Discoveries in the Physics & Astronomy shop | Science, curiosities, and surprises
While exploring a potential site for measurement equipment, it’s important to keep an eye on the local wildlife. After a long time underground, those big red eyes are just taking it all in.
Not pictured: all of the other cicadas all over the place. Because where there’s one, there are bound to be many, many more. Brood XIV, maybe?
It really wasn’t that long ago that computers came equipped with optical disc drives, and they were effective means of data storage, and the density you could store on a DVD instead of a CD was pretty exciting. Now? They’re not only borderline-useless, but the features that we used to reference as a cultural touchstone are no longer obvious to our students.
It’s not that they don’t know what these are. It’s that they haven’t handled a million of them to know their dimensions, to understand the diffraction rainbow they make. The physicists around here remember using the inescapable AOL discs as cheap, readily available diffraction gratings back in grad school. The astronomers use their proportions to illustrate the shape of the Milky Way Galaxy. Students now need to physically hold one of these to get the idea, because they don’t have a mental image ready to go.
Our Galaxy, if you were wondering, is roughly proportioned as a CD, only instead of being a millimeter and a half thick, is more like 1,000 light years. Very roughly, anyway.
This is what happens when you burn a candle at both ends!
Make a pivot, light both ends, and the burning and dripping wax creates oscillations. In our limited experience, pretty irregular and chaotic. It’s really quite cool.
Here, our more modern sodium light sources, using a clever design that enabled a reduction from the minimum 35W to as little as 18W in 1977. Cool, yeah?
Unfortunately, Philips finally bowed out of the low pressure sodium lamp game in 2019, mean we’ve got these dinosaurs running for as long as we can scour spare lamps online. Once the supply’s gone, it’s gone.
Hey, look! Sodium metal! Highly reactive, so it’s inside with a mixture of 99% neon and 1% argon, neither of which deigns to react with, well, anything. That’s why, when it starts up, we see a purplish glow from the noble gases before tube reaches 260°C and vaporizes the sodium. After that, it’s an intense monochromatic yellow-orange that’s hard to look at.
Remember the old, aggressively-yellow street lighting that pre-dated LEDs, ceramic metal halide, and high pressure sodium? Turns out it’s very useful for physics, as the two strong emission lines near 589nm are handy for various experiments.
The lamps themselves are fairly tough, and the ballasts that operate them even more so. But, eventually, they burn out.
General Electric ceased production on these lamps back in 1972. So, no, sorry, replacements are not readily available.
Lead bricks are useful things. This one – still bearing the stamp of Nuclear Associates, of Carle Place, NY – has had its fair share of scuffs and dents. (Lead’s soft stuff, you know.) These days it functions as a handy doorstop and a hands-on tool for explaining the density of matter.
Denser than water, than aluminum, than a nickel-iron meteorite. (All easy samples to acquire for demonstration.) Less dense than osmium; about half as much. (Not on hand, unfortunately.) Definitely less dense than the core of our Sun, by an order of magnitude-plus.
Also no handy samples of stellar core plasma on hand.
Take two function generators, an old CRT oscilloscope, a couple of power and BNC cables, and look! Whirling, dancing lissajous figures!
Chunky knobs! Clicky buttons! Drifty outputs! Squiggly curves!
Need a thing, but can’t get it in the right size, right shape, right odd set of dimensions? That’s one reason to keep a workshop in the basement. If we can possibly make it, we’ll certainly try.
Pictured: a custom optics breadboard, for a very specific apparatus, with many, many drilled, tapped, and cleaned 1/4″-20 mounting holes. It’s big, and shiny, and has a bright future ahead!
Probably with lasers or something. Lots of lasers around here.
The color for next semester’s toy kits: violet.
Look, sometimes the very specific version you want only exists in a format that’s hard to make use of, like a VHS cassette. That’s why we have helpful, talented people with specific sorts of tech savvy to help us out with bringing oldies but goodies into a more modern format that’s still destined to veer into obsolescence after a while. Thanks, Wes!
For those wondering, AAPT stands for the American Association of Physics Teachers.
In this case, anyway. But for a thought experiment, imagine the collapse of Galloping Gertie as narrated by these other AAPT organizations and/or acronym users:
Some of those could be really entertaining. Just don’t mention poor Tubby the cocker spaniel to the animal assisted play folks.