Notes, 2025-06-30

• Here's a fun idea: Build a battery electric train that just goes back and forth between two locations, one of which is uphill of the other. The uphill location happens to contain a bunch of heavy stuff, say iron ore, and every time you drive the train downhill you basically just ride the (regenerative) brakes, charging your battery as you go. Then you offload the heavy stuff and head back uphill, draining the battery. Repeat this process, back and forth, until I guess the batteries wear out and need to be replaced; if you get the elevation change and the regenerative braking right, you'll never actually have to plug the train in and charge it.
  
  Related: According to this 2009 report, prepared for the Army Corps of Engineers, pumped hydroelectric storage has an efficiency of 79-80%. This means that we can take electricity from the grid and use it to pump water uphill, keep it there in a lake or reservoir, and then release it through a turbine to generate electricity as it flows back downhill. Here is Wikipedia's list of pumped-storage facilities in the US; keep in mind, though, that a lot of pumped-storage infrastructure is underground and might not be easily visible from its surrounding landscape.
• A few notes on progress, which I wrote about re: cordage recently:
  • I watched Mountainhead last week, and chuckled at the way the word "progress" was employed as a rallying cry for otherwise unthinkable actions.
  • In 1933, in the middle of the Great Depression, a World's Fair was held in Chicago on the 100-year anniversary of that city's founding. It was billed as the Century of Progress International Exposition, and it aimed to directly link scientific progress with the experience of everyday life. It emphasized "technology and progress, a utopia, or perfect world, founded on democracy and manufacturing. The Chicago Fair's official guidebook conveyed a basic slogan: 'Science Finds—Industry Applies—Man Conforms.' The message was that science and American life were wedded."
    
    One of the fair's exhibits was the Homes of Tomorrow Exhibition, which highlighted then-recent innovations in construction technology, including linoleum, masonite, and a synthetic stone product called Rostone. One of the houses included its own airplane hanger, and another had a helicopter pad. The exhibit was apparently successful, and after the fair closed five of the Homes of Tomorrow were barged across Lake Michigan and installed in Beverly Shores, Indiana. They were eventually protected there, alongside a few prefabricated Lustron Houses, into the Century of Progress Architectural District, which the National Parks Service gives a tour of once a year, at the end of September.
• A decent way to spend a few minutes: Browsing the online inventory of repurposedmaterialsinc.com, which bills itself as America's largest "industrial thrift store."

One interesting thing about the five senses is that for the most part you can’t perceive a given physical phenomenon through two different senses. I can think of three exceptions to this. The first involves chemical analysis, which occurs through both smell and taste. The second is touch; we use touch to learn all sorts of things about the world around us, many of which we can sense through vision. For instance, I can learn about an object’s texture by looking at it, or by touching it.

But the one I really like is the fact that we can, in certain circumstances, see the same physical vibrations that we mostly perceive through hearing. That’s what hearing is: A way to perceive how the stuff around us is shaking. The “stuff” around us is mostly air, and our ears have evolved to track the speed at which air shakes. Our ears focus on things that shake between about twenty times a second on the low end, and about twenty thousand times a second on the high end. The thing that’s cool, though, is that we can also witness things vibrating at twenty cycles per second using our eyesight. Here’s a video of an octobasse being played, it’s low-end notes clocking in at a thundering (but inaudible to most human listeners) sixteen Hertz. At this frequency its strings quiver visibly in a distinct wave, whose waveform gets longer as the player moves down the instrument’s register.

“Oh, vision is so powerful,” you might think, “it makes sense that we rely on it so much." But hearing has other tricks up its sleeve. Want to learn about an object's texture, but can’t touch or see it? Rub another object against it, and listen to the sound that’s produced; smooth objects will sound distinctly different than rough ones. We can even hear temperature, to some extent, as certain objects (like a pot of boiling water) tend to shake when they’re heated up. And even if they don’t shake, they can still sound different when they’re hot.

Imagine an organism that lives in some sort of fluid. The fluid has particles suspended in it — different kinds of particles, millions of kinds maybe, and each kind of particle has a unique shape. Some of the particles are lethal to the organism. Others can provide near-guaranteed nourishment, or shelter, or something else the organism wants. Some of the particles pose a risk, but also a reward.

In the beginning, we presume, the organism might not have a way to tell one kind of particle from another. But it learns. One part of its body, called an OR, evolves to fit one particular kind of particle — like two puzzle pieces snapping together. When that soft, satisfying snap occurs, the organism’s brain gets a signal from the OR, whereupon the organism might spring into action, searching for the source of the particle or, as the case may be, running away from it.

More ORs develop. ORs to sense particles associated with good food, ORs to sense particles associated with rot. ORs for springtime, ORs for fall, ORs for the forest and ORs for the sea. ORs for your parents’ closet, and ORs for your newborn baby. Humans have something like four hundred ORs, mostly in our nose but also in our kidneys, our skin, and (I did not know this previously) our prostate glands, testes, and sperm. ORs are what give us our sense of smell — but I like to think of them as a puzzle-piece-matching game we play with the fluid that we spend most of our lives swimming in.

I imagine my nose as a puzzle box, its lid discarded and its pieces waving around in the air. I imagine the odor molecules in the air — esters, ketones, thiols, coming off a slice of pizza or a piece of freshly-folded laundry — floating there in the air around my puzzle box. But the odor molecules, to make my metaphor work, have been scaled up to the same size of the puzzle pieces. By chance, I wave my puzzle box by a diacetyl molecule, and snap — it clicks with my diacetyl puzzle piece. A signal is sent to my brain, and I experience it as the smell of butter.

But when multiple puzzle pieces happen to snap together at the same time, the way we perceive them gets complex. From a 2020 NIH study:

Studies using simple odors suggest that when we smell something, a particular combination of neurons are activated. This combination of activity forms a coded message that’s sent to the brain and is then perceived as a particular odor... But when two or three odors were mixed together, a more complex system of nerve cell responses appeared.

The scientists found that one odor could alter a cell’s response to another odor, even if the first odor didn’t trigger a response in that cell when delivered alone. Such interactions affected the strength of the neuron’s response, either enhancing or suppressing the effect of the neuron’s preferred odor. As a result, the code sent to the brain for a mixture of odors was different than what would be predicted from the sum of each odor’s normal nerve cell signal response.

It is the first day of the twenty-seventh week of the year. I know this because I keep track of it, writing the week number down every Monday when I plan my week out. The twenty-seventh week marks the beginning of the second half of the year; today is the first day of the third quarter.