Category Archives: Physics

Chernobyl

It’s been a little over 21 years now since the nuclear power plant in Chernobyl blew up. I wrote about it on the 20th anniversary and a few years earlier, but the MetaFilter thread Chernobyl – 20 years later has some new (at least to me) links on the topic.

My Journey to Chernobyl: 20 Years After the Disaster is an article with photos by Mark Resnicoff, who traveled to the contamination zone in June 2006. There also is a discussion about his essay.

Chernobyl Legacy by Paul Fusco:

On April 26th, 1986, Chernobyl’s Reactor No. 4 unleashed a thoroughly modern plague that emptied cities, condemned entire regions, and seeped invisibly into the bodies of those exposed to its destructive presence.

Photographer Paul Fusco faces the dark legacy of Chernobyl, focusing on the horrifying human consequences of the event that is now 20 years in the past. Fusco’s work forces us to remember an important nightmare that we would forget at the peril of our morality and our future.

It takes a while for the site to load, but it’s worth the wait. At least look at and listen to “Chernobyl legacy” from the menu.

Karol Lasia has a collection of black-and-white photos from the area. Lasia was born in 1986 and traveled to Chernobyl and Pripyat in the summer of 2006.

The Kaye Effect

I don’t remember where I found the link, but I was fascinated by what can happen (YouTube link to the same video) when you pour shampoo or other viscous liquids. The Wikipedia article states that “the surface suddenly spout[s] an upcoming jet of liquid which merge[s] with the downgoing one.” Arthur Kaye first described the phenomenon in 1963, but only a year ago, in April 2006, did a group of Dutch scientists (Michel Versluis et al.) manage to explain the effect. They also discovered a method to create a stable Kaye effect. You can download their article, “Leaping shampoo and the stable Kaye effect.” Michel Versluis et al, J. Stat. Mech. (2006) P07007, here at the IOP, or here.

Lunar eclipse

A total lunar eclipse will be visible from almost everywhere on earth tomorrow night (March 3rd/4th, 2007). This site links to several webcasts and gives the beginning and ending times:

“The Moon encounters the penumbra, the Earth’s outermost shadow zone, at 20:18 Universal Time (UT). About thirty minutes later a slight dusky shading can be noticed on the leading edge of the Moon.

At 21:30 UT the Moon begins its entry into the innermost shadow zone, or umbra. For more than an hour a circular shadow creeps across the Moon’s face. At 22:44 UT, the Moon will lie completely within Earth’s dark shadow.[…]

Totality will end at 23:58 UT, when the moon’s leading edge exits the umbra. The moon will leave the umbra completely at 01:11 UT, and the eclipse will end at 02:23 UT when the moon makes its last contact with the penumbra.”

I just looked out of the window at the moon in an almost clear nightsky. If the weather is like this tomorrow, it’s going to be fun to watch the eclipse from the office without getting cold outside. ;-)

Did it ever occur to you that whenever a lunar eclipse occurs on earth, there’s a solar eclipse on moon at the same time because the earth blocks the sun? It never did to me even though I teach how eclipses work at least once every year, and my students usually come up with all sorts of interesting ideas and questions. Here’s a picture of what it would look like.

It’s a pity I only found out about the eclipse now, I would have liked to tell my students about it – I’m covering related topics in two of the three physics classes I teach at the moment (basic optics including lunar and solar eclipses in 8th grade, Kepler‘s laws of planetary motion in 11th grade).

Simulate your own solar system – and more!

Sometimes MetaFilter has links to sites right up my alley: Physics simulators. Lots of physics simulators.

“PhET – Physics Education Technology offers this astoundingly large library of online physics simulations.

Play orbital billiards. Land on a cheesy moon. Experiment with sound. Or try more advanced quantum physics simulators. Still bored? Try the “cutting edge” catagory. Here’s the complete index. (Warnings: Frames, Flash, Javascript, Java applets, graphics, sound, quantum timesuck.)“

I especially like the orbit simulator because I once had to program one in university. During my third semester (I was still aiming for a master in physics back then) I took a course on theoretical mechanics, and we had to write a program that simulated the paths of the moon relative to the earth and the sun. The masses and velocities of the objects were adjustable.

It took me weeks and weeks to finish because I had never programmed anything serious before, but it still didn’t calculate correct paths the day before the deadline, so I had to ask for some more time. Two frustrating afternoons later, I finally found the sign error in one of the formulas… Sigh.

I just realized that this must have been in February of 1996, so more than a decade has passed since then. I guess they do different programming tasks in theoretical mechanics now that you can just download applications like this from the web. Which is a good thing for me because now I can use these spiffy simulations in my lessons instead of my amateurish ones. I’m sure the students are going to appreciate it.