Thursday, March 30, 2017

RIP Alexei Abrikosov

A Nobel Laureate and a giant in the field of theoretical condensed matter physics, Alexei Abrikosov passed away yesterday at the age of 88.

If you have been lucky enough to have met him, you'll see that this was a very gentle man who loved to sit down and chat with you about anything and everything. Once he has met you or have seen you, he never failed to acknowledge you or say hi even if he barely remembered who you are.


Wednesday, March 29, 2017

Oh, The Hypocrisy!

I just came across a bill in the US House of Representative which asked "Do EPA Regulations and Assessments Need to be Based Only on Science That's Publicly Available?" This was introduced by Rep. Lamar Smith who isn't really someone who can't be proud of his anti-science stance in many instances.

The bill passed the House with 228 Yea and 194 Nay.

On the surface, it appears to be something sound. After all, why wouldn't you base something like this on valid science?

But it turns out that it is not that simple. The EPA cannot prevent the introduction of something without any data that are available publicly that it isn't safe.

However, what is very laughable is that this very same people who voted for this bill somehow switch the rules and are the same ones who will dismiss the issue of global warming and the human cause of it, DESPITE all the available data and peer-reviewed science. So why do they accept scientific data in one, but not the other?

Thus, the hypocrisy.


Saturday, March 25, 2017

Experimental Evidence of Indefinite Causal Order

So not only do we have a superposition of observables, we also have a superposition of causality, in which the order of events happening is also in a quantum superposition.

This evidence has been experimentally observed in a new paper published in Science Advances this past week[1]. See the press release here.

What they appear to have developed is this more robust "causal witness" that allows them to sample the superposition without destroying the coherence of the system.

Now, despite the headlines of the press release and the so-called implications, this isn't a result that destroys causality. What I seem to gather here is that, in the case where there is an uncertainty on which event occurs first, i.e. the causal order itself is in a superposition, then it is only upon a measurement will we get to know which comes first, the chicken or the egg. After that, things follows as usual. This experiment shows evidence that, yes, chicken followed by egg, and egg followed by chicken, are both there before a measurement.


[1] G. Rubino et al., Sci. Adv., 3, e1602589 (2017).

Saturday, March 18, 2017

Minutephysics's "How To Teleport Schrodinger's Cat"

It used to be that Minute Physics videos are roughly.... a minute long. But that is no longer true. Here, he tackles quantum entanglement via trying an illustration of teleporting the infamous Schrodinger's Cat.

I'm sorry, but how many of you managed to follow this?

I think I'll stick to my "Quantum Entanglement for Dummies". :)


Thursday, March 16, 2017

DOE's Office Of Science Faces Disastrous Cuts

The first Trump budget proposal presents a major disaster for scientific funding and especially to DOE Office of Science budget.

President Donald Trump's first budget request to Congress, to be released at 7 a.m. Thursday, will call for cutting the 2018 budget of the National Institutes of Health (NIH) by $6 billion, or nearly 20%, according to sources familiar with the proposal. The Department of Energy's (DOE's) Office of Science would lose $900 million, or nearly 20% of its $5 billion budget. The proposal also calls for deep cuts to the research programs at the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA), and a 5% cut to NASA's earth science budget. And it would eliminate DOE's roughly $300 million Advanced Research Projects Agency-Energy.

I don't know in what sense this will make America "great again". It is certainly not in science, that's for sure.


Born Rule Confirmed To An Even Tighter Bound

I must say that I might have missed this paper if Chad Orzel didn't mention it in his article. Here, he highlighted a paper by Kauten et al. from New Journal of Physics (open access) that performed 5-slit interference test with the purpose of detecting any higher-order interference beyond that predicted by the Born rule. They found none, and imposed a tighter bound on any higher-order effects.

As Orzel reported:

That's what the NJP paper linked above is about. One of the ways you might get the Born rule from some deeper principle would be to have it be merely an approximation to some more fundamental structure. That, in turn, might very well involve a procedure other than "squaring" the wavefunction to get the probability of various measurement outcomes. In which case, you would expect to see some higher-order contributions to the probability-- the wavefunction cubed, say, or to the fourth power.
Sadly, for fans of variant models of quantum probability, what they actually do is the latter. They don't see any deviation from the ordinary Born rule, and can say with confidence that all the higher-order contributions are zero, to something like a hundredth of a percent.

Of course, this won't stop the continuation of the search, because that is what we do. But it is amazing that QM has withstood numerous challenges throughout its history.


Sunday, March 12, 2017

The Weak Nuclear Force

I'm going to highlight this latest video by Fermilab's Don Lincoln for a number of reasons. First, the video:

Second, this is one video packed with a number of very important and illuminating stuff. First he explains about the concept of "spin" in both the classical and quantum picture. This is important because to many people who do not study physics, the word "spin" conjures up a certain idea that is not correct when applied to quantum mechanics. So this video hopefully will enlighten the idea a bit.

But what is more fascinating here is his brief historical overview of the first proposal of the connection between the weak interaction and spin, and how Chien Shiung Wu should have received the Nobel Prize for this with Yang and Lee. This might be another case of gender bias that prevented a brilliant Chinese female physicist from a deserving prize. Considering the time that she lived in and the societal and cultural obstacles that she had to overcome, she simply had to be just too outstanding to be able to get to where she was.

So this is one terrific video all around, and you get to learn a bit about the weak interaction to boot!


Friday, March 10, 2017

APS Endorses March Of Science

The American Physical Society has unanimously endorsed the upcoming March for Science.

I'll be flying out of town on that exact day of the March, so I had decided a while back to simply contribute to it. I get the sentiment and the mission. However, I'm skeptical on the degree of impact that it will make. It will get publicity, and maybe focuses some of the issues, especially funding in the physical sciences, to the public.

But for it to take hold, it can't simply be a one-day event, and as much as I've involved myself in many outreach programs, I still see a lot of misinformation and ignorance among the public about science, and physics in particular.

Here's something I've always wanted to do, but never followed through and lack the resources to do it. How about we do something similar to a family tree genealogy. But instead of tracing human ancestors, we focus on technology "family tree". I've always wanted to start with the iPhone capacitive touch screen. Trace back up the technology and scientific roots of this component. I bet you there were a lot of various material science, engineering, and physics that were part of various patents, published papers, etc. that eventually gave birth to this touch screen.

What it will do is show the public that what they have so gotten used to came out of very basic research in physics and engineering. We can even list out all the funding agencies that were part of the direct line of "descendants" of the device and show them how money spent on basic science actually became a major component of our economy.

By doing this, you don't beat around the bush. You TELL the public what they can actually get out of an investment in science with a concrete example. And it may come out of areas that they never made connection before.


Thursday, March 09, 2017

Time Crystal

This is quite an astonishing feat. It was only back in 2012 that Frank Wilczek proposed the possibility of a "time crystal", where a certain symmetry repeats in time, rather than in space. This was followed soon enough by a formal proposal for such a crystal. And now, we appear to have two experimental evidence.[1,2]

Potter is part of the team led by researchers at the University of Maryland who successfully created the first time crystal from ions, or electrically charged atoms, of the element ytterbium. By applying just the right electrical field, the researchers levitated 10 of these ions above a surface like a magician’s assistant. Next, they whacked the atoms with a laser pulse, causing them to flip head over heels. Then they hit them again and again in a regular rhythm. That set up a pattern of flips that repeated in time.

Crucially, Potter noted, the pattern of atom flips repeated only half as fast as the laser pulses. This would be like pounding on a bunch of piano keys twice a second and notes coming out only once a second. This weird quantum behavior was a signature that he and his colleagues predicted, and helped confirm that the result was indeed a time crystal.

Like I said, this is quite a feat to come up with a scheme to be able to create and test this.


[1] J. Zhang et al., Nature 543, 217 (2017).
[2] S. Choi et al., Nature 543, 221 (2017).

Monday, March 06, 2017

The Race To Make Quantum Computers

We still don't quite have a truly-accepted working model, even from D-Wave. So it is interesting to see this latest news of both Google and IBM launching projects to produce and eventually sell these quantum computers.

The folks from Google's Quantum AI Laboratory wrote a comment in Nature, while IBM's intention is reported in the news.

With the Chinese company Alibaba collaborating with the Chinese Academy of Sciences to also go into this area, the next several years will be fascinating to watch.


Sunday, March 05, 2017

Raman Spectroscopy Used To Detect Skin Cancer

I found this piece of news while reading the Flash Physics section on Physics World. And if you've followed this blog for a while, you know that I will highlight this without any shame.

Chalk this up to another important application of something that came out of physics research and subsequently finds a usefulness in medical diagnostics. Many of us in Material Science/Condensed Matter Physics/Chemistry are aware of Raman spectroscopy techniques in the study of molecules and materials. It has been a common technique in these areas of study for many, many years since its first proposal in.... get this.... 1929![1]

So already it is a very useful technique in chemistry and material science. But now it has found another application, in medical diagnostics. It turns out that this same technique can be used to find hard-to-detect skin cancer.[2]

Abstract: Melanoma is the most deadly form of skin cancer with a yearly global incidence over 232,000 patients. Individuals with fair skin and red hair exhibit the highest risk for developing melanoma, with evidence suggesting the red/blond pigment known as pheomelanin may elevate melanoma risk through both UV radiation-dependent and -independent mechanisms. Although the ability to identify, characterize, and monitor pheomelanin within skin is vital for improving our understanding of the underlying biology of these lesions, no tools exist for real-time, in vivo detection of the pigment. Here we show that the distribution of pheomelanin in cells and tissues can be visually characterized non-destructively and noninvasively in vivo with coherent anti-Stokes Raman scattering (CARS) microscopy, a label-free vibrational imaging technique. We validated our CARS imaging strategy in vitro to in vivo with synthetic pheomelanin, isolated melanocytes, and the Mc1re/e, red-haired mouse model. Nests of pheomelanotic melanocytes were observed in the red-haired animals, but not in the genetically matched Mc1re/e; Tyrc/c (“albino-red-haired”) mice. Importantly, samples from human amelanotic melanomas subjected to CARS imaging exhibited strong pheomelanotic signals. This is the first time, to our knowledge, that pheomelanin has been visualized and spatially localized in melanocytes, skin, and human amelanotic melanomas.

This is another example where experimental technique in physics EVENTUALLY finds applications elsewhere. I've highlighted other examples of this, with this being the most recent one before this post. Also note the "gestation" period between when this method was first proposed, and then when it became common in physics, to when it found other applications outside of its original main use. This is not new. Look at how long between when NMR became a common technique to when it evolved into MRI. Medical technology would not have evolved and advanced without a much earlier advancement in physics and physics experiments!

What I'm trying to emphasize here is that you may not feel the pain NOW when you cut funding to basic science research. But the pain WILL be felt later, by your children and grandchildren, because it takes years for what we work on now to become a useful technique elsewhere. That physics that we used to detect some esoteric particles that you don't care about may just one day be the diagnostic tool that saves someone's life!


[1]C.V. Raman and K.S. Krishnan, The optical analog of the Compton effect, Nature 121, 711 (1928); G. Landsberg and L. Mandelstam, A novel effect of light scattering in crystals, Naturwissenschaften 16, 557 (1928); C.V. Raman and K.S. Khrishnan, The production of new radiations by light scattering, Proc. Roy. Soc. (London) 122, 23, (1929).
[2] H. Wang et al., Scientific Reports 6, Article number: 37986 (2016). Paper is open access.

Friday, March 03, 2017

The Laws Of Life

Physics Today has made the article "The Laws of Life" from the March 2017 issue available for free. In the article, astrobiologist Charles Cockell describes how the fundamental laws of physics influences the forms of life on Earth.


Thursday, March 02, 2017

Online Homework Assignment - Are They Effective?

I read this news with a bit of interest. It appears that a student at Brooklyn College is gathering petition signatures to end the use of something called "Expert TA". This sounds like an online HW assignment that has been used by the physics department at that school.

Each homework assignment has about 15 to 20 questions, but each question has multiple parts. The number of questions, attempts, and credit reductions for wrong answers is dependent on the instructor. The instructor has the option to deduct points when a student accesses hints, and feedbacks. Expert TA consists of two types of feedback: Direct and Socratic. Direct feedback let’s a student know exactly what they did wrong, while a Socratic feedback poses a question such as “Have you considered the following?” Though this may sound quite useful, students feel otherwise.

It would be a bit more informative, and more persuasive, if a specific example on how this online tool is ineffective. For example, the best complaint that I can read from the report said this:

“The problem doesn’t lie in the concepts,” said Manasherov. “It’s more like how can we navigate this website and give the right answer—the right answer meaning what the website is looking for.”
“The hints aren’t always helpful and the feedback isn’t always clear either,” said sophomore Melissa Beagle. “And they only give you a limited number of tries, which doesn’t really help.”

There types of comments are not really that informative. It is similar to you telling your doctor "I just don't feel right" without giving any specific description of what is wrong.

I have a bit of experience in dealing with such online HW assignment. I've written about it in an earlier blog post on here. In fact, I will also add that I actually worked though the online HW assignment that my students would be facing, and I can see and experience what they will have to go through. I can see good points and bad points about it. But as I've said in that earlier blog post, the biggest issue I have about online anything is the question on whether the student doing it had any external help. But that is an issue that would be present in the traditional, written HW assignment as well since the student can easily copy or had help in completing the assignment. Except for one major difference.

You see, traditional written HW assignment requires that the student show work in arriving at an answer. You normally do not see that with online assignment. From what I can gather when chatting with students, all they care about is getting the right answer to type into those answer boxes. Often time, their "work" in deriving the answer is either done haphazardly, or not as complete and clear as one that would be required in a written HW assignment that is being submitted for grading. So in some instances, these students really could not recall what they did right and what they did wrong.

I'm still divided on my opinion regarding this type of HW assignment. I see some value in it. It certainly makes the job of an instructor a bit easier. But I also see how this can make the student being lazy to really learn what is needed in solving a particular problem.

If you have gone through such online HW assignment, or if you're an instructor whose course use such a thing, I'd like to hear from you.


Wednesday, March 01, 2017

Lenz's Law Is A "Quirk" Of Physics?

I've never heard of "fidget toys" before till after I read this piece. This one is describing a fidget toy that supposedly has "antigravity" effects that simulates the low gravitational field of the moon and Mars, making the object falls slower. The toy is called Moondrop.

Based around the principle of Lenz’s law — which *deep breath* states that the current induced in a circuit due to a change or motion in a magnetic field will create a field that opposes the charge that produced it — Moondrop is a gravity-defying fidget desk toy that imitates the differential gravitational free fall on Mars and the Moon.

OK, so immediately, there are two issues here:

1. Lenz's law is not a "quirk" of physics, as stated in the title of this report. In fact, it is quite a central phenomenon in physics that is responsible for power generators to create our household electricity! So how is that a "quirk"?

2. Any physics undergraduate can spot the error in the definition given for Lenz's law. Lenz's law is the effect whereby a magnetic field is generated to oppose the CHANGE in the external magnetic field. Maybe there is a typo in the definition given, that it should have been "change" instead of "charge". That one word (or in this case, one letter) change results in an astounding difference in the physics.

If I recall correctly, there are magnetic breaks that use the same principle. I remember reading something on roller coaster rides that made use of such magnetic breaks, so that it ensure that the vehicle can still be safely stopped even when the power goes off.

So the application of Lenz's law is neither that highly unusual, nor is it a quirk of physics.

Or maybe the writer meant a "quark" of physics?