North star is an airplane

Lots of people know a little about science.

During my rather disastrous commute home from Palo Alto today a man looked over, saw the book I was reading, and started talking to me about the atomic bomb. “I’m lousy at math,” he said. “but I understand physical principles well.” This was exciting to me, so I asked him what he meant. “For example, Einstein gets the credit for the atomic bomb, but it was really M—- who did most of the work. He was Einstein’s collaborator, but no one’s heard of him cause Einstein took all the credit.” This was not a physical principle. “Lots of people worked on the atomic bomb,” I said. He ignored me. I named 5 in my head.

“I’m in school, too, you know.” He said.
“I’m not in school.”

“Have you heard of Tesla?”

Did I know that he invented a laser, that it could shoot through the earth and turn ions negative in the atmosphere so that they changed the earth’s gravity because the magnetic field of the earth goes around like this and the ions go around like this… Now environmentalists were worried about the effect so they confiscated his invention because it was capable of making the surface of the water rise into the air did you know this and then you’d have black rain, have you heard of black rain? which is iron, it would levitate things, and fish and frogs would fall out of the sky too, isn’t that wild?

I thought about that for a second. “Like in a tornado?” He continued on. The more he talked, the more excited he got, he began stuttering and saying things that were logically disconnected. Between the noise of the bus pulling itself up highway 17 and this guy’s lack of coherence, I stopped caring and returned to my book. I was just starting a chapter on standard candles and getting excited about the Cepheid variables that had made such a buzz in cosmology. I tried to remember what Feynman had said about them,

Two different populations of stars… Cepheid variables of one type… but there’s another type… universe must be twice, or three times, or even four times older than we thought!

Meanwhile, bus guy does not stop talking. “Have you heard of frictional force?” he asks. I just look at him.

He explains. Bring together 5 people… I did this with my friends. When we all rubbed our hands together we generated enough frictional energy to levitate off the ground… just our hands… He showed me his hands. And rubbed them together to demonstrate what it looked like when you rubbed your hands together. I didn’t like that very much. I wasn’t trying to ignore him, but I was pretty bored. “Cepheid variables are named after the star delta Cephei,” I read from my book. Energy force, man… I swear to god I’m not lying… highly luminous supergiant stars… I swear to god this is the truth… pulsationally unstable… periods between 1.5 and 60 days… 400 pounds, a box… I just lifted it with my bare hands…. relationship between period and flux… would have never happened if I hadn’t rubbed my hands together… you know how it feels warm when you do that?… rare stars… hey… nearest Cepheid is Polaris… difficulty is calibrating luminosity… hey… north star is a variable star. North star is a variable star. I thought there was something profound in that.

… hey! Are you listening??

Can you hear me??

“Ok look,” I hadn’t said anything in about 20 minutes. “You think I can read my book?”

He looked unhappy and I was a little sorry for it. Poor guy didn’t know anything about physical principles. He’d absorbed a couple of keywords here and there, heard about some concepts, and pieced them together into a random narrative that didn’t make a bit of sense. This guy was a little busted but it’s something I’ve been seeing a lot of lately. The assumption is that knowing the names of things is the same as knowing the things. It’s an equivalence of the scientific endeavor which is vast and noble with its by-products, and connected with the idea that the thing science should not be encouraged because of what humans do with the knowledge gained. I glanced at an open book on the dining room table today (The Omnivore’s Dilemma) which accused science of being “reductionist”:

To reduce such a vast biological complexity to NPK represented the scientific method at its reductionist worst. Complex qualities are reduced to simple quantities; biology gives way to chemistry… The problem is that once science has reduced a complex phenomenon to a couple of variables, however important they may be, the natural tendency is to overlook everything else, to assume that what you can measure is all there is, or at least all that really matters.

This criticism of the scientific method, for instance, is no criticism of the scientific method at all. It’s a criticism of human beings with limited capacity for complexity and ambiguity. If a thing can be described by a finite set of parameters, and they each have an effect on the whole, then they, by definition, can be measured (in principle, at least). Science attempts to determine some of these parameters in order to understand better a more fundamental mechanism. If we were to stop at simply describing the properties of the thing itself, then the knowledge gained is narrow and more or less useless (“stamp collecting,” as Rutherford called it), so scientists tend to move on from a particular subject after some time in search of the answers to a more interesting question. They provide documentation of their research so that others may focus on another aspect of the same topic and extend their investigation in perhaps another, also interesting, direction. This gets somehow interpreted as reduction. The actual reduction is not occurring at the level of the science, but at the level of those who are applying some small bit of knowledge gained to public policy, who are careless or pragmatic or what-else. I just can’t justify the defensiveness of the general populace when it comes to scientific principles. I can only imagine it is a reaction to the exclusivity maintained by the scientific community. The average person feels like an absolute outsider, informed by loose threads of dubious journalism which twist the truth this way and that in order to suit a certain personal world view. Then they get scared and think science is trying to take away their individuality. Lately I’ve noticed mainly two kinds of reactions to any general scientific discussion: a complete refusal to participate (“that stuff’s never made any sense to me”) and a thorough and immediate recall of every bit of scientific trivia related to the matter at hand. A general fear of the conversation.

Back on the bus, friction man was disgruntled. Mumbled something about being in the army and a gunshot to the head then stared straight ahead. I didn’t ask him to elaborate.

I did start wishing, though, that I had my pepper spray on me, pepper spray that wasn’t shaped like a toy gun (dad…). Even though that would be a pretty lame thing to do on a bus. I couldn’t read any more for having to watch him out of the side of my eyes. He fidgeted a whole bunch. 5 minutes pass. Finally, he picked up his backpack, and with the dignity worthy of a king, walked up to the only other empty seat on the bus, and sat down, 3 rows up.

I breathed a sigh of relief and read some more about standard candles.

We ended up being on that bus for 3 hours. I realized today (sitting on that bus) that Highway 17 is really the mechanism that preserves this certain “unique”-ness that folks like to attribute to Santa Cruz. In an excruciating way but mindful, discouraging newness like geography and a poorly designed transit systems only could, through its sheer stubbornness and difficulty. When the only artery in and out of a city is a winding, 2 lane “highway” through the mountains for 25 miles with a speed limit of 45, which comes to a frequent and complete halt in the case of any traffic incident or volume (google “highway 17 accidents”), a place can feel pretty isolated. Santa Cruz is less than 30 miles from the heart of the Silicon Valley. Yet it has no living industry besides tourism. It has none of the hustle-bustle intensity of its neighbors, none of the mass-produced mass-consumed mass culture, none of the ambition and restlessness. It’s idyllic– like a beautiful accident. But it’s no accident. Many people are grateful of the state of the place without knowing what they’re grateful toward. It seems to me that Santa Cruz is more a place where people come to settle down. It’s the town of Spectre in the movie Big Fish. This is where young people come to experiment with doing nothing, wind up growing old and living forever.

Jammed up end to a pseudo-science day

We were all thinking the same thing. We had a lot of time. We were 40 people sitting in silence, making private, furious plans to one day move closer to where we work. I made a flow chart.


I didn’t seem to have too many options.

We had waited at the bus stop for the 7:45 until 8:15. And now, finally on the road, the bus hadn’t moved a meter in 45 minutes. When I got sick of reading, I entertained myself by contemplating the nature of traffic jams. How, in a bottleneck-free situation, jams propagate like longitudinal waves through a medium. The cars ahead of the jam dissipate as cars behind pile on, and as long as a constant flow of cars is maintained with a flux which is high enough per unit of time for a car to get from one end of the jam to the other, the jam moves through the cars like a constant amplitude, constant velocity density wave. Much like the spiral arms of the Milky Way Galaxy. Regions of high density, which are the result of small velocity and density fluctuations in the interstellar gas, are not made of the same stars and planets and particles always, instead, stars and gases pass through these regions, like we pass through traffic jams. Eventually.

Some have even proposed that the passing of the Solar System through the spiral arms of the Milky Way could be the cause for the temperature and climate fluctuations on Earth. Much like being stuck in a traffic jam could have effects on the temperament and blood pressure of its constituents, the solar system, bathed in the cosmic rays of these more active regions, may experience noticeable changes as well. However, researchers claim to have debunked this theory using more precise mappings of the galaxy. I remember doing this lab in 8.14 (Experimental Physics) using a radio telescope to measure the abundance and redshift of hydrogen gas in the Milky Way. It was not an easy lab. Our errors were pretty huge. This was the best we could do for the location of the spiral arms.

On the other hand, if there is a bottleneck in the road, and vehicles are forced to move bumper-to-bumper, I imagine traffic could be approximated quite well by an incompressible flow with smooth boundary conditions. That’s just a flow with a constant density, or particles per unit volume, everywhere, that runs into no sudden stops or sharp corners. The key concept here in the steady state solution is then conservation of mass. We place the restriction that the rate of mass entering any imaginary volume you draw within the flow must equal the rate of mass leaving (otherwise the density within this volume would change and it would no longer be considered incompressible). If, in particular, you align your volume so that it has an area A perpendicular to the direction of flow and length x that is parallel, you can write

The above holds for all locations in the flow. This implies for any two sites

Applied to our idealized traffic situation, an expression can be found for the average speed of a vehicle stuck in the traffic queue as a function of the speed of traffic currently passing through the bottleneck and the lane reduction.

For instance, an accident causes a 3 to 1 lane reduction. This necessarily results in backed-up traffic moving at about 1/3 the speed of traffic currently passing the site of the accident. Now imagine that this is a really spectacular accident and there is a lot to see. The folks passing by the commotion want to get a good view so they’re driving 15 mph. This limits the speed of the poor blokes in the vehicles farther back to an average of about 5 mph. This is the effect of “rubbernecking”. It’s unlikely that it will end though, who doesn’t want to reap the rewards of hours of boring waiting?

(Of course there are limitations to this highly simplified model. For instance, the assumption of an incompressible flow is unrealistic when vehicle velocities are high, as safe driving practices do not dictate driving bumper-to-bumper at 45 mph. When incompressibility breaks down enter the density waves discussed earlier. In addition, since lane closures do not constitute a smooth transition but rather an abrupt change in boundary conditions, there’s a feedback mechanism which limits the speed of cars in the bottleneck according to how smoothly they can merge and how quickly they can accelerate, which then goes on to affect cars farther back in the queue.)

Anyhow, 2 1/2 hours of crawling later we got our moment. Faces went immediately to the windows.

There were 10 cop cars and 3 tow trucks at the site of the accident and one slow-moving lane of traffic. And though I rubbernecked as hard as I could, I could see no wreck in the darkness. Just 15 or so cops standing on the side of the road with their hands in their pockets. Like they were bored. Like nothing had happened at all.

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3 thoughts on “North star is an airplane

  1. Angelica says:

    hello–

    my twin is a (sophomore) physics major, and i want to give her some Feynman books for our birthday. any suggestions? i believe she has six easy pieces, six not so easy pieces, and QED.

    btw, your blog and photographs (goodness, the photographs!) are fantastic 🙂

    angelica

  2. Lulu Liu says:

    You’ve definitely gotta go with surely you’re joking. I’ve not read the other autobiographical piece (what do you care what other people think) but probably will soon 😛

    I have his lecture series- they come in a set- bound beautifully- makes for a nice presentation

  3. Your writing is lovely.
    And you have EVERY option that “shut up and ride the bus” fails to contain.In other words; there’s a whole world out there, and you can go anywhere and do anything in/on it.
    Sometimes, we set limits for ourselves that don’t exist.
    We set them for ourselves, we feel obligated to accept them because of someone else…
    Flowcharts are good, but better drawn on a plane (mathematical and aeronautical), than on a sheet of paper on a bus.

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