Accelerator in a Bowl

This is a cool demonstration to illustrate how they accelerate particles at the Tevatron at Fermilab.



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Ettore Majorana And His Heritage Seventy Years Later

For those who are not familiar with the story of Ettore Majorana, this is probably a good introduction to his life, and his contribution to physics within such a short period of time till he mysteriously disappeared some 70 years ago. I consider him the Emelia Earhart or the Jimmy Hoffa of physics because of this disappearance, which still has not been solved.

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An Inquiry Into the Reproduction of Physics-Phobic Children by Physics-Phobic Teachers

I know! I was intrigued by the title as well! :)

First of all, this is a paper that was originally published in Japanese, and this English version is, what appears to be, an almost direct translation. So there will be some awkward passages here and there. If you keep that in mind, everything should be OK (just think of literal translation and you'll be fine).

The authors studied the effect of teachers who themselves have little understanding or interest in physics on students. Somehow, the teachers disinterest in physics can (surprise!) transfers itself to the students.

It is interesting to note that, with the budget crisis in physics in the US and UK, we tout the high investments in science in Europe and Asia, particularly Japan, China, and Korea. But it is obvious from this report that even in Japan, they also face, to a lesser degree, problems in getting students to do physics, not just as a career, but in terms of being educated or literate in it.

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Considering Science Education

There has been only one essay so far in which I flat out tell everyone to go read it. It was the Helen Quinn essay "Belief and Knowledge - A Plea About Language".

OK, so here comes another one. In the March 21, 2008 issue of Science, an editorial by Bruce Alberts is a MUST READ by everyone and anyone (Science, v.319. p.1589 (2008)). He argues why science education is important to everyone, and not just science students.

I consider science education to be critically important to both science and the world, and I shall frequently address this topic on this page. Let's start with a big-picture view. The scientific enterprise has greatly advanced our understanding of the natural world and has thereby enabled the creation of countless medicines and useful devices. It has also led to behaviors that have improved lives. The public appreciates these practical benefits of science, and science and scientists are generally respected, even by those who are not familiar with how science works or what exactly it has discovered.

But society may less appreciate the advantage of having everyone aquire, as part of their formal education, the ways of thinking and behaving that are central to the practice of successful science: scientific habits of mind. These habits include a skeptical attitude toward dogmatic claims and a strong desire for logic and evidence. As famed astronomer Carl Sagan put it, science is our best "bunk" detector. Individuals and societies clearly need a means to logically test the onslaught of constant clever attempts to manipulate our purchasing and political decisions. They also need to challenge what is irrational, including the intolerance that fuels so many regional and global conflicts.

I totally agree. If you have read the beginning of my series on revamping the intro physics labs, I've always argued that these labs can be a valuable tool to these students (the majority of whom are not physics majors) as an illustration on how we accept something to be valid, or how we arrive at some of our knowledge. We should emphasize the idea that using scientific technique to verify something is the strongest degree of certainty that one can have in any endeavor. It is why scientific evidence is different than anecdotal evidence. It is why astrology is not a science, whereas astronomy is. The fact that many still can't tell the difference is an important reflection on how these arrive at what they perceive to be true. This means that many of the decisions they make may not be based on valid information or evidence.

So think of what happens when they vote for their political leaders....

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The Squeeze at Argonne And Fermilab

.. and this "squeeze" comes both in terms of funding and science.

Three months into the disastrous Omnibus bill, this article looks at the impact on the two national laboratories in the Chicago area - Fermi National Accelerator and Argonne National Laboratory.

To say that the mood and the morale are low is to put it mildly. One good thing about this article is that it highlights each of the facility that has been affected, and what kind of science and impact it has.

As far as I can tell, the outlook for the immediate future isn't rosy either. Even though the president's FY09 proposal calls for immediate increase in all affected areas, everyone here is almost certain that Congress is not going to pass this budget any time soon and will wait instead until after the general election. This means that we will be saddled with a continuing resolution, and will adopt the disastrous FY08 budget for the remainder of the year and into next year.

Things are not looking good for science in the US, despite all the lip service that has been given about its importance.

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The Science of Tangled Cord

Next time you have to untangled the cords from your electronics, you can at least think of it as a complicated physics process. :)

This news article describes a recent PNAS paper on this very issue.

Knot formation had been studied a lot by mathematicians, but not much by physicists. Smith was worried that the work wouldn't be taken seriously, but it ended up being published in the prestigious Proceedings of the National Academy of Sciences.

"The way that you get a knot is the string has to bend back on itself, coil back on itself," Smith said. As a string or cord tumbles, the end of it has a 50 percent chance of weaving to the left or the right of the coils, and under or over the coils, sort of like random braiding, Smith said.

The exact citation for this paper (which none of these popular newspapers ever give) is:

Dorian M. Raymer and Douglas E. Smith, PNAS v.104, p.16432 (2007).

Don't get all tied up with it.

:)

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Interpretation of Quantum Mechanics - The New Religion

First of all, a clarification and a qualification. Most physicists (at least the ones that I come in contact with throughout my years as a student and as a physicist) don't really care about the various interpretations of quantum mechanics. It really is a non-issues 99.9% of the time. So essentially, we practice Feynman's "Shut Up And Calculate" philosophy where the formalism and what empirical evidence that it can produce is what we care about.

Now, in one of my rants in "Imagination Without Knowledge is Ignorance Waiting to Happen", I mention about many crackpots who have argued that physicists simply want to keep the status quo as far as our understanding of the universe goes, that all we care about is upholding the current laws and theories. We can't, as some put it, work "outside the box". Some even compare to our "devotion" towards not wanting to drop our current understanding as a "religion".

This, of course, is stupid, and false, on many different levels, as I've mentioned in that blog entry. Still, there is one aspect of physics in which, I hate to say, is starting to look like a religion, and it has nothing to do whatsoever with what these crackpots have in mind. In fact, I don't think any of them could even comprehend these things well enough to know any better.

What I find in physics to be no different than a religion is the rabid devotion of some people, physicists included, to the various interpretation of quantum mechanics. These interpretations could range from the "popular" Copenhagen Interpretation (CI), to Many-World Interpretation (MWI), to Bohm Pilot Wave (BPW), etc.. etc. Now, again, to be fair, this issue comes up only in a very small percentage of practicing physicists. I tend to find more of these discussions on physics forums rather than in prominent physics journals. And certainly, amateurs and philosophers tend to be more fascinated by this issue than the overwhelming majority of physicists. So in physics, this "religion problem" isn't a widespread epidemic.

Still, those who are devoted to this is not doing physics any favor. I find that the rabid devotion to such various interpretation (rather than just a casual attitude about it) rather puzzling and contrary to how one accepts something to be valid in physics. This is why I find that the devotion to any such interpretation as being no different than a religion:

1. There's no empirical evidence that shows one being "better" than the other. All of them come up with the same analytical form within the formal QM. The similarities with religion is obvious here. This means that there's nothing to support which is better, and they all come up with the same answer, at best, so far.

2. Yet, the devotees in each camp tout why such-and-such is more "logical" or "rational" or "conceptually sensible", etc. Without empirical evidence to support such claim, this is nothing more than a preference based on a matter of tastes! We might as well argue for our favorite color, or, in this case, our favorite religion. This is no different than the different religions and the many followers that they have. Each one will tout the superiority of its belief system, or why it is the "truth", etc. Yet, in none of these are there any empirical evidence to separate and support these claims.

Now one could argue that isn't what is being taught in QM classes more along the lines of adopting the CI? I don't believe so, because in the end, it is the formalism that is more important, and there's no ambiguity at all there. And if it really is CI that is being instilled into these students, how come most of them grow up and adopt the "Shut Up and Calculate" point of view and not become a CI devotee?

I'm not saying that at some point, there won't be a "tie-breaker", be it a further refinement to these various interpretations that make them distinctly different from each other, and/or new tests would come out to allow for direct verification of each one. But until then, why are people "believing" in something that, at the very foundation, is simply a matter of tastes?

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Iron-Based High-Tc Superconductors

This certainly came out of nowhere.

There's another "high-Tc" superconductor joining the fun. This time, unlike the cuprates, it consist of iron-arsenic planes, and is doped with fluoride atoms. Currently, it has a Tc of 26K, but that would probably change.

From preliminary report, it seems that it is not phonon-mediated, but rather via spin-fluctuation. It would be interesting to see if it has the same phase diagram as the cuprates and if it also has a pseudogap state.

Update 04/18/08 : There's a rather good summary on this in a Science daily news.

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What is the Matter with the Uuniverse?

More CP violation results out of KEK on the B meson.

To find out the team created pairs of matter and antimatter particles, called B mesons and anti B mesons, and measured how they behaved. The study has come up with a better estimate of earlier measurements that suggest that there is a difference in the rate of decay (they decay into a kaon and pion).

"We have measured two differences of decay rates between b and anti-b," says Prof Hou. " It is around 9 per cent for neutral B and anti-B, and 7 per cent for charged B and anti-B. The bigger mystery, and gist of our paper, is posing the question of why there is this difference."

But the end of the article mentioned about waiting for more results out of BaBar at SLAC. I thought SLAC is no longer doing any particle collider experiment and is already being converted into the LCLS? Did something changed? Or are still going to do limited collider experiment in between LCLS runs?

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Addendum: I just finished reading the paper in Nature (Lin et al, Nature v.452, p.332 (2008)) and the Perspective on this work by Michael Peskin in the same issue of Nature. The BaBar result they are expecting is the analysis of the large, existing data that have already been collected. So it isn't from any future BaBar experiment. That clears things up a bit, at least for me.

More Addendum: See a report on this in PhysicsWorld.

HiRes Confirms GZK Cutoff

This could be one of HiRes last triumphs. It has now down a "negative result" experiment and confirms the GZK cutoff (link may be open for a limited time), signifying a threshold of energy for cosmic rays.

This energy ‘cut-off’ was predicted in 1966 by Kenneth Greisen of Cornell University in Ithaca, New York, and in the same year by Soviet physicists Georgiy Zatsepin and Vadim Kuzmin of the Lebedev Institute of Physics in Moscow. They predicted that there would be very few cosmic rays with energies greater than about 6×1019 electronvolts (eV) because of energy losses through interactions with the ubiquitous photons of the cosmic microwave background, the radiation that fills the Universe.

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The Hummer is NOT More Environmentally-Friendly Than a Prius

It's amazing how a report that is full of holes can gain such a foothold once some talking heads on TV adopted it.

A while back, there was a rather dubious report called "Dust to Dust" that essentially drew up a conclusion that the monstrous Hummer is more "environmentally friendly" than the Prius, based on all the energy accounting that is being used to research, manufacture, and run the vehicles. Slate.com has a brief synopsis of the whole thing. Luckily, they also tackled the validity of that claim and cited several prominent (and certainly, NOT dubious) research work. It essentially debunked that myth.

Moral of the story: never accept the validity of science/engineering issues from politicians, TV personalities, or popular news media.

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More Challenges Against Non-Local Hidden Variables Theory

Science Daily is reporting a new experimental measurement out of NIST and Maryland that challenges the validity of a certain aspect of non-local hidden variables theory.

Experiments so far have ruled out locality and realism as a combination. But could a theory assuming only one of them be correct" Nonlocal hidden variables (NLHV) theories would allow for the possibility of hidden variables but would concede nonlocality, the idea that a measurement on a particle at one location may have an immediate effect on a particle at a separate location.

Measuring the polarizations of the pairs of entangled particles in their setup, the researchers showed that the results did not agree with the predictions of certain NLHV theories but did agree with the predictions of quantum mechanics. In this way, they were able to rule out certain NLHV theories. Their results agree with other groups that have performed similar experiments.

I may have missed it, but I don't recall ever seeing any experiment on entanglement that hasn't produced any result that's consistent with QM. One can argue that such-and-such an experiment doesn't rule out that and that theory, but QM is batting with 100% hits here with zero strike-out. I find that rather impressive, and impressively convincing.

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Public Impatience With Science

Argonne's Director Robert Rosner spoke to the Chicago Council on Science and Technology, a not-for-profit organization is committed to promoting science and technology in the greater Chicago area. Some of the things he said bears repeating here, especially on the part where it takes decades for a basic scientific breakthrough to make it to the consumer.

Computers were around for 30 years before they became useful to business, and solid-state electronics consumer products didn't catch on until a generation after the transistor was discovered, said Rosner, director of Argonne National Laboratory.

"When a basic discovery is made, no one has any idea what it will lead to," said Rosner. And this disconnect is behind the financial crisis now afflicting Argonne and its sister institution, Fermilab.

"People believe that basic science can wait," said Rosner, "but the truth is that if you don't do the basic research today, you won't reap the fruits in 20 to 30 years. We have to invest now to benefit our children and grandchildren. But to a culture that expects instant results, such patience is a hard sell.

I think most people do forget that. Even within the sciences themselves, many forget that some of the advancement in biochemistry, for example, were brought about because of something that was developed in physics years before. Synchrotron light sources came out of research in high energy physics, and it took many decades before the field of biochemistry, medicine, and pharmacy realized that such facilities can be valuable to their work. This is just one example of something that came out of basic research that appeared to have no direct application at that time.

Just how do we convey that to the public and, especially, those politicians?

Edit: The original link appears to no longer work. However, there is a link directly to the Chicago Council on Science and Technology with a video of the talk.

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What Makes A Successful "Letters"?

The "Letters" in this case is the Physical Review Letters (PRL), one of the top 3 most prestigious publication for physics papers. The Physical Review website has an editorial on what makes a suitable and successful PRL paper. With the criteria for acceptance being more tight, and with the editors at PRL now having a larger role in weeding out submission, it is more important to pay attention to these guidelines on what they are looking for.

A successful Letter of course begins with a valid result, one that is important and interesting. This is glib, however, because it lacks explanations of “important” and “interesting.” So, here are attempts to define each, in single sentences: An important result provides insight that changes the way others view and understand the topic, allows them to improve their own approaches, and thus leads to substantial progress. An interesting result will make readers glad to learn of it, because it is important to their own work or the work of others, or because it is science of uncommon beauty, aesthetically. In the context of a manuscript there is a third element: accessibility. Regardless of its content, a manuscript will be of lesser interest if it is impenetrable, and a manuscript that attracts fewer readers will be less important.

Present PRL policy incorporates these three concepts by seeking to publish work that should not be missed by researchers in the given field and also those in at least some related fields. Broader interest, in general, is better, as is greater importance, but the two are not independent. Work that is extremely important to a few might be as worthy as work that is moderately important to many, which again leads directly to presentation. A manuscript that can be understood only by a narrow audience will be less likely to be suitable for PRL, because it will lose its chance to be moderately important to a wide audience.

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How Fundamental Particles Lose Track Of Quantum Mechanical Properties

We have another report on the study on the mechanism of the differences between the quantum world and our classical world. This is another study on the effect of decoherence on a quantum system that couples to an external "bath".

It would be interesting to compare this to an earlier report on the emergence of a classical system from a single-particle state after just one interaction. It is also interesting to see how Roger Penrose would handle this. He seems to think that our classical world emerges due to some coupling or interaction between the quantum systems and gravity, and that eventually destroys the quantum system and out comes the classical system. These two papers above seems to indicate that the mere act of decoherence might be sufficient to produce the classical world.

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Revamping Intro Physics Laboratory - Part 4

Continuing with this series, here's another experiment that I would propose. This would still be something that can easily be done at the beginning of the semester, which means it doesn't require that the students would have already learned any physics related to it. BTW, in case people think that all the experiments that I'm going to propose are this "simple", that is not going to be the case. These "no physics" experiments are aimed only at the beginning of the semester and where we want to introduce to the students that physics is nothing more than a systematic way of deriving what is valid and how to figure out a way to understand the relationship between things. It reinforces the idea that one doesn't need to abandon all that we already know to understand physics. In fact, we need to bringing in our "common sense" and the sense of "play" to do physics, or at least, these physics experiments. As the semester progresses and, presumably, the students' understanding gets more sophisticated, the experiments should also evolve the same way.

OK, for this experiments, we will deal with springs and masses, so again, it shouldn't be something difficult. The task this time is simple:

You will be given a "mystery" object in which you need to determine its mass. You are given a set of springs, and a set of calibrated masses. In addition, you will also have access to a ruler and a stopwatch if you need them. Figure out how you can determine, as accurately as possible, the mass of this mystery object. You must describe explicitly how you go about doing this determination.

Now, of course, in many intro physics class, this type of experiment typically requires that they find the spring constant by looking at the extension versus force or mass applied to the spring. I'm going about this the other way. Forget about the spring constant for now. The key thing here is that the student learns about the relationship between the spring extension as different masses are added to the spring. This to me would be the most obvious technique that most of the students would do. They would find the extension of the spring with different masses. Then, when given mystery mass, they may have to do some interpolation or extrapolation to estimate the mass of that object.

Now, there's also a possibility that some students may do this differently. They could, instead, let each of the known masses oscillates one at a time and find the relationship between the mass and the period of oscillation. They won't end up with a straight line, but as in the previous suggested experiment, this is OK. While we tell them they need to do this as accurately as possible, in the end, we really don't care as long as they explain what they did and how they did it. So even if they had to extrapolate/interpolate by hand, this is perfectly fine.

Now, what we can do further is this. For the students that did the first method (hanging the mass and finding the spring extension), we can ask them this:

Now, often it is difficult to get the spring to be very still - the mass tends to oscillate up and down. So maybe it might also be a good idea to see if we can make use of this property to see if there's an additional relationship here between the mass on the spring, and the period of oscillation. Can you determine the mass of the mystery object this way? Does it give the same answer? It is always more convincing when two different methods give consistent answers.

For those who did the the second method (oscillating the mass and finding the period), you then say:

Oscillating the spring doesn't allow you to read off the mass very quickly, which is something you need quite often. So is there another way to determine the mass quicker? How about looking at how much the spring extends as you hang different masses? Can this lead you to a different way to measure the mystery mass? Does this value agrees with the one you got earlier? It is always more convincing when two different methods give consistent answers.

.. and voila, you've gotten them to do this in both ways! They also learn that in science, it is always more convincing when you can show a consistent result from two different techniques (although, to be technically accurate, these are not really two different techniques, but this is a good enough demonstration at this level). Now the fun starts if they come up with very different answers. This is where they need to figure out (with the help of an instructor) on what went wrong. To me, figuring out what went wrong is as important and what went right.

After the students have done both, you then can pose an additional question such as this:

What you have now is a graph that you always need to use whenever you want to determine a mass. Is there a way to know the mass of something without having to resort to using such a graph? Can we figure out a way in which, if we know how much the spring extends, we can simply punch that number in and out comes the mass?

I think you know where I'm going with this, don't you? Considering that the students should have a background in sufficient mathematics, they would have seen a straight line equation. If not, a bit of help and hand-holding is called for, which, at this point, should be alright.

So in essence, we have done the mass-spring experiment, but done in a different manner. Rather than giving out the necessary steps that the students have to do, we instead "coerced" them into doing them by a series of questions and tasks that we want them to accomplish by themselves. Inadvertently, they "discover" Hooke's Law by themselves.

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"This Coincidence Cannot Be Accidental"

That's the most dramatic statement coming out of a newly-published paper in Science, and that was the title that Doug Scalapino used in his Perspective article on this paper in the same issue.

Just when we think that we know everything there is to know about conventional, metallic superconductors, Mother Nature throws a wrench at that fallacy. Reported today by Ayanajian et al.[1], metallic superconductors such as Pb and Nb still holds a mystery. This time, it appears that the exact phonon energies of the Kohn anomalies happen to coincide with the superconducting binding energies of the cooper pairs of that particular metal. This is something that was not expected, and current formalism of conventional superconductivity says nothing about such a thing. As Scalapino pointed out his is Perspective article[2],

... although the polarization created by the conduction electrons and the response to the ionic lattice contribute to determining both the Kohn anomaly and the pair binding energy, there must be something else at work that locks (the superconducting gap) to (Kohn anomaly energy). As noted, this could mean that there is some new physics that is not captured by the Eliashberg formulation.

I love it! I love unexpected surprises like this!

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[1] P. Ayanajian et al., Science v.319, p.1509 (2008).
[2] D.J. Scalapino, Science v.319, p.1492 (2008).

Dark Matter Music From CDMS

This is a bit out of the ordinary.

This is taken from Fermilab Today newsletter for March 13, 2008:

Karl Ramberg sometimes incorporates music into his artwork. But a trip with his brother, Fermilab physicist Erik Ramberg, added science to his palette. Karl, with the help of scientists, produced a full-scale, plastic model of a dark matter detector that translates its data into light and sound.

"The end result is that you get an experience, aurally and visually, of subatomic affects," Karl said. "You get a better understanding of what the data is saying."

The musical detector, a YouTube sensation, is modeled after the real Cryogenic Dark Matter Search, an underground experiment searching for dark matter particles. The actual CDMS experiment detects and records the energies of particles that strike its five towers. The model takes that one step further, expressing the data in color and tone according to particles and their properties. The idea for the model was inspired by a trip to the Soudan, Minn. mine that houses the CDMS experiment, where Erik, a CDMS collaborator, took shifts.

So this is essentially data translated into music.



It could pass for a New Age music, I would think. :)

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Revamping Intro Physics Laboratory - Part 3 (Follow-Up)

OK, I got some very interesting responses to my suggestion of an experiment that can be done for an intro physics lab. I think I didn't explain myself too clearly on the premise and how I'm going to present it on here, so I should do that now.

While I tried to be explicit in describing the experiment and what would be a good way to do it, I don't actually want to reveal the whole hand. That's why I went along with the idea that there could be a dependence of the period with varying weights, because that is a very likely path that the students might attempt. If someone is thinking of actually trying to introduce this experiment in an intro lab, I don't want the possibility that some student might google it and find my blog where the whole thing has been revealed. :) That would defeat the purpose of them doing this without any kind of "previous knowledge".

So while I'm trying to be as clear and complete as possible in the experimental description, and the "philosophy" behind it, I don't really want to reveal everything either. In fact, I'm hoping that there WILL be students who decided to figure out if they can do it by changing just the weights. I consider discovering something that cannot work to be very educational. In fact, in science, knowing what doesn't work can be quite important (re: Michaelson-Morley experiment). They at least now know that changing the weights would not work. If they are curious enough, they'll try to find out WHY it doesn't work, and this is where the physics can be introduced.

Note that the experiment that I had suggested does NOT require that they have learned anything in intro physics. It is quite independent of the lesson they might have received in class. So in principle, this experiment could be done even during the first week of class. It doesn't require that they had learned about simple pendulum.

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New WMAP Data Once Again Agrees With Cosmological Model

The more they test it, the more convincing it becomes.

The new report out of the new analysis of WMAP data on the neutrino background has again produced a result consistent with the Big Bang Nucleosynthesis.

As such, the cosmic microwave background provides an independent estimate of the number of neutrino “families” in nature: 4.4 ± 1.5. Despite having been inferred from a totally different cosmological epoch, this value agrees with constraints from Big-Bang nucleosynthesis, the first few minutes of the universe during which light nuclei were manufactured, and with precision measurements at particle accelerators which fix the number of families at three. The WMAP5 data also constrain the combined mass of all types of neutrino to be less than 0.61 eV.

“The discovery of the neutrino background tells us that our models are pretty much right,” says cosmologist Pedro Ferreira of the University of Oxford. “Stuff from particle physics that you’re not putting in by hand just drops out of them — that’s pretty cool if you ask me.”

Yes, very cool! :)

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