Friday, November 17, 2017

Reviews of "The Quantum Labyrinth"

Paul Halpern's story of "when Feynman met Wheeler" in his book "The Quantum Labyrinth" has two interesting reviews that you can read (here and here). In the history of physics and human civilization, the meeting of the minds of these two giants in the world of physics must be rank up there with other partnerships, such as Lennon and McCartney, Hewlett and Packard, peanut butter and jelly, etc....

I have not read the book yet, and probably won't get to it till some time next year. But if you have read it, I'd like to hear what you think of it.

Zz.

Can A Simple Physics Error Cast Doubt On A da Vinci Paintaing?

It seems that the recent auction of a Leonardo da Vinci painting (for $450 million no less) has what everyone seems to call a physics flaw. It involves the crystal orb that is being held in the painting.

A major flaw in the painting — which is the only one of da Vinci's that remains in private hands — makes some historians think it's a fake. The crystal orb in the image doesn't distort light in the way that natural physics does, which would be an unusual error for da Vinci.

My reaction when I first read this is that, it is not as if da Vinci was painting this live with the actual Jesus Christ holding the orb. So either he made a mistake, or he knew what he was doing and didn't think it would matter. I don't think this observation is enough to call the painting a fake.

Still, it may make a good class example in Intro Physics optics.

Zz.

Saturday, November 11, 2017

Lorentz Gamma Factor

Don Lincoln has another video related to Relativity. This time, he's diving into more details on the Lorentz Gamma factor. At the beginning of the video, he's referring to another video he made on the misleading concept of relativistic mass, which I've linked to.



Zz.

Thursday, November 09, 2017

SLAC's LCLS Upgrade and What It Might Mean To You

Just in case you don't know what's going on at SLAC's LCLS, and the upcoming upgrade to bring it to LCLS-II, here's a CNET article meant for the general public to tell what what they have been up to, and what they hope to accomplish with the upgrade.

Keep in mind that LCLS is a "light source", albeit it is a very unique, highly-intense x-ray light source. SLAC is also part of the DOE's US National Laboratories, which include Brookhaven, Fermilab, Berkeley, Argonne, Los Alamos, .... etc.

Zz.

Friday, November 03, 2017

Muons, The Little Particles That Could

These muons are becoming the fashionable particles of the moment.

I mentioned at the beginning of this year (2017) of the use of muon tomography to image the damaged core at Fukushima. Now, muons are making headlines in two separate applications.

The first is the use of cosmic muons imaging that discovered hidden chambers inside Khufu's Pyramid at Giza. The second is more use of muons to probe the status of nuclear waste safely.

The comment I wrote in the first link still stands. We needed to know the fundamental properties of muons FIRST before we could actually use then to all these applications. And that fundamental knowledge came from high-energy/elementary particle physics.

So chalk this up to another application of such an esoteric field of study.

Zz.

Tuesday, October 31, 2017

Are University Admission Biased?

This is a rather interesting Minute Physics video. It is tackling what is known as the Simpson Paradox. What is interesting is that it is applying it to an example where on first glance, there appears to be no form of statistical bias, but when viewed another way, it seems that there is.



What is interesting here is that several years ago, I mentioned of an AIP study examining universities in the US that have very small number of physics faculty and how many of those that do not have a single female faculty member. The result found that, statistically, this is what is expected based on the number of female physics PhDs, meaning that we can't simply accuse these schools (and hiring of female physicist in general) of bias against female physicists. This Minute Physics video appears to provide an illustration of what is expected statistically without imposing even any bias to the sample.

Again, I'm not saying that female physicists and faculty members do not face unfair or more challenges in their career when compared to male physicists. But illustrations such as these should also be considered so that we tackle problems that are real and meaningful and not chase something is not the source of the problem.

Zz.

Thursday, October 26, 2017

Google Science Journal App

I've asked and discussed about various apps that I've come across that I thought might be either interesting or useful, or both, for someone in science, and in physics in particular. I still haven't found a data analysis and graphing app for my iPad that rivals, say, the Origin or any other full-blown computer program of that type. But I'll continue to search and keep an eye out for one.

I read about this "Google Science Journal" app before, but it appears that they've made significant improvements to it. It is available on both iOS and Android (of course). This app looks like it might be useful to high school science students, and maybe even in intro physics classes as part of a demo.

I'll probably install it on my phone and play with it for a bit to see what it actually can do. But if you have had some experience with this app, or better yet, have used it as part of a lesson, I definitely want to hear about it.

Zz.

Tuesday, October 24, 2017

How Does Proton Radiation Therapy Work?

Here's a video from Don Lincoln on a physicist's view of proton radiation therapy in attacking a tumor.



If you want a more detailed and technical information on proton therapy, you may access a more in-depth paper here. This, btw, is another example of the application of accelerator physics and elementary particle physics, in case you didn't know.

Zz.

Want To Read Stephen Hawking's Thesis?

I saw a news report that Cambridge is finally making Stephen Hawking's thesis available online. So I clicked the link to look at it, and nothing happened. Went back a few minutes later, clicked on it again, and nothing happened.

Turned out that all the news announcements on this has crashed the Cambridge's website due to the overwhelming request to want to see this! :)

In honor of Open Access Week, the University of Cambridge on Monday put the 1966 PhD thesis, "Properties of Expanding Universes," on its open access repository. Shortly after it went live, requests to view the research crashed the website.
As of Monday afternoon, the main research page was reachable after several minutes, but nothing on the page was.
So if you are planning on checking it out, good luck!
Zz.

Saturday, October 14, 2017

Lazy Reporting And Taking Way Too Much Credit

It is not surprising that whenever a major discovery is made or a major award is given, as many people and institutions want to ride the coattail and be a part of it. I understand that.

But sometime, it is stretching it a bit waaaay too much, especially when the report itself sounds very lazy and weak.

The recent announcement of the Nobel Prize in physics being awarded to 3 figures who are instrumental in the discovery of gravitational waves seem to be one such case. I stumble across this news article out of what I believe is a local newspaper called the "Gonzales Weekly Citizen". The headline said:

LSU scientists win Nobel Prize in Physics

Of course, that perked my interest since I didn't know any of the 3 men who were awarded the prize are known to be associated with LSU (Louisiana State University, for those who are not familiar with this).

Now, it seems that the reporter is playing fast and loose. Rainer Weiss is listed as an "adjunct professor" in the LSU physics dept. Now, we all know that an adjunct professor is nothing more than a "contractor". That person is not considered as a staff member, but rather hired on a per-term basis or based on a contract. In most cases, the person is probably associated by another institution rather than the one where he/she is an adjunct professor of.

In fact, in this case, Rainer Weiss is more well-known as being associated with MIT than anywhere else. It is what is listed in all the news report for this award. In fact, if you look at the Nobel Prize page that announced this award, the profile on Weiss says:


Affiliation at the time of the award: LIGO/VIRGO Collaboration, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA

No mention of LSU. In fact, the LIGO project itself is a consortium of many universities and it is jointly administered by MIT and Caltech. One of the facilities may be in Louisiana, and LSU is involved in the project, but that's about it. They should be proud of their contribution to the project, but to over play it to this level is not quite right.

So this news report is misleading at best!

But that's not all! There's a certain level of laziness in the reporting.

LSU adjunct professor and MIT professor Emeritus Rainer Weiss and California professor Emeritus Kip Thorne are co-founders of the collaboration. Weiss won half of the prize, and the other half went to the California Institute of Technology professors involved.

I'm sorry, but they could not even bother to mention Barry Barish name? He's being relegated to being part of the "... California Institute of Technology professors involved." REALLY!


As I said, rather lazy reporting.

Zz.

Wednesday, October 11, 2017

Electron Is Still A Point Particle

There have been experiments to measure the electric dipole moment of an electron, if any, which would indicate that (i) an electron has an internal structure and (ii) consequently it isn't a point particle that we have been assuming within QED. So far, all the experiments have not found any, and each measurement continues to increase the precision of the previous measurement.

Chalk this one up to follow the same trend[1]. This time, they are using a different technique to measure the electron dipole moment by using trapped molecular ions. The result of the experiment is an even more precise measurement, and lowered the upper bound of the dipole moment by several orders of magnitude when compared to the previous result.

Electron is still a spherical cow!

Zz.

[1] W.B. Cairncross et al., Phys. Rev. Lett. v.119, p.153001 (2017).

Tuesday, October 03, 2017

Why You Can't Go Faster Than Light

Don Lincoln tackles our speed limit.



Zz.

2017 Physics Nobel Prize Goes To Gravitational Wave Discovery

To say that this is a no-brainer and no surprise are an understatement.

The 2017 Nobel Prize in Physics goes to 3 central figures that made LIGO possible and the eventual discovery of gravitational wave in 2015.

The Nobel Prize in Physics 2017 was divided, one half awarded to Rainer Weiss, the other half jointly to Barry C. Barish and Kip S. Thorne "for decisive contributions to the LIGO detector and the observation of gravitational waves".

Congratulations to all of them!

Zz.

Friday, September 22, 2017

Common Mistakes By Students In Intro Physics

Rhett Allain has listed 3 common mistakes and misunderstanding done by student in intro kinematics physics courses.

I kinda agree with all of them, and I've seen them myself. In fact, when I teach "F=ma" and try to impress upon them its validity, I will ask them that if it is true, why do you need to keep your foot on the gas pedal to keep the vehicle moving at constant speed while driving? This appears to indicate that "F" produces a constant "speed", and thus, "a=0".

Tackling this is important, because the students already have a set of understanding of how the world around the works, whether correctly or not. It needs to be tackled head-on. I tackled this also in dealing with current where we calculate the drift velocity of conduction electrons. The students discover that the drift velocity is excruciatingly slow. So then I ask them that if the conduction electrons move like molasses, why does it appear that when I turn the switch on, the light comes on almost instantaneously?

Still, if we are nitpicking here, I have a small issue with the first item on Allain's list:

What happens when you have a constant force on an object? A very common student answer is that a constant force on an object will make it move at a constant speed—which is wrong, but it sort of makes sense.

Because he's using "speed" and not "velocity", it opens up a possibility of a special case of a central force, or even a centripetal force, in a circular motion where the object has a net force acting on it, but its speed remains the same. Because the central force is always perpendicular to the motion of the particle, it imparts no increase in speed, just a change in direction. So yes, the velocity changes, but the magnitude of the velocity (the speed) does not. So the misconception here isn't always wrong.

Zz.