shakabuku

Hola, mis amigos! Jen-Luc Piquant and I have returned from our South American sojourn, well-rested, and a bit too well-fed, thanks to great, cheap food and those tasty little alfajores -- dulce de leche sandwiched between wafer cookies -- that one can purchase on practically every street corner. (Argentines are diehard meat and potatoes and pastry people; we barely saw any fresh vegetables at all during our stay, save for some wilted iceberg lettuce and one pale excuse for a tomato, together gamely attempting to masquerade as a "salad.") Mega-kudos to guest-blogger Lee Kottner for filling in so ably and eloquently in our absence; she'll be posting at least once more in the future with an update on the space elevator story, so sci-fi fans, stay tuned.

We are, needless to say, a bit out of touch with what's been going on the last 10 days in the dear old U.S. of A. (The first thing that caught Jen-Luc's gourmand eye this morning is the news that scientists have created a hybrid form of chocolate that won't melt to a sticky goo in the heat.) Among other things, Internet access was sporadic at best: once a day we repaired to the corner locutorio to use one of the public broadband connections, and there really wasn't much time for leisurely perusal of our usual feeds.

But that's okay. Because there's something about being in a foreign country that shifts one's perspective -- in a good way.  We all need to view things from a different angle now and then, intellectually, emotionally, and physically. A trip to a different hemisphere can be just the ticket. It reminds me of a scene in one of my all-time favorite films, Grosse Pointe Blank, in which John Cusack's amoral (but reforming) hitman is having drinks with the lost love of his life, former high school prom date Debi. "You know what you need?" she tells him. "Shakabuku." She describes it as "a swift, spiritual kick to the head that alters your reality forever."

I was reminded of shakabuku while perusing a tome of deep profundity on my vacation: Huw Price's Time's Arrow and Archimedes' Point. (Yes, we know it's hardly light summer reading; blame it on Jen-Luc's pernicious influence. Left to my own devices, I mostly read about pirates.) Price is a philosopher by trade, with an abiding interest in physics, and in this instance he tackles the problem of entropy and time's arrow -- why time only moves forward into the future, not backward into the past, in our everyday reality, even though mathematically, there is no such distinction between past and present -- from the perspective of philosophy. The entire book essentially deals with how scientists can be limited by their constrained perspectives, particularly when it comes to the knotty problem of time, and emphasizes how useful it can be to look at familiar subjects from a new vantage point. (For all his redundancy and tangled "academese" -- which makes for a rather labored prose style -- Price is not lacking a sense of humor; his preface opens with a quote from Groucho Marx: "Time flies like an arrow; fruit flies like a banana.")

Archimedes, you may recall, was a natural philosopher (a.k.a., early scientist) in ancient Greece who famously offered to move the Earth, provided someone would supply him not just with a big enough lever, but a broader perspective -- a vantage point outside his earth-bound reality from which he could, for instance, view both a pebble and the earth as exactly the same kind of thing, "differing only in size." Archimedes called this the "view from nowhere."

Price contends that when it comes to time's arrow, physicists need to take a "view from nowhen," being more vigilant about taking their own embedded perceptions about time into account when constructing theories about the universe. Per Price: "We are creatures in time, and this has a very great effect on how we think about time and the temporal aspects of reality.... [I]t is very difficult to distinguish what is an aspect of reality from what is a kind of appearance, or artifact, of the particular perspective from which we regard reality."

Price is the first to point out that this notion of a fresh vantage point is not a new one, in philosophy or science. In fact, that's what often leads to revolutionary breakthroughs -- the most obvious example being the heliocentric (sun-centered) cosmology of Copernicus, which eventually toppled the earth-centric view of the solar system espoused since the days of Ptolemy. Charles Darwin's theory of evolution impelled a similar perspective-shifting breakthrough in biology.

When it comes to entropy and time's arrow, the prevailing modern view dates back to an Austrian physicist named Ludwig Boltzmann. The son of a taxation official, Boltzmann earned his PhD in physics from the University of Vienna under the tutelage of Josef Stefan. He moved around a lot in his academic career, partly due to his mercurial mood swings: he joked that these were due to his being born (in 1844) during the dying hours of a Mardi Gras ball, but there is some evidence that he suffered from what we now call bipolar disorder. He also engaged in numerous intellectual feuds with his fellow scientists, most notably with Ernst Mach.

Boltzmann's doctoral thesis was on the kinetic theory of gases, and this ultimately led to his invention of statistical mechanics, which connected the properties and behavior of individual atoms and molecules with the macro-scale properties and behavior of the substances made of those atoms and molecules -- substances like, say, a gas. Boltzmann is the one who derived, statistically, the second law of thermodynamics,  namely, that entropy always increases. We experience this every day: heat cannot flow from a colder to a hotter body; a cup of coffee cools at room temperature, rather than the other way around. Shatter the cup, and it won't miraculously self-assemble, either. That's entropy, the basis for the arrow of time. Entropy also has important ramifications for cosmology: entropy increases because our universe began in a state of extremely low entropy, but physicists still can't explain how that highly unlikely low-entropic state came about to begin with.  (We have no deep thoughts on this particular conundrum, having not quite finished Price's rather dense tome -- besides, cosmologists themselves are still trying to puzzle it out.)

Before Boltzmann, entropy was deemed to be an absolute law of physics. But when viewed from a statistical viewpoint, an increase in entropy in any given system is merely the most likely probability. There is a tiny, infinitesimal chance that entropy could decrease in a system. The best analogy is to envision a glass container filled with a gas. Uncork the container, and the atoms and molecules that make up the gas will be released into the atmosphere at large, gradually dissipating among all the other atoms and molecules. It is highly unlikely, statistically speaking, that we could get each and every original molecule of gas back into the container, any more than we could toss a glass of water into the sea and then retrieve the same exact glass of water.

This statistical, probabilistic view is also the basis for a famous 19th century thought experiment by British physicist James Clerk Maxwell, dubbed "Maxwell's Demon." Maxwell envisioned an imaginary microscopic creature able to wring order out of disorder to produce energy, chiefly by making heat flow from a cold substance to a hot one in (apparent) violation of the second law of thermodynamics. The imp guards a small hole in a wall separating two compartments of a gas-filled container, and can open and close a small shutter covering the hole at will. The gas in each compartment begins in a state of statistical equilibrium, with the average speed and temperature of the molecules being roughly the same.

But this equilibrium doesn't last. Whenever the demon sees a fast-moving molecule in the right-hand compartment approach the pinhole, he opens the shutter briefly to let it through the left side, and he does the same to enable slower-moving molecules on the left to enter the right-hand compartment. So over time, the gas on the left gets hotter while that on the right gets colder. (Physics students will recall that this temperature difference creates potential energy, which can be converted into kinetic energy and harnessed to perform "work.") The demon wrings order out of disorder, almost as if time were "flowing" backwards. Maxwell himself insisted it was essentially a trick question: the demon is putting energy into the system, and itself requires energy in order to do so, ergo, entropy is not violated.

This statistical approach was hotly debated among Boltzmann's scientific contemporaries, and these and other clashes took their toll on the physicist's already fragile mental state. In 1906, while vacationing with his wife and daughter near Trieste, Italy, Boltzmann hanged himself while said wife and daughter were out swimming. His equation for entropy adorns his tombstone (pictured at right). There's quite a bit of speculation as to why Boltzmann chose to end his life; it may or may not have been to growing depression over the non-acceptance of his ideas by the scientific establishment. If so, his despair was premature. Boltzmann's statistical approach to thermodynamics gave birth to quantum physics, thanks to the work of Max Planck in 1900 on black body radiation.

In physics, a "black body" isn't necessarily black -- it's just a term to describe an object that is a perfect emitter and absorber of electromagnetic radiation. When German scientists first studied the problem experimentally around 1900, they expected that as the temperature of the object rose, the amount of emitted radiation would rise accordingly, essentially into infinity. And this was indeed the case, at least until they hit the ultraviolet regime -- at which point the emitted radiation suddenly began to get smaller and smaller again. They dubbed this the "ultraviolet catastrophe." (The average layperson considers, say, a major earthquake to be an actual catastrophe, but physicists really, really hate it when experiment fails to agree with theory -- it's on a par with being hit with an unexpected tsunami.)

Science historians have dubbed Planck a "reluctant revolutionary," because he initially resisted a statistical approach when grappling with the problem of black body radiation. But it proved to hold the key to solving the riddle, and this new perspective on an old problem gave rise to the notion of quanta: namely that atoms can only absorb or emit radiation energy in little packets of fixed amounts, much like currency only comes in fixed monetary units. We won't go into the specifics of how this solved the problem, except to say that infinity is primarily a mathematical concept; in the real world, there always seems to be a limit or threshold of sorts. Planck's quanta effectively placed a cap on how much the emitted radiation of a black body could increase, and once it hit that threshold, it would start decreasing again -- in keeping with experimental observation. And the quantum revolution ensued. That's the power of shakabuku.

No discussion of scientific shakabuku would be complete without mentioning Albert Einstein. Legend has it that his notion of special relativity -- specifically, that there is no fixed frame of reference -- was inspired by a train trip in his youth. As the train pulled out of the station, he pondered how his experience of motion as a passenger on a moving train would be different from the perspective of someone standing on the platform. Years later, he remembered that experience as he was formulating his theory of special relativity, which (among other things) merges three-dimensional space with a fourth dimension of time. And with general relativity, he brought a fresh perspective to gravity, viewing it as the result of curved spacetime caused by the mass of celestial objects. We simply can't see that curvature from our limited perspective, any more than we can feel the curvature of the earth on a cross-country drive from Washington, DC, to, say, Los Angeles. As far as we're concerned, from our limited perspective creeping along the earth's surface, we're driving in a fairly straight line.

These days, string theory is all the rage, having captured the popular imagination with its notion of even more extra dimensions of space -- nine (or ten, if M theory is your hobby horse) spatial dimensions and one dimension of time. (Offering an alternative fresh perspective, Stephen Hawking has also introduced the notion of a second temporal dimension, dubbed "imaginary time," that essentially runs perpendicular to linear time, giving it a kind of "surface area.") As string theory's growing number of naysayers are fond of pointing out, the problem with this extra-dimensional perspective is that physics has yet to figure out a good way to test the theory, however mathematically impressive it may be. Einstein, for instance, predicted that light would be bent by curved spacetime, and this could be (and was, in 1919) observed during an eclipse. But modern technology has yet to catch up with the mathematical theories of string theory, although some physicists hold out hope of finding evidence of extra dimensions once CERN's Large Hadron Collider is up and running.

Whether or not that turns out to be the case, regardless of whether string theory is proved right or wrong, I think we can safely say that if nothing else, it has served to offer a fresh perspective, which will in turn lead to yet another new vantage point -- and one of these is bound to give rise to yet another unprecedented revolution.  It's all about fostering scientific shakabuku. Jen-Luc and I are waiting on tenterhooks to see how it all turns out.

Comments

[RRooter]

It is 'Hola mis amigos'.

[JenLucPiquant]

Gracias. We have duly made the correction. We were forever mixing French and Spanish during our Argentine stay, much to the confusion of the local inhabitants....

[David]

Just dropped by from a science link at DKos. Great site!

[chautauqua]

Another DKos migrant, bookmarking, intent on returning. Very nice blog.

[Neal Deesit]

I've come here from Kos, and I am impressed by your blog. I started college as a science major, switched to philosophy, and took three semesters of History of Science. I still love reading about science and scientists.

As Ahnold says "I'll be back." But before I leave, I want to discuss this bit:

"We experience this every day: heat cannot flow from a colder to a hotter body; a cup of coffee cools at room temperature, rather than the other way around."

Perhaps this is a quibble, but we do not experience that heat "cannot" flow fom a colder to a hotter object. We experience only hot cups of coffee cooling to room temperature.

Based on that, we may justifiably report that heat has not flowed from the colder body to the hotter. By inductive reasoning, we may predict that heat will never flow that way.

But our experience of hot coffee and induction do not prove the impossibily of heat's flowing from cooler to warmer bodies any more than our experience of swans' being white and a similar inductive leap prove the impossibility of swans' being black.

In 1697 in western Australia, Dutch explorers discovered black swans; today, Starbucks' customers all over the world await that "tiny, infinitesimal chance" that their cooling cups of java will warm themselves.

[Jennifer Ouellette]

Neal is absolutely right, and had my brain been a little less fried from an all-night inter-continental flight, I might have expressed that aspect a bit more clearly. That is the fascinating thing about Boltzmann's statistical approach to entropy. His stance that the heat is only most likely to flow from a hotter body to a cooler one was considered quite radical, since implicit in those statistics is a tiny possibility that the opposite could happen. However, I should point out that this kind of statistical fluctuation is so incredibly rare that you'd need to span a time scale that is roughly the age of the universe -- if not more -- in order for this to happen. (Whether this is also true of black swans, I can't say.) Starbucks hasn't been around nearly that long -- although they're mushrooming all over the world on every street corner -- so I hope those customers are prepared for a pretty long wait. :)

[Fred Ross]

String theory not only hasn't produced predictions our experiments could check, it hasn't produced any predictions whatsoever. But more to the point, here are some fun things about the statistical arrow of time that you might enjoy as well.

van Kampen wrote a paper called 'Ten Theorems about Quantum Mechanical Measurements' which is available in a stripped down form in a collection of his writings for laymen called 'Views of a Physicist.' The main example from it goes like this: imagine the two slit experiment. In normal discussions, if you don't 'measure' whether the photon goes through one slit or the other, you get interference. If you do measure it, you don't. And then there is handwaving about collapse of the wave function. van Kampen puts in some physical reality: say we stick an atom in an excited state in one of the slits, but which cannot deexcite unless something distorts its electric field (like a passing particle). If the particle we shoot at the slits goes through the slit with the atom, the atom deexcites and a photon goes whizzing off. It is statistically possible for the photon to return and the atom to reexcite, just horrendously improbable. What we measure is the photon. So the states we have to talk about are not just our incident particle, but the whole system. The space of states divides into two: those in which the photon did go flying off, and those that don't, and it so happens that which slit the particle goes through is entangled with it, so we get a measurement of where it is. As with many paradoxes in probability, the problems only arise when you try to hack up the system into pieces inappropriately. Classically we can, just as the probability paradoxes go away if everything is deterministic, but in the quantum world things don't decompose the same way. Incidentally, collapse of the wave function in this case becomes a theorem: it's the proper way to decompose the spaces given the presence of a measuring apparatus.

In a similar vein, Landau and one of his students proved that in relativistic quantum mechanics, every measurement has a minimal space-time interval which it can occupy. I don't have the reference to hand, but if you look in volume 4 of Landau's Course of Theoretical Physics it's there in the first chapter, or I could dig it up if anyone's interested.

Maxwell's ideas about his demon were made precise in the 20th century, largely by Landauer from IBM's research labs. In fact, it costs entropy kT ln 2 to destroy a bit of information (and by "destroy" I mean mix off into the heat bath until it's irretrievable). These arguments apply to biological systems equally well: enzymes are generally lovely examples of Maxwell demons.

And finally, on the cosmology side, it has nothing to do with origins, but I ran across a pretty little paper about a year ago (again, reference not to hand, I am not in my office, I can dig it out if anyone cares) which says that although the entropy of the universe is increasing, it is not increasing as fast as the maximum possible entropy of the universe, which would just be one big black hole.

[N. Peter Armitage]

And speaking of prefaces with senses of humor, as well as Boltzman... Poor Ludwig also features prominently in one of the best lead-ins into a textbook I have come across - David Goodstein's classic reference on statisical physics, *States of Matter* .

"Ludwig Boltzmann, who spent much of his life studying statistical mechanics, died in 1906, by his own hand. Paul Ehrenfest, carrying on the work, died similarly in 1933. Now it is our turn to study statistical mechanics... Perhaps it will be wise to approach the subject cautiously..."

Makes you wanna dive into eh?

[Alison Chaiken]

Welcome back. The recently published book of Richard Feynman's letters mentions that he and his son Carl had discussed the possibility of two time dimensions. Amusingly Feynman says that he couldn't visualize the resulting space-time but that Carl could.

Another fascinating perspective on time comes from Carver Mead's recent _Collective Electrodynamics_. Mead claims that the obvious way out of the infamous EPR paradox is that time runs backwards sometimes. Mead introduces the idea by picking at Feynman's discussion of electromagnetism in the _Lectures on Physics_. Mead's book is a bit technical but well worth reading for anyone who is comfortable with Jackson's _Classical Electrodynamics_.

The Price book sounds like a winner. I'd have time to read it if weren't for all these dumb blogs.

[JPL]

N. Peter Armitage

Funny but unfortunate that you mention Feynman and Carver Mead in the same comment. The two did not get along as Feynman had to correct Mead a little too often, specially about the issue of reversible computation (which Mean hasn't still understood, so it seems). Mead's book isn't that technical, just worthless. The idea that time-reversibility can "pacify" the EPR paradox is not his but originates with Olivier Costa-de Beauregard and was recently taken up, a lot more constructively, by Aharonov and Vaidman. This, by the way, is also well handled in Price's book which Jennifer so wisely picked and reviews above. If I were you I would sell Mead's book on Amazon and use the proceeds to by me Price's.
Have a nice summer.

[James Kronefield]

Can somebody explain what does "mercurial mood swings" mean?

[anonymous]

really nice psot.

[Leon]

Very entertaining, witty, likeable and inspiring blog.