Monday, April 14, 2014

Learn Quantum Mechanics From Ellen DeGeneres

Hey, why not? :)



Although, there isn't much of "quantum mechanics" in here, but rather more on black holes and general relativity. Oh well!

Zz.

Science Is Running Out Of Things To Discover?

John Horgan is spewing out the same garbage again in his latest opinion piece (and yes, I'm not mincing my words here). His latest lob into this controversy is the so-called evidence that in physics, the time difference between the original work and when the Nobel prize is finally awarded is getting longer, and thus, his point that physics, especially "fundamental physics", is running out of things to discover.

In their brief Nature letter, Fortunato and co-authors do not speculate on the larger significance of their data, except to say that they are concerned about the future of the Nobel Prizes. But in an unpublished paper called "The Nobel delay: A sign of the decline of Physics?" they suggest that the Nobel time lag "seems to confirm the common feeling of an increasing time needed to achieve new discoveries in basic natural sciences—a somewhat worrisome trend."

This comment reminds me of an essay published in Nature a year ago, "After Einstein: Scientific genius is extinct." The author, psychologist Dean Keith Simonton, suggested that scientists have become victims of their own success. "Our theories and instruments now probe the earliest seconds and farthest reaches of the universe," he writes. Hence, scientists may produce no more "momentous leaps" but only "extensions of already-established, domain-specific expertise." Or, as I wrote in The End of Science, "further research may yield no more great revelations or revolutions, but only incremental, diminishing returns."
So, haven't we learned anything from the history of science? The last time someone thought that we knew all there was to know about an area of physics, and all that we could do was simply to make incremental understanding of the area,  it was pre-1985 before Mother Nature smacked us right in the face with the discovery of high-Tc superconductors.

There is a singular problem with this opinion piece. It equates "fundamental physics" with elementary particle/high energy/cosmology/string/etc. This neglects the fact that (i) the Higgs mechanism came out of condensed matter physics, (ii) "fundamental" understanding of various aspects of quantum field theory and other exotica such as Majorana fermions and magnetic monopole are coming out of condensed matter physics, (iii) the so-called "fundamental physics" doesn't have a monopoly on the physics Nobel prizes. It is interesting that Horgan pointed out the time lapse between the theory and Nobel prizes for superfluidity (of He3), but neglected the short time frame between discovery and the Nobel prize for graphene, or high-Tc superconductors.

As we know more and more, the problems that remain and new ones that popped up become more and more difficult to decipher and observe. Naturally, this will make the confirmation/acceptance up to the level of Nobel prize to be lengthier, both in terms of peer-reviewed evaluation and in time. But this metric does NOT reflect on whether we lack things to discover. Anyone who had done scientific research can tell you that as you try to solve something, other puzzling things pop up! I can guarantee you that the act of trying to solve the Dark Energy and Dark Matter problem will provide us with MORE puzzling observations, even if we solve those two. That has always been the pattern in scientific discovery from the beginning of human beings trying to decipher the world around us! In fact, I would say that we have a lot more things we don't know of now than before, because we have so many amazing instruments that are giving us more puzzling and unexpected things.

Unfortunately, Horgan seems to dismiss whole areas of physics as being unimportant and not "fundamental".

Zz.

Thursday, April 10, 2014

Graphene Closer To Commercial Use

When an article related to physics makes it to the CNN website, you know it is a major news.

This article covers the recent "breakthrough" in graphene that may make it even more viable for commercial use. I'm highlighting it here in case you or someone else needs more evidence of the "application" of physics, and if anyone who thinks that something that got awarded the Nobel Prize in is usually esoteric and useless.

Zz.

Tuesday, April 08, 2014

"An Engineering Guide To Photoinjectors"

How would you like to own a 335-page book on the physics and engineering of electron photoinjectors? For free!

That is what you will get if you click on the link. If you are ever interested in electron accelerators, especially at the "birthing" end where the electrons are generated and given the initial acceleration, this is the review book to get. It explores not only the engineering aspect of the photoinjectors, but also the physics of photocathodes, and what makes a good photocathode for accelerator applications.

Highly recommended.

Zz.

"Introduction to superfluidity -- Field-theoretical approach and applications"

A very useful book chapter on superfluids if you are so inclined to study this subject in a bit more detail.

Zz.

Sunday, April 06, 2014

Exploding Anvil In "Outrageous Acts of Science"

Rhett Allain vented his frustration on the bad physics being used to explain the "exploding anvil" situation from the TV show "Outrageous Acts of Science".

See if you can take up his challenge and come up with a better diagram and explanation. :)

Zz.

Friday, April 04, 2014

Physics In Health And Industry

I always try to show people that many of the stuff they now use, came out of the research work that had almost no apparent and immediate practical application. I often use high energy physics as an example, because in many camps, this is the poster child of esoteric physics that has no clear applications. Yet, people forget that the World Wide Web, the medical detector and diagnostics, and many others, came about as direct spin-offs of experiments in high energy physics.

This report of a recent conference on advanced radiation detectors will reinforce this point.

The first afternoon was rounded up by Colin Latimer of the University of Belfast and member of the EPS Executive Committee. He illustrated the varying timescales between invention and mass-application multi-billion-dollar markets, with a number of example technologies including optical fibres (1928), liquid-crystal displays (1936), magnetic-resonance imaging (MRI) scanners (1945) and lasers (1958), with high-temperature superconductors (1986) and graphene (2004) still waiting to make a major impact. Latimer went on to present results from the recent study commissioned by the EPS from the Centre for Economics and Business Research, which has shown the importance of physics to the European economy.
.
.
.
Erik Heijne, a pioneer of silicon and silicon-pixel detectors at CERN, started by discussing innovation in instrumentation through the use of microelectronics technology. Miniaturization to sub-micron silicon technologies allows many functions to be compacted into a small volume. This has led in turn to the integration of sensors and processing electronics in powerful devices, and has opened up new fields of applications (CERN Courier March 2014 p26). In high-energy particle physics, the new experiments at the LHC have been based on sophisticated chips that allow unprecedented event rates of up to 40 MHz. Some of the chips – or at least the underlying ideas – have found applications in materials analysis, medical imaging and other types of industrial equipment. The radiation imaging matrix, for example, based on silicon-pixel and integrated read-out chips, has many applications already.

Without the effort and the need to push the capabilities of these detectors, there would be no reason to innovate, and the pace of advancement in many of these detectors will slow down considerably. The need to make better detectors to do high energy physics experiments DRIVES innovation in these various areas that have a clear and direct spin-offs into practical applications.

This is the part that many, including politicians, seem to not be aware of.

Zz.

Wednesday, April 02, 2014

Relativity Isn't Relative

This is a good Minute Physics video. Most people when they superficially read about Relativity (Special and General) pay most of their attention to the "relative" quantities, such as mass, length, and time. Yet, the most important aspect of SR and GR, and other areas of physics such as gauge theory, the thing that we want are the covariant/invariant quantities. These are things, as the video stated, that aren't based on perspective, or relative to anything. It is why, for example, that we can state the mass of the many elementary particles without the need to state the speed of these particles (not that the concept of "relativistic mass" makes much sense in the first place).

So if all you have heard about Relativity is how everything is relative, then this video will be useful to you.



Zz.

The Real Physics Behind "Star Trek"

This is a rather last-minute notice, but if you are in the Chicago area, Dirk Morr will discuss the physics and technology behind Star Trek, today, Wednesday, April 2, 2014, at the University of Illinois at Chicago campus.

Dirk K. Morr, a professor at the University of Illinois at Chicago, joins us to discuss the scientific ideas behind Star Trek technologies. Morr will present his findings at 6:00 pm on Wednesday at the University of Illinois at Chicago in the Behavioral Science Building.

You may read the rest of the article to see what science and technologies from Star Trek that have some resemblance to what we do now.

Zz.

Friday, March 28, 2014

10 Things That Can Tangle Your Brain?

A blog on the Huffington Post listed 10 things in physics that can "tangle" one's brain. Normally, I would read this and shrug. But there's a bit of misleading and incorrect information here that should be corrected. Let's go through the list:

1. Space ripples

OK, this one was on the news a lot the past couple of weeks. Nothing much to say here since the coverage is appropriately on the superficial level, which is fine this this is meant for the masses.

2. Quark-gluon plasma

I'm not going to nitpick this one since the description doesn't say much more than some generalization of what it is.



3. Time is slowing down

This is where the trouble begins. The argument for "time slowing down" is given by "Tidal friction caused by the Moon's gravitational pull is causing Earth's rotation to slow so that a day on Earth gets 1.4 milliseconds longer about every 100 years. " Sorry, but this is NOT time slowing down. It is the earth's rotation that is slowing down. The rate of oscillation of cesium atom in an atomic clock remains the same.




4. Light can be stopped completely


This is not new, but it might appear to be if you read it here: "Last year scientists in Germany successfully stopped light from traveling for an entire minute, by trapping it in a crystal." Light has been stopped in atomic gasses since way back in 2001, especially from Lene Hau's group at Harvard.. That's more than a decade! They may not have done it as long as the German group, but they have stopped it, completely!

5. Teleportation

6. Quantum entanglement

I'm grouping these two together because they are basically the same thing. The claim that a photon has been "teleported" is false, because what is teleported is not the photo, but rather a particular property of the photon, and that is tightly connected to quantum entanglement. If you read the article, you'd think this is your "teleportation" that one sees in Star Trek. It isn't.

7. Quantum foam

OK, so this is vacuum fluctuation.

8. Light bends matter

On one hand, this may be unusual to most people. But if one learns a little bit about physics, is this really new and unexpected? Compton scattering, anyone? That old and well-known phenomenon alone shows that light of a certain wavelength can change the trajectory of matter (electrons, for example). And let's not forget, particle accelerators around the world use RF sources to accelerate, bend, and manipulate charged particle trajectories.

9. Invisibility cloak?

10. The "God particle"

Nothing much to comment on there.

Anyhow, I guess it should be commended that a mainstream news source is covering something in physics. I just wish that they would at least find an expert FIRST to clean up the article, rather than just use "an education research assistant" as the other contributing author. I'm always surprised that people without the proper background seem think that they can write an accurate description of something which clearly is way over their heads.

Zz.

Wednesday, March 26, 2014

"Brief history for the search and discovery of the Higgs particle - A personal perspective"

I find this "personal perspective" on the search for the Higgs to be extremely enjoyable. Don't be deceived by the title. This article has a lot of tabulated values and information that one can easily refer. It also explained why physicists were looking for the Higgs and why there was such a huge range of mass that had to be explored before it could be narrowed down during the final years before its discovery at the LHC.

Highly recommended.

Zz.

One Of The Most Common Practice That Students Make

Over the years, I've seen several things that students make repeatedly that had to be "corrected". I know I've made some of these things myself when I was a student. I've talked to a number of professors, and they too have commented that these things that students do are quite common before they learned not to do it.

One of the most common ones happen when they have to plot a graph. Inevitably, physics students will have to produce a report that includes graphs. This often continues into graduate school where they either will have to produce graphs for publication, or for presentation.

Inevitably, when they first do this, the most common thing they failed to do is to resize the labels and the axis titles. What they typically will do is simply to use the default setting of whatever data plotting/analysis software that they were using. For example, the graph below was done using Origin, and I simply used whatever the default settings that the software had:


Now, here's the problem. The labels are just too small! These may be fine at "normal" size, but they present a problem when (i) one is submitting this for publication where graphs are often required to fit inside a 2-column paper, and (ii) you are presenting this on the screen and expect everyone, especially in the back row, to see this.

My graduate students meet with me and a couple of other faculty members weekly to discuss the work being done. During these meetings, the students often present their results and whatever else that they did, and inevitably, there will be a few graphs. The new students ALWAYS, never fail, did what I had just described. Most of the time, we could hardly see the axis labels and values on the screen because they were so small. It is almost a right of passage that one of us will have to tell them that they have to resize these things and make them bigger. If they forget to do this when they're submitting a manuscript for publication, then they will encounter a comment from the editor of the journal about resizing the labels.

Eventually, they learn, as with other things, as part of their process of becoming a scientist. In the scheme of things, this is not a big issue, but I find it amusing that almost every single student that I've encountered started out by doing this identical habit.

Zz.

Tuesday, March 25, 2014

Walter Kohn and The Creation Of DFT

You all know that I try to highlight the lives and contribution of physicists that many in the general public are not aware of. This is another such example.

I cannot vouch for the accuracy of the article, since I haven't read any other biography on him, but this one describes the life of Walter Kohn, the person most responsible for the creation of Density Functional Theory (DFT), which has become a ubiquitous method in computing band structure and other properties of atoms, molecules, and solids.

Abstract: The theoretical solid-state physicist Walter Kohn was awarded one-half of the 1998 Nobel Prize in Chemistry for his mid-1960's creation of an approach to the many-particle problem in quantum mechanics called density functional theory (DFT). In its exact form, DFT establishes that the total charge density of any system of electrons and nuclei provides all the information needed for a complete description of that system. This was a breakthrough for the study of atoms, molecules, gases, liquids, and solids. Before DFT, it was thought that only the vastly more complicated many-electron wave function was needed for a complete description of such systems. Today, fifty years after its introduction, DFT (in one of its approximate forms) is the method of choice used by most scientists to calculate the physical properties of materials of all kinds. In this paper, I present a biographical essay of Kohn's educational experiences and professional career up to and including the creation of DFT.

The purpose of all my effort in pointing out the stories of these various physicists is not for us to worship and idolize these figures. I see people quoting many of these famous scientists as if they are word of god, and using those as if they are a sufficient counter argument. Far from it. I highlight them because we need to know that many of the things we accept and use and take for granted came from many of these nameless folks. It is trying to instill a sense of gratitude that the intelligence, creativity, and hard work of many of these people gave us the numerous convenience and advances that we enjoy today. You may not know before how much they had affected your lives, but you should now. You've gained another piece of knowledge/information that you didn't have before about someone who mattered.

Zz.

Wednesday, March 19, 2014

Flex Your BICEP

... or in this case, BICEP2.

The recent BICEP2 results seem to have caught a lot of media attention. News coverage ranges from NY Times to CNN, etc. And let's face it, this isn't easy to understand even if the news media coverage glosses over the physics on why this is such an important discovery.

To add to the body of "explanation" given out there, here's MinutePhysics version of it.



With all the euphoria surrounding this, Neil Turok voice his caution to all the brouhaha surrounding this result.

"If...and it's a big if...this is true, it would be spectacular evidence for what happened at the Big Bang," Turok told physicsworld.com. While he agreed that at first glance, the BICEP2 observations are in keeping with inflation "as suggested over 30 years ago, wherein space–time would resonate with the aftershocks of inflation and would ring like a bell", a closer look at the discrepancy between the new results and previous data from the Planck and WMAP telescopes is what worries Turok. Indeed, the tensor-to-scalar ratio of 0.20 that BICEP2 measured is considered to be significantly larger than that expected from previous analyses of data. But the BICEP2 researchers said in their press conference yesterday that they believe certain tweaks could be made to an extension of the ΛCDM cosmological model that could make the two results agree. 

As with ALL experimental observations and discovery, there has to be reproducibility, and agreement with other types of experiments that point to one single, consistent picture. This is what makes science different than other areas of human endeavor. We NEVER confirm something with just one single experiment or with just one single type of experiment. Superconductivity is confirmed with resistivity measurement and magnetic susceptibility measurement.

So while this is certainly a major discovery, there's a lot of hard work left to be done to confirm this observation.

Zz.

Tuesday, March 18, 2014

Single-Photon Detectors

This topic came up a few times during the past month in online discussions and with a few people that I've met. Most of these were in context with the photon detectors used in the EPR-type experiments, but a few came up due to the photon detectors used in detecting Cerenkov light from neutrino experiments.

A lot of people are confused with, and misinterpret, the meaning of "single-photon detectors". Most of them who are not familiar with it think that such detectors can detect every single photons that the detector comes in contact with, i.e. if there's a photon hitting a detector, it will detect it.

This is false. A single-photon detector is sensitive down to detecting single photons. So this is a sensitivity issue. However, it doesn't mean that it has a 100% efficiency. It doesn't detect every single photons that it encounters.

A photodetector such as a photomultiplier tube used in many photon detector is often made up of a photocathode (it converts the incoming photon into a photoelectron), an electron amplifier (something that multiply that single photoelectron into many electrons), and a signal generator/converter that converts the many electrons into an electrical signal. This is what we eventually detect in our electrical signal.

The problem here is that the photocathode does not have a 100% quantum efficiency. In fact, most photocathodes used in photodetector tubes have quantum efficiency less than 50%. What this means that if 100 photons hit the photocathode, less than 50 of them will be successful in generating a photoelectron each. The rest of the photons that hit the photocathode will generate no photoelectron and are lost.

So while the detector is sensitive down to the single-photon level, it is not 100% efficient. Single-photon detectors refer to the sensitivity, not the efficiency, of the detectors.

Zz.

Snapshot of 2014 APS March Meeting

If you didn't get to attend this year's APS March Meeting, or didn't get to the highlights they listed here, APS Physics has a summary of 4 of the major presentations at the recently-ended meeting. They range from "no-photon laser" to hyperbolic metamaterial.

Don't miss it.

Zz.