Sunday, August 29, 2010

Volgograd: the new Tacoma Narrows

If you're not signed up for Arbor Scientific's CoolStuff newsletter, you might have missed this.

The newly-opened Volgograd Bridge in southern Russia is experiencing a "resonance malfunction."

This is 70 years after the original Tacoma Narrows Bridge fell. Like Obi-Wan Kenobi, though, the demise of the Tacoma Narrows Bridge made it more powerful than anyone could have possibly imagined. Its oscillations of doom revolutionized bridge design and made it the most famous bridge in physics lore.

Russian authorities closed the bridge amid the resonant rippling, but reopened it days later following a safety inspection.

Still though, if you feel you were cheated by time out of a thrill ride on "Galloping Gertie," you might want to book travel to Russia. And you might want to do it soon. The original Tacoma Narrows Bridge carried traffic for four months.

Monday, August 16, 2010

STAR 2010 scores are up!

The 2010 STAR scores are now live. The high-flying Physics CST scores continue to climb.

Here's the statewide skinny:
72,766 students took the 2010 Physics CST
21% performed at the Advanced level
28% were Proficient
33% were Basic
11% were Below Basic
8% were Far Below Basic

The percent of Advanced and Proficient scores stands at 49%, up from last year's pack-leading 46%. The number of physics students earning Advanced or Proficient status has increased by 20% since 2003. No other subject-area test has seen anything close that kind of performance gain. Here's an obligatory Excel graph to show the story of the stats.

(click image to embiggen)

Congratulations, California physics teachers!

STAR 2010 results should be up soon

Keep a browser tab refreshed at the Standardized Testing and Reporting (STAR) website. I'll post an update when the 2010 results are up.

Monday, August 09, 2010

Time to ditch those "Scientific Method" posters

I never liked those Scientific Method posters. Or the equivalent lists that occupied Chapter One of so many science textbooks. They seemed too sterile and prescribed, and made science seem like a very clean business carried out by automatons.

So my pulse raced on my first viewing of The Mechanical Universe episode devoted to The Millikan Experiment. The narrative trashes the so-called scientific method. I thought that was fairly bold for a program devoted to science. The Mechanical Universe story laid out the fact that scientists are biased when they enter the lab. They usually know what they're looking for. And so on. It went on to describe how science succeeds despite scientists.

While working on my Master's degree, I found out that the "scientific method" as outlined in posters and schoolbooks was the creation of an education academician. No wonder I didn't care for it!

Carl Sagan suggested we need a Baloney Detection Kit when evaluating scientific claims. Michael Shermer describes, in detail, what such a kit might include. Here it is in video form.

I think a poster form of this Baloney Detection Kit would be a better use of precious science classroom real estate than those tired Scientific Method posters. Even better: a bulletin board where examples of pseudoscience can be added, organized by their most obvious baloney flags. Just a thought.

Saturday, August 07, 2010

Circumhorizontal arc at Angel's Landing

My brother, his wife, and I were hiking the strenuous and perilous Angel's Landing trail in Zion National Park earlier this week.

Physics lessons abound in work (elevation gain is 1500 ft), friction (footing), tension (chains), equilibrium (precarious balance), etc. But after returning from Angel's Landing to Scout Lookout, my brother directed my attention to a spectrum in the cirrus clouds above.

I had never seen such a color band in the sky. It was clearly the interaction of sunlight and cirrus cloud ice crystals. But it was at a much greater angle from the sun than the oft-seen 22° halo. The colors were spread wider and were more deeply saturated.

Upon returning to the connected world (which is a small world, indeed, when you're at the mercy of AT&T), I googled "cirrus cloud rainbow" and discovered that what we were seeing was a circumhorizontal arc (CHA).

A circumhorizontal arc lies 46° from the sun and is observed only when and where the sun is more than 58° above the horizon. We get more of them in the States than they do in Europe.

The heart of CHA optics is the hexagonal ice crystal. For CHA, we need plates rather than rods. Sunlight enters a vertical side (rectangular) face and exits the bottom (hexagonal) face.

Of course, the different colors in the sunlight are refracted by different amounts. The dispersion of colors is fairly wide in CHA.

For more images of this atmospheric grooviness, you can check out this filtered gallery, or image-search "circumhorizntal arc." (Remember that an image-search will give you many results that are incorrectly tagged.) My favorite CHA image is the "fire rainbow" photograph taken near the Idaho/Washington border some years ago. It caused enough of a stir to get its own Snopes article!

My travel shots and landscapes from the trip are here.