So Light Is A Particle In This Demo?

I love these videos coming out of JLab's Forstbite theater. They're hilarious and usually quite educational as well.

However, this time I think the "evidence" that they are using to show that light is a particle isn't that obvious.



Certainly their conclusion is correct that (i) no matter how bright (intense) the red laser is, it cannot activate the fluorescence and (ii) the green laser has a higher energy and thus, can cause the fluorescence, no matter how weak the intensity. However, all this does is show that the intensity does not correlate to the energy.

Now, if one understands the photoelectric effect picture and the Einstein's model, then one can see that this is ONE aspect of that model, which points to the photon picture. But this is just ONE aspect of the model. By itself, it isn't obvious from this experiment that light is a particle.

I think experiments such as the which-way experiment are the ones that would have a more solid claim of showing that light is a particle.

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The Case Against Cold Fusion

If there ever is a blog article that has compiled an amazing history of Cold Fusion, this one could be it. Jennifer Ouellette at Cocktail Physics has updated an article on this topic due to a new film called "The Believers". This article is full of other links and references that you might also want to read, and it also includes description and comments on the effort to separate "cold fusion" from low-energy nuclear reaction (LENR).

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E=mc^2 Is Incomplete

I wonder if people who do not study physics actually realize that the actual equation has another term in it?



I lost count how many times someone has told me that since E=mc^2, and photon has energy, then it MUST have mass!

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The Beginning and End of the Universe

If you have 1 hr and 10 minutes to spare, you might want to watch/listen to this video (you can play it in the background - there's not that much to see). Especially if you are a layman and want to know what physics says about the topic, this video will be of interest to you.



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Single-Pixel Digital Ghost Holography

Hey, just in time for the Halloween season, we see this paper being published in PRA.

Holographic imaging is typically done by splitting a laser beam in two, shining one beam on an object and then letting that modified light interfere with a reference beam that does not hit the object. The recorded interference pattern can be read out with another laser to form a three-dimensional real image. By using multipixel electronic cameras rather than photographic film, researchers can computationally analyze and process the data for better effect. Clemente et al. modify this setup for ghost imaging by replacing the camera with a single-pixel detector (as conventionally used in ghost imaging) by using a randomly structured optical beam and scanning for a set of discrete phase shifts in the reference beam (that is, the beam not directly influenced by the object).

Just don't do this while wearing you ghoulish costumes.

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More Evidence of No Hidden Variables

The idea of quantum and contextuality is being tested in this latest report.[1]

The experimental setup and techniques are simple, elegant, and quite well controlled. The research group had little room for error, since the discrepancy between the classical bound (or inequality) imposed by the Yu-Oh formulation of SIC and the value predicted by quantum mechanics is tiny (only about 4%). Despite unavoidable experimental uncertainties, the measurements by Zu et al. violated the classical bound (thus ruling out noncontextuality) by about 5 standard deviations, irrespective of the prepared system’s state. This statistically significant result sets a very good benchmark for experimental SIC with a single quantum system.

Of course, if you read further, it doesn't rule out all of the classical noncontextuality due to the nagging problem with many photon systems - the detection loophole. Still, if you go by the body of evidence, the QM scenario has shown perfect agreement with experiments so far.

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[1] C. Zu, Y-X. et al., Phys. Rev. Lett. 109, 150401 (2012).

Using Muons From Cosmic Rays To Peek Into Fukushima?

What a clever idea!

A PRL paper published last week[1] had an interesting proposal. Use muons generated in the upper atmosphere due to cosmic ray collisions to peek into the Fukushima reactors.

To radiograph inaccessible parts of Fukushima reactors, Borozdin et al. propose a similar approach based on muon detectors placed right outside the reactor building. The authors compared two imaging methods: attenuation radiography, which measures how muons are absorbed inside the reactor, and scattering radiography, which monitors how their path is deviated. They show that scattering radiography would deliver more reliable images of the nuclear core after only a few weeks of measurement, allowing the visualization of melted fuel as well as debris.

That report has a link to the PRL paper that you can get under the Creative Commons license.

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[1]K. Borozdin et al.,Phys. Rev. Lett. 109, 152501 (2012).

Is This What It Looks Like To "Learn" Quantum Physics?

When I first saw this piece, I didn't want to comment on this because, frankly, it's one of the most ridiculous, irrelevant, and inaccurate report that I've ever seen. But I couldn't help myself. So here it is.

This Gizmodo article highlights some "art", or photography snapshot of blackboards that supposedly show how it looks like when one "learns" quantum physics. The photos show various shots of messy, jumbled up scribbles all over the place. There was no explanation anywhere on where exactly these were taken, or under what circumstances (was it after a class, was it after two people discussing something, was it in someone's office?).

I will tell you why I consider this to be utterly ridiculous and irrelevant:

1. Everyone who does physics knows that we tend to have either blackboards or whiteboards in our offices. I have one. It is used quite a lot. In fact, we have white boards along the hallways of our offices. Frequently, when we talk and discuss things, we go to one of such boards to either illustrate our ideas, or work something out. Inevitably, after this is done many, many times, the board looks very much like the mess you see in those photos. It has nothing to do with learning quantum physics. It has everything to do with performing one's job. This is not philosophy where esoteric ideas are thrown out verbally. Physics (and sciences in general), mathematics, and engineering all require visual illustrations and descriptions. Any kind of discussion inevitably will require writing down something, be it a piece of paper, a board, or a cocktail napkin!

2. The point where these scribbles are indecipherable seems to imply that this is unique to physics, or to learning quantum physics. Nonsense! Put a bunch of musical notes on the board. I'm musically illiterate, and they might as well be a bunch of gooblygook. So why would a bunch of mathematical symbols be any different? This is not unique to physics. Look at something that you are not an expert in, and you should EXPECT to see a bunch of things that you don't understand. Is this that difficult to comprehend?

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Does The US Really Not Have Enough Skilled Workers?

This is a topic that is related to something that was talked about in the last presidential debate between Barack Obama and Mitt Romney. The moderator asked whether jobs in assembling electronics such as iPhone, iPad, etc. can be brought back to the US. You may read the responses on your own from that news link.

However, later on in the news article, this issue came up about the lack of industrial engineers in the US as one reason Steve Jobs gave for being unable to have such manufacturing jobs in the US.

There's another catch, and it's one that politicians don't like to talk about: China has many more skilled engineers than the United States does.

Steve Jobs, Apple's late CEO, brought the issue up during an October 2010 meeting with President Obama. He called America's lackluster education system an obstacle for Apple, which needed 30,000 industrial engineers to support its on-site factory workers.

"You can't find that many in America to hire," Jobs told the president, according to his biographer, Walter Isaacson. "If you could educate these engineers, we could move more manufacturing plants here."

Now this is interesting in the sense of timing, because last week, Science journal website published an interesting review of a book at attacks such a point of view and put the blame squarely on the industries that complained on such lack of expertise. The book is titled: "Why Good People Can't Get Jobs: The Skills Gap and What Companies Can Do About It." It was written by Peter Cappelli, a professor of management and director of the Wharton School’s Center for Human Resources at the University of Pennsylvania.

That's because the book resolves the vexing conundrum of how two conflicting narratives about high-skilled employment have coexisted in our national conversation. On the one hand, countless unemployed or underemployed workers with perfectly good skills, education, and experience are struggling through a severe job drought, many sending out hundreds of applications and resumes to no avail. On the other hand, employers (especially in technical fields) complain of great difficulty finding workers, citing serious gaps between the requirements of available jobs and the skills of the workforce. One company that Cappelli mentions didn’t find a single worker that it considered qualified among 25,000 applicants for a fairly ordinary engineering job. Employers and their organizations fault an inadequate school system that fails to prepare Americans and restrictive immigration laws that prevent employers from importing the skilled workers they need from abroad.

He wrote in particular about companies getting "lazy" in trying to not only hire someone with a potential to do an amazing job, but also the lack of patience in recruiting someone and providing adequate training.

The main reason that companies aren’t finding the workers they seek in an ocean of available ability, Cappelli believes, is that in recent decades, for reasons he explains, those companies have allowed their traditional human resources (HR) departments and training programs to atrophy. Another reason is that some complaining companies simply offer too little money to attract the people they want.

The current lack of adequately staffed HR departments, and companies’ refusal to teach workers on the job, have combined to produce what the book terms “a Home Depot view of the hiring process, in which filling a job vacancy is seen as akin to replacing a part in a washing machine. … Like a replacement part, job requirements have very precise specifications. Job candidates must fit them perfectly or the job won’t be filled.”

There's more, so you should either read the entire article, or get the book (which I intend to do). Now, wouldn't it be more interesting if reporters (or debate moderators) actually do their homework and read about these things way ahead of time before they ask politicians and CEOs such questions? I would love to hear these CEOs try to respond to what has been brought up in this book.

Interestingly enough, what industries seem to tend not want to do, those in Academia continue to practice such things. We seldom get postdocs who are completely compatible with the skills that we are looking for. So it is a given that we try to nurture and train them with new skills, so much so they become experts in those areas by the time they are done. This is one clear example on why certain organizations should  not be run like a business!

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Angry Birds Bumps With CERN

So I don't have any clue on what would be the outcome of such a "marriage". Still, it appears that Rovio, the makers of the wildly-popular Angry Birds (and Angry Pigs) games are teaming up with CERN to come up with some educational games.

Rovio told TechCrunch the collaboration will involve co-producing learning support materials with CERN — including, initially, books and a board game. More products will be added later, the company said. We’ve also reached out to CERN to ask for more details and will update with any response.

“Modern physics has been around for 100 years, but it’s still a mystery to many people. Working together with Rovio, we can teach kids quantum physics by making it fun and easy to understand,” said CERN’s Head of Education, Rolf Landua, speaking at the Frankfurt Book Fair where the Rovio launch took place.

 Er... ok. I am certainly curious to see what they come up with. Angry photons smashing into fat, lazy quarks?

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The Origin Of Quantum Physics

Another educational and entertaining video. This time, on the origin of quantum physics.



And to think that it all started by a light bulb!

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Felix Baumgartner's Supersonic Speed

Not that this is a puzzle, but here's a simple explanation on how Felix Baumgartner's achived a supersonic speed during his free fall.

I still think this is a crazy thing to do. Fascinating, sure, but still, CRAZY! :)

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No Supersolid In New Experiment

OK, there are two separate issues here.

First, a new experiment, done by the person responsible for the first announcement of the possible discovery of supersolid, has now shown no evidence for that.

Many other theoretical and experimental results finally convinced Chan to redo the experiments. With postdoctoral researcher Duk Kim, he completely redesigned the torsional oscillator, taking every precaution to eliminate space for elastic helium. This time, the changes in oscillation previously attributed to a supersolid state were completely absent.

Chan realizes that this almost closes the book on supersolid helium. ”I’m in an awkward position, since we started the whole damn thing,” says Chan. “But I’m glad we were the ones who found the explanation.” Beamish agrees that these are extremely subtle effects, which is why it took so long to sort them out: “I give Moses the greatest credit for all the years he spent trying to find out what it was, rather than trying to prove it was what he said it was.” He also notes that the hunt for supersolids actually seeded new research on what has become known as quantum plasticity—the tendency of a material to deform macroscopically based on its quantum properties.

Which brings me to my second issue here of the utmost respect we all should have to Moses Chan for illustrating what a true scientist should do when faced with a contradicting evidence. Here is a person who received quite a coverage and reception when the first supersolid discovery was announced. Yet, he continues to investigate the effects in light of the responses he got, and now, after redoing the experiment and found that his original conclusion was wrong, he went ahead and published it! (Taleyarkhan, are you paying attention to all this?)

Have any religious leaders nowadays done such a thing? And yet, there are still people out there who insist that science is a religion?

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Wineland and Haroche's PRL Papers

On the heels of AIP's free listing of the papers by this year's Physics Nobel Prize winners, the APS is making available for free the papers by these two authors that were published in PRL.

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Physics That You Already Know

Another good video.



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AIP Papers By This Year's Nobel Prize Winners

The AIP has generously provided a list of papers from their journals that were authored/coauthor end by this year' physics Nobel prize winners. I think you get all, if not most, of the papers for free.

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2012 Physics Nobel Prizes

This one certainly came out of nowhere.

The 2012 Nobel Prize for Physics has been awarded to Serge Haroche and David Wineland.

The Nobel citation said the award was for "ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems".

... which is rather vague!

The Nobel website does have a more in-depth description of it for the laymen.

Still waiting for a woman to win the Physics Nobel Prize in my lifetime.

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Work Function And Photoemission Threshold

It is no secret to anyone who has read this blog for a while that I do not like Wikipedia. I think that there's a fundamental flaw with the whole concept and philosophy of it. While I think that it may be useful to many who need a quick lookup for something, it is unfortunate that even more are using it almost as their primary source of information. And this is scary considering that (i) the validity of the information being presented is never guaranteed and (ii) the pedagogical presentation of the material is often shoddy, making the subject even more confusing.

I often get asked to look at such-and-such Wikipedia entry, or someone is trying to convince me of something and using a Wikipedia entry as a "reference" to back up his/her argument. It is usually during such instances that I find inaccuracies, confusing statements, and something outright errors in such entries. I was doing my own search on something a few minutes ago, and I decided, out of curiosity, to see what Wikipedia has to say about "Work Function". Now, keep in mind that this is a common terminology, especially for physics students, since the photoelectric effect is a "must-know" topic for these students. One would think that this should be a topic that a Wikipedia entry would get it right, considering how many people would look up such a thing, AND, the fact that errors and inaccuracy would, by now, be ironed out.

WRONG!

This is what I saw on the Wikipedia page TODAY.

I posted today's date in the screen capture as a date stamp on when this was viewed.

The offending passage has been highlighted with a red box. Let's look at it closely, shall we?

The description here is on what happened for an insulator (or a semiconductor, for that matter). The figure shown is the simplified band diagram for such a system (i.e. an intrinsic semiconductor, for example), and defines the various quantities such as the work function, band gap, electron affinity, etc. The problematic statement says this:

For an insulator, the Fermi level lies within the band gap, indicating an empty conduction band; in this case, the minimum energy to remove an electron is about the sum of half the band gap and the electron affinity.

 The first part of that paragraph which says ".... For an insulator, the Fermi level lies within the band gap, indicating an empty conduction band ..." is OK. However, the second part is very puzzling and an outright error : "... in this case, the minimum energy to remove an electron is about the sum of half the band gap and the electron affinity ..."

Whoever wrote this is STILL thinking that the work function (Phi) is still the minimum energy needed to produce photoemission, as in the case of a metal. This is FALSE, and anyone who looks at the band diagram can tell. Half of the band gap plus the electron affinity is the work function Phi, but this is the energy between the vacuum level and the Fermi level. The Fermi level for insulator/semiconductor has NO STATES, and thus, no electrons to excite! After all, it resides in the band gap! So what is being excited here?

For an insulator/semiconductor, while the work function may still be defined as the energy between the Fermi level and the vacuum level, it no longer corresponds to the photoemission threshold! The photoemission threshold now is the full band gap energy PLUS the electron affinity. You need to excite, at the minimum, the electrons from the top of the valence band to the vacuum level. One can see this clearly by looking at the band diagram in the figure.

I hope no one was using on this Wikipedia entry for something useful or important.

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Real World Telekinesis

Despite the title, there's nothing "supernatural" about this video, and it might be useful for someone who just want some simple intro to electromagnetic field.



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"It Is Not Acceptable To Promote Bad Science"

This is a wonderful video of Brian Cox that you should sit down and spend some time watching and listening.



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From A Gymnast To A Physicist

Can't make it as a work class gymnast due to health issues? Why, study to be a physicist instead!



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The Standard Model

Here's an informative video for the general public on the Standard Model of elementary particle.



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First Images Of Landau Levels

Ok, I didn't realize that we haven't had a measurement of such landau levels till now. It appears that this has finally been imaged.

Using scanning tunnelling spectroscopy - a spatially resolved probe that interacts directly with the electrons - scientists at institutions including the University of Warwick and Tohoku University have revealed the internal ring-like structure of these Landau Levels at the surface of a semiconductor.

What is also interesting that this could tie in to the standard definition of a kilogram.

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