Vote For Your Favorite PhotoWalk Photos

Voting has started for you to vote on your favorite Particle Physics PhotoWalk contest. There are some stunning photos in here, and I don't know how I can choose just 3.

So get your votes in!

Zz.

Science At Work

A rather fascinating video out of Fermilab. In some ways, this is a "propaganda" video, but in other ways, it actually is a very informative look at not only what the Lab does (or will do), but also what "high energy physics" is. The personal angle that is included in the video provides some "emotional" content that the general public can relate to.

Here's the synopsis of the video:

Six days. Three frontiers. One amazing lab. From 2010 to 2012, a film crew followed a group of scientists at the Department of Energy's Fermilab and filmed them at work and at home. This 40-minute documentary shows the diversity of the people, research and work at Fermilab. Viewers catch a true behind-the-scenes look of the United States' premier particle physics laboratory while scientists explain why their research is important to them and the world.

It's a long, 40-minute video, though. But it is worth sitting down and watching it, especially if you want to learn a bit more about high energy physics here in the US, and what Fermilab did and will do.



Zz.

FFAG Review

I wrote quite a while back about this Fixed Field Alternating Gradient accelerator, including the unfortunate acronym that it has adopted. This document provides a good review of this area. It was presented at a 2011 CERN Accelerator school.

Zz.

"Quantum photonic devices in single-crystal diamond"

A very interesting report on the ability to control single-photons in photonic devices.

Physicists in the US are the first to make an integrated device that extracts photons from a tiny piece of diamond before the light is sent through a waveguide to the outside world. The photons all have the same frequency and originate in a nitrogen vacancy (NV), which is a defect that occurs in diamond when two neighbouring carbon atoms are replaced by a nitrogen atom and an empty lattice site. According to the researchers, the chip could be used to create quantum-information technology such as quantum repeaters.
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Researchers are particularly interested in extracting photons that do not interact with the surrounding lattice because these "zero phonon line" (ZPL) photons have a well defined frequency. Unfortunately, one challenge in building NV-based quantum systems is how to reliably get ZPL photons out of the diamond and into an integrated optical system, where it can be processed further. What Andrei Faraon and colleagues from Caltech, Hewlett Packard and the University of Washington have managed to do is to create an integrated optical system that does just that.

You can get free access to the paper at the New Journal of Physics website.

Notice that this work was partly funded by DARPA.

Zz.

Kelvin Probe

Hey, I'm an experimentalist. It may be a revelation to some because I see this blog linked to many different sites, and some of them referred to it as ".. written by a high energy theorist..."! Me? High energy theorist? :)

Anyhow, I think it is always good to highlight certain experimental techniques, especially the ones that I'm quite familiar with. So here's one.

Often, for most of us, our first encounter to measuring the work function of something is via the photoelectric effect. Later on, if some of us go into photoemission spectroscopy, we deal with the work function there as well. However, that is not the only means to measure the work function. A technique that does not require the use of any light source to perform such measurement is called the Kelvin probe.

If you understand the physics behind a pn junction in semiconductors, then you've already understood the physics used in a Kelvin probe. You have a metal (the probe) with a particular Fermi energy, in close proximity (or in contact) with another material that has a different Fermi energy. This creates a contact potential difference. The Kelvin probe measures this contact potential difference, which is the difference between the two Fermi energies.

The link that I gave above gives you more details on such a measurement. If you know the value of the Fermi energy of the probe, you get the value of the work function of the material being studied. The only caveat here is that if the sample you are looking at is a semiconductor, you do not get the "work function", but rather, the value of the Fermi energy with respect to the vacuum state. In many cases, this is called the work function (energy between the Fermi level and the vacuum state) of the semiconductor, but one should not confuse this with the photoemission threshold, because the Fermi level resides in the gap. The photoemission threshold is the energy between the top of the valence band and the vacuum level.

Confused? Let's go on.

A significant improvement in the Kelvin probe technique was introduced with the invention of the Atomic Force Microscopy (AFM). It turns out that one can adapt an AFM system to work in the Kelvin probe mode. This technique is now called Kelvin Probe Force Microscopy (KPFM). I've linked to a very nice review paper on the physics and capabilities of KPFM technique. This technique allows for the mapping of the surface potential (or work function if you know the work function of the tip) of a surface with spatial resolution of the order of 100 nm.

So why is this useful. Obviously, knowledge of the surface potential is crucial in the understanding of the behavior of many materials (read some of the references in the KPFM review paper). It is another parameter that is part of the characteristics of the material. It also provides another check to the value of the work function that are often obtained from photoemission experiments. In fact, some material actually react to the exposure of light (especially UV), and the value of the work function obtained may not be as accurate as it should be from photoemission measurement.

There. So now, if you haven't heard about this before, you've learned something new! :)

Zz.

No Ignition For National Ignition Facility

The soft whispers about issues and skepticism with the National Ignition Facility (NIF) got louder with the review reports on its failure to meet its milestone last year.

The US$3.5 billion National Ignition Facility (NIF), at the Lawrence Livermore National Laboratory in Livermore, California, is designed to crush tiny pellets of hydrogen isotopes until they fuse into helium. The goal is to release more energy than goes into the pellet and in doing so roughly mimic conditions inside a modern nuclear warhead.

That was the goal, but a six-year “ignition campaign” came up short in September, sparking introspection amongst scientists, federal officials and congressional funders. Introspection in Washington inevitably leads to reports, and in November and December, a series of reviews of the project were released—including plans to shift the giant laser facility away from ignition work and towards weapons.

The gist of the conclusion given in the committee report is in this paragraph:

The important conclusion from the NIC is that the pressent understanding of the physics of the hahlraum and capsule implosion as embodied in modeling and computer simulation is insufficient to predict the results of the implosion experiments aimed at achieving ignition. Reviewers indicated that, while progress towards ignition had been made, a program of scientific experiments and modeling focused on understanding the various physical effects, in isolation, that impact the integrated implosion experiments provides the best approach to eventually either achieve ignition, or to understand definitively why it may not be achievable with indirect drive using the NIF laser. Executing such a program will also require enhancing the number of diagnostic measurements of both the future focused experiments and integrated implosion experiments.

The ignition program certainly has a major task ahead of it, and this failure to initiate ignition certainly generates even strong skepticism of its program.

Zz.

70 Years Of Schrodinger's "What Is Life?" Lectures

If you were not alive 70 years ago, this news article provides a very good summary of the landmark set of lectures by Erwin Schrodinger on a surprising topic for a physicists - What is Life?

One of Schrödinger's key aims was to explain how living things apparently defy the second law of thermodynamics – according to which all order in the universe tends to break down. It was this that led my colleague Professor Brian Cox to use Schrödinger as the starting point of his BBC series Wonders of Life, leading to What is Life? shooting up the Amazon sales chart.

But Schrödinger's book contains something far more important than his attempt to fuse physics and biology. In that lecture 70 years ago, he introduced some of the most important concepts in the history of biology, which continue to frame how we see life.

I'm wondering if many crackpots and creationists got the idea of the evolution of life violating the 2nd law from this lecture. It might easily be the impetus for such misinformation to be passed on.

Anyhow, this is a very good news article to get a brief idea on that monumental lecture in the history of science.

Zz.

Store Photons. Then Make Them Intract With Each Other

It's amazing to see the development in this area. Just a few years ago, we were amazed at the accomplishments coming out of Lene Hau's lab in being able to not only store photons, but also to "replay" them back. Now comes this, which is another step in refining and improving the capability of storing photons.

What Charles Adams and colleagues at Durham University have now done is come up with a way of storing individual optical photons in highly excited states of an atomic gas. Once stored, the photons can be made to interact strongly, before being released again. An important feature of the technique is that it uses microwaves, which are also used to control some types of stationary qubit. 

 http://arxiv.org/pdf/1207.6007v3.pdf

Apparently, this is to be published in PRL.

Definitely a commendable accomplishment here in the evolution of our capability of using photons for quantum communications.

Zz.

The Emergence Of QCD

This is a nice review of how QCD came about and its role in the Standard Model, written by Nobel Laureates David Gross and Franck Wilczek.

Zz.

Steven Chu Resigns

In case you didn't see this already, Steven Chu announced his resignation as the US Energy Secretary.

Chu will enter the record books as the longest-serving Secretary in DOE's 35-year history, and the first Nobel laureate to lead the sprawling, $27 billion department. Once a successor is named, Chu says that he plans to return to California. He spent 17 years on the faculty of Stanford University before moving to the University of California, Berkeley, and was director of DOE's Lawrence Berkeley National Laboratory before coming to Washington in January 2009.

Despite the Solyndra debacle, I thought he did an admirable job considering that he was faced with a hostile congress that was determined to cut funding to the sciences regardless of the harm it will do not only to the advancement of knowledge, but also to the US economy.

It will be interesting to see who President Obama will nominate to replace him. I'm hoping that it will be someone who is a scientist and not a science-challenged bureaucrat (cough bill richardson cough!).

Zz.

A Laser-Based Table-Top Neutron Source? I'll Take One!

Exciting news for those who depend on neutron sources for to study things. A new development in using high-powered laser to produce energetic neutrons with reasonable flux has been reported.

Neutrons are a valuable tool for scientists in many fields, allowing them to probe the structure and dynamics of a range of materials. Today, the main drawback of neutron science is that intense beams of neutrons must be produced in either nuclear reactors or dedicated accelerator facilities – making a laser-based table-top source very attractive.

This scheme has now been put into practice by Markus Roth of the Technische Universität Darmstadt and colleagues at Los Alamos and Sandia National Laboratories. Roth's team directed extremely powerful and well defined pulses from the Los Alamos TRIDENT laser onto a 400-nm-thick plastic target doped with deuterium atoms. This was positioned just 5 mm in front of a secondary target made from beryllium.

Even though the pulses delivered less than a quarter of the energy employed in previous experiments, they produced neutrons that were nearly 10 times as energetic – up to 150 MeV – and also nearly 10 times as numerous. In addition, many of these neutrons were emitted in the forward direction, which the researchers attribute to one specific kind of nuclear reaction, the break-up of deuterons.

This has the potential to either replace, or supplement spallation neutron sources. There's still a lot of work to be done, but it looks like this could make having neutron source for material study as easily has having x-ray sources for such a study. Of course, we haven't considered the safety issues here since neutrons are significantly more dangerous to deal with here.

Zz.

RHIC In Danger Of Being Shut Down

In operation for only about 12 years, the Relativistic Heavy Ion Collider at Brookhaven is in danger of being shut down, due to budget shortall for DOE's Nuclear Physics division.

A panel of scientists has recommended shutting the last U.S. grand atom smasher, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, New York, to make room in a tight budget for other projects funded by the Department of Energy (DOE).

Closing RHIC would be a disaster for the U.S. nuclear physics community, says Robert Tribble, a nuclear physicist at Texas A&M University, College Station, who chaired the committee that suggested doing exactly that in a report today to DOE's Nuclear Science Advisory Committee (NSAC). "I don't think there are winners and losers here," he says. "We're all losers if this comes to pass." NSAC is expected to approve the report tomorrow, and DOE has usually followed such recommendations from its advisory panels. 

While this is a sad news, it is not unexpected, considering what the panel had to deal with, especially when faced with the 2 new construction projects that they had to consider.

The Tribble committee weighed the relative importance of three very different facilities. RHIC uses twin accelerators to smash heavy nuclei together to produce fleeting puffs of a weird type of matter called a quark gluon plasma that filled the newborn universe. In contrast, DOE's other existing major nuclear physics rig, the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson National Accelerator Facility in Newport News, Virginia, fires electrons into protons and neutrons to study their inner workings. In addition, physicists plan to build a $615 million Facility for Rare Isotope Beams (FRIB) at Michigan State University in East Lansing that would generate myriad exotic nuclei usually produced only in supernova explosion.

Researchers are currently finishing a $310 million upgrade to CEBAF, and the committee recommended exploiting that investment, Tribble told NSAC. That forced the group to choose between continuing to run RHIC, which has been collecting data since 2000, and building FRIB, which could start taking data by the end of the decade. The committee included representatives from all three projects, says Tribble, who declined to give the vote tally.

As has been said, we are all losers if this facility shuts down.

Zz.

Quantum Biology

I had mentioned already on the emerging connection between quantum mechanics and some aspects of biological phenomena (see here, here, and here). This BBC science article reviews the current effort to use quantum mechanics to explain some of the biological effects.

The most established of the three is photosynthesis - the staggeringly efficient process by which plants and some bacteria build the molecules they need, using energy from sunlight. It seems to use what is called "superposition" - being seemingly in more than one place at one time.

Watch the process closely enough and it appears there are little packets of energy simultaneously "trying" all of the possible paths to get where they need to go, and then settling on the most efficient.

You may read the other examples that they gave in that article. But what irked me slightly is what was mentioned near the beginning of the article.

Disappearing in one place and reappearing in another. Being in two places at once. Communicating information seemingly faster than the speed of light

This kind of weird behaviour is commonplace in dark, still laboratories studying the branch of physics called quantum mechanics, but what might it have to do with fresh flowers, migrating birds, and the smell of rotten eggs?
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Until recently, the delicate states of matter predicted by quantum mechanics have only been accessed with the most careful experiments: isolated particles at blisteringly low temperatures or pressures approaching that of deep space. 

That is utterly false, because our modern electronics are the proof to counter that. QM isn't restricted to such esoteric conditions. QM is what is responsible for our iPhones, iPads, computers, MRI, electron microscopes, flat-panel TVs, PET scans, etc... etc. Sure, to be able to observe the "weird" behavior of QM, we will have to go to extremely difficult conditions, but the description of QM are directly used for many everyday items and process. After all, this is what the biologist here are trying to do as well, use the description of QM to explain observed, macroscopic biological phenomena.

BBC News science section needs to get rid of this myth quickly. It undermines the usefulness of QM.

Zz.

Update On the Mansuripur "Paradox"

I had mentioned the rebuttals that this "paradox" has been getting ever since it appeared. Science has an updated review on the status of this thing and has essentially declared it solved.

Mansuripur is sticking to his guns. He argues that hidden momentum, which was identified in the 1960s, is an ill-defined concept that merely papers over the problem. "That's always been the problem with hidden momentum," Mansuripur says. "You know that something is missing, so you just postulate its existence." He says his approach eliminates the need for hidden momentum.

Others say that hidden momentum is part and parcel of relativity. "If you have a system with internal motion that is subject to an external force, then hidden momentum is a general property," says Daniel Vanzella, a commenter at the University of São Paulo in São Carlos, Brazil. "It's not an ad hoc invention put in to reconcile things." Vanzella also notes that mathematically, the Lorentz force law can be written in a form that guarantees it will jibe with relativity, so it's "simply impossible" for it to contradict the theory.

There was a question towards the end of this article on whether this should have been published or not. I see no problem in it getting published (although, I don't think it should have been in PRL). Mansuripur clearly found something intriguing that needed to be sorted out. It was not done out of deceit and it was definitely a legitimate question. The rest of the community then responded in kind to correct what they see missing or in error. That's what this whole publication process is supposed to do, and this is how it should work. Publication never guarantees validity.

Zz.

We Don't Need No Stinking Theory Of Everything!

This is a Q&A with Lisa Randall.

The reason why I'm highlighting this is that the questions being asked is the type of questions many of us faced with we talk to the public. The very first question, for example, is rather typical:

Doesn't every physicist dream of one neat theory of everything?

Of course not! But the public has a very narrow idea of what physics is. Many are surprised when I tell them that the largest percentage of physicists in the US are working in the area of condensed matter/material science, which is not the first of study that directly involves the Higgs, high energy physics, string, etc. So for many of us, this "theory of everything" isn't something we dwell on that much, not to mention, there are even prominent physicists who think that this "theory of everything" is a myth.

In any case, this article covers some of the common questions that we often see.

Zz.

Immovable Object vs. Unstoppable Force

As stated in the video, I too have seen such a question being asked on the internet numerous times. And as can be seen in the video also, question like this is often asked without clearly think of what the question actually means. This is important in physics because the question that we ask can sometime be as important as the answer that we get. So having a clearly defined question is crucial.



Zz.

"I Want To Ride My Bicycle, I Want To Ride My Bike...."

Bicycle! Bicycle!

Yes, we are doing bicycle physics! I already mentioned about this quite a while back. But there's new coverage on this not-as-simple-as-you-think phenomenon of riding a bicycle. The new coverage doesn't present anything new, though, but merely reemphasize the fact that 'steering' is an important factor in how one can balance on 2 wheels on a moving bicycle.

Partially through this research, physicists have come up with an explanation for why bicycles don’t tip over: they always turn toward the direction they’re falling. When the bicycle begins to tilt to one side, the front wheel turns in that same direction, which prevents the bike from falling over. This can be verified by locking the handlebars so that the bicycle can’t turn. When you do this and give the bike a push, it topples over.

Now, the reason why the bicycle steers in the direction that it is about to topple over isn't as clear.

That’s where things get really complicated. Rather than a simple explanation, scientists have developed a formula that determines whether or not a bicycle design will have this essential attribute. Insomuch as it has been tested, the formula works. Unfortunately, it’s not a simple two- or three-variable equation: it requires 25 different characteristics of the bicycle to make a prediction.

So do we know how a bicycle works? Technically, yes. We have an equation that can predict whether or not a particular design will be easy to balance. But that doesn’t mean we fully understand what’s going on and the one-sentence explanation of what keeps it upright only leads to more questions that aren’t so easily answered.

So there! Even the everything, common thing that we all are familiar with can still be puzzling.

Zz.

Dance The Higgs

Ah, another one of those!

I made no bones about my feeling on such things. This appears to be another attempt at incorporating physics into the arts. In particular, they're incorporating the apparent discovery of the Higgs into dance and photography.

Our Reintegrate project will translate the details of the Higgs boson discovery into a series of precisely choreographed visual images. By translating potentially the greatest breakthrough in particle physics in the 21st century through the intersecting artistic mediums of photography and dance, we will investigate the problem and benefits of communication across three disciplines that weigh heavily toward the non-verbal articulation of ideas.

 First of all, I don't quite understand exactly what is meant by the phrase that I've bold in that paragraph. Secondly, since we're "talking" about non-verbal articulation of ideas here, I would like to challenge the organizers to try this experiment: DO NOT tell your audience in advance what the dance is about. Don't even give them a title (thus, the non-verbal part). Just present the dance. After the presentation, do a poll and see what they think the dance is about. What are the chances that they actually will say "Oh, it is about the problem and benefits of communication across physics, dance, and photography on the discovery of the Higgs boson"?

Now, you could ask me "But ZapperZ, arts, such as dance, is very subjective and interpretive. You don't expect them to actually come up with not only an accurate answer, but also one consistent answer, do you?" And I would say, that's my whole point! If you want to communicate about the discovery of the Higgs, the importance of the physics of the Higgs, etc., your BEST BET in doing that is to convey an UNAMBIGUOUS message is via direct, verbal communication! It cannot be done effectively and unambiguously via "dance". I just don't see it.

If you want to do this simply for entertainment, fine. Knock yourself out. But I seriously question when this thing is being "intellectualized" as if such an exercise can actually produce anything meaningful, informative, and accurate. This is just too close to being an Emperor's New Clothes to me. A lot of people are going along with the "intent" but there hasn't been a lot of substance.

Zz.

Physics Is Fun?

I've posted something on this topic before, and I'll continue to do it. I always like to highlight classes and/or teachers that go beyond what they have been asked to do and try to make a physics lesson more interesting and more engaging to the students. This is one such example.

Montgomery's physics class is certainly not what one would think of as a traditional classroom.

Yes, there are lectures. Yes, there is homework. But there's also a lot more that this group of seniors gets to experience.

"The fun thing about older kids, they're still kids," she said. "They just want to play."

I also like the observation that she had on her students.

The hands-on activities help students relate to what they are studying. But even that doesn't always make it easy.

"They still struggle. When you go to paper and pencil, it helps that they have that interest. But they have to apply the math," she said. "Physics is hard."

In the past, almost no one took physics at the high school level. Until the State of Ohio stepped in and gave it a boost.

"They made it so you have to have physics to get an honors diploma. Our numbers practically doubled after that," she said. "They might not be excited to take it, but they find something about it that is interesting to them."

Being that the class is generally made up of some of the brightest students in the senior class, Montgomery said the students don't always deal well with struggling to understand the difficult subject matter.

"They still think that because they're good at everything else, they expect to get every question right the first time," she said. "I still have to go back and look at questions more than once sometimes."

As we all had to do if we're in education.

Zz.

So I Am Your Intro Physics Instructor

{I wrote an essay on what I would say to my student if I were his/her academic advisor. Since this is the beginning of the semester for many schools (or the beginning of the school year in parts of the world), I thought it would be appropriate for me to "publish" another "speech". This time, I'm directing it to a class of  intro physics students.}


Dear Students,

Welcome to the intro physics course. For many of you, this is your first college level physics course that you are taking. Hopefully, it will lay the foundation for the rest of your undergraduate education and becomes something that you will find useful.

I would like to let you know of some of my expectations from you, and would like to let you know of what you can expect from me. I know that many of you are taking this course because you have to, not because you want to. I am also aware that the majority of you are not physics majors. However, I hope to impress upon you why you would want to do well in this class. Besides the fact that it will affect your overall GPA, I want to make you aware that there are a lot of things you can learn and acquire from this class that will be very useful to you not only in your academic pursuit, but also in other parts of your life later on.

The most important point I want to make is this: while the material that we will be covering is important for you to understand to do well in this class, what is equally important is the ability in analyzing a problem that you are faced with, and figuring out how to systematically solve it. I want you to pay attention not only to the content of the course, but also to how I approach a problem and how I go about solving it. I will try to teach you the physics and also the problem-solving technique. I will try, as best as I can, describe to you what I'm thinking when I look at a problem, and how I analyze it to know what to start with and how to proceed.

Keep in mind that while this is something that I can attempt to teach you, it really is a skill that you can only acquire after repeated practice. It is very much like learning how to ride a bike. I can tell you what to do, but you'll never gain the skill to ride a bike until you have practiced several times, and taken a tumble here and there. The homework that you will have to do is meant to be your vehicle to practice on to acquire such skill.

At some point, you may question why we are studying certain things, or why we are trying to tackle a certain type of problem. One example that I can bring up is the projectile motion that you will see and have to solve till you're sick of it. You may find it strange that we are asking you to solve various configurations of the projectile motion problem. Are we trying to train you to be an artillery person? No.

You see, I could teach you that F=ma and then walk away. There. We've covered a huge section of our semester already. Now, go use that to build me a house. Chances are, you can't. What you've received is only a superficial knowledge. You may know the relationship between F, m, and a, but you don't understand how it is used or how it can be applied. Knowing how to do that will give you knowledge beyond the superficial level. So we try to apply F=ma in a number of examples. Unfortunately, the examples that we can use that are simple enough are limited. We can't exactly apply all the real-life conditions to an example because it will them make the problem too complex, and you will be thoroughly confused. You will be distracted by the complexity and lose the focus on how F=ma is applied. So we have to deal with simplified examples on how we use F=ma, and this is where examples of projectile motion, motion of objects sliding on inclined planes, etc.. come in. We are not trying to turn in you experts in artillery or building a slide. You should not be focusing on the nature of the example. You should be focusing on the aim of these examples, i.e. how F=ma is applied.

Now, because I want you to understand both the material and the technique, you should not hesitate to ask me questions if you do not understand anything. This is especially true if you do not understand why, in solving a problem, I would do such-and-such, or how I know to start with such-and-such if it is not obvious to you. It is important that you make sure you understand things every step of the way, because we will be building on you learn early in the semester and apply it to more complex situations later on. If you start with a shaky foundation, you will not be able to master the material that you will be faced with later in the semester. So please, ask me questions in class, or come to my office hours. I have been paid to serve you and impart knowledge and skills. Make use of this opportunity.

My last advice to you here is that the process of learning is a very private, internal activity. While you have your texts, your notes, your instructor, etc. to help you, in the end, it is YOU who have to make the effort to acquire such knowledge and skills. It must sink in for you. At some point, you have to figure things out for yourself. It means that you need to understand things on your own, and be able to do your own thinking. You have to figure our how you understand things and what you need to do to get something.

And this is where this physics course can be of a tremendous value to you, not just for your future academic pursuit, but in your later life. To put it bluntly, you will consciously learn how to think and how to analyze a problem. You will learn to what degree you can say that A causes B, and how can you figure out what affects what. This ability transcends a physics class and will be extremely useful to you as you become a responsible citizen.

I hope you have a productive and enjoyable time in this class. Now let's get to work.

Zz.