When I was at MIT I worked on a cute little planet-finder satellite whose instruments were built and tested on the 5th floor of a certain Building 37. 37 was how it was known around campus, but it had an official name, too, it was the Kavli Center for Astrophysics and Space Research. Anyways, they gave me a key to the front doors for after-hours access and as I had scant few keys I took a little pride in letting it jangle around on my keychain. I ended up doing my senior thesis with this group, come spring I probably spent more nights in that building than in my dorm room, going through tank after tank of liquid nitrogen. Where I really wanted to be back then, though, was one floor up. The theoretical astrophysics at MIT happened on the 6th floor of the Kavli Building. It was much better lit, for some reason, with an open floor plan, wood doors and accents, lounges and common rooms, populated with couches, tables, coffee stations, fresh paint coated every wall. It just exuded this warmth that contrasted the long narrow bleakness of the 5th floor hall. When I took Quantum, General Relativity, I had occasion to venture up there, to drop off homework, to visit a professor, to attend office hours in one of its well-groomed nooks. But I never did work up the nerve to ask to join a theory group. I had this confidence issue that I’ve still not managed to shake completely.
Anyways that was the Kavli Center I knew at MIT. Building 37 where I studied physics and researched engineering. Fast forward a year later I would be so shocked in my sojourns to come across another Kavli Institute. Number two. This time at Stanford– KIPAC, it’s called, its hard-to-pronounce acronym short for Kavli Institute for Particle Astrophysics and Cosmology. Now this was a little different. Stanford is famously home to the longest linear particle accelerator in the world, so naturally, much of what goes on in astrophysics here acquires a particle physics tint– one of the more interesting interdisciplinary fields in my opinion. This Kavli Institute is a bit of a maze. Forget the long, straight halls of Building 37, this one’s filled with round-abouts and dead-ends. It took me 2 months to find the staircase to the second floor. Even so, out of habit I still come in on the elevator and leave through the patio. I’m working with a theory group here. So it resembles more the 6th floor than the 5th. I’ve yet to see a liquid nitrogen tank floating around the halls and that’s just fine with me. They’ve set me up in the visitor’s office and sometimes when most everyone is gone in the evenings I take off my shoes and plod around on the hardwood, marveling at just how clean and smooth the floors are.
Where there’s two, there must be more. Today I was reading an article on a rendition of Copenhagen to take place at UCSB, when I ran into mention of Kavli Institute Number 3:
Gross, director of UCSB’s Kavli Institute for Theoretical Physics, plays Heisenberg — whom he met early in his career. The play is structured around Heisenberg’s famous uncertainty principle: the dizzying notion that observing an event changes it, and so nothing can be known with precision. (…)
Aside from 9 mentions of the Nobel Prize in a 500 word article, it’s actually pretty interesting. I found it particularly curious the bit at the end, where Gross mentions having been able to ascertain the actors’ lack of scientific background from a few telling slips during the performance. Considering a play is scripted I wonder what he could mean.
Where there’s three, there must be many. So finally, today, I looked up the Kavli Institutes. 15 scattered all around the world, seeded by one Fred Kavli, physicist by training, engineer and businessman by trade, one of the world’s most successful private contractors by the age of 40– a self-made man in every way. Some of these institutes he started from scratch, some were existing organizations to which he gave huge sums of money, all in order to further three specific fields which he finds to be most promising: Astrophysics/Theoretical Physics, Nanoscience, and Neuroscience (‘from the biggest, to the smallest, to the most complex‘, he says). The goal? To seed new ideas in their earliest stages, to be the first to offer support, and no doubt to make a name for himself as one of the greatest philanthropists alive.
Right now I’m amused to read about a man like this. At this point, he has made more contribution to science as an entrepreneur than he ever would have as a research scientist or even a professor. Just something to think about.
I woke up this morning with a deep sense of well-being. In my bones I felt like something had changed. Maybe it was that for the first time since October, I woke up warm, easy, and unconcerned, having gone out last night to Ross’s on River St and purchased a beige-colored faux down second comforter with my now-expendable income. I didn’t wear a sweatshirt to bed. I woke up all wrapped up in a plethora of fabric.
Maybe it was just that it reminded me of home, that when I opened my eyes I expected to see the original pale blue walls of my old room in Connecticut. It would be winter now and the heat would be on low to save on gas bills, the frost which grows on the tree branches outside would have crawled halfway up my window in the night. My nose would be cold in the dim morning but my body warm under the covers. I peek at the clock: 7:05. I peek at the dresser: 6 feet away. I pull the covers over my head instead. I may seem to be making only incremental progress but beneath my sleepy visage there raged a shifting, fierce battle in which I was slowly gaining the upper hand.
As always, a glass of chocolate milk and a peanut butter cookie greets me on the kitchen table. The spoils of war.
No one is born with a love of science. I’ve met folks who take to science like fish take to water, but even so, they weren’t born knowing it. There are formative years, when we morph like clay to any external stimulus, when we really lay the wires for the decisions to come that will motivate us to live and resolve us to our endeavors, that many will attribute to an innate love of science. But even this is untapped potential without exposure. My friend once joked that half our graduating class at MIT are here because of Bill Nye the Science Guy. I used to watch Bill Nye the Science Guy and the Magic School Bus back-to-back after school. I discovered science as something I loved about the same time I discovered chocolate cake.
There’s much distrust and fear of science. There’s much detraction and misunderstanding of its goals. Sometimes I stand up for the institution which I think is noble and good but sometimes I think they’re not entirely wrong.
My housemate once said something I found egregious. We had been talking about the events of 9/11 and I was commenting on the importance of skepticism at the time. I had asked him if he had done any fact-checking on the validity of the evidence which has convinced him of his particular views. “It’s impossible to check all the facts,” he replied. “that’s why we rely on ‘expert testimony’.” As I was thinking about how to respond to that comment, he added, “You like physics, right? Well, have you gone through and fact-checked every piece of information your professors have given you?” For a second, I was stunned, then, I was horrified. “No, but I should,” it started making sense to me. “And I will. Eventually, I have to.” Why all these people are so skeptical of “science” when “science” is just the name given to a pursuit of knowledge.
Truth. Truth with a capital T is not a matter of definition. It’s independent of the instruments which discover it, the methods by which it’s disseminated. I tried to explain. Science lives by its fact checkers. If we didn’t question established rules there would never be any progress toward the truth. We’d be as ignorant today as the day we first walked the Earth. Yes, I’m guilty of taking some unconfirmed assertions as fact, but that’s a mere coincidence of my inexperience– what you’re alluding to is the fault of a person, not the decree of a science.
But the damage has already been done. For as long as science has existed, pseudoscience has been right by its side. But something alarming is the case in this so-called scientific age. Most people perceive no difference between the two. In part, science journalism is to blame. The business of “selling science” has left the public in a doozy. First, coffee is good for you; then, coffee will give you a heart attack; coffee will make you smarter, stupider, live forever. Readers are left to hang on a few percentage points without ever being educated about the margin of error. They’re sent into a panic about the possibility of disaster without being informed of the insignificant odds. And journalists are only feeding the frenzy, overextending facts to break big interesting stories with magazine sales through the roof and intellectual honesty all but out the window.
No wonder the public backlash against science. Listen to us, we seem to be saying, we’re experts, our opinions are as good as fact. Then what of actual facts? Are our journalists are not discriminating enough to sort them out, our public too uneducated to put it together? We lie by omission. We appeal to authority. And when experts disagree with each other we’re left to conclude there must be no objective fact, the truth is our invention, what’s real and what’s imaginary is simply a matter of opinion. Presented in this form, science is no better than just another form of indoctrination. Propaganda. No wonder.
Good science teachers encourage us to see for ourselves. When I was 10 or 11 I came home one day to Bill Nye the Science Guy on my TV chattering about different wavelengths of light. It is selective absorption of light which gives things color, he announced, to great fanfare. Light carries energy. This is why black things are warmer than white things. See for yourself!
So I went around touching things. For days I did. I started noticing how much warmer black cars were than white cars, how my hair seemed to catch fire in the direct sun. I even conducted an experiment with my mom’s collection of fabrics. I cut little swatches out of each material and lined them all up under the kitchen light. I let them sit for an appropriate amount of time and then with my eyes closed tried to separate the dark ones from the light ones (this endeavor was only somewhat successful). But there really was a difference! And so I was convinced of this particular fact.
How easy it is for me to put my faith in science when I’ve felt like a participant for most of my life. Yet I was not born with a love of science. My privilege was to be included in the scientific dialog. My education consisted of progressive versions of reality. Each beloved theory a model carefully constructed, dressed up, and committed to memory only to be mercilessly toppled and replaced by the next. And so, like this, I learned that science is about not knowing. A friend and classmate used to say that the only result of his scientific education was that he was not sure of anything any more. Good scientific journalism must recognize this fact– present the evidence, explain the logic– lift the veil of invincibility and open a real line of communication with the public.
In some ways, scientists are to blame. The scientific community is a community of people, and as such is not free of human quarrels, intrigue, pride, short-sightedness. It’s not unusual for even great scientists to make it their objective to “thin the herd”. The herd is, of course, referring to interested non-professionals, prospective students of their discipline, even peers. The objective? Ostensibly an improved level of dialogue, a higher mean quality of work, and undeniably, exclusivity.
3rd year students at MIT majoring in physics take a year-long lab sequence which introduces them to some landmark physics experiments of the 20th century. “Junior Lab”, as it’s termed, is, for most students, their very first exposure to what it takes (at least from the experiment portion onwards) to conduct a truly independent investigation in science. Each of the 10 experiments culminates in a scientific paper and a 15-minute oral presentation. Most students who go on to be physicists find this experience invaluable. But there is much dread, as well. Junior Lab is high pressure, fast-paced, and generally unsympathetic. In every way a weeder course for the physics major except that it occurs way too late into our studies.
Certain professors of the course have accumulated over the years particularly frightful reputations. One professor, a pioneer in the field of quantum computing, was legendary among the student for his offensively direct, sometimes unduly harsh, criticisms. His evaluations, instead of comments on the quality of the students’ work, often strayed into an assessment of a student’s abilities. Sometimes they were humorous. On a graded paper, I once saw the following annotation, “Much better than last time, but still terrible.”
Other times, they seemed to border on malicious. He took the opportunity of the public oral oftentimes to really drive home some of his earlier critiques. The public oral (held at the end of the first semester), was an opportunity for students to practice speaking to a large audience. Students, friends, and professors are all invited to attend. There are snacks and projectors and everybody’s dressed up. It can be a nerve-wracking experience. There would be follow-up questions on the apparatus, the data gathered, the analysis, then, “You’re an awful physicist,” he would spit out, during the question-answer session following a presentation. “You’re embarrassing yourself. You should drop this class.” I’m not sure if anybody ever attempted to defend the kids at the front of the room. Even as they stood there crying.
Scientists have a reputation for heartlessness. They have a stigma for being only tenuously human, curious and stubborn creatures with a fuzzy moral code. They do little to disabuse the public of this impression. In fact, it’s not out of the question that it’s even a source of pride, this “otherness”.
There’s no doubt that we’re looking at an elite crowd. But then who can blame the public for their distrust of scientists, and in turn, suspicion toward scientific evidence and the basic tenets which guide the scientific endeavor? Exclusivity and exclusion are one in the same. But this raises several questions, does the public really deserve to be ostracized? Is this ultimately beneficial to our cause?
Who among my generation of scientists has not heard of Carl Sagan? In his series, “Cosmos”, Carl Sagan said, “Cosmos is a Greek word for the order of the universe. In a way, it’s the opposite of chaos. It implies a deep interconnectedness of all things. The intricate and subtle way that the universe is put together.” Ultimately, he devoted his public life to addressing just one question, “why science?” His answer was two decades long and his strategy was to have a conversation with the people. He presupposed their capacity to understand. He impressed them with his humanness. And the people responded en masse.
But ironically, Sagan was least popular with those for whom he advocated the most. In 1992 Carl Sagan came before the National Academy of Sciences as a nominee for membership in the most prestigious of science organizations in the world and was rejected despite the thumbs-up vote from the astronomy sub-community of members. His public persona was to blame. By that time he had written over 20 books, directed several movies and TV shows. (Not to mention he had also published some 600 scientific papers and made significant contributions to the study of planetary astronomy) But that was enough. As it turns out, his popularity discredited him. He was an egomaniac, they said, not a real scientist.
This is not an unfamiliar tune. When I mentioned to a professor once an interest in science journalism, his kindly response was that he thought I might be capable of a lot “more”. When I made the decision to put off graduate school until I’ve better defined my interests, I was warned against the implication this would have on my chances of being taken seriously later on. That there are precious few real ambassadors of science is no doubt a testament to the great command of the purist view point over the scientific minds of today. Our nostalgia for the past great eras of discovery and innovation have driven us to, at times, rally against our best interests. The unfortunate truth is that the business of science has superseded our love of it — what set us going from the beginning, this devotion to truth and progress, is now just an afterthought. It’s a sickness in the scientific community that goes to show just how human we really are. But while we judge and quarrel and blame and bicker, the next generation of scientists have just opened their eyes and are glimpsing our world for the first time. If science is to live on, it cannot lose its advocates.
A recent study of Google Earth images revealed a preferential spatial alignment for grazing and resting cattle. In a survey of over 8000 cows in about 300 pastures, the study found conclusive evidence of a significant deviation from random orientation with preference for a magnetic North-South direction. They were able to use global differences in positions to rule out the effects of wind and sun, and show a statistical correlation which favored magnetic north over geographic north as a predictor of cattle pointing direction. In other words, cows are dipoles. But they’re not the only ones. Deer show an even stronger alignment with the magnetic poles. Look at this diagram from the original paper:
A is cattle, B is roe deer, C is red deer.
That’s a great looking distribution in the middle. I wish they’d clean it up and fit to it. I expect to see a follow-up study calculating the effective magnetic dipole moment of the cow.
The theory. If you’ve ever played with two bar magnets you know there is an orientation to the magnetic attraction between them. Indeed, the magnetic field is a vector field and dipoles tend to line up along its field lines. The needle of a compass for example is a magnetic dipole. If allowed to spin freely, it will point toward magnetic north/south. A dipole in a magnetic field feels a torque which is proportional to the strength of the field and the magnetic moment of the dipole.
T is the torque, u is the magnetic moment, B is the external magnetic field (of the earth, in this case).
This torque will tend to spin it in the direction of the magnetic field line. Viewed another way, the energy of a dipole in an external magnetic field is:
The natural inclination of a system is to move from a higher energy state to a lower energy state. The lowest energy in this case is represented by the case where u and B are aligned (theta = 0), therefore their dot product is maximized, and the energy is most negative.
Now, cows are lazy, and they undergo some kind of random motion, so naturally there will be a width to the distribution of the probability that a cow will be pointing in a given direction. Now, if this random motion is associated purely with thermal energy, the pointing probability could be calculated exactly. My guess is that it’s more complicated than that. If I come up with a good way to model it, I’ll probably publish the follow-up paper.
An interesting side note is that many animals have already been well-documented to have internal magnetic sensors. Birds and salmon have been known to use magnetic field lines to navigate their migration. Apparently, even rodents possess some kind of internal magnetic compass. What they need it for is beyond me. Interestingly, some studies suggest humans who sleep oriented East-West experience shorter REM sleep periods than humans who sleep oriented North-South. REM sleep is apparently important for memory, alertness, creativity, and every other good thing our brain does. There’s something, after all, to be said for feng-shuing your room.
From randomness, order.
My life has been evolving slowly to become more and more structured and less and less what I feel like I really ought to be doing. In addition I’ve experienced a noticeable decrease in REM sleep lately as my days and nights have really filled themselves up. This is only adding to my sense of confusion.
Mondays and Fridays I teach at the UC. Mondays are discussion sections and Fridays are labs. I’ve been doing this for 3 weeks now and it hasn’t gotten any easier carrying 50 lab notebooks across Science Hill.
Tuesdays and Thursdays I tutor middle and high school students in Aptos. This last Thursday one of my duties was to help a 7th grader finish his auto-biographical slideshow presentation. His accomplishments included being the last to be cut from the basketball team and almost making the honor roll in the 5th grade. His goals were one day be richer than Bill Gates.
Wednesdays I head up to Stanford to report on the meager progress I’ve made that week in my research. This wednesday I bring up the issue of funding for probably the last time.
Yesterday I helped bartend at a frat party. Someone stole a handle of vodka and a $1.50 jug of safeway brand orange juice. A vinyl record was pilfered from the DJs. Party was eventually broken up by the police around 11:30. Pretty classy stuff. I’ve been thinking about getting a job in sustainable energy and bartending on the side.
In other news I bought a used 2000 Volkswaggen Passat with a V6 engine and a moon roof. I’m going to use it to learn how to drive stick. Also, I’ll probably use it to get around.
And move.
I don’t know where I’m going to move to come spring but I will move somewhere.
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.
Ancient Egyptians lived inside of a great celestial sphere. To them, the sun, the stars, the moon, were all points of light plastered on the under-surface of this sphere, born each night out of the horizon as the sphere rotated east to west. All these things: stars, sun, moon, horizon, held deep wonder and spiritual meaning for the civilization. And life revolved delicately around these beliefs.
But no, the truth is more beautiful. We are points of light floating in deep space; we are one of many. I’d like to think they’d be amazed to hear it.
I remember from cosmology class the Night Sky Problem. It’s a great illustration of the many things we take for granted. In 1826 Olber asked a simple question, why is the night sky dark?, and astonished everyone. You see, back then, we believed the Universe was infinitely large and infinitely old, filled with an infinite number of stars at some finite density and luminosity. This means, intuitively (also rigorously, but that won’t be necessary here), every line of sight should end on a star. The sky should be, on average, everywhere as bright as our sun.
It was Edgar Allen Poe who preempted all the scientists by providing the first hint at a solution to the problem. Finite time. He wrote, in the rather controversial “Eureka”:
“Were the succession of stars endless, then the background of the sky would present us an uniform density… since there could be absolutely no point, in all that background, at which would not exist a star. The only mode, therefore, in which, under such a state of affairs, we could comprehend the voids which our telescopes find in innumerable directions, would be by supposing the distance of the invisible background so immense that no ray from it has yet been able to reach us at all.”
No one would be sure whether or not he was joking, (“because nothing was, therefore all things are.”), but on this topic, he would be right. The universe (that we know and live in) has a finite age. Current estimates place it at approximately 13.5 billion years. Light also travels at a finite speed. As we look deeper into space, we look further back in time. In fact, the whole history and evolution of the universe is painted right into the sky, it’s there for us to read if we know how, and where, to look. Imagine being able to look at a person, or an object, and see its whole history. This is one of the most profound things about cosmology.
The horizon distance is the distance to the edge of the current, observable universe. The distance from which light emitted immediately after the Big Bang is just now reaching the earth. This distance is very large. But it is not infinite. This is the main reason why the sky is full of holes.
But not the only. Light from the most distant sources are also redshifted dramatically as it travels to earth, by the continuing expansion of the universe. For example, the sky is nearly isotropically covered in a faint glow of microwaves from the last scattering of photons by the plasma which pervaded the early universe (at redshift 1100). Since our eyes cannot see in radio, or microwaves, or infrared, the sky appears dark to our eyes where it doesn’t, say, to a powerful radio telescope.
On the other hand, if you were to climb to Glacier Point in Yosemite and look up into the night sky there, you might not think it dark at all…
(This all goes back to the importance of asking questions. Easy questions. Obvious questions. Those are usually the ones most difficult to answer.)
Meanwhile, back on earth, my to-do list hasn’t changed in 2 weeks:
finish cosmology problem sets
read papers
order b&w film
The last time I worked with film was high school. But then we had to develop our own negatives and enlarge our own prints in the dark room. For a small(?) fee of $7 here, Fuji will do all the work for you. I got my first 2 rolls of slide film back, shot with a borrowed Nikon FE film camera with a 35 mm lens and UV filter. The film is Velvia ISO 50 slide film, which is famous for its warm tones and almost offensively vivid colors.
Slides are such dainty little things.
A few I’ve scanned into the computer using AJ’s scanner. All shot during the last 2 weeks in Santa Cruz, CA.
My brain’s telling me there’s some really satisfying quality about these pictures that I can’t achieve with digital. But maybe it’s just the placebo effect. In any case, I really need to go back to Wilder Ranch.
