energy physics to provide for such open access will commence with them appropriating the budget for all papers produced out of that institution to include the open access fee.


Happy 60th Birthday, Clifford Will

The distinguish physicist in gravity/general relativity is celebrating his 60th birthday with a fest-cum-symposium. Well deserved!


The Physics of Superheroes

I suppose if we can have books on the physics of golf and the physics of Star Trek, why not the physics of superheroes? That was probably just what University of Minnesota professor James Kakalios thought. So he wrote the book.

Not sure how effective such a thing is in educating the general public on physics, but I'm guessing it is an entertaining read. Has anyone read it yet?


Wednesday, November 08, 2006

Color Me Physics

The American Physical Society (APS) has produced a book, and I quote, ".... that introduces children to physics and some of its most famous characters..." How effective this is at achieving its goal remains to be seen, and depends very much on you if you have kids and decide to try this. If you do, I would love to hear from you.


Cheating in College This Common?

It appears that even top notch schools such as Cornell is not immune to a large percentage of cheating. If it happens here that much, how high can it be at other schools?


Another Publication Scandal?

OK, so this is not quite exactly on the same disaster level as the infamous Schon debacle from a few year ago. However, it is still making the headlines, especially in this week's Nature.

The paper involves a landmark experimental work from published in Nature in 1993 titled "Atomic-resolution chemical analysis using a scanning transmission electron microscope" (N.D. Browning, et al. Nature 366, 143 (1993). According to Nature, while one referee endosed it, the other referee was more hesitant, and expressed the opinion that the manuscript had "disquieting questions" that remained unanswered. Nature's editor decided to publish the paper at that time.

In this week's issue of Nature (Nature 444, 123-124 (9 November 2006)), a correction has been made to this paper more than 10 years after it was published. It is the result of a series of rather unusual event. Let me see if I can outline it from the way I understood it for those of you who do not have access to Nature.

1. 2 of the authors of the Nature paper submitted a preprint to ArXiv in 1995 (Varela, M. et al. (2005)). In the first version of the paper, there were data what appeared to be identical to the one they published earlier for a conference, but using different technique than the one used for the ArXiv paper. There was also an issue of a data being duplicated to make a "mirror image".

2. Others started noticing this issue by Spring of 2006 when a version of the paper was submitted to Nature Physics.

3. Within days of the authors being alerted to the possible concerns of the paper, the authors submitted another version in which references were given for all but one set of data. The duplicated mirror image data were also removed or cropped.

4. This led to Oak Ridge appointing an investigative committee. The panel found that while there were errors in judgement, no deliberate falsification or fabrication of data occured.

5. Here's where I have to make my own inference. Due to the investigation, the authors realized mistakes in the earlier Nature paper. In particular, they did the identical mistake in which they included experimental data from an earlier conference paper using different analysis/background subtraction. At that time, the authors had provided Nature's editor with a firm reassurance over the referees uneasiness.

6. A correction is now published in the current issue of Nature indicating the data set that were differently handled.

While the overall result of the paper right now did not hinder the progress of the field, many physicists that were interviewed loudly wonder why the paper, with some of the main data that are now questionable, is not withdrawn. Nature has offered an explanation over why it did not see fit to ask for a retraction (you have to read the issue, it's too long to type).

At best, this whole debacle has caused many to distrust the work and results coming out of this group.


The BIG One That Got Away

Back in 1999 when I started my postdoctoral work, the "hot" and sexy topic to study on high-Tc superconductors was the underdoped regime of the phase diagram. This is where a bunch of exotic properties that are still mysterious appear, such as the pseudogap state, the unusually large energy gap in the superconducting state even though Tc is dropping, etc. I, on the other hand, decided to go the other way, into a territory that most people in the community thought was boring and not many exotica - the overdoped regime. This is where the cuprate compounds were highly overdoped with holes that its Tc also starts to drop. Most people thought that in this regime, the cuprates will now start to resemble the conventional superconductivity - the Fermi Liquid picture will start appearing. That's why they didn't find it interesting since this is well-known.

In any case, I jumped head first into it. The main reason is that I obtained the most overdoped samples of the Bi-Sr-Ca-Cu-O family ever created and has never been studied. So that in itself is new. Using angle-resolved photoemission spectroscopy, I studied the spectral function along 2 high-symmetry directions of the crystal structure. We managed to obtain two very important results:

1. The spectral peak (or the quasiparticle peak) in the antinodal direction persists well into the normal state. This is different than the optimally-doped and the underdoped cuprates where the peak disappears above Tc.

2. The behavior of the quasiparticle spectra now tends to approach that of the Fermi liquid predictions with some deviation. Such behavior was only predicted, but never measured before, for the overdoped regime.

We thought we had a good enough result to submit to PRL (and we did). However, during the writing of this paper, I attended an electron spectroscopy conference in Berkeley and presented a poster of the result there. My postdoc supervisor alerted several of his contacts at Stanford (he graduated from there) regarding the results we had obtained and the fact that I will be presenting them there. So as expected, a bunch of Stanford people came over to the poster, especially one person who showed a keen interest in it. I've met him before at previous physics conferences, so we were on friendly terms. He was interested in it because the existence of the peak way above the normal state slightly contradicted a paper that he published in Science about a year earlier.

We had a lively and interesting conversation. He paid extra attention to the data that were on the poster and we exchange several info regarding it.

About 8 months later, a preprint came via e-mail from him to me and my boss. In it, he had made the same experiment on an identically-doped material. He reproduced and confirmed all that we had discovered, but he found something else, something that WE MISSED!

The Bi-Sr-Ca-Cu-O that we were looking at has 2 CuO layers per unit cell. This compound is a popular material used in photoemission because one can obtain a large single crystal, but more importantly, it is easily cleaved parallel to the CuO planes. Thus, you can obtain a clean, freshly cleaved surface in vacuum. Early photoemission spectroscopy done on this material in the optimally-doped and underdoped regime have revealed a wealth of information, but many reported that they did not detect the bands coming from the 2-layer CuO planes - the so-called bilayer bands. All that have been observed so far is just a single band.

Now this is puzzling from the band-structure point of view because when you have two "active" layers, you should get an interaction between them. In fact, there have been theoretical calculations showing that the coupling between the two layers will produce a "split" bilayer bands resulting in the bonding band, and the antibonding band. Angle-resolved photoemission should be able to detect this, and none has been reported.

... till that manuscript. The Stanford guy, after looking at my data, went back and obtained some highly overdoped samples. He and his group looked at the same symmetry directions as I did, but in a different orientation of the detector. When they did that, they CLEARLY noticed something that appear to be the long sought-after bilayer split bands! They analyzed the data further and the degree of splitting agrees with theoretical predictions. They also showed that the split band doesn't appear when they used the compound with just a single CuO plane.

The manuscript was sent to us for us to comment on. They acknowledged the fact that we gave them the idea. In any case, both my paper and the Stanford paper were published in PRL. I went back and looked at the raw data that I obtained, and a head-smacking moment occured several times when I realized that I actually DID see the bilayer splitting in the data. Although the configuration wasn't idential to the Stanford measurement, it was also very clear in the data I collected. Had I realize what they were, we could have easily made appropriate further studies on it and would have gotten the same thing.

The bilayer splitting since then had received a lot of attention. It is another puzzle that has been solved, and it gave theorists the energy scale of coupling that occurs between intra-CuO planes. My subsequent meetings with the Stanford guy has been very pleasent - in fact we have become very good friends and continued our professional contact. He has publically admitted that the impetus to look for the bilayer bands came directly from the data he observed on my poster. While I was happy with what we observed and published, there is always in the back of my mind, the regret of not looking any closer at what I observed. I think I was thrilled at getting the initial data that clearly was new, without realizing that there's another even more spectacular discovery hiding in the same set of data.

No matter how much we know, or how hard we work, and element of chance, luck, and pure accident/coincidence can play a huge role. Someone once said that the more prepared you are, the luckier you get. I wish I was more prepared to have not let this big one get away...


Soccer and String Theory

Physicists playing soccer and debating String Theory. I suppose this is better than a fist fight! :)


Tuesday, November 07, 2006

Astronomical Observatories on the Moon?

This month's issue of Physics Today has a pro and contra article on the proposal to build an astronomical observatory on the moon.

Considering that the astronomy budget has been cut back and NASA is barely doing any science, I don't know how realistic something like this will be.


Contributions of Physics to the Information Age

As most of you may know, I get very tired very quickly when people ask for the "uses" or application of physics. I think many people are still under the impression that physics deals mainly with esoteric subjects that have very little direct impact on most people's lives. It doesn't help that when physics does get some form of publicity, it main comes in the form of String Theory, astrophysics, and other forms that have little direct impact on most people.

So for my small part in getting rid of such ignorance, I thought I should point out this very good site on the central role that physics has played in the area that impacts everyone here - information technology.

It should have plenty of links and info for the general public to realize that a lot of physics and physicists were involved in ALL of the advanced electronics that they now enjoy.


A Teacher Inspiring Physics Students

We read often of how schools are failing students, and how physics is simply not being taught well in high school. But once in a while, we read a story like this that clearly reinforce the fact that it can be done if we have the right combination of students and educators. It isn't easy, and it requires dedication, but it can be done.


Monday, November 06, 2006

Berkeley Professor Becomes Online Celebrity

UC Berkeley Prof. Richard A. Muller has become quite well-known for his online physics lectures. These are available on Goodle video.


My Physics Journey

When I started as a freshman (that's first year of university for those who are not familiar with US college terminology) physics major, I think I had the same grandiose (or jaundice) view of physics as most incoming students - that of theoreticians working on particle or nuclear physics. I thought that was what I wanted to do. So I went through the standard curriculum for a physics major. One of the major turning points came in my Junior year (3rd year) when I interned during the summer at Fermilab. Since I had aspirations of going into particle physics, this was a logical thing to do. It was an eye-opening experience. I discovered how LARGE the project was, and how, even if I were a full-blown physicist, I would be only one small player in the whole project. At the end of my internship, I knew that particle physics was NOT something I want to do.

One of the things that happened not by design was my discovery of solid state physics. During my Senior year (4th year), I had several graduate level classes that I could take to fill up the required number of credits. So I opted for a class in that subject. I will admit that it was god-awful boring. But it did opened my eyes to a wider view of physics in that many of the useful things we take for granted did originate out of an area in physics, and that physics and its applications wasn't just something esoteric and "pure knowlege" alone. I think this was the first time I decided to actually explore on my own all the various areas of physics.

One of the disconcerting feeling I had was when I received my undergraduate degree, looked at the piece of paper, and asked myself "Now what exactly do you know and can you do?" I had a nagging feeling that I really didn't know that much, and have very few skills. Other than teaching high schools (which I did for a year and a half), I had no other ability. It was when I made a decision to go to graduate school, and not only that, become an experimentalist. Strangely enough, I didn't have a clear idea in what area of physics I wanted to go into. I did know for certain that I wasn't going into particle physics. Probably at that point, getting a Ph.D was an end in itself for me. So after passing the qualifying exam, I literally "shopped around". I went to various professors and asked what research work they were doing. I also asked around various more senior graduate students asking for their perspective, especially with regards to the "intangibles", such as which professor was easy to work with, and which were more difficult. The one area that struck my fancy was the technique of using tunneling spectroscopy to study properties of superconductors. At that time, high-Tc superconductors was still a very hot area of study. Even I was fully aware of that. So that became my research project and my thesis research work. I studied tunneling spectroscopies of almost everything, from conventional superconductors (in which I reproduced all the "textbook" results) to high-Tc superconductors. Not only that, even the tunneling technique came in several different flavors. I did both planar junction technique and point-contact technique.

One of the most important aspect of experimental work that I discovered was that you seldom just do one thing. Although my primary activity centered around the actually tunneling measurments, I did not do just that. I was also involved sometime in the fabrication process, especially when we were doing planar tunnel junctions. I actually made thin films using sputtering technique, and then fabricated the insulating layer, made terminal contacts, etc. In the process, one also needs to know the quality of the thin films one has made, so I ended up learning how to use and analyze x-ray diffraction method to characterize the film I fabricated. Even the process of the tunneling measurement itself required me to learn about cryogenics, since I had to deal with liquid nitrogen and liquid helium. So one just simply do not learn just one thing - one ends up having to learn a series of methods, equipments, techniques, etc.

The other important discovery was, of course, publicizing one's work either by publishing, or via presenting it at a conference. This can be fun, nerve-wrecking, informative, frustrating, and joyful, all at the same time. This is something that isn't part of a formal education in becoming a physicist, but yet, it has to be one of the most important aspect of becoming a physicist. I felt lucky today that I had a supervisor who insisted that I had these experiences as part of my training. By the time I received my Ph.D, we managed to published several papers and I had given several presentations at various conferences.

I went on to do my postdoctoral fellowship in a slightly different experimental area - photoemission spectroscopy, but with a focus on the same type of material, high-Tc superconductors, and later on, expanding to strongly-correlated electron systems. In principle, there is an intimate relationship between tunneling spectroscopy, and photoemission spectroscopy, especially angle-resolved photoemission spectroscopy (ARPES). Tunneling spectroscopy measures the "momentum averaged" single-particle excitation spectroscopy. So it can give an energy resolved spectrum. ARPES, on the other hand, measures both energy and momentum resolved spectrum. So in principle, if you take a complete ARPES result, sum up all the momentum, you should end up with what tunneling experiement should get (if only life is THIS easy!).

In any case, I spent 2 1/2 years working in this area, and it was extremely productive professionally. It was, I think, my first taste of what it would be like to be a "professional" physicist, doing nothing by research work, and no classes, no tests, no exams to worry about. Alas, all good things must come to an end, and a postdoctoral position is only transitional. I made a major turn in my career by accepting a job at Argonne National Lab, and file this in the Irony Hall of Fame, I joined the High Energy Physics division! After swearing off particle physics, it was rather funny to be in this position, but I didn't sell my soul to the devil completely. I actually joined the accelerator group to work on their photocathode development. To produce electrons that they will accelerate using their novel technique, they shine high intensity lasers onto a cathode, creating photoelectrons. It was why they wanted someone who has worked in photoemission (me) to join the group. It did mean that I have to learn a whole new area of accelerator physics. This is where, if you have been equipted well during graduate school, you should be able to adapt to whatever situation you are in.

If there's any one impression that I wish someone can take from this story is to be "flexible". To be able to do this, one needs as wide of an experience as possible while in college. I did many things and many studies during my graduate years that never went anywhere, never became part of research work, or never ended up in my thesis. But in the process of doing those things, I developed many skills that I had to call upon later on during my professional career. Again, these are the stuff they don't teach you in school - you only acquire them by doing.

I look forward to your questions/comments, or even share your own journey to get to where you are in physics.


Sunday, November 05, 2006

Certainty and Uncertainty in the Practice of Science: Electrons, Muons, and Taus

This article was written back in 1999 by Martin Perl, who won the Nobel Prize in physics in 1995. It remains one of the best essay on the practice of physics that I've ever read. If you have some time, you might want to read this carefully.


More Bashing of String Theory

The Oregonian has published another bashing of String Theory done by Smolin and Woit. This is basically a report of the two books published by these gentlemen against the practice of String Theory.

The backlash continues. Whether it is warranted or not, at the very least, the public (some of them anyway) is now aware of the issues surrounding String Theory, and that many physicists look at it in horror. Maybe that would cause the young, impressionable students to think twice before being seduced into it.


Saturday, November 04, 2006

Forum on Physics and Society Oct. 2006

The Forum on Physics and Society Oct. 2006 newsletter is now available online.


Friday, November 03, 2006

Physics Myths and Legends

This is another entertaining article by Robert Crease. Maybe if you have a physics story such as the ones he has described, you could submit it to him.


Refereeing Physics Papers

Anyone who has read some of my postings, especially those smacking the quacks, would have noticed that I emphasized frequently the call for peer-reviewed journals. It is not that I'm in love with them, it is just that from history (at least since the beginning of the 20th century), there have been NO discoveries or ideas that have made significant advancement in the body of knowledge of physics that have not appeared in peer-reviwed journals. This means that for something to make any impact on physics at all, the necessary, but not sufficient criteria is that it must first appear in a peer-reviewed journal, not on someone's webpage, or some e-print repository, or some discussion site. No matter what the claim is, if it hasn't appeared in a peer-reviewed journal, it has ZERO possibility of making ANY dent in the physics body of knowledge. There has been no exception.

The most common misconception about papers in peer-reviewed journals is that, since it has appeared in print, it must be valid. This isn't true, nor is it the aim of peer-reviewed journals. In science, and physics especially, the validity of something cannot be established immediately. Experimental discovery must be repeated, especially by independent parties, for there to be confirmation that such a discovery is real. Theoretical ideas require a slew of experimental verifications and tests for it to be confirmed as a valid description of a phenomenon. So all of these take time, and certainly several more publications. Hence, the "validity" of something isn't guaranteed just because it appeared in print.

What is more relevant though is that a paper in a peer-reviewed journal is (i) not written out of ignorance (ii) not obviously wrong (iii) full of enough information for someone else to reproduce either the experiment or the calculation (iv) written in a clear and understandable manner. This is where the referee comes in. The referee's task is to make sure at least those criteria are met (other more prestigious journals such as Nature, Science, and PRL have additional requirements).

Refereeing is done voluntarily. It is part of one's duty to the community, and referees get no compensation of any kind from the journals other than a thank you. You referee in your area of expertise, so the journals will send you papers in your area, and often, written by your competitors. I think journals like the Physical Reviews keep track of a referee's activities, how prompt he/she is at responding, how much "complaints" that referee has received, etc. etc... (these are just my guess upon my casual conversations with a few of the editors). While the editors know who is refereeing what, the referees themselves are anonymous to the authors of the paper. So for better or for worse, the referees are free to criticize the paper being considered without revealing their identities (the editors do sometime intervene if referees get out of hand with their reviews, but I do not know how often this occurs. It certainly hasn't occured to me).

To be considered as a referee for a journal, one has to demonstrate one's expertise in a specific area of physics. Most often, it is by publishing in that particular journal. That's the most direct way of establishing one's reputation and expertise. I think that some journals such as the Phys. Review do keep track of a referee's publication track record (again, another guess).

My involvement in refereeing physics papers began when I was a postdoc. I already had published several papers in PRL, PRB, Nature, and Physica C at that time. One day, my postdoc supervisor contacted me and told me that he was going to refer the paper that he had been asked to review to me because, in his words, "you know more about this than I do". So he formally informed the editors of PRL to send the manuscripts to me to review. That's how I got onto the Physical Review referee database and I've been reviewing papers for them ever since. I also am the referee for J. Elect. Spect. because I attended a conference on Electron spectroscopy and refereed a proceeding paper that appeared in that journal.

My approach to refereeing a paper involves several steps. The first and foremost is, is the paper clear in what it is trying to convey? At this stage, I really don't care yet if it's accurate, valid, or consistent, or even possibily of any importance. I want to know if they have been clear on what they're trying to say. A confusing paper does more harm towards the advancement of knowledge than a wrong paper. I want to make sure the authors has made as clear as possible what they are trying to convey.

The second step is to see if the result is obviously wrong or impossible. I tend to referee experimental work, so the capabilities of the experimental setup is always something I pay attention to. To claim to be able to detect something beyond the resolution of a particular instrument would be a warning bell, for example. So trying to figure out if there are anything obvious would be the most logical step.

Thirdly, have the authors described in full their work to allow for someone else to reproduce? At the very least, they should include a citation of their experimental details if they have appeared elsewhere.

Fourth, are the results being presented clear and "complete". Often, a referee can make suggestions to further bolster the authors result by including either additional data, or even a new experimental measurement (this is the sign of a good referee).

Fifth, is the result consistent and/or contradictory to already-published theories and/or experiments? This is where a referee really comes in, because the referee is expected to know the state of knowledge of that particular field. This means being aware of all the possible papers in that field of study so that something that is claiming contradictory results must address all that have been published. Thus, if a paper is claiming something contradictory, it MUST address this contradiction. Why is it different? Are the previous papers wrong? Is this a different angle of attack? Is it consistent with established ideas? Is this new? etc.. etc. This usually takes the most effort out of a referee because he/she sometime may have to do some "homework" to double check facts and what have already been published or reported.

Finally, for journals such as PRL, Nature, and Science, there is an additional requirement that the paper just have wide-ranging impact beyond just that narrow field of study. While most papers in peer-reviewed journals reports on new ideas and results, these 3 journals require that the paper contains significantly important information that scientists from other areas too may find informative. So this is a tougher criteria to fulfill.

Note that for many journals, a manuscript being considered is often sent to more than 1 referee. It is not uncommon for PRL, Nature, and Science to send a manuscript to 3, even 4 referees. All of them must approve that paper for it to be published. So one can imagine how difficult it is to publish in these journals.

While science is still a human endeavor, peer-reviewed journals are still the best means of communication we have so far in advancing legitimate work.


Stephen Hawking Visiting Isreal

Looks like Stephen Hawking will be getting the VIP treatment when he visits Isreal in December.


Thursday, November 02, 2006

U. Chicago-Led Team to Manage Fermilab

A consortium led by the University of Chicago will manage Fermilab.

This comes on the heels of University of Chicago winning the bid to continue to manage Argonne via the newly set-up Argonne Chicago LLC entity.


Wednesday, November 01, 2006

Quantum Criticality

Quantum critically is one of the most important principle in condensed matter physics (high-Tc superconductors, for example, exhibits properties that indicate that its phase is close to such criticality). To mark last year's World Year of Physics 2005, Piers Coleman and Andrew Schofield wrote a summary of Einstein's contribution to the physics of solids, from the point of view of his contribution to quantum criticality. The article was published in Nature, but you can get a copy of it here.