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Breaking the Ice Shelf - Why Hide the Crack?


The ice shelf breaks away. Click to enlarge.
In December 2006 it was widely reported that the 25.5-square-mile Ayles ice-shelf broke free from Ellesmere island, some 500 miles south of the North Pole. (See the National Geographic report for more details.)

This event actually occurred in 2005 when it had been observed by satellite images (click here for animations of the event), but, according to Luke Copeland of the University of Ottawa Global Laboratory for Cryospheric Research, the information was not released until the reasons for the split could be determined.

Not surprisingly, Copeland and colleagues found that the event, which was sizeable enough to register on earthquake monitors 155 miles away, is consistent with global warming.

I understand that scientists should be as deliberate as possible in doing their research, and circumspect (or silent) about their work until all of the essential methodology of good scientific research prior to publishing are carried out.

But I find it incredibly surprising that the news of the ice-shelf breaking off was held back from publication for almost one-and-a-half years! After all, the ice-shelf cracking is incontrovertible data that is not in question. More important, it is essential data for all inhabitants of this planet.

Why was the news withheld? In all of the news reports and blog posts I have seen covering the ice-shelf split there’s been no questioning of the reason given for the delay. I have even seen some reporting erroneously that satellite photos had recorded the shelf-cracking when it happened, but that this was not noticed on the photos until recently. (See the Climate Audit post by S. McIntyre, who states that "the catastrophe actually occurred in August 2005, but no one noticed until 16 months later.")

No doubt publication of the news would have caused many to speculate that global warming was at work here, and the grim prognostications of global warming predicted for so many years - icebergs breaking free and wreaking unimaginable havoc - were finally coming true. Copeland and his colleagues would have been peppered with requests to say why the shelf had split. Extreme eco-groups would have used the news to bolster their efforts at energizing others to join their cause. Maybe these possibilities were considerations in holding back the news, in addition to the scientific reason.

Or maybe there were political considerations - the scientists were being extremely careful to check all data and analyses before reporting because those who don’t believe in global warming, or, if they do, don’t believe that it is due to human activity, will seize on any inaccuracy or inconsistency to not support efforts to slow down global warming.

I don’t buy any of these reasons - nothing can justify the withholding of factual news of such a large-scale event.

Categories Politics Science Weather & Climate

Locally Localized Gravity, or If I Only Had a Brane


The Institute of Contemporary Art (ICA), at the University of Pennsylvania will be running a very interesting show titled Locally Localized Gravity from January 20 - March 25, 2007. From the ICA website description:

Locally Localized Gravity responds to an alternative mode of art making wherein artists produce events, run collectives and galleries, publish zines and small artist's books—generally acting as catalysts in their communities. In other words, they rarely focus only on traditional object-based practices. The exhibition, which will include over 100 artists, musicians, designers, lecturers, performers, and creators from Philadelphia and other cities, will be one non-stop event and on view in ICA's first floor galleries and terrace. ... The title is borrowed from string theory, a complex scientific term describing four-dimensional gravity (three dimensions of space and one of time). It was suggested to the curators by artist Matthew Ritchie, whose own work explores ideas of string theory, among many things. The term locally localized gravity can be applied to art scenes where artists, by generating a huge amount of energy, can create centers of gravity.

This description of the meaning of LLG is maximally condensed for public consumption. It is not the point of the exhibit, nor the role of ICA to give a detailed explanation. However, because I have participated in an ICA event in the past, I was asked to send them a more detailed blurb on locally localized gravity. While my piece might not make the ICA material, I am posting my submission here because LLG touches on the most extreme questions one can ask of any physical model, namely what is the ultimate nature of the universe?

So here goes.

LLG is a potentially viable theory that may answer one of the most fundamental metaphysical questions about the nature of the universe. Specifically, why do we live in 3-dimensions of space and 1 of time? Although this question might appear to be as unanswerable as "why is a ball round", for years physicists have struggled to reconcile some odd predictions that have come out of attempts to unify gravity and the other three forces that make up the totality of interactions in the observable universe . These predictions call for anything from 5-dimensions up through 26-dimensions. Debates about these theories have a how-many-angels-fit-on-the-head-of-a-pin type quality, but really the ultimate response has been: OK, we'll accept some number of extra dimensions because our theories call for them. Just where in @#$^ are they? Here's where branes come in. Branes are basically membranes that exist in higher-dimension worlds. For example, the surface of a balloon is a 2-dimensional membrane that happens to take on its balloon quality only in a 3-dimensional world. One explanation of the dimension problem is then that the universe that we experience is really a 3+1 (space + time)- dimensioned brane in a larger universe of much higher dimensions. We don't see the extra dimensions because we are literally trapped on our brane (and some would argue trapped in our vision by our brain.) Most do not feel that this is a satisfactory answer to why we see only 3 spatial dimensions. Just what is so special about 3+1 dimensions? A possible answer to this question is one that marries theoretical branes and gravitational brawn. Because of strange quirks with gravity, gravity does not exist on a brane. Instead it sort of "leaks" around branes, and as a result is pretty weak in our brane, but it can be very strong outside our brane. The idea of locally localized gravity is that this intense gravity can cause our brane to look 3-dimensional, even though space has a much higher dimension. Theoretical physicists have already shown that this theory is mathematically viable - they find that either 3- or 7-dimensional branes are the most likely given the assumptions they make for the effect due to the gravity "local" to the brane. This suggests that inhabitants in other parts of the universe might experience other dimensions. (With future advances in space travel, the extra dimensions would make such a location a potentially fantastic vacation resort!)

Given the complexity of these ideas (and their associated very scary mathematics), it is natural to wonder whether the brane-eyed model really provides a deep understanding of the nature of our universe.

I am not qualified to answer this - I barely know anything more about string theory other than what has made it into the popular media. To try to understand string theory enough to understand the brane view of the universe may be possible for me, but not without an extraordinary amount of time and effort.

Because of this lack of understanding on my part, and even though I should know better, I tend to think of all of this brane stuff and hyper-dimensional space as mathematical constructs first - cherished for their mathematically beauty. i.e. I am skeptical about the brane-view of the universe because of my inadequate background in string theory.

This is unfair, I know. But isn’t this what happens with most scientific models and theories that are publicized in some way? It’s not surprising that there are many skeptics - and it’s not really because scientists are not trusted as much as they used to be. Instead, it’s because the skeptics don’t have the background and conceptual framework needed to understand where the understanding comes from.

In short, there can be no understanding of the nature of physical reality without an understanding of how models generate this understanding.

This reflection raises an interesting question, then: if a model is only understandable to a very few, how can it ever have a chance of becoming accepted scientific fact, law, or worldview? I am on dangerous ground here, uncomfortably close to implying that theories are more socially constructed than they are the true facts about the universe.

I don’t see anyway out of this argument though - without a society of "understanders", a theory or model is bankrupt.

Brane or no-brane, I can’t get outside of Plato’s Cave on this one, so I’ll remain in my select corner of the universe, glad that whatever accounts for gravity in my neck of the woods is still working in all dimensions.

For more info on the dimensionality question and LLG, check out Why do we live in 3+1 dimensions?, a summary + set of links describing these wild ideas on the Backreaction blog of Sabine Hossenfelder and Stefan Scherer, theoretical physicists and also wife and husband Their blog, described as Events on the world lines of two theoretical physicists, from the horizon to timelike infinity. A scientifically minded blog with varying amounts of entertainment, distractions, and every day trivialities, is definitely worth a deeper investigation than just this article.

And how does all this connect with art and artists? You’ll just have to check out the ICA show.

Categories Art Philosophy Understanding & Prediction

In Praise of Friction The Media Slips Again


I recently posted a complaint about physics misconceptions promulgated by the media. To be fair, I need to report a good job describing the physics of a situation when it appears.

In an article posted on Dec. 27, 2006 by the op/ed staff of the North County Times (near San Diego), and titled A Physics Lesson, the authors do a very nice job of describing the role of friction in driving:

Your tires rely on friction to speed up, turn or stop. On a dry day, there's usually plenty of friction when the rubber hits the road. When it rains, the weight of your car must push water out of the way for the tires to reach the road. The faster you drive, the greater amount of water your tires must push aside. If that water gets trapped between the asphalt and the tires, you'll lose control of your car -- you'll be hydroplaning. The lesson here is that when the roads are wet, you can't drive as fast as you would on a normal day. Even if the rain is light, slow down at least five to 10 mph.

When I teach a first-semester course in Physics, I typically begin the first day trying to get students to identify forces acting on them as they do basic things. My favorite example is on walking. I ask the following question: if you go from standing still to walking at a steady pace, you accelerated. According to Newton there must be an unbalanced force acting on you in the direction of your acceleration. What is this force?

For those who have never taken a physics course, answers typically range from "my legs", "my feet", "my muscles" to even "my mind." The answer is always a surprise to most students: the force pushing you forward, in effect causing your acceleration, is the force of friction between the floor and your shoes. To understand this, consider that walking on very sheer ice, i.e. a nearly frictionless surface, will get you nowhere!

Later in the course, when circular motion is analyzed, the role of friction in providing the centripetal force needed for turning on a flat curve is then discussed.

So the North County Times do a nice service by stating that "our tires rely on friction to speed up, turn or stop." Indeed, most will tend to identify friction as only a stopping force.

Unfortunately, the authors make an error towards the end of their article.

Rain makes it harder to stop, too. Consider Newton's First Law of Motion: An object in motion tends to stay in motion unless acted upon by another force. That other force, hopefully, is your brakes. The faster you're driving, the longer it's going to take to slow down and stop. When the roads are wet, it takes even more time because there's less friction. Give yourself space -- the lost art of Follow Distance -- when turning, stopping and trailing other drivers. If you're reading bumper stickers in the rain, you're too close.

The error here is mixing in the idea of the force due to the brakes. The force of the brakes do not slow down the car! This is explained by a basic Newtonian fact: for a car to slow down there must be an unbalanced force that opposes the car’s motion. The force of the brakes are not applied in a direction opposite to your motion. Depending on the type of brake (disk brake vs. drum brake), the force is perpendicular to your motion (the brake pad pressing against the wheel in disc brakes), or the force is applied radially outward (brake shoes pressing outward against a brake drum). (See HowStuffWorks for an excellent tutorial on automobile braking.)

The ONLY force that will slow the car down then is the friction between the car and the road. If you still believe that the brakes slow the car down, consider the fact that, even with the best braking system in the world, if there’s no friction the car will slide even if the wheels are completely locked due to the brakes.

So what do the brakes actually do? Surely I can’t be saying that the brakes aren’t necessary to slow the car down! The brakes DO slow down and (hopefully) stop the rotation of the wheels by exerting a torque on the wheels in a direction opposite to the angular velocity of the wheels! Friction plays a huge role here - but it is the friction between the brake pad and disk, or brake shoe and brake drum. More important, it is not the force, but the torque produced by the force that is slowing down the wheel. Water can reduce this friction and hence torque to almost nothing, which is why stopping after driving through a deep puddle is often very iffy.

Some might see my complaint as merely semantics: so the brake force slow down the wheels’ rotation - what’s the big deal in saying that the brake force slows down the car? The problem is in learning how to apply Newton’s Laws successfully, and specifically the 2nd law, one must identify the forces that are acting on a particular object, or system of objects, and analyze these forces in terms of a coordinate system that is used to describe the motion. For rotational motion, it is torques that must be identified and analyzed. It is essential then to be clear: brakes only act on wheels via frictional torques, the road only acts on tires via frictional forces.

So I applaud the North County times for their treatment of friction between the tires and the road, but must call them on their incorrect reference to the brake force.

The article will serve as a good example (or even test question) down the road….

Categories Education Media Science

A Jolting Message: Hemingway's Snow and Climate Change


  Kilimanjaro, then and now. Click to enlarge.I have remarked before on the ever-increasing media coverage given to global warming. As more and more scientific evidence comes in about the effects of global warming (see my recent post On the Increase in Greenland Ice Loss), the facts, interpretations, scientific theories, and political reactions to climate change are incredibly varied in the face of almost overwhelming evidence. Making sense of what is really happening, and how we should react, calls for insightful commentary from expert sources.

One such source is an article by Doug Macdougall of the Scripps Institution of Oceanography titled Jolting Messages on Climate Change. (The Chronicle, April 2006). In addition to his clear enunciation of global climate change facts and a strong call for "jolting messages" that will move "politicians and the public into effective action," Macdougall reviews five books about climate change published in 2005 and 2006:

  • Climate Crash: Abrupt Climate Change and What it Means for our Future, by John D. Cox
  • Field Notes From a Catastrophe: Man, Nature, and Climate Change, by Elizabeth Kolbert
  • Kicking the Carbon Habit: Global Warming and the Case for Renewable and Nuclear Energy by William Sweet
  • The Weather Makers: The History and Future Impact of Climate Change, by Tim Flannery
  • The Winds of Change: Climate, Weather, and the Destruction of Civilizations, by Eugene Linden

According to Macdougall, each of these books have strong points. I encourage you to read Macdougall’s reviews, which are very even-handed. Some of the authors are more pessimistic than the others in terms of what can be done (via science, engineering, politics), but all agree on the scope of the problem. Most of the books do take on the sudden climate changes that were first observed in studies of the Greenland ice sheet.

Greenland’s ice loss is shocking, but it is hard to capture visually. For a very stark image of the advance in ice & snow loss, there are none more alarming than the satellite shots of Mt. Kiliminjaro taken in February of 1993 and 2000. Hemingway’s Snow is fast disappearing. (Note: I am aware that it is the ice that is disappearing, not the Snow. I am also aware of the raging debate on the causes of the warming that is leading to the vanishing ice. I will get to this point in a future post. For now, I merely report the evidence of warming itself.)

Given that melting snow & ice is correlated with higher temperatures, these pictures support the view that global warming is happening, but they don’t confirm that such warming is human-induced. This is where the political, ideological, and scientific debate hits the proverbial road up the creek without a mathematical model.

Just arguing about the causes is tantamount to doing nothing, however.

Given the nature of political debate in the U.S., and the dismaying statistics on U.S. attitudes towards science and science education, I can’t be anything other than pessimistic that a unified populace and government willing to pursue an active public policy averting (actually, it is more like stemming) global warming is imminent.

But my position is softened somewhat by a quote Macdougall relates from William Sweet’s Kicking the Carbon Habit:

Sweet is impressed by the force of the scientific evidence for human-induced global warming. "So strong is the consensus," he writes, that "journalists have begun to wonder whether their normal instinct to tell both sides of a story has actually led them to produce unbalanced work— giving skeptics about global warming much more leeway than they deserve."

However, I would argue that using the term "skeptic" is itself granting "leeway" to those whose arguing against the facts go beyond any informed skepticism, and often come from pure ideology and/or inadequate science education. (See The Evolution of the 40-40 Club for a recent post about the numbers in the US who believe in the status quo for science education.)

But what do I know? I actually believe that there needs to be more, and better, science education for all students. Then maybe we won’t argue and do nothing; we can argue constructively, and do something about the changing world around us.

Categories Education Politics Science Weather & Climate

Frisbees in Space: Gettin' Funky With Gravity


This is a cautionary tale of frisbees in space, and those in the media who report about them…

Probably the main issue in all of physics education is how to help students learn in the face of their often serious misconceptions about the nature of forces in the world. Most carry with them an Aristotelian view of physics, in which forces are needed for motion. This view is in direct contrast with Newton’s Laws (specifically the First Law). According to Newton, forces are needed to change motion, i.e. accelerate an object.

The Aristotelian view leads to totally incorrect views of everyday situations, views that are repeated continually because they have become so ingrained in our thinking and reactions. For example,when a driver moves to the left when making a sharp-right-hand turn, the common statement is that there is a "centrifugal force" pushing leftward. There is no such force: the driver is moving straight while the car moves to the right. The driver then feels the door on the left - the inclination is then to assume that a force "pushed" the driver into the door. There are many other situations where we instinctively believe that a force is acting when in fact it isn’t. (See Aristotelian Physics and Why We Hate It by R.G. Brown of Duke U.)

An analogous misreading of nature is to assume that there is no force when in fact there is. This situation often occurs in descriptions of weightlessness. The concept of weightlessness is almost always handled incorrectly, even by those who should know better.

Weightlessness occurs when there is no force countering the force of gravity. If you weren’t standing on a floor that supported your weight, but were instead falling down an elevator shaft, you would be in free fall - the only force on you being gravity (I am discounting the upward force on you due to air resistance. To make this assumption more palatable, assume that you are falling in an elevator shaft in a vacuum.) If you are holding onto something - say your briefcase - and let it go, it will float in front of you just like the scenes of astronauts floating in a space station with their breakfast pouch suspended in front of them. Of course, it only appears floating to you as you scream down the shaft. To an observer who could look into the elevator, the briefcase and you are both plummeting at ever-increasing speed.

Which brings me to spaceflight, and ultimately the subject of this post, frisbees in space. The reason that astronauts and their breakfast pouches float in their capsule/space station as they orbit the earth is that they are continually falling towards the center of the earth while at the same time they are moving tangential to their orbit. If the orbital speed is just right, the amount they drop towards the earth is matched by the amount that move tangential. The net effect is that they maintain their same height above the surface of the earth.

Many people simply assume that there is "no gravity", or "zero gravity" when they see the astronaut pictures. While this belief may seem logical for those who have not had a physics class at any level, it is a particularly egregious error for a columnist writing in the science section of a large city newspaper.

Last Friday (Dec. 15, 2006), Don Sapatkin of the Philadelphia Inquirer wrote an article describing the (then) upcoming effort by astronaut and former Swedish Frisbee champion Christer Fuglesang to beat he previous world record for Maximum Time Aloft of a frisbee. With a time aloft of 20 sec, he did beat the previous record of 16.74 sec, set in 1984 by Don Cain, on earth. (Note: there are strict rules for determining the MTA set by the World Flying Disc Federation, although none stipulate that the record only holds for a terrestrial launch.)

From the Philly Inquirer article:

In the absence of gravity, the 49-year-old physicist almost certainly will succeed.

This line made me want to toss my lunch - not a frisbee.

Not only is this wrong because there is gravity in space at a typical space station altitude (there is only approx. a 10% reduction in gravity strength at 400 km from the earth’s surface), it is horribly wrong because without gravity nothing can orbit the earth in the first place!!!!

See The Physics Classroom for a tutorial on weightlessness, and how to fight your pre-conceived notions. Actually, the Inquirer staff, just about anyone else should visit this site to learn how to shed off those preconceived Aristotelian notions - notions that are severe impediments to learning about the world.

Check out the Inquirer page for assorted frisbee in space links, including a video of the space toss.

And don’t forget to check out James Brown for the final word on Gravity:

brownjamesgravity0420065vj.jpg In the twenty-first century You can dance Get your feet off the ground And if you believe Then you can fly Hit it, gravity, yow Horns Heh, yeah, wait a minute Lookie here Gravity, the big G G-r-a-v-i-t-y (gravity) Say it, got a hold on me For the third verse, the sun I've been trying to get The funky job doneAnd work that ?? Don't mess in the Wrong honky tonk-a You got no sense You dance too fast You burn all night You'll never last If every man can dream Then he can fly G-r-a-v-i-t-y Gravity, wow, big G G-r-a-v-i-t-y Gravity G-r-a-v-i-t-y Wait a minute Slow it down, big city There's a fat cat here Sitting pretty Watch me break out In a cold sweat Jump back, baby You ain't seen nothing yet You shake it up You dance too fast You think it will Make it last If every man can dream Then he can fly G-r-a-v-i-t-y Gravity, the big G (Gravity) oww G-r-a-v-i-t-y, say it Gravity, got a hold on me Let me say that if You can dream Then you can fly G-r-a-v-i-t-y If you can love Then you can fly G-r-a-v-i-t-y G-r-a-v-i-t-y Good god Gravity G-r-a-v-i-t-y Gravity, say it Get funky, gravity Everybody say it now G-r-a-v-i-t-y Gravity, ha

Categories Education Media Science

It's No Fluke: When Mandates Meet Models


In today’s news, NJ & NYfishermen are understandably upset because the allowed number offlukepermitted to becaughtin the upcoming season has been reduced by 28%. Just as the number of deer is regulated, with certain numbers of permits issued during deer season, several fish species, and spawning and feeding areas are tightly controlled. Both of these "game" speciesare subjectto three often irreconcilable forces: scientific predictions in the form of regulatory commissions, local needs of those relying on the game for a livelihood, and the contingencies ofpolitics.

The amount of any species permitted to be caught ("harvested" in the parlance of population minders and modelers) is chosen with one of two possible goals:

  1. to keep the overall population in a steady state, i.e. the harvesting rate is basically the net birth rate (absolute birth rate - death rate)
  2. to increase the overall population - i.e. the harvesting rate is greater than the net birth rate
Presumably the 3rd option - harvesting faster than the series can regenerate, is not a consideration in game or food species, or there soon would be no species left.

Population modeling has a long tradition, and especially within Chaos Theory. As shown byworld-famouspopulation modeler Robert May, the standard Logistic Map model of population growth undergoes period doubling and ultimate chaotic dynamics (population swings) as the net growth rate parameter increases through critical values. (And of course this is the same mapping made famous by Feigenbaum in his historic study of period doubling.)

Often times, a logistic differential equation (or system of differential equations with one or more logistically-modelled species) is used instead of a logistic map to model the population. In this case, chaotic dynamics are usually not observed, unless the system has at least three species and is suitably non-linear and coupled.

There are many more models than logistic, certainly, but all modelsthat can lead to a steady-state population contain a parameter known as the carrying capacity of the population. The carrying capacity is a single number that represents a lot of hidden detail;basically, however, it effectively the equilibrium value of species that the particular eco-nichecan sustain. Once this value is obtained, as well as the netgrowth rate- bothempirical determinations- the other main parameter, the harvesting rate, is adjusted until the overall population dynamics follow one of the two options listed above.

Game commissions use these model predictions then to issue mandates on allowed catch tonnage, number of hunting licenses, etc.

The fluke situation is more complex than most because three agencies are involved in setting limits - presumably they may all be using different models.

Now, back to theNortheast Atlantic coastsituation. Because of extreme over harvesting years ago, a number of agencies have been setting the harvest limits on a yearly basisin order to meet Goal #2 above. Even with increasing numbers of fluke (a number that fluke fisherman claim to be the highest in over 10 years), the total weight of fluke permitted to be fished is being cut by over 6 million pounds from this past year’s allowed catch of 23.6 million pounds. This new limithas been setbecause the available fluke count is not increasing fast enough, i.e. whatever model(s) are being used, the predictions are not coming true.

When a model’s prediction don’t pan out, the question isfairly simple- is the model wrong, or are the parameter(s) used in the model incorrect? Presumably the model equation(s) are OK; modeling fish dynamics has a pretty robust and successful history. Interestingly, the parameter that may be incorrect here is the carrying capacity. The carrying capacity may in fact be lower than the value being used in the models, which would mean that the fluke population cannot reach the value chosen that will allow full levels of fishing. In other words, the mandated bottom-line population can’t be met, implying that the fishermen will never fish for fluke at the same levels again.

That is unless the regulatory agencies revisit their models and assumptions There is enouogh of an outcry from affected fishermen that this hopefully will happen.

I find this story interesting and important because it points out some of the difficulties of setting policy based on mathematical models whose predictions are not accurate. It is imperative that we always know when decisions are being made using predictive models - and especially if the models don’t seem to be working!

Categories Modeling Politics Understanding & Prediction

Predicting Nothing and Next - to - Nothing: A Nobel Thought


Temperature fluctuations in CMB. Click to enlarge.John Mather and George Smoot were named winners of the 2006 Nobel Prize in Physics this past month. Their work on the NASA Cosmic Background Explorer (COBE)is primarily experimental. Theaccuracy of their instruments and subsequent precision of theirresults are remarkableachievements.

What the measurements imply is even more remarkable, and is a great example of the deep interplay between understanding and prediction that happens when things break the right way, when theory and experiment mutually reinforce each other illuminating a deep secret about the universe. ( Hence the Nobel prize…)

Mather and Smoot were checking on the two major predictions of inflationary Big Bang theory:

  • The cosmic microwave background (CMB)- a measure of the intensity of radiation present in the universe as a function of wavelength. Theory predicted that the measured radiation should follow an almost-perfect blackbody spectrum. (i.e. should follow the mathematical form first determined by Planckin 1900 - the beginning of Quantum Mechanics). The major parameter used to fit CMB to a blackbody spectrum is temperature, hence finding an experimental blackbody curvecan bea very accurate thermometer
  • The temperature of the CMB should vary very slightly for different portions of the sky, i.e. theuniverse. It is only with these fluctuations that inflationary theory predicts the eventual clumping of interstellar matter to form stars, proto-galaxies and ultimately the solar system and planets.

Measured vs. Theoretical CMB. Click to enlarge.Click on the graph to the left to see a fit that’s"almost perfect" It is a graph of the experimentally measured spectrum superimposed on a black body function. The size of the data squares represent the uncertainties in measurement. The fit is astonishingly good - as perfect a fit as has ever been seen in an experiment as complex as theCOBE. So the first piece of the puzzle came in as desired. What about the temperature fluctuations?

The figure at the top of this post shows the temperature variation of the CMB over a certain region of the sky. Mather and Smoot measured incredibly tinytemperature variations - approx. 30 microkelvin, again, in line with theory.

So the Nobel goes to experimenters who measured "nothing" - i.e. no measurable deviation from a perfect black-body spectrum, and next-to-nothing - temperature variations so miniscule that a few clusters of atoms moving with slightly different velocities would throw off the results.

What to make of these results? By themselves, the results are merely facts - interesting facts, to be sure, but simply facts. It is only in coordination with theoretical predictions that these facts come alive - stating for all that there is something to thetheory in the first place. And, because of that very positive reinforcement, the data+theory yields an understanding about the universe that is much deeper, and stronger, than at any other stage in the history of thecosmological beliefs of Earth’s inhabitants.

Categories Science Understanding & Prediction

The Evolution of the 40 - 40 Club


This just in from the Nov. 28, 2006 Onion - Kansas Outlaws Practice Of Evolution:

TOPEKA, KS - Any living being that undergoes genetic modification favoring survival could face jail time under the new law.

A really clever piece on our favorite state, Ienjoyed reading it today probably a whole lot more than if I had seen it yesterday - a day of unfortunate and fortunate events.

I was atPenn State attending a meeting of the Scientific Benchmark subcommittee of the PA Governor’s Commission on College and Career Success. The subcommittee’s charge includes proposingrevisions to the current PA state teaching standards. This was my first meeting, and I was amazed to meet such anenergetic and dedicated group of secondary and higher-ed facultyworking on this important project. Everyone in the room has one overarching goal - to ensure that ALL studentslearn essential mathematics and science concepts and skills- necessary for success in today’s, and especially tomorrow’s world.

This was the fortunate event.

The unfortunate events were myreading two disturbing articles earlier in the day. In one, I read a report of the August survey done by Jon Miller of Michigan State University.The results of the poll suggest that only 40% of the U.S. believe in evolution (BTW, the only country with a smaller percentage is Turkey, while countries such as Sweden and Denmark have an 80% belief rate) Miller’s study attributes this disturbing dichotomy as a perfect-storm effect of religion, politics, and LACK of GENERAL SCIENTIFIC KNOWLEDGEof core biological ideas. (Check out the National Geographic report on the poll.)

The other article was even more depressing: The Chronicle of Higher Ed reported thatin a survey by the American Council on Education, 46% of those polled said that colleges and universities should not require students to take more courses in math and science, while 46 percent said students should be required to do so. This deep division is evidence that all of the messages and news about American students falling farther and farther behind in terms of essential skills for the 21st Century are not being heard.(Click hereto read the original study -"Math and Science Education and United States Competitiveness: Does the Public Care?")

Where is the Math/Science PR?With the constant stream of news stories about American students falling further and further behind the rest of the world’s students, itseems to be everywhere, but no one (or at least 40% aren’t listening.

Luckily for me, but really luckily for our students and our country, the fortunate event outweighed the unfortunate events. The effort to make science standards the best they can be as a preparation for our students’ future successwill also produce a perfect PR machine, as students who are successful realize that it was the mathematics and science that formed the foundation of their success.And the students who follow them will generate the demand that will lead to more math and science at all education levels.

Then we won’t be in the 40-40 club anymore, which will be quite an evolution!

Categories Education Evolution Politics

Where There's Smoke There's Hot Air: Prediction Without Understanding


Montgolfier Balloon over Paris, 1783. Click to enlarge.Sometimes prediction is easy without any understanding. Take driving a car, for example. Stepping on the gas causes the car to accelerate if it is in gear. How many drivers actually understand why this happens, short of the basic guess that "more gas" somehow got to the engine? Clearly one doesn’t have to understand anything about internal combustion engines to predict what will happen when the engine gets more gas, or gets the wrong octane gas, and so forth.

So Prediction without Understanding is a common occurrence.

A related happenstance is when accurate prediction occurs even with a totally incorrect understanding.

Consider the first human flight, which occurred on Nov. 21, 1783 when two Frenchmen ascended above Paris in a hot air balloon. The balloon was designed by the Montgolfier brothers, who believed that thick smoke caused the balloon to stay in the air. Of course, the thick smoke was a byproduct of whatever they burned in the fire at the throat of the balloon , but it was the hot air (less dense air) caused by the fire that actually led to the balloon floating.

OK, so the Montgolfiers weren’t that far off - you don’t have to dig too far to find the connection between thick smoke and hot air, after all. But this example does raise a more interesting question: when is it the case that understanding is totally lacking, yet predictions are right on?

I have read tales of grudging acceptance of Einstein’sspecial relativity in which relativity’s predictive power was acknowledged, but the basic postulates were not, i.e.some were aghast at the essential strangeness of the universeas postulated by Einstein. They were claiming then that understanding of the universe was sorely lacking in a theory with great predictive power.

Einstein himself fell was not beneath this same claim about the work of others: he fought notoriously against the probabilistic interpretation of quantum mechanics, and especially the Copenhagen Interpretation of Bohr and Heisenberg. He admitted the predictive power of the theory, but denied the underlying interpretation, in effect stating that Copenhagen adherents did not have the correct understanding of the reality.

So where does this lead? Isn’t it enough to say that prediction is understanding? If a model predicts accurately, doesn’t that mean that whatever is beingmodeled is "understood" at some level? While this approach is probably OK in many situations - I know what type of gas to put in my car to get it to run better, even though I don’t know a thing about octane, e.g., there is a fundamental problem with not being diligent about seeking the deepest level of understanding possible. Simply stated, if there is no physical basis to the model that yields the predictions, there will always be that hesitancy to trust the prediction - almost as if the prediction is a result of a lucky guess, and maybe we won’t be so lucky next time.

Note that this position is itself the result of an overriding model of the universe: thatthe stuff of the universe obeys basic "laws" - Newton, quantum, and so on. But without this belief in laws, without this understanding of basic physics principles and the predictions that flow from models based on these principles, how does one explain that people were willing to sit in a hot air balloon over Paris in 1783?

Click hereto read more about the first balloon filght over Paris (from APS News, Nov. 2006). For more onall things floating, check outthe History of Airships and Balloons by Mary Bellis.

Categories Modeling Understanding & Prediction

On the Mathematical Nature of the World


I had one of those very rewarding teaching moments yesterday in my General Physics lab. Some students and I got into a discussion of just what is physics, what is the connection between mathematics and physics, and whether the world is itself mathematical.

The nature of the world as mathematical is a common theme in the Chaos and Fractals course. I have developed a seminar module that has one main reading, and I keep finding supplemental readings every time I teach the course. I list a few of these here in order to collect them in one place - for future renditions of the course, andas a post that will hopefully generate some debate from interested readers.

The main reading is John Barrow’s The Mathematical Universein which he poses the question "The orderliness of nature can be expressed mathematically. Why?" This articleis an excellent summary of the main schools of mathematical philosophy - realism, inventionism, formalism, and constructivism.

Anyone interested indeeper views of mathematical realismmust read The Unreasonable Effectiveness of Mathematics in the Natural Sciences. This 1960 article by Eugene Wigner isdefinitely the "mother-of-all mathematics and the world"arguments for realism. In it he describesthe uncanny connection between mathematics developed as part of pure, formal, abstract systems and physical observation, which naturally leads to ontological questions on themathematical nature of the world:

The first point is that mathematical concepts turn up in entirely unexpected connections. Moreover, they often permit an unexpectedly close and accurate description of the phenomena in these connections. Secondly, just because of this circumstance, and because we do not understand the reasons of their usefulness, we cannot know whether a theory formulated in terms of mathematical concepts is uniquely appropriate.

Wigner’s idea of the unreasonable effectivenessof mathematics is a major precursor to the work of 20th century philosophers W.V.O. Quine and H. Putnam in their indispensability argument for mathematical realism.You can read all about this argument in Mark Colyvan’s excellent Indispensability Arguments in the Philosophy of Mathematics from The Stanford Encyclopedia of Philosophy.Colyvan’s piece also includes the strong arguments against the indispensability argument byHartry Field and Penelope Maddy.


A recent article by 2004 Physics Nobel LaureateFrank Wilczek in the Nov. 2006 issue of Physics Today is a provocative new look at Wigner’s thesis. Titled "Reasonably effective: I. Deconstructing a miracle", Wilczek attempts to show that the effectiveness of mathematics is not unreasonable. Using arguments of symmetry and locality, Wilczek ultimatelyfinds that there is a deep reason for mathematical effectiveness:

When people like Archimedes, Johannes Kepler, and Galileo discovered the earliest "unreasonably effective" mathematical laws of nature, each such law seemed like a newly revealed miracle, unanticipated and logically disconnected from the others. After traversing a long history, we can now look back to see the same laws in quite a different way, as particular consequences of a more profound and encompassing theoretical framework in which symmetry and locality emerge as dominant features of the world's deep structure. Having found those dominant features, we've uncovered the underlying reasons why mathematics is so effective in describing nature (that is, when it is!).

Wilczek makes some very strong claims - some of which are way beyond my ability to understand and comment on. Yet his enthusiasm for the program of physics is palpable. He foresees future experiments that will show even more the mathematical nature of the world as phenomena predicted by physics theories that fully incorporate symmetry and locality are found:

Eventual discovery of any or—as I expect—all of these new phenomena will be wonderful new confirmation of the effectiveness of mathematics in natural science. But those discoveries will constitute the pinnacle of reason, not an "unreasonable" anomaly.

Categories Mathematics Philosophy