Wednesday, May 30, 2012

What Does It Mean To Be An Experimentalist?

OK, so last time, I tackled the issue of pursuing to be a theorist. Looks like up to this point, I didn't get hate mail for getting it wrong or having the wrong assessment of that profession. Since I survived that in one piece, I will now tackle something I know quite a bit more - being an experimentalist. However, since I seldom learn my lesson, I will tackle head on on areas of physics in which the term "experimentalist" can be rather vague.

For most of us, when we talk about an experimentalist, the image of someone in a lab coat, bending over a table full of chemicals, etc. would come to mind. While this may be true in fields such as chemistry or biology, nothing can be further from the truth in physics. In all the years that I've been an experimentalist, I've never worn a lab coat (I don't even own one, ever!). The interesting thing about physics is that it is such a wide and varied field, and consequently, the experiments that we do can look very different from one field to another, and even within the same field!

My intention to bring this up is based on a comment made by JRA in that theorist blog, and also based on my observation and conversation with other experimentalist. What does it mean to be an experimentalist in physics? If you are like me who came out of an experimental condensed matter program, chances are you had to build/assemble/maintain a vacuum system, had to perform your own diagnostics, do your own measurement, mount your own sample, do your own repair, etc.. etc. You are also in a relatively small group, and you do most of the experiments/work yourself. If your work gets published, more than 80% of the work that being reported probably involved you more you directly. In many cases, you also get to design the equipment, procure the parts, and then assemble it, often with help from engineers, etc. if you're lucky. The point here is that, in such a situation, you really are doing hands-on stuff, get your fingers dirty, crawl on your hands and knees, and doing physical labor work.

Now, on the other hand, if you are a high energy physics experimentalist, chances are, you spend most of your time in front of a computer, watching data come in, and spending most of your time doing analysis, or simulations, etc. There's a good chance that you didn't build the instrument that you are using, and that you hardly deal with the hardware involved in your experiments. I don't think that you're expected to build anything. The exception in such a situation is if you're building or designing a detector. In high energy physics, often the physics of the detector is part of the field itself. High energy physics often have to innovate and design its own detectors, since they can't simply open a catalog and buy one. But even then, the actual building and assembly are often done by technicians and engineers. In other words, if you are a high energy experimentalist, chances are you don't actually perform and control an experiment. This is probably why, as JRA has said, theorists can sneak in and be involved in experiments, thus, becoming experimentalists.

I may have described the two extreme cases here, and certainly there is a whole spectrum in between those two. Other fields of physics have varying degree of work. In accelerator physics, a lot of work done by physicists look more like engineering than physics, which is why accelerator physics is often populated by both physicists and electrical engineers. Still, we come back to our original question. What does it mean to be an experimentalist? I know that my example of a condensed matter experimentalist is what I can unequivocally categorize as being an experimentalist. But would my description of a high energy experimentalist be something what we consider to be an experimentalist? I talked to many high energy physics grad students and postdocs, and all they do is write codes, do Monte Carlo simulations and/or analysis, and data processing. They sound more like programmers to me, and I don't consider programmers as experimentalists.

So do you consider them to be experimentalists? Are you a high energy physics experimentalist with a different experience than what I just described? Do you consider yourself as an experimentalist?


Tuesday, May 29, 2012

ATLAS On A Smartphone

If you have an Android device (smartphone, tablets), then LHsee app from the Android Marketplace might be something you want to look at.

LHsee is an educational tool available for Android OS mobile smartphones and tablet PCs. It has been custom  designed to provide an accurate and interactive visual representation of complex high-energy physics events recorded by the ATLAS detector. Features include live streaming and reconstruction of collision data from the CERN Large Hadron Collider.

It's interesting that they only released this on the Android platform ONLY and not on iOS, considering that a lot of people that I know of who work at ATLAS use Apple devices.

You can get a more comprehensive description of this app and what it can do by downloading this paper, which you can get for free.


"The Unwritten Rules of Journalism"

I wonder if the written rules of journalism is "sexy sell"? In any case, this is an interesting and certainly-accurate UNwritten rules of science journalism. Read it and see how many fits into the popular science article that you've read recently in the media. If you need some help to refresh your memory, try this one.


Saturday, May 26, 2012

"Differences in visual attention between those who correctly and incorrectly answer physics problems"

This is a rather unique study that I haven't seen before done to people who are tackling physics problems. They tracked the eye movement of the participants in dealing with a particular physics problem, and they noticed differences on the area of focus between those who are just learning physics versus those who are already experts/physicists.

Abstract: This study investigated how visual attention differed between those who correctly versus incorrectly answered introductory physics problems. We recorded eye movements of 24 individuals on six different conceptual physics problems where the necessary information to solve the problem was contained in a diagram. The problems also contained areas consistent with a novicelike response and areas of high perceptual salience. Participants ranged from those who had only taken one high school physics course to those who had completed a Physics Ph.D. We found that participants who answered correctly spent a higher percentage of time looking at the relevant areas of the diagram, and those who answered incorrectly spent a higher percentage of time looking in areas of the diagram consistent with a novicelike answer. Thus, when solving physics problems, top-down processing plays a key role in guiding visual selective attention either to thematically relevant areas or novicelike areas depending on the accuracy of a student’s physics knowledge. This result has implications for the use of visual cues to redirect individuals’ attention to relevant portions of the diagrams and may potentially influence the way they reason about these problems.

You should be able to get a copy of the paper for free at the link above.


Thursday, May 24, 2012

Paper On Possible Sign Of Majorana Fermions In Solid-State System Published

I mentioned this a while back on the possible discovery of Majorna fermions in a solid state system. While the paper has appeared earlier, it has now officially been published by Science.

V. Mourik et al., Science v.336, p.1003 (2012).

Abstract: Majorana fermions are particles identical to their own antiparticles. They have been theoretically predicted to exist in topological superconductors. Here, we report electrical measurements on indium antimonide nanowires contacted with one normal (gold) and one superconducting (niobium titanium nitride) electrode. Gate voltages vary electron density and define a tunnel barrier between normal and superconducting contacts. In the presence of magnetic fields on the order of 100 millitesla, we observe bound, midgap states at zero bias voltage. These bound states remain fixed to zero bias, even when magnetic fields and gate voltages are changed over considerable ranges. Our observations support the hypothesis of Majorana fermions in nanowires coupled to superconductors. 

I'm sure they'll continue to have a better experiment to nail this down even more.


No Incompatibility Between Lorentz Force Law And Special Relativity

If you had missed the brouhaha surrounding the publication of the paper in PRL about an "incontrovertible" evidence of the incompatibility between the well-known Lorentz force law and Special Relativity, then you must have been asleep the past few weeks.

In any case, I've updated the blog entry that mentioned this topic a while back, and there are already several rebuttals appearing everywhere that countered the original argument. I highlighted two of them at the bottom of the blog entry, just in case you haven't caught up in the latest development. The latest argument present by Griffiths and Hnizdo sounds very compelling.


Friday, May 18, 2012

Stupid Politician Making Stupid Rants!

In another example of a politician shooting off his mouth without doing any kind of basic investigation, Representative Dana Rohrabacher, who himself is a member of the U.S. House of Representatives Committee on Science, Space, and Technology (meaning, he should KNOW better), ran off a series of rants against science funding that involves US collaboration with China.

Here's some example of the stupid remarks that he had made (you can read it for yourself if you have the stomach for such silliness):

Why did the Department of Energy give $5.3 million to Brookhaven National Laboratory in the Daya Bay nuclear project in China? That’s over $5 million. By the way, that’s $5 million to this nuclear facility.

Let me just note that, in my district, we have a problem with a nuclear power plant that’s going through some very serious problems right now, San Onofre. We maybe could have used that $5 million to help us correct the problems at the San Onofre plant. But no. We borrowed the money from China to give it back to them to solve their problems while our children will be forced to pay that debt off. We get no benefit out of it except a load of debt on our children.

Why did the Department of Energy give $256,000 to the Rensselaer Polytechnic Institute for research at the Daya Bay nuclear project in China? Again, another $250,000 to this Daya Bay nuclear project. It could have been the next year because this is over a 3-year period. These are some of these. By the way, it’s not anywhere near all of them over the 3-year period, but all of these are taken from a list over that 3-year period. Yes, we could have used some of that money to make sure that we didn’t have a problem in our own districts.

Why did the Department of Energy give over $500,000 to the University of Houston for a proposal to measure neutrino mixing at the Daya Bay nuclear experiment in China? Again, over a half a million dollars while we’re having trouble with our own nuclear program. We should be developing our own new generation of nuclear power which will be safe—and we can do it—but we don’t have the money to do it. Why? We’re giving millions of dollars to China and to others, money that should go to developing our own new technology here. Of course, we are borrowing the money from China in order to give it to them, which leaves our children in debt, and they’ll have to pay it all off with interest
Can you believe such crap?

The astounding issue here isn't that he disagree in the funding of such projects. The astounding part is that HE COULD HAVE EASILY ASKED the relevant officials on why such fundings were given in the first place! I mean, DOE officials, etc. could have easily briefed him (if they haven't done so already) on not only why these were funding, but also the NATURE of the funding. For example, the Daya Bay project is NOT about nuclear power plants, even though it uses neutrinos generate from nuclear power plants. It is a project that is funded out of DOE's Office of Science High Energy Physics division, NOT nuclear physics division. So to say that the money could have been used to help solve some problems at a US plant is hysterically off-base! It shows a complete ignorance on what the project is all about and what the money is being  used for! And the fact that he could have easily found out boggles the mind on why he has no qualm in making such stupid statements first before checking.

And oh, here's another thing. Why don't you fund such projects in the US if you really want to money to stay here? You make such rants, yet, you cut fundings to high energy physics. The biggest neutrino project that has been proposed, LBNE, has now had to rethink of what it can do based on the severe funding cutbacks. So when you limit such funding, how do you expect people do continue doing their scientific research? Why, they go ELSEWHERE to where they can continue with their work!

In other words, the funding to various projects outside of the US, including China, is a DIRECT RESULT OF budget cutbacks to science research funding, especially in physics! In other words, Representative Rohrabacher, you only have you and your colleagues to blame for this!

BTW, this obviously isn't the first time these people are not ashamed to reveal their ignorance AND to show their unwillingness to try and LEARN about the things they are ranting about. Read an earlier blog entry on other previous silliness coming out of the US Congress. You can't read that and not be skeptical that these clowns have learned anything. This is why we need more scientists, and more physicists, in such circles.


Thursday, May 17, 2012

"High energy particle colliders: past 20 years, next 20 years and beyond"

Hey, if you want to read about the history of particle colliders, and the prospect for it in the next 20 years, this article might be something that interest you.

Abstract: Particle colliders for high energy physics have been in the forefront of scientific discoveries for more than half a century. The accelerator technology of the collider has progressed immensely, while the beam energy, luminosity, facility size and the cost have grown by several orders of magnitude. The method of colliding beams has not fully exhausted its potential but its pace of progress has greatly slowed down. In this paper we very briefly review the method and the history of colliders, discuss in detail the developments over the past two decades and the directions of the R&D toward near future colliders which are currently being explored. Finally, we make an attempt to look beyond the current horizon and outline the changes in the paradigm required for the next breakthroughs. 


SNOLAB Inaugurated

In case you missed it, here's the press release on the inauguration of SNOLAB:

The lab is situated 2km beneath the surface of the Earth and will enable researchers ton answer fundamental questions about the history and the composition of the Universe. They will also be able to use the infrastructure to conduct research into the nature of supernovas, our own star – the Sun – and Earth itself. SNOLAB will indeed be at the heart of a wide range of experiments, including PICASSO, an international project that is being lead by UdeM researchers. “In terms of current and future experiments, around half about the detection of dark matter in the Universe and ‘weakly interacting massive particles’ or ‘WIMPs’ in particular. PICASSO is one such research project. WIMPs are in fact particules that we do not know anything about and that would be a part of what we call ‘new physics’,” explained PICASSO Project Leader Professor Viktor Zacek, of the University of Montreal’s Department of Physics. “In fact, the presence of dark energy and dark matter are proof that we are still very far from having completely understood physics and the world that surrounds us.”
A lot of physics are now done underground, literally! :)


Tuesday, May 15, 2012

Bad Physics Reporting In Abundance!

I was just going to let this go, but I couldn't. I can't stand how bad this report is, and it came from TIME, not some rinky-dink college paper!

Here's part of the original report:

Harry Potter and Star Trek fans, rejoice! Teleportation is real. Using powerful lasers and optics to manipulate photons, or units of light, researchers in China set a record for teleporting a photon more than 10 miles, TIME reported in 2010. Now, a different team of physicists at the University of Science and Technology of China in Shanghai say they have shattered that record, claiming to have sent a photon more than 60 miles.

Quantum teleportation, which has been around since 1997, is a little different than what you see in sci-fi movies. Considered “one of the holy grails of practical quantum communication,” as the scientists write in their abstract, teleportation is the ability to essentially move one object from one place to another without traversing the space in between. But, as Forbes explains, the actual object is not moving from point A to point B. Rather, the distant photon mirrors the information contained by the original photon, essentially becoming an identical twin.

What pissed me off is that they know what they're reporting isn't accurate, but they keep repeating that inaccurate information!

Let's examine this carefully. First, they mislead the reader into thinking that this is "teleportation" that we encounter in "Harry Porter" and "Star Trek":
Harry Potter and Star Trek fans, rejoice! Teleportation is real.
Then they make the first physics mistake:
Using powerful lasers and optics to manipulate photons, or units of light, researchers in China set a record for teleporting a photon more than 10 miles, TIME reported in 2010. Now, a different team of physicists at the University of Science and Technology of China in Shanghai say they have shattered that record, claiming to have sent a photon more than 60 miles.
No. As we shall see, the photo is not the one that is being "teleported", but rather, it is a particular STATE of the photon, or what the article later called "information contained by the original photon". The photons move in a "normal" manner here. Nothing is being teleported as far as the photon entity itself is concerned.

OK, so they already misled people into thinking that this is the Star Trek teleportation. But then, they corrected themselves by saying this:
Quantum teleportation, which has been around since 1997, is a little different than what you see in sci-fi movies.
You think everything should be fine from now on. Oh, but then, they resort back to the stupid Star Trek teleportation:

Considered “one of the holy grails of practical quantum communication,” as the scientists write in their abstract, teleportation is the ability to essentially move one object from one place to another without traversing the space in between.
Oh, so now we are back to moving objects, rather than a state or information, from one place to another. But wait, they then correct themselves back, and this is where the "information" part appears:

But, as Forbes explains, the actual object is not moving from point A to point B. Rather, the distant photon mirrors the information contained by the original photon, essentially becoming an identical twin.
So, how many twists and turns, and self-contradictions can one have in just 2 paragraphs? They know what the correct idea of quantum teleportation is, but they keep weaving this in and out with the Star Trek teleportation. And then we wonder how the general public may understand the wrong thing when they read about science reports in popular media!

TIME, for this report, you get a D-minus!


Monday, May 14, 2012

The Problem Of Pursuing To Be A Theorist

First, a declaration. I'm NOT a theorist. I'm an experimentalist (and proud to be one, damn it!) :) So one can say that my take on this can easily be inaccurate and based on superficial observations. However, having looked at it for many, many years, and talking to many theorists for quite a while, I think I have a view that isn't too far off for someone who isn't one.

This thought came up because I keep coming across students just starting out (some even still in high school) wanting to be theoretical physicists. Neglecting the fact that many of them have a mistaken idea of what "theoretical physics" is, I think that most (if not all) of these kids do not realize just how difficult it is to not only graduate with a PhD in physics, but also having the chance to actually be employed as a theorist.

Let's start from the most obvious: there are more experimentalists than there are theorists working in physics. Regardless of the field of study (outside of string/etc, I mean), experimentalists tend to outnumber theorists, often by a lot (see, for example, condensed matter physics and accelerator physics). So already the "phase space" for employment does not look very appealing to theorists.

Experiments and experimentalists tend to bring in more funding to a particular institutions. Now granted that in many of these funding, both theorists and experimentalists are involved. But even in such situation, the funding proposal tends to have more experimentalists than theorists. This is also one reason why there are more employment for experimentalists than theorists.

A project may get by without a theorist, even if it requires theoretical work. More often than not, an experimentalist can pick up the task that a theorist does, but it is more daunting for a theorist to do an experimentalist job. I'm not saying that this is true all the time, but in my experience, I've seen experimentalists do theory (especially in high energy physics), or use tools such as packaged software to perform theoretical simulations (especially in accelerator physics) without officially needing a theorist. Now, they may consult a theorist on site, but such tasks are often done by experimentalists without needing to employ another theorist to do such jobs. I haven't seen the reverse yet in my experience, i.e. group of theorists taking on jobs done by experimentalists, without needing to hire or have the presence of experimentalists. In fact, last time a theorist got close to my vacuum components, he ruined it by touching a clean part with his bare hands!!

Finally, the competition for the few positions in theoretical physics, be it in Academia or other institutions, is fierce! I do not envy the theorists at in this aspect. Because of the small number of positions available, even the good ones will have a tough time finding a job in their respected fields. In fact, if you did not come from a top-tier school, and your mentor isn't a "brand-name, world famous theorist", there's a very good chance that you will not get accepted to such a position in a good institution in your field. I think that the "pedigree" factor is a lot more prominent for theorists than for experimentalists, mainly because of such limited job opportunities. There are just too many outstanding candidates. What this means is that newly-minted PhDs from less well-known schools or supervisors seldom have a chance for employment as a theorist in their fields, leading to many to go into other fields or even outside of physics completely.

I'm sure there are many exception to what I've just described. But I believe that, on average, this is what is going on based on my years of observation. So, are you a theorist? Did I get it right, or was I just blowing smoke?


Friday, May 11, 2012

Data On Career Preference

Hum... I don't think I've ever seen this type of data/survey before. This is a report on a recent survey of graduate students in science and how their career preference change over time as they go through their graduate program.

Here's the result that has gotten the most press: Academic research careers were less popular with the late cohorts than the early ones in all disciplines, suggesting, perhaps, that graduate students are disillusioned by exposure to the lives and careers of their faculty advisers.
There's a breakdown of the study into various subject areas, and you may read that for yourself.

But the implication to such a shift is interesting, and something that I've tried to instill into students who are interested in majoring in physics.

Instead, we should all be worrying about the difficulty Ph.D. graduates often have locating jobs in, and making transitions into, some of those other work sectors that they appear to view favorably. We also need to worry about whether science careers in any sector are sufficiently rewarding, remunerative, and stable to justify the long time investment, the frustrations of training, and the forgone earnings; if they're not, we can't expect the most capable young people to choose careers in science. Instead, they'll choose other careers with better prospects, like finance or figuring out how to make people click on banner ads on Facebook.

We should also worry about whether those students are receiving the training they need to compete for jobs in sectors beyond academia. Our graduate programs already do the most important thing extremely well: The best way to convey strong analytical skills is to teach students to be outstanding researchers. But there is plenty of room for improvement when it comes to even the most basic professional skills.
Definitely! It is a FACT that there aren't that many tenure-track faculty positions in most fields, and this includes physics. Students going into such fields with the sole aim to obtain such a position need to have a reality check so that they can best prepare for other possible careers.


Thursday, May 10, 2012

"Preliminary investigation of instructor effects on gender gap in introductory physics"

I did a quick read of this paper. Here's the abstract:

Gender differences in student learning in the introductory, calculus-based electricity and magnetism course were assessed by administering the Conceptual Survey of Electricity and Magnetism pre- and postcourse. As expected, male students outgained females in traditionally taught sections as well as sections that incorporated interactive engagement (IE) techniques. In two of the IE course sections, however, the gains of female students were comparable to those of male students. Classroom observations of the course sections involved were made over an extended period. In this paper, we characterize the observed instructor-student interactions using a framework from educational psychology referred to as wise schooling. Results suggest that instructor practices affect differential learning, and that wise schooling techniques may constitute an effective strategy for promoting gender equity in the physics classroom.

Without reading the references, I must say that I am a bit puzzled on what exactly is this "wise schooling". It appears to be more of a "mentoring" than teaching. And I hate to say this, but in some aspects, it borders on "political correctness".

Now, before you jump all over me on that, if you have read this blog for any considerable period of time, you would have clearly known by opinion on gender imbalance in physics, and what *I* have personally done to promote science, and especially physics, among girls and women. So I'm all for studies like this that not only can identify a potential source of the problem, but also recommends steps to remedy them. However, after reading this paper, I feel rather scared to say anything because I'm afraid I might inadvertently discourage the affirmation for the "domain belongingness". I'm also all for positive reinforcements, but at some point, when something isn't correct, you have to say it without any adornment and with no BS.

So, did I completely misread this paper?


Wednesday, May 09, 2012

Teaching Physics Using Roller Coasters

Granted, not many schools (is there even one?) will have a roller coaster on campus to be used to teach physics. So do the next best thing. Bring the kids to an amusement park and let them ride these coasters!

That's what happened during Physics Day at a Six Flags amusement park.
They are here for the one day a year the amusement park is closed to the general public, while the roller coasters and other thrill rides become tools in a unique learning experience.
Faletti uses amusement park videos throughout the year. Her students have done the math problems and diagrams, explaining the physics behind the rides. Today they carry instruments to help them do their own calculations.

One is called an accelerometer, which measures the force of gravity on the roller coaster. Another is a protractor to measure centripetal force on the circle rides.
Let me just say that it is extremely nice of these amusement park operators to have a special day for just this. So let's tip our hats to them. I hope the kids had fun AND learn some physics at the same time.


Tuesday, May 08, 2012

Possibility of LHC Data Pile-Up

Too  much of a good thing is not necessarily a good thing.

So they want a lot of collisions, now they might get too many to handle. The detectors at LHC are preparing for the possibility of data pile-up, now that the LHC is operating at a higher energy and higher luminosity than what the detectors are designed to handle.

Every time two tightly packed bunches of protons cross, they generate not one collision, but on average 27, Lamont says. But within a few weeks, that number is expected to rise into the mid-30s, peaking at around 40 collisions per crossing. The two main detectors at the LHC were designed to handle only around two dozen collisions at once. But they have managed to cope so far.
While this is a good problem to have, it is still a problem, because you simply don't want to have to discard something simply because you can't handle it. It appears that they can, so far, but I can easily see that this number will continue to increase. Considering the daunting size and what they are trying to do, the LHC continues to be an astounding machine that is performing incredibly better than expected.


Monday, May 07, 2012

The Physics Of Spilled Coffee

As someone mentioned at the end of this article, this work is destined for the Ig Nobel prize.

If you wish to know more about how and why coffee often gets spilled when being transported in a mug, this might be of interest to you. It was even published in PRE.

A fluid's back-and-forth movement has a certain natural frequency, and this is determined by the size of its container. In their paper published last week in Physical Review E, Krechetnikov and Mayer show that everyday mug sizes produce natural frequencies that just happen to match those of a person's leg movements during walking. This means that walking alone, without any other interference, is tuned to drive coffee to oscillate in a mug. But the researchers also found that even small irregularities in a person's walking are important: These amplify the wilder oscillations, or sloshing, which bumps up the chance of a spillage. 
 So go for either very small mugs, or very big ones (I vote for big). :)


The Physics Of "The Avengers"

Hey, did you go see "The Avengers" this past weekend and were a part of the folks who help set a new box office record for an opening weekend? I did. I don't normally go for this type of movie, but I went and see it anyway, and I was glad I did. The movie was a lot of fun, witty dialog, and hilariously funny. And oh, if you plan on seeing it, DO NOT LEAVE TILL THE CREDITS END. You'll be sorry if you did.

Anyway, as is the case whenever a movie like this opens, and opens big, you get some discussion on the physics involved in the movie. This blog article discussed the "tesseract", the almost-infinite energy source that is the center of this movie, and what everyone seems to want.

Still, with a movie like this, one has to take many of the artistic license with a grain of salt. They certainly bend the rules of physics quite a bit.

All of this does not detract from a very enjoyable movie.


Friday, May 04, 2012

The Saga Of Lisa

Funding problems are plaguing the European effort at detecting gravitational waves. It appears that the LISA project, and its reincarnation NGO project, are not going anywhere.

But everyone you speak to still says it represented marvellous science. So why did it lose out?

There're probably a few reasons, and I'll try to summarise the comments that have been made to me.

One was the price tag. Even in its remodelled format, the mission would have cost Esa more than 1,000 million euros (the Lisa/NGO team disputes the reality of this figure) and this was substantially above the ceiling of 650 million the agency had set.

Another reason was launch readiness. Esa's executive did not believe the mission could be made ready before 2025, and it wants to maintain a certain flight cadence for its science projects, ie Esa needs to be seen to be doing stuff regularly.
This is an excruciatingly difficult experiment to do, so it will be an astounding effort if they can detect such gravitational wave. But like the Higgs, it is an aspect that needs to be verified and confirmed for GR (as with the Standard Model for the Higgs).


Thursday, May 03, 2012

Achievements and Lessons from Tevatron

One always looks back with nostalgia at something that is gone. This is no different with a facility such as the Tevatron that has produced an amazing body of knowledge for high energy physics for such a long time.

This article looks back at all the achievements of the Tevatron, and also what has been learned from that facility. Hopefully, if you didn't know much about it, you'll appreciate what has come out of it.


Is Lorentz Force Law Incompatible with Special Relativity?

This paper has been getting quite a bit of brouhaha among physicists, but not with the General Public since most probably don't get the big deal or understand what a "Lorentz force law" is. Of course, among physics students and physicists, the Lorentz force law is one of the first things we learn in intro physics classes. So it would be astounding that a textbook principle is shown to violate Special Relativity right in front of us. But does it?

The paper is to appear in PRL (if it hasn't already), but you can find the preprint here. Adrian Cho at Science covered it last week in the News and Analysis section. It highlights the status so far where people think there's something wrong with the analysis, but no one can figure out where.

“If it's true, it's astonishing,” says Stephen Barnett, a theorist at the University of Strathclyde in Glasgow, U.K. “I suspect there is something subtle going on here” that doesn't contradict relativity. But Rodney Loudon, a theorist retired from the University of Essex in the United Kingdom, says, “As far as I can tell, [the analysis] is right."
I tell ya, even now, classical E&M can still spring a few surprises! I love it!


Edit (5/8/2012): As one can imagine, there are already responses to this paper. One just appeared on arXiv today:

I'm sure we'll hear a lot more.

Edit (5/24/2012): More rebuttals against this paper, and this time, it comes from someone who should know what he is taking about:

I believe this effectively solves the "paradox" in the original paper.