Interesting Papers
X-ray Diffraction on the web
10/10/11 21:31
I ran across a wonderful x-ray diffraction resource on the web at the site Powder Diffraction on the Web. It’s material from a course at the University of London. It seems like a very good resource for some quick information (especially when the books are not near by).
Nuclear info
14/03/11 19:23
With the current on-going crisis in Japan, I have been getting inundated with calls from family and friends regarding nuclear power and what’s going on. News programs and blogs seem to completely from one end of the spectrum to the other.
My personal thoughts? I’m watching with increased concern and feeling helpless. I’d initially thought that the worst that would happen would be internal core meltdowns, though no loss of containment. Now that appears almost something to hope for in light of the new information. It appears that the official statements thus far have seemed truthful and also indicative of their own lack of knowledge to the facilities.
There are too many unknowns for me to prognosticate as to exactly what will happen.
As a great resource, I’ll invite you to have a look at a lecture, Nuclear Power, Nuclear Accidents, Nuclear Weapons, Nuclear Perceptions, posted by one of my former professors at the University of Washington, Prof. G. Seidler. It’s a 2 hour long lecture, so there’s plenty of information. He’s a great lecturer, very easy to understand, and it is even entertaining. The lecture was from an Energy Science course he taught (for the first time I believe) Fall of 2010. It obviously won’t tell you the specifics of what is occurring in Japan right now, but it’s a great resource.
Another interesting, though thick and very dated source of information about “worst case” releases of information is a long review article in the Review of Modern Physics : Report to The American Physical Society of the study group on radionuclide release from severe accidents at nuclear power plants Rev. Mod. Phys. 57, S1-144(1985). It should be freely available to anyone that wishes to download it.
CO2 mitigation and polar bears
03/02/11 18:53
Here’s a reasonably good paper (well, good based on my pedestrian understanding of climate science) regarding the relative impact of possible CO2 mitigation:
http://www.nature.com/nature/journal/v468/n7326/abs/nature09653.html
(sorry to those of you that cannot get the Nature papers directly)
The general gist of the article seems to be twofold and of relatively good news. First they say that CO2 mitigation efforts could have a definite impact on the conditions in the arctic. As such, they find that we have not yet crossed a “tipping point” from which the reversal of changes becomes much more difficult. Secondly they do not seem to find any tipping point, at least in the short term, to exist. All of that should come as welcome news, especially if you happen to like polar bears. Figures 3 and 5 seem particularly easy to follow.
Bad physics language...
08/09/10 01:13
I came across a really useful online essay/collection of thoughts about the language people should (or should not) use when teaching physics or physical science. The author is Donald Simanek, an emeritus professor of physics and he begins with a quote from one of my favorite books.
His essay is very worthwhile for anyone teaching physics. It’s probably not the “single best thing” you can do to improve your teaching, but it’s nonetheless a wonderful collection of common errors of language that we use. And imperfections in the speech of an instructor really can have a significant effect on pedagogy. So far I’ve even found a couple of statements that I make on his list. They’re easy to dismiss as unimportant or as being too pedantic. However, if what I’m saying and what I’m trying to say are 2 different things, it really can make things more difficult for students.
Back in action, x-rays from tape
14/01/10 17:04
Sigh... well, at least they fixed it. Rapidweaver, my old nemesis and blogging software package, suffered a severe setback in Nov-Dec. It would frequently crash, delete entries, and do various other nasty, terrible things. They released an update which I eventually managed to install and now things seem to be ok. We’ll see how long it lasts. In the meantime I hope to add the entries that were lost from Nov and Dec.
For now I’ll leave you with a link, not just a single article, but several from a guy at UCLA that has been generating x-rays using scotch tape. Move over MacGyver. I don’t think they will be replacing synchrotrons any time soon, but it’s a clever example of nature behaving in a way that A) nobody was really expecting and B) in hind-sight makes a great deal of sense.
For now I’ll leave you with a link, not just a single article, but several from a guy at UCLA that has been generating x-rays using scotch tape. Move over MacGyver. I don’t think they will be replacing synchrotrons any time soon, but it’s a clever example of nature behaving in a way that A) nobody was really expecting and B) in hind-sight makes a great deal of sense.
Interacting Compasses
02/10/09 17:59
A short article Héctor G. Riveros and Julián Betancourt was published in The Physics Teacher this month that is quite fun. The paper centers on what happens when compasses interact.
Basically, if the magnetic fields are strong enough and you bring them close enough together, then compasses will influence each other. Ok fine, that’s not so interesting in and of itself until you make use of it. They arrayed lots of compasses together in a hexagonal packing arrangement, all as close as possible to each other.
On the top, the compasses are responding to an external magnetic field.
What’s really cool is when they take the external magnetic field away as you see on the right hand side (or bottom). The compasses form magnetic domains!
This is a really beautiful demonstration of how magnetic materials behave and I bet would make a great tool for teaching. I would not have thought that the magnetic fields produced by individual compasses would be sufficient to cause this kind of interaction.
Now, the next step is to see if you could add temperature to the mix. Given that we’re approximating spins as compasses, then it might be possible to approximate temperature as some sort of small random motion. Take each compass, put it on a small spring (or place small springs between each), and then shake the how ensemble. Eventually the shaking should be enough to cause the compasses to lose their orientation and the magnetic domains will disappear. Voila, you’ve got a Curie temperature.