Thursday, October 31, 2013

Yes, We Have No WIMPS, So Far

I guess the big news of the week is the result out of LUX that they found no signature of dark matter candidate called WIMPS that was reported elsewhere earlier. The news was important enough that there was even a news piece on the CNN website.

After analysing three months of data taken by LUX, physicists found no evidence for dark-matter collisions. However, because the experiment is the most sensitive yet to a range of WIMP masses, LUX has provided important new information about what dark matter is not. In particular, LUX is more than 20 times more sensitive than previous experiments when it comes to detecting low-mass WIMPs – those with masses of about 5–10 GeV/c2

Dark matter remains elusive, at least on earth and for this type. However, up in space, the Alpha Magnetic Spectrometer has a different story, obviously. We still need a better understanding of those excess positron.


Monday, October 28, 2013

Interview With John Pendry

You heard all about those metamaterials, recent news on cloaking, and left-handed materials? Well John Pendry has a major influence on the advancement of this area.

This video is an interview about his life and his science.


Sunday, October 27, 2013

What's In A Name?

I've dealt with many non-scientists who put too much emphasis on the names or labels given in  science, and especially physics. Because they do not understand the physics attached to these names, they put all their understanding based on what the name seems to imply. Examples are the over-emphasis on the name "theory" and "law" and "model", etc.

With the Higgs, a lot of people, especially crackpots, pseudoscientists, and downright misguided people seem to have jumped on the moniker given to the Higgs by Leon Lederman, which was the "god particle". People seem to think that this particle has a more important significance or that it carries religious meanings. All this with many of these people not even having the capability to understand the physics associated with the Higgs.

This is a rather amusing article on how some of the names given in physics have a rather mundane, and utterly boring origin, devoid of any deeper significance. For example, on how the Higgs particle got its name:

There are two-and-a-half theories to explain why Higgs' name won the title, Carroll said. One is that the works of Higgs, et al., were cited in a study by Steven Weinberg in 1967, but Higgs was listed first, unintentionally leading later researchers to cite his work ahead of the others. The second is that physicist Benjamin Lee, who wrote and spoke about the theory and is credited with popularizing it, read Higgs' paper first, and began using the shorthand "Higgs" to describe it, Carroll said. And finally, he said, "Higgs boson" just sounds better than "Brout boson."

"Once it was there, there was never a strong attempt to change it," Carroll said. "And it's just a name."

This is not unusual. Often, another researcher citing another paper would tend to either give it a name, or a short abbreviation, rather than citing the full thing over and over again. In publications such as Phys. Rev. Lett., where there is a page limit, you don't want to type down the full thing. So you either give it a short name, or abbreviation (example: BCS theory). That's how many of the names and labels orginated.

Moral of the story: stop paying too much attention to the names and labels. Understand the underlying physics. That is more important.


Friday, October 25, 2013

Leviton Says "Hello World!"

Say hello the the leviton, everyone!

A new type of quasiparticle – dubbed the "leviton" – has been seen by physicists in France and Switzerland. First predicted in 1996 by a team led by Leonid Levitov, the phenomenon involves the excitation of as few as one electron to create a wave that propagates coherently through a metal. The ability to make levitons on demand could lead to the creation of quantum-electronics circuits that involve sending single electrons through tiny circuits. 

I tell ya, the 2D electron gas universe is just so rich, we will discover a whole lot more. We already have seen fractional quantum hall effect in such a system, and it may even exhibit signs of Luttinger liquid properties. So I will not be surprised if there are more to come.


The Physics of Whistling Tea Kettle

I kid you not.

I would think that, considering that this is quite common already, people would have known the intricate physics of the whistling kettle. Turns out, I was wrong!

Cambridge University researchers recently published a paper in the journal The Physics of Fluids, describing what’s considered the first accurate model for kettle whistling dynamics.

Think this is trivial research? It actually has more far reaching implications. According to the press release, these dynamics could be used to stop pipes in household plumbing from squealing or car exhausts from sounding, well, exhausted.
There you have it!


Wednesday, October 23, 2013

MOOC On "The Discovery Of The Higgs Boson"

The registration is now open for the massive online open course (MOOC) on "The Discovery of the Higgs Boson".

This MOOC introduces the theoretic tools needed to appreciate the discovery, and presents the elementary particles at the tiniest scales ever explored. Beginning with basic concepts in classical mechanics, the story unfolds through relativity and quantum mechanics, describing forces, matter and the unification of theories with an understanding driven by the tools of mathematics.

Narrating the journey through experimental results which led to the discovery in 2012, the course invites you to learn from a team of world-class physicists at Edinburgh University. Learners participate in discussion of the consequences of the Higgs boson, to physics and cosmology, and towards a stronger understanding and new description of the universe.

Note the knowledge requirement to enroll for this course:

The course requires a basic level of mathematical skills, at the level of a final-year school pupil. A basic knowledge of physics is helpful, but not required.

So there ya go! If you are a non-physicist, and you are serious about learning about the Higgs and also a bit about elementary particle physics and the Standard Model, this is your chance! There are people trying to make it accessible for you to understand these things.


Saturday, October 19, 2013

Magnetic Levitation

You learn about magnetic levitation, and a little bit about magnetism, in this video.


Is There A Link Between Intelligence And Entropy?

It's an interesting question, and there are certainly models that point to such a link. The latest one is a very clear example the strong possibility that intelligence can be linked to entropy.

Entropy measures the number of internal arrangements of a system that result in the same outward appearance. Entropy rises because, for statistical reasons, a system evolves toward states that have many internal arrangements. A variety of previous research has provided “lots of hints that there’s some sort of association between intelligence and entropy maximization,” says Alex Wissner-Gross of Harvard University and the Massachusetts Institute of Technology (MIT). On the grandest scale, for example, theorists have argued that choosing possible universes that create the most entropy favors cosmological models that allow the emergence of intelligent observers.
This, I think, would give some degree of a quantitative description of intelligence, a characteristics that so far defy such a clear description. And yes, I'm discounting the silly IQ test as a measure of intelligence. Linking it to a concept in physics allows for a more definite foundation to define and measure intelligence.

Will be fascinating to see how far this will lead.


Friday, October 18, 2013

You Can't Escape The Heisenberg Uncertainty Limit

A rather interesting treatment of redefining the Heisenberg uncertainty principle, in light of recent advancement in the so-called weak-measurement experiments.

The popular conception of the Heisenberg uncertainty principle is that measurement is unavoidably invasive. We disturb an object when we observe it, thus introducing error into subsequent measurements. However, recent experiments (see 6 September 2012 Synopsis) claim to have measurement errors below the Heisenberg limit. To address this apparent contradiction, a paper in Physical Review Letters reports a new formulation of the uncertainty principle in which measurement disturbance depends on the performance of the measuring device, which is quantified as the maximum possible change in the state of the object.
Paul Busch of the University of York in the UK and his colleagues believe there is no contradiction here, but only a misunderstanding over how to characterize the effects of measurement. Previously, measurement-induced errors have been calculated on a state-by-state basis, by comparing the state of a system “before” and “after” a measurement. But Busch et al. show that defining measurement error in a state-independent way, through a kind of calibration process of the measuring device, leads to limits in line with the uncertainty principle.
 I expect more of something like this to occur as we probe the more minute detail of QM.


Thursday, October 17, 2013

Science In The Classroom

This is a new project by Science Magazine, with funding from the US National Science Foundation. Called Science in the Classroom (SitC), this is an educational material aimed at pre-college, university students, and the public in general to read a scientific research paper (at least one) by the time he/she completes school. Or in the case of the general public, being able to at least read one scientific paper and understand how scientists work.

The initial offering so far covers topics in Chemistry, Biology, and Physics, and it is expected the amount of papers being offered will expand.


Wednesday, October 16, 2013

Light Ties The Knot

An amazing theoretical advancement on a very old and well-established set of equations.

Physicists have found a very interesting solution to the well-known Maxwell Equations, one in which can form light into interesting geometries and knots.

In the late 1980s, a researcher discovered exact solutions of Maxwell’s equations in free space (containing no electric charge) with the odd property that every field line formed a closed loop, and each loop was linked to another. This structure is called a Hopf fibration, which has been found in other places such as liquid-crystal physics (see 3 June 2013 Viewpoint). Kedia et al. now go a step further with their discovery of exact solutions that are both linked and knotted: the field lines are tied around each other inside a torus.

More coverage and explanation on Physics World.

Identified by Hridesh Kedia at the University of Chicago, along with colleagues at the Polish Academy of Sciences in Warsaw and the Spanish National Research Council in Madrid, the new family of solutions to Maxwell's equations have field lines describing all "torus knots" and "links". Torus knots are those knots that can lie on the surface of a torus, whereas a link is a collection of such knots.

One solution involves magnetic-field lines that trace out a familiar "trefoil" knot around a torus that is aligned in the plane perpendicular to the direction of propagation of the light (see figure). As the light propagates, the knot is distorted but retains the topological property of being a trefoil knot. The electric-field lines have the same structure as the magnetic-field lines but are rotated about the propagation axis by an angle that depends upon the knot. Other solutions include cinquefoil knots and linked rings. 

Still plenty of surprises and interesting solutions out of the old equations!


Tuesday, October 15, 2013

Paper Isn't Dead Yet

.. and no, I'm not referring to this hilarious video either! :)

Anyone who has followed this blog would have known that I'm all for new technology if it actually has a beneficial effect on what we do. I mentioned a while back of trying to use tablets instead of papers in an undergraduate intro physics labs. I think this is possible, and certainly something we should expose the students to, considering that by the time they enter the job market, these technologies will be ubiquitous in their will place.

However, I find that, in some cases, I still prefer the old-fashion paper. This has nothing to do with being stubborn and wanting to do it in ways that I'm familiar with. Rather, it has more to do with convenience. The one area that I still prefer to have a printed copy in my hands is when I referee/review a manuscript.

What I like the most about having a paper copy is that I can more easily write comments on the paper itself. This is actually not that convenient to do on a tablet. While there are apps that allow you to write on PDF documents on a tablet, I still do not find a standard tablet large enough to accommodate a substantial amount of comments/annotations/etc. Besides, the typical stylus that one use with a tablet are not as responsive as a pen-on-paper combination.

The other aspect of paper-refereeing where paper trumps over electronic version is when I have to keep on referring to figures or tables. Let me explain. A typical manuscript that I often get to be reviewed are often typed double-spaced, and the figures, tables, and captions are grouped at the end of the manuscripts. They are not imbedded within the text. This is because the typesetting will be done by the editors after the manuscript has been accepted for publication. So what usually happens is that when I read a reference to a figure or a table in the text, I often have to go back and forth looking at the figure and reading the relevant text referring to that figure. It is tedious to do electronically. One can lessen the effort on an actual computer where one opens more than one window to display the same manuscript, so that in one window, one has the text, and the other window one can display the relevant figure. So in this case, one only need to switch between windows. But try to do this on a tablet! Oy vey!

What I often do is to print a copy of the manuscript to use to read the text, but also display the manuscript on my iPad by showing the figures. This way, I can read the text, and look at the relevant figures on the tablet. I find that to be the most convenient. Still, the hard-copy print makes it a convenience.

Do you still use paper copies? In what way?


Monday, October 14, 2013

The First Physics MOOC From MITx

This is a rather interesting article for anyone interested in online physics courses. It is a report on MIT's first Massive Online Open Course.

Abstract: Massive Open Online Courses are an exciting new avenue for instruction and research, yet they are full of unknowns. In the Spring of 2013, MITx released its first introductory physics MOOC through the edX platform, generating a total enrollment of 43,000 students from around the world. We describe the population of participants in terms of their age, gender, level of education, and country of origin, highlighting both the diversity of 8.02x enrollees as well as gender gap and retention. Using three midterm exams and the final as waypoints, we highlight performance by different demographic subpopulations and their retention rates. Our work is generally aimed at making a bridge between available MOOC data and topics associated with the Physics Education Research community.

I am still not sure how effective such a course is when compared to the traditional method of brick-and-mortar classrooms. Certainly, modern advancement inevitably will expand the way we all attend classes beyond the common practice. Still, based on the conclusion derived from this study, such a course may still not be suitable for first-time learner.

Our analysis of retention points toward the possible outcome of 8.02x being better suited for advanced degree holders versus college undergraduates. Some MOOCs have realized the importance of designing courses for population with education beyond a bachelor degree (e.g. a MOOC targeting high school physics teachers


The Higgs Bosuns?

One sometimes wonder if news outlets have done away completely with copy editors, who should catch obvious mistakes and typos such as this.

This morning, while browsing through the news, I stumbled upon the Economist page reporting the Nobel Prizes, and had a chuckle with the title line read "Higgs's Bosuns". Maybe this is on purpose, I don't know, because the rest of the article had the correct spelling. Still, there's nothing in the article to imply anything about Higgs's "bosuns".


Tuesday, October 08, 2013

2013 Physics Nobel Prize

So it is not a surprise at all that this year's Nobel Prize in Physics goes to two theorists who were the prominent figures in the development of the Higgs mechanism.

The 2013 Physics Nobel Prize has been awarded to two physicists who were instrumental in developing the theory that helps explain the origin of mass of elementary particles and predicts the existence of the Higgs Boson discovered last year. The prize, which recognizes the contributions of Fran├žois Englert (Universite Libre de Bruxelles) and Peter Higgs (University of Edinburgh) for the theory of broken symmetry in electroweak physics, echoes the announcement of the 2010 American Physical Society’s J. J. Sakurai prize, which was awarded to the two Nobel Laureates as well as four additional physicists who made comparable contributions to the symmetry breaking work.

The link above also gives you access to free copies of the two relevant papers.

I think that the Nobel committee might be reserving another round to award the Nobel Prize for the experimental discovery.


Thursday, October 03, 2013

Accelerating Charge Particles Using Visible Light

This accelerating scheme should see a large interest after this proof-of-principle demonstration. Two separate papers are showing the feasibility of accelerating electrons using the E-field from visible light, as opposed to the RF fields used in a typical accelerating structures.

Two teams now report rapid acceleration of electrons using small silica structures to shape light fields into patterns similar to those in a linear accelerator. In both of the experiments, the researchers sent electrons skating just over a silica surface that contained narrow grooves in the direction perpendicular to the electron beam. They then shined ultrashort laser pulses directly onto the surface (called a grating), which generated a pattern where the electric field was alternately enhanced and diminished in neighboring “zones” just above the surface. This pattern of fields reversed direction twice during every oscillation cycle of the laser light and could accelerate electrons (see YouTube video).

Here's the YouTube video:

Of course, with any initial advancement, there's still plenty of work to do. For many applications, getting to higher energy alone isn't the only issue. In FEL's, for example, the emittance of the beam is equally crucial. So accelerating scheme such as this must show the ability to not cause an emittance blow-up. The other issue that is often critical is the question on how much charge per bunch that can be accelerated. For many applications, the standard "high-brightness" beam requires a 1 nC per bunch charge. So the scheme must be able to handle beams of that magnitude without sacrificing the quality.

Still, this promises to be another exciting avenue for future accelerators.


Tuesday, October 01, 2013

US Particle Physics Community Plans For The Future

As the US govt. starts its shutdown due to the US Congress's lack of ability to do the work they were elected to do (how come we don't dock their pay when they can't come up with a budget on time?), we have a report on the last "Snomass on the Mississippi" workshop by US Particle Physicists in prioritizing the different projects that US particle physicists should be involved in. It is a rather challenging task considering the severe budget cuts and constraints being put on science funding in the US as a whole, and on high energy physics in particular.

As stated at the end of the article, the US has lost its "leader" status in high energy physics. That's gone, and if the ILC is built in Japan, and funding continues to be dismal due to the political bickering by the dimwit politicians, then I don't see it coming back. I do not see the LBNE, even if it is built to its original specifications, getting the same global interest and status as the LHC and the ILC, certainly not in the public's eye.