Sunday, December 31, 2006

Happy New Year

Happy New Year, everyone! May it be a glorious one.

As for physics in the US, the first half or 2/3 will be brutal with the continuing resolution with the budget. I may not even make it to the Particle Accelerator Conference this year because we're trying to save money. We shall see....


Saturday, December 30, 2006

So You Want To Be A Physicist

If you came here from the PhysicsForums website, you would probably have come across the series of essays that I wrote on this topic. If not, then this will be new to you.

I started writing, in installments, a series of essays on my take of the process one goes through in being a physicist. It started out of the discussion I had with members of our #physics channel on the Undernet IRC server. I then realized that were many issues that most undergraduates and graduate students do not know but should know that are not available in their school brochures and program bulletin. There were also many misconception on not only the profession, but also the process.

So I decided to write what I know of the process in becoming a physicist. The original essays were started on the Undernetphysics Yahoo group. Within a few chapters of the essay, I started getting feedbacks from several people that these were becoming something of value, even though my production rate on these essays was rather slow.

Since then, I have also posted a copy of the essay on the PhysicsForums, and have gotten quite a response there. Other than a copy of a few earlier chapters of the essay posted on PhysicsPost, the thread on the PhysicsForums and the Undernetphysics Yahoo group are the only two places that you can read the complete version of the essays so far.

The series is still ongoing, although the ending could be in sight. I am hoping that, once it is finished, I will re-edit the series (correcting spelling and grammatical errors) and find some place to host the complete essay.


Friday, December 29, 2006

Top 10 Stories

Nature has picked it's Top 10 science stories of 2006. Unlike Science journal, there are several physics-related stories and news reports. Check out several of the links on that page. Note that many of them require a subscription or site-wide subscription access.


Thursday, December 28, 2006

A Physics Lesson

This is pretty elementary for anyone who has taken intro physics, but it still drives the point (no pun intended) on what happens when simply basic physics is ignored - you get car crashes when the roads are wet.


Tuesday, December 26, 2006

As reported here earlier, Nobel Laureate Carl Wieman is leaving Colorado University for University of British Columbia. This news report provides a brief interview of Wieman's reason for leaving Colorado. If I were CU's administrator, I'd would be truly unhappy with the state of my university for a Nobel Laureate to leave under such circumstances. It is a devastating public relations image.


Monday, December 25, 2006

Breakthrough of the Year

Science journal editors have compiled and named the breakthrough of the year, and the other 9 runner-ups. The breakthrough of 2006 is the proof of the Poincare Conjecture.

None of the runner-ups are in physics, unfortunately, even though the area of "optical lattice" is an area to watch in 2007.


Leading an Underground Laboratory

Stony Brook University is hoping to win the project to build and manage a new underground laboratory in the US. This is the one area that the US is really behind when compared to Europe and Japan.

With the current budget continuing resolution, though, I don't know how realistic it is to expect a decision by Spring 2007 regarding any funding for such a huge project.


Sunday, December 24, 2006

The Physics of Santa

More on how the jolly bearded man and his reindeer will manage to complete their task tonight.

To everyone who celebrates this time of the year, Season Greetings and a very safe Holidays!


Landmark Physical Review Paper - NMR

During this slow physics news period of the holidays, I'll try to highlight some of the webpages that you may have missed. It'll give you some interesting and informative stuff that you might want to read.

This is is part of the APS website series on landmark Physical Review papers. This time, it traces the publication of important work in the discovery and development in the field of nuclear magnetic resonance (NMR), the father of magnetic resonance imaging (MRI) used in the medical field.


Friday, December 22, 2006

Monthly Highlights of the Year

PhysicsWeb has listed the highlights of each month for the Year 2006. There are quite a number of significant discoveries and observations here.


Thursday, December 21, 2006

Last Working Day

Today is the last working day here at the lab. Things are winding down, we're making sure everything that can be shut down gets shut down. Our Division's holiday party will be this evening before everyone leaves for the holidays, so that should be fun, although I think quite a few have left already by looking at the number of vehicles in the parking lot.

It has been a good year, even with our severe budget constraints. Our annual review in March went well (they STILL can't believe we can do that much with so little and so few personnel), the AAC06 workshop we ran in the summer went extremely well, and the results we have from our high-gradient dielectric tube structure got enough heads turning that we received an invited talk to the upcoming PAC next year. So all in all, a very productive year.

The coming year will be a tough one. The continuing budget resolution to stick to the budget for Fiscal Year 2006 will severely affect our program. Our plan on building a second accelerator beamline may be hampered by this, which would mean that our ability to clearly demonstrate that we have achieved the accelerating gradient that we claim will be limited. I think everyone here at the lab is just trying to just stay above water for the next year and hope to come out unscathed by the time Congress gets their act together and do something productive. It does however means that in the meantime, a lot of projects that have been previously approved, would be at a stand-still without the approved funds.

2007 is going to be an adventure.


Wednesday, December 20, 2006

Neutron Radiative Decay Has Been Observed

As published in Nature this week, the first ever observation of a neutron radiative decay has been accomplished[1]. This decay is different from your typical, more familiar neutron beta decay, where a neutron decays into a proton, electron, and an electron antineutrino. In a neutron radiative decay, which occurs in free neutrons, you get the same 3 products PLUS the emission of a photon. This is one particular channel of decay that has been predicted by QED but never observed till now.

Looks like another triumph for QED.


[1] J.S. Nico, J. S. et al., Nature v.444, p.1059 (2006).

Edit: News coverage here.

Tuesday, December 19, 2006

How Does Santa Delivers All Those Gifts In One Night?

Such question comes up every year around this time. Of course, kids have their own explanation on how Santa does it, but so do scientists! In this article, you get the kids' explanations, and also a like to Fermilab where the scientists there have made an estimate on how fast Santa has to move to deliver all those gifts.

However, I think they forgot to factor in extra time for Santa to snack on the cookies and milk.



Einstein and Superconductivity

While Einstein is more well-known for his work in Relativity, Photoelectric Effect, attempts at a Unified Field Theory, it is less well-known that at some point, he dabbled in the theoretical aspect of Superconductivity. This preprint gives an overview of Einstein's role, and his thoughts, on the phenomenon.

It is interesting to note that superconductivity is the clearest manifestation of quantum pheonomenon at the macroscopic scale. According to Carver Mead[1]:

Although superconductivity was discovered in 1911, the recognition that superconductors manifest quantum phenomena on a macroscopic scale (4) came too late to play a role in the formulation of quantum mechanics. Through modern experimental methods, however, superconducting structures give us direct access to the quantum nature of matter. The superconducting state is a coherent state formed by the collective interaction of a large fraction of the free electrons in a material. Its properties are dominated by known and controllable interactions within the collective ensemble. The dominant interaction is collective because the properties of each electron depend on the state of the entire ensemble, and it is electromagnetic because it couples to the charges of the electrons. Nowhere in natural phenomena do the basic laws of physics manifest themselves with more crystalline clarity.


[1] C.A. Mead, PNAS v.94, p.6013 (1997); or you may be able to access it here.

Monday, December 18, 2006

The Physics of a Golf Swing

I'm sure there are golfers who read this blog. If you are one of them, then this page might be of interest to you, not that it might help since you still need to have the skill to be able to execute the technique.


All-Science Auction Sells Modestly

London's Christie first All-Science auction sold modestly. Manuscripts by Einstein and Darwin fetched the big bucks, but a historically-significant box of light bulbs by Edison did not fetch the reserved price.


Scientists Search for Own Errors

This is a very good article to read, especially if you are not familiar with how science is done.

The thing that I find ironic is that, for those of us who are in science, and physics in particular, we deal with things that often have degree of certainty significantly higher than, let's say, various ideas and "principles" in social sciences such as politics, economics, etc. Yet, we care a lot more in terms of errors and ambiguities in what we do, while in politics, you very seldom see anything resembling something similar. What you do see are definite statements about something, where people seem to have no qualm to attribute the cause-and-effect with utmost certainty.

I've always said that a science education, and certainly a physics education, is valuable not simply to learn the subject matter, but to learn the process on how we arrive at a conclusion and to what extent is the conclusion valid. Most people seem to not be aware of any kind of "degree of certainty" in the things they hear and accept. Evolution isn't 100% proven? Of course! But it has a higher degree of certainty than MANY other things that one readily accepts! Furthermore, scientific ideas and principle are NEVER proven, unlike mathematics. They only have degree of certainty. The degree of certainty of Newton's Law is so high, we use it to build houses and buildings in which depend our lives on. But is Newton's Law "proven" to be 100% correct? Nope! There is no such thing as 100% correct in physics.

Yet, we see politicians, social scientists, and economists routinely proclaim many of their ideas to be 100% correct. The fallacy perpetuates.....


Sunday, December 17, 2006

What Would Einstein Tell Us If He Were Still Alive?

This is a rather interesting review of a new book that I hadn't hear about before. It is titled "Please, Mr. Einstein". It has an interesting premise of having Einstein being still alive in this day and age.

Has anyone read this book yet? I would be intersted in hearing another review of it. It certainly sounds like it might be a material for a movie.


Saturday, December 16, 2006

Physicists Set Record For Network Data Transfer

The recent Supercomputing 2006 Bandwidth Challenge set a record for sustained data transfer. This is in anticipation of the huge amount of data that will be coming out of the LHC once it is operational. Such huge data will also be distributed to many parts of the world and certainly presents a significant computing and network challenge.

I think a lot of people do not realize how much of the technological advancement in computing/networking, especially high-speed networking, have been driven by the needs that came out of physics. Forget about the invention of the World Wide Web at CERN (which many people still don't realize). The need to handle such large amount of data, and to be able to transfer it efficiently to all over the world, have driven many improvement and advances in computing that are now being used in places such as stock exchanges.

There are many things that people see as a direct outcome of scientific research, but there are also many things they take for granted that they do not realize that also came as the byproduct of scientific research. This is one such example.


Friday, December 15, 2006

A Looming Crisis in US Science Funding

There is a crisis brewing in the US Science funding. As reported in Science, the present Congress that will be controlled by the Democrat for the upcoming year, has decided to adjourn session without passing a budget for the fiscal year 2007. A continuing resolution has been adopted, and possibly extended till the end of fiscal year 2007. This means that (i) current spending levels will be maintained till end of September and (ii) funds that have been approved as part of the fiscal year 2007 budget would not be approved and available.

This would be disasterious for many scientific projects that are continuing or scheduled to be started in this fiscal year. Already, facilities such as RHIC at Brookhaven, and JLab are looking at not only cutbacks, but also a possible shut down! Maybe other scientific projects are also in limbo because they simply do not have the money to start.

You may read more of the Science report here, but the full article is accessible only via subscription. If you are a US citizen, and if this is something you care about, I urge you to write to your respresentatives and ask them to not take the easy way out and sweep everything under the carpet. The "laziness" at coming up with an appropriate budget and approving the money that have already been allocated will severely affect several important projects. It will take an even MORE money to bring these projects back up to speed later on, so it makes no sense to criple them now.

Oh, what am I saying? Since when do things have to make sense in politics?


Thursday, December 14, 2006

Theorists Propose New State of Matter in Semiconductor

S.C. Zhang at Stanford and 2 of his current/former graduate students are proposing a new state of matter in semiconductors. They called it "quantum spin Hall states". The proposed state is to be published in Science (B. A. Bernevig, T. L. Hughes, S.-C. Zhang, Science 314, 1757 (2006)). You may read the Stanford press released on this idea here.


Cal Band Reenacts Big Bang

This is rather amusing. The University of California marching band, under the direction of recent Nobel winner George Smoot, reenacts the Big Bang at Cal Stadium. There's a video of this "explosive" event. It was shown during Smoot's acceptance of his Nobel Prize.


Wednesday, December 13, 2006

AirFly Update 1

It's going to be a very long day today. I arrived at work around 6:30 am, and it looks like I will be here till at least 7:00 pm. We finally have all the allignment done, both for our beamline, and their external chamber. After lunch, we finally got our electron beam to pass through their chamber. We are now calibrating our signals and adjusting things here and there to improve the signal-to-noise ratio.

It's a tough, long day, but these are some of the nicest and wonderful people to work with. So even though the work is hard, I always have fun and interesting time working with them.

I'm guessing that the time we have left (they're here till end of Friday) might not be sufficient to complete all the intended measurements. So it looks like this project might continue into next year.


Tuesday, December 12, 2006

Did This Really Happened?

I found this "Message from a Physics Prof". Please read it and then, come back here and see what I have to say.

Did this REALLY happened? I smell a hoax, or someone's fabrication. This is because this was the same thing that Martin Gardner had asked a long time ago. In his book "Mathematical Magic Show" (Mathematical Association of America, 1989), he asked this exact question. On page 141, Question 23 asked "Give at least three ways a barometer can be used to determine the height of a tall building." In his answer, he gave 5:

1. Lower the barometer using a string from the roof and then measure the length of the string (this, btw, happens to correspond to the FIRST answer given by the "student" in that article).

2. Same as #1, but let it swing like a pendulum and measure the frequency or period.

3. Drop the barometer from the roof and measure the time taken.

4. On a sunny day, find the ratio of the height of the barometer to the height of the building

5. Find superitendent of the building, give him the barometer if he tells you the height of the building (this last answer happens to also correspond to the student's last answer. Coincidence? I don't think so.).

My conclusion: whoever wrote the article made up this story and that this scenario never happened.


Clowning Around with Physics

Circus Physics introduces physics to youngsters using a clown. I suppose this is a rather entertaining way to make kids learn without them actually realizing that they learn something. I just wish they could do without the "centrifugal force" part. It'll take physics teachers years to correct that.


Monday, December 11, 2006

Saga of a 4-Year Old Manuscript Updated

I mentioned earlier about the saga of a 4-year old manuscript that I wrote for publication that was in limbo till a couple of months ago when we finally submitted it to Phys. Rev. B. We finally received the referee reports. It was sent to 3 referees. I must say that it was received better than I expected. All 3 referees agreed that the manuscript should be published. However, we have to make quite a few changes to it. There were a lot of comments from all 3 referees asking for clarifications, and a few things that weren't very clear to them.

So there's still a lot of work to be done to address the referees' comments, but I think if we do all of that, this thing should be published. I just wish that we had done it a lot sooner since we could have easily get it in to Phys. Rev. Lett.


Discord in the Definition of a Planet

If you think the issue of the demotion of Pluto from being a planet is a done deal, think again. It appears that in an upcoming article in the Planetary and Space Science journal, a new criteria is proposed for what a planet is and possibly restore Pluto as one.

Frankly, I am just amazed that professional scientists spend THIS much time and effort with something THIS superficial. I mean, how does it change the physics of the situation? NADA? Then get over it and tackle something that will actually make a difference already!

Oy vey!


Sunday, December 10, 2006

AirFly Flying In

This week will be a very busy and I will probably be putting in a lot of long hours. We are running again a series of experiments as part of the AirFly collaboration. This collaboration is part of a larger project under the Auger Observatory.

The AirFly people have been at our facility a few times. We collaborate with them at our accelerator beamline by provide them a high-quality electron beam with energies ranging from 3 MeV to 14 MeV. What they do with these electron beams is have them pass through air and nitrogen gas at several different pressures to measure the fluorescence created by the electron beam as it passed through. They then use the fluorescence (light in the UV range) to calibrate their instruments that will be part of the Auger Observatory detector. The energy range that our facility can provide fills in the gap in the fluorescence data that currently exists.

This is one of the few times that outside collaborators come in to use the electron beam that we can generate. There have been other astrophysics experiments done here, and other groups using our accelerators to test their beam diagnostic techniques. So even though we have an accelerator experimental facility that we currently use to study advanced accelerator physics, often the quality of our facility becomes very enticing for our group outside of our field to want to use it. While we can't simply open it up to anyone that want to use it (we are, after all, not a user facility, and we have a primary mission for our existence), it is still interesting that we can accomodate such requests quite often. Not only that, we also become collaborators in these external projects and are listed in the authors list when papers are published.

It's a win-win situation, really. :)


The Physics of James Bond

More "The Physics of....". We had the physics of Star Trek, the physics of golf, the physics of football, etc. We now have the physics of James Bond.

I'm expecting the physics of Dancing with the Stars any day now. :)


Friday, December 08, 2006

Einstein's Impact on 20th Century Physics

This is a long paper, but it is worth reading.

Most people are more familiar with Einstein's Special and General Relativity, and think that this is all Einstein was good for. Yet, his work has permeated in almost every aspect of physics, including the physics of the materials that you are using in your modern electronics.

Not only that, if you have a term paper to write about Einstein's legacy, this paper is undoubtedly invaluable.


Thursday, December 07, 2006

Laser Wakefields

There have been two recent impressive results on using the laser-plasma wakefield technique to accelerate electrons. The first was the paper by Wim Leemans and company at Berkeley. In this technique, they claim to have achieved an acceleration up to 1 GeV in just 3.3. cm.

The second was just published this week in Nature. Victor Malka group at Palaiseau Ecole Polytechnique has managed to stabilize this type of acceleration mechanism and produced a reliable and highly controllable scheme.

These two are terrific results in the effort towards an advanced accelerator technique. There are, of course, other acceleration technique competing with this, such as the dielectric-loaded structure which also uses wakefields generated in the dielectric.

The only issue that has yet to be addressed in the laser wakefield technique is the amount of charge that is accelerated. In these experiments, a charge of the order of pC (pico Coulombs) per bunch is typically the amount that is accelerated. This is considerably smaller than the "standard" that is required for what is known as a "high brightness" beam, which is 1 nC at 1 mm-mrad emittance. I think FEL (free electron laser) facilities would require charge bunches of around such a value.

I hope they can scale up their experiements to be able to accelerate larger amount of charges that would make such a technique practical.


Gerald Gabrielse Seminar

Wow, this is a coincidence. After I pointed out the AIP top physics stories of the year in which Gerald Gabrielse's work on the most accurate measurement of the electron magnetic moment, he's coming here to Argonne to give a talk on that very same subject. He's giving the Physics Division colloquium this coming Friday.

If I'm not stuck with running our beamline, I might try to attend this.


Wednesday, December 06, 2006

Particle Accelerators Are Not Just For Colliders

Many people mistaken "particle accelerators" to be the same as "particle colliders" and lump them with particle/high energy physics. This is of course a mistake. While particle accelerators certainly is a major component of any particle physics experiment, its use is not just restricted to such an area. Any facility that needs a beam of charged particles requires a particle accelerator. This can range from synchrotron facilities all the way to your doctor's office. Synchrotron centers require the injection of electrons into a circular storage ring. The electron bunches must be of high "quality", i.e. a small range of energy and a small emittance so that they don't deteriorate while going around the ring. Doctors offices require a compact accelerator to produce x-rays (google "medical accelerator"). Some of these x-ray sources may even be used at airports to scan your bags!

There is a further, direct use of accelerators for medical purposes, as in using the beam itself for therapy. This article describes one such example where it is used to fight cancer.


AIP's Physics Story of the Year

As is traditionally done at the end of each year, the American Institute of Physics's Physics News Update compilled what they believe to be the top physics news of the year. The story that ended up at #1? The most accurate determination of the electron's magnetic moment.

You may read the rest of their top stories of the year here.


Princeton Plasma Physics Laboratory

This is a good overview of the famous Princeton Plasma Physics Laboratory, whose contract to manage the laboratory is up for bidding (as is the case for most US Nat'l Lab nowadays when the contract is about to expire). It is good to know that, even with the construction and operations of ITER, the lab still has a purpose and function within the plasma physics research.


Tuesday, December 05, 2006

Calibration of MINOS Detector

For those of you not familiar with MINOS, you may read about it at their homepage. This is an experiment that not only detects, but measure the neutrino oscillation. The neutrinos are created from the Main Injector at Fermilab and shoots out to two detectors: the near detector a few meters away at Fermilab, and the far detector in a mine near Soudan, Minnesota. The neutrinos actually pass through the earth on its way to Soudan.

Anyway, the seminar that I attended this afternoon was on the calibration of both the near and far detector. It was extremely fascinating, because the exercise in calibration isn't trivial, not by any stretch of the imagination. It is amazing how much effort is put in just on characterizing the behavior of the detectors and how to calibrate such a thing. There are even Ph.D thesis on nothing but such detector calibration.

It isn't surprising that such efforts are being put in, considering that for one to trust the experimental data, the detector must be fully understood.


China and High Energy Physics

A good article on the evolution of high energy physics experiments in China. Note somewhere in the article of the very possible and devastating future of high energy physics experiments in the US, where both the Tevatron and SLAC are scheduled to shut down all high energy physics experiments by the end of this decade (SLAC will morph as a light source with the completion of the LCLS).

With LHC about to start running, Japan with KEK/RIKEN continuing to produce results, and China emerging with incresing funding and upgrading their program, the center of high energy physics will certainly shift away from the US, especially if the ILC is built elsewhere.


A Negative is a Positive

Wow. I didn't realize that we haven't detected a negatively-charged molecule in space, and didn't know it was that important.

It has been reported that scientists at the Harvard Smithsonian Center for Astrophysics have detected this negatively-charged atom/molecule for the very first time. It seems that the presence of such particles is essential in astro-chemistry.

Well, bravo! And I learned another new thing.


Monday, December 04, 2006

Physics Meets the Brain

This is a fascinating profile of Dr. Terry Sejnowski, who started out as a graduate student in physics and ended up as a neuroscientist. It is interesting to see how his background in physics plays a role in his new field.


Material Science Film Festival?

I would not have believed this if it werent for the fact that it was reported in Nature's daily update.

The Materials Research Society innaugurated their film festival (if you can call it that) during their Autumn meeting. Short films with a material science theme battled it out to in first prize. The description of some of the film competing was quite .... er ... interesting, including the one titled Material Combat that has ".... a man farting in a lift to demonstrate gaseous diffusion".


Certainly, Cannes Film Festival it is not. :)


Sunday, December 03, 2006

The Entanglement of Physics

OK, I'll make this as plain as possible. If you do not subscribe to Physics Today, READ THIS ARTICLE! READ THIS ARTICLE!

Was that clear enough? This is a terrific article to give to someone who does not know what physics is, what it does, how it works, etc. It is about time something like this is written. It emphasizes something that I've been telling a lot of people, especially quacks, who think that one can simply "learn" one aspect of physics while ignoring others. In particular, pay attention to this passage:

Consider the case of Bose–Einstein condensates (figure 2), existing at the intersection of atomic, condensed matter, and statistical physics, belonging to all those fields and to none of them alone. In addition, BECs could not have been produced, let alone studied, without the tools of optical physics, without manipulating electric and magnetic fields, without understanding gas and fluid dynamics, or without innovations in low-temperature physics. The experts will no doubt tell me what else I failed to mention. The point is that BEC research depends critically on the synergistic entanglement of all these sometimes separate fields of study. Take the contributions of one away and the program to make BECs collapses. It's more than interdisciplinary physics coming together to solve a problem. It's a deep entanglement of fields that gives rise to something qualitatively different, the emergence of an entirely new field.

A terrific article.


Football Physics

We seem to have the physics of a lot of things lately. We have the physics of golf, the physics of Star Trek, etc.. which is all good! People need to be aware that physics isn't just some esoteric subject that has no relevance to their lives.

This article is on Football Physics, written by Timothy Gay, a physics professor at the University of Nebraska. Coincidentally, Prof. Gay was also asked in another media publication about the loudness of the cheering crowd at a typical football match.


Physics in the UK

This article describes the declining popularity of science, and physics in particular, in the United Kingdom. The article is probably a result of the recent debacle on the closure of the physics dept. at Reading University.

As difficult of a task that we have here in the US in promoting physics to students, I somehow think that they are having even a tougher time there in the UK.


Saturday, December 02, 2006

Berkeley Lab

A brief look at the history and accomplishments of Lawrence Berkeley National Laboratory. The amount of historic and landmark discoveries that came out of this lab is incredible.


Hawking on Big Brother?

Oh Brother!

The producers of Celebrity Big Brother attempt to get Stephen Hawking to appear on their show! Are they serious?

I hope it doesn't happen, because I can see a lot of jokes being done at his expense.


Friday, December 01, 2006

The Physicist Behind The Physics of Star Trek

This is a very entertaining conversation with Lawrence Krauss, who wrote the very popular book The Physics of Star Trek. The most entertaining part, for me, is where he blows up a few pie-in-the-sky ideas coming out of Star Trek. That's because I am such a stinker!



James Clerk Maxwell

A terrific review of the life and accomplishment of James Clerk Maxwell. In his case, it is certainly an example of "Only the Good Die Young". To think of what he could have accomplished had he lived just a few more years.


Physics Quiz of the Year

PhysicsWeb has a quiz on how much you know about the physics news of this year. Take it and see how well you do.


Superluminal Tunneling?

There have been claims made now and then of an apparent superluminal signal occuring in quantum tunneling process. Of course, quacks like to jump all over something like this and going off into their own laa-laa land to come up with their outlandish theories.

However, the issue isn't as simple, and in fact, could be explained via re-examining on what actually is being timed during tunneling. Several publications have dealt with such a thing. See the list below:

H. Winful, PRL v.90, p.023901 (2003)
M. Buttiker and S. Washburn, Nature v.422, p.271 (2003)

The most recent comprehensive treatment of this issue was published by H. Winful, where he again expanded upon his PRL paper and explained away the apparent superluminal paradox in various tunneling phenomena.

H. Winful, Phys. Rep. v.436, p.1 (2006).

Of course, this may not sit well with some people, and I'm sure there will be a lot more being discussed about this. However, the point here is that claims of superluminal tunneling is far from convincing.