When vaccination rates are high, most positive cases will be among the vaccinated (and that's okay)

Two recent COVID outbreaks have made headlines because of the high proportion of "breakthrough" cases, where people test positive for COVID despite being fully vaccinated.  San Francisco hospitals in July reported 50 staff members tested positive for COVID, despite 75% of them being vaccinated.  In Provincetown, MA, a July outbreak of the delta variant led to several hundred new cases, the majority of whom were fully vaccinated.

• Physicians, nurses, ancillary staff': How hundreds of SFGH and UCSF staff got infected with COVID

• Most Covid-19 cases in Massachusetts outbreak among vaccinated: CDC, United States News & Top Stories

How can the majority of new cases be among the vaccinated?  Some people wrongly (if understandably) worry this means the vaccines aren't working, particularly against the delta variant. 

The truth is the numbers show that the vaccines ARE very effective, even against the delta variant.

The problem here is the reporting.  News agencies are going for provocative headlines, and in the process are falling for what is known in statistics as the "low base rate fallacy" or base rate bias.  In this case, breakthrough infections have a very low base rate, and all of other numbers are meaningless without keeping that in mind.  

The low base rate of breakthrough infections should be the focus in reporting.  For instance, the headline does not mention that the 50 new cases in July among SF hospital staff is out of 7,500 staff members, a breakthrough base rate of less than 1%.  They don't mention that until later in the article.

How can positive rates be higher among the vaccinated?

What does it mean that, in the delta outbreak in Provincetown, there were a higher proportion of positive cases among vaccinated folks compared to unvaccinated?  Does it mean the vaccine is ineffective agains the delta?  NO.  Because of the low base rate, when vaccination rates are high, more positive cases will be among the vaccinated.  

What it really means is just that most people in MA are vaccinated! To understand this, a picture is worth 1000 words. I came across this diagram that clearly shows what's going on. 

source: https://i.redd.it/cpjwvqv2s0d71.png

The left half of the diagram shows what happens in a highly vaccinated population, based on real-world data from England.  There was a 2% chance of getting symptomatic COVID among the unvaccinated (red dots).  For the vaccinated, it was a much smaller percentage who got COVID (only 20% of 2%, aka 0.4%).  But since so many more people were vaccinated (over 10x as many), that led to a higher number of vaccinated people who tested positive (blue dots).  This explains the counterintuitive result that even though the vaccine is working, more people who test positive are vaccinated.  There's just so many more vaccinated people! (Notice there are still way fewer vaccinated who end up hospitalized.)

The right half of the diagram shows what happens when a lower percentage of the population is vaccinated.  First - and most importantly - there are more overall cases and hospitalizations.  Second, since there are more unvaccinated people, the higher proportion of people who test positive are unvaccinated.  This matches our usual intuitions.

In summary: When most people are vaccinated, it brings down the total # of positive cases drastically (yay!), but can end up with a higher proportion of positive cases among vaccinated folks. This can be confusing, because humans aren't great at doing statistics when there's a low base rate involved.  It really helps to visualize it. 

Remember that breakthrough cases are normal and to be expected, and extremely rare in reality (much less than 1% in MA and nationwide). The vaccines help in multiple ways: they reduce positive cases and also lead to a lower rate of hospitalization among those who test positive (only 1% of vaccinated positives from the recent MA delta outbreak were hospitalized). 

TLDR: Vaccines are working well, even when a higher percentage of positive cases are among the vaccinated!

Epilogue: Simpson's Paradox

The base rate fallacy leads to all sorts of funky, counterintuitive results:  

  

• My favorite comes from baseball - In 1989 Andy Van Slyke had a higher batting average than David Justice (0.237 vs. 0.235).  In 1990 Van Slyke again had a higher average than David Justice (0.284 vs. 0.282).  But when you look at their combined 2-year battering average 1989-1990, David Justice is the one with the higher average (0.278, compared with Van Slyke's 0.261).  How can this be?  David Justice had far fewer at bats in 1989, so his combined average is skewed closer to his 1990 season.  
• Simpson's paradox is what philosophers and statisticians call an association between variables at the population level that reverses when divided into subpopulations.  Understanding Simpson's paradox has important ramifications for epidemiology and for equity.
• At the population level, vaccinated people are less likely to get COVID.  But when comparing vaccinated to unvaccinated, a higher proportion of new cases can be among the vaccinated.  This is Simpson's paradox.  Of course, it's not truly a paradox - it is just so counterintuitive you have to think it through carefully. Every. Time.

Who are we? Don't ask our neurons, they're a bunch of idiots. And don't answer with your gut, because your gut isn't even human.

As the philosopher Daniel Dennett likes to remind us, each one of us is made up of trillions and trillions of living organisms (we call them 'cells'), and not a single one of these living things that make us up has any idea who we are, or even cares.

Take a moment to let that sink in.

Now, don't blame the cells for not caring; they are all living organisms and thus have their own metabolism, their own respiration, and their own reproduction to manage.  They don't have the time to worry about the bigger picture.  Nor do they have the mental capacity.  Even neurons--the living organisms that do our thinking for us--are quite dumb, when considered on an individual level.  Even though it is our neurons that allow us to think and learn, no individual neuron can think or learn.  Each one follows very simple rules of behavior: basically if a certain number of its neighbors are firing, they fire too.  That's it.  And yet somehow, out of all those mindless firings of neurons, a mind emerges--a mind that can even write a blog post about the neurons mindlessly making a mind.

Three stupid neurons.

More than human.
It gets even weirder.  A good proportion of the cells that make us up aren't even human!  Before I tell you what percentage, I invite you to take a guess: What percentage of the cells in our body are human cells?  90%? 70%? 50%?  So far, you're way off.  (Are your neurons even firing correctly?  Sheesh.)  Truth is, human cells are the in the minority amongst humans, by a long shot.

Human cells comprise only about 10% of the 100 trillion cells in a human.  10%.  The rest of the cells in our body are mostly bacteria, which generally take up residence in our gut.  Far from being invasive, our bacterial friends are an integral part of our digestive system, breaking down food and passing along the energy and vitamins to us after they're done with them.

Are you the same "you" that you were 10 years ago?
Biologically speaking, not exactly.  The living organisms that make us up generally do not live long enough to see us grow old.  Our body may grown and develop at a steady, slow pace, but that is due to a complex flux of cells dying and new cells being born to take their place (here's a nice NYT article on this).  The skin that covers your entire body--the thing that makes you look like "you" with your dimples and wrinkles and all--is not even the same skin you had two weeks ago.  The stable patterns in our skin, including our fingerprints and dimples and wrinkles and all, are sort of like traffic jams that persist even after all individual the cars that started the jam travel on down the road.

Down another level, they say that most of the atoms and molecules that make up the cells are replaced by other atoms (of the same variety) every year or so.  Since the new atoms are functionally equivalent to the old atoms, we would never know the difference.

So what are we to make of this?
So, if the neurons that make us think are all stupid, and the cells that make us up are dying all the time, how do we think?  How do we persist?

Part of what makes this all so mysterious is that we are so far removed from the microscopic level of the goings-on of our body that we have no sense of how the micro-level goings-on give rise to the macro-patterns of our daily life.  But there are some systems in nature where the levels are not so far removed, and so we can learn something about this mystery by studying them.  I will briefly introduce you to two of them: slime molds, and ant colonies.

Slime molds
The slime mold may be one of the grossest organisms on earth, but it is also one of the most fascinating.  We humans like to think of our life cycle in terms of our whole body, not our cells, but the life cycle of the slime mold doesn't work like that.

The slime mold spends much of its life as a single-celled organism, not unlike an amoeba, generally sliming around.  But there comes a point in the life cycle where tens of thousands of individual cells come together and act like one big organism.  First this aggregate organism looks like a slug, slithering around, eating, sliming, and doing whatever it is slugs like to do.  Then during it's reproductive stage the slime mold self-organizes into a mushroom-like stalk, releasing new spores into the surrounding environment and starting the whole process over again.

Although individual slime mold cells are just about as dumb as our individual neurons, the aggregate of slime mold cells can be pretty darned smart.  For example, they can find their way through a complicated maze to get to food:

Ant colonies
Although ants may be smarter than slime mold cells, they are still pretty dumb.  What I mean by that is that ants follow a very simple algorithm for guiding their behavior, a very simple decision-making procedure based entirely on pheromones.

If, in their walking around, an ant happens to cross paths with another ant, they give each other an antennae high-five and sniff out the pheromones.  There is a pheromone that signal one of a few basic meanings: "I found food" and one for "I'm working on the hive" and another for "there's a threat to the colony".  If they sniff the pheromone for "I found food", then they head in the direction that ant was coming from, repeating the process with other ants, until it ultimately finds the food.  This is not much different than our dumb neurons' algorithm of "if my neighbors are firing, I will too".

Now, despite being made up of dumb ants, an ant colony is pretty darned smart.  For instance, they can solve the complicated problem of allocating the optimal number of ants to various food sources at various distances with varying amounts of food.  (here's a nice TED talk on the emergent intelligence of ant colonies)


Also, ant colonies persist for decades, even though the individual ants generally die after several months or at most a few years.  (The queen is the exception to this rule, she's around for up to 21 years).

So, ant colonies and slime molds each give us insight on how a form of intelligence can emerge from the collective behavior of dumb individuals, much like mindless neurons can collectively make a mind. They also lend insight onto the persistence problem, how we can be around for decades when most of our cells are long dead by then.

The bigger picture.
Now that we've seen there's no real magic to how we can be composed out of a bunch of dumb organisms but still be relatively smart, there are more questions to consider.  Should we feel bad if we scratch our cheek and kill thousands if not millions of living organisms?  Is it possible that individual humans could be part of some larger system that is even smarter than any individual humans?  If so, should that system feel bad if it happens to "scratch it's cheek" and wipe out thousands if not millions of humans?  And what should we call that system?  I propose that we call this hypothetical system "Frank."  Frank, if you're listening, please don't scratch your cheek!!!


Extra goodies:

• this article also reports on a finding that human cells even forage for food in a pattern similar to other scavengers, including sharks and um, penguins
• another video of slime mold finding the shortest path to food through a maze 
• here's a research article on the how ant colonies solve complicated problems with dumb ants

Do you have the time? Some surprising facts about how consciousness works

Surprising fact: The neural signals from a drummer's foot take almost of a third of a second longer than do the signals from the hand when they are playing the same beat.

That's not all.  Whenever you stub your toe, there are pain signals that get to the brain almost a third of a second slower than the others, even though they contribute to the very same pain sensation.

How does the brain work this out to end up with one conscious experience of pain, or of a funky drum beat?  Does the brain wait for the last signal to come in before it puts it all together into a feeling?  Or can it revise and resubmit sensory information to the running journal of conscious experience?

An illusion called 'the phi illusion' helps to further illustrate the problem, and how the brain works it out. The result is really quite crazy.

The Phi Illusion

The phi illusion is the reason why we can watch movies and see them as motion rather than as a sequence of still pictures, which is all a movie really is.

For example, here is the first movie ever made: 1st movie ever.  In 1878 Eadweard Muybridge filmed it by lining a stretch of track 12 cameras that went off as a horse ran by.  When we experience the horse's continuous motion means that we are, in a sense, filling in the blanks between pictures.

The illusion is hard to appreciate, because we are so familiar with motion pictures.  But a way to notice the illusion more clearly is to focus on one or two features changing between frames.  Here is an animation of a dot that looks like it's moving back and forth while changing colors, at least for certain settings of the framerate.  But really, it's just two dots, one red and one green, flashing on and off with just the right delay between dots.

When you experience that dot moving back and forth, it seems you must been extrapolationg, somehow, where the dot was between frames of the animation.  And what color it was.  But just what color was it?  And where exactly did you "see" it in between frames?  Are those things somehow registered somewhere in your brain as sensory information?  Or are you just telling yourself a story about what happened and the details are left ambiguous and unexamined by your consciousness?  According to the philosopher and cognitive scientist Daniel Dennett, conscious experience is more like a story you tell yourself about what happened.  There is no "halfway dot" registered anywhere in your visual cortex.

Daniel Dennett has explained this illusion with his "multiple drafts" model of consciousness.  This theory says that we are always making up narratives of "what's going on".  There are usually more than one versions of the story floating around, and its never too late to revise...your consciousness experience is what emerges from an evolutionary-like battle between ideas of what happened.  In the phi illusion, stories that involve motion get selected for so that they end up in the later "drafts" of the story.

The dot appears to move back and forth because when it goes from say, being a red dot on the left to being a red dot on the right, because once that red dot appears we revise the story to include motion, and a color change.

So when a drummer plays a funky beat, he does not have to wait for all the neurons to reach his brain to from his foot as it hits the kick drum before he truly experiences the beat.  And the beat is not experienced as "smeared out" in time, either.  This is despite the fact that multiple kinds of neural signals contribute to the same sensation, some that arrive up to a third of a second later.  Once those straggling neurons deliver their message, the drummer's conscious experience of "the beat" is revised accordingly.


You may have experienced for yourself how the experience of the past can be "retrospectively presented" to the present version of consciousness, say, when you suddenly notice a church bell has been ringing and you are still able to count the chimes, even though you didn't notice it when it started ringing.  You just submitted a new draft that includes revised information about the past.  The versions of your story of consciousness that did not contain bells ringing got beat out by versions that included bells ringing, even though the battle took some time.

Okay, that's all I have time to write.  Or at least that's what I'm telling myself.

Here are some more links for the phi illusion, and related illusions:

• http://www.philosophy.uncc.edu/faculty/phi/Phi_Color2.html
• http://www1.psych.purdue.edu/Magniphi/SimpliPhi.html
• http://highered.mcgraw-hill.com/sites/0070579431/student_view0/chapter8/phi_phenomenon_activity.html
• http://www.lifesci.sussex.ac.uk/home/George_Mather/TwoStrokeFlash.htm
• picture-a-day for 3.5 years

What's wrong with the Bill Gates' foray into educational research & reform

#1 Bill Gates is not an education researcher, let alone an educator, or a researcher.
Don't get me wrong.  I love that Bill Gates is identifying education as a key issue to focus on.  I love that he is taking an interest in improving education.  I am not questioning his motives.  Just his methods.

What I hate is that his approach is the same know-it-all attitude that many take towards education and education research.  It's the old "I turned out okay, and I know what worked for me, therefore I am an expert on education" approach.

Good ol' Uncle Bill knows all there is to know about education reform

Which would be bad enough if he were just Uncle Bill, telling-it-how-it-is from his comfy chair at a holiday party.  But instead, he is using his name to garner authority on a subject he knows little about.

#2 His ENTIRE research program is explicitly based upon students' scores on standardized tests
The following is taken from a recent report by Gates' MET project:

THE THREE PREMISES OF THE MET PROJECT
The MET project is based on three simple premises: 

• First, whenever feasible, a teacher’s evaluation should include his or her students’ achievement gains.
• Second, any additional components of the evaluation (e.g., classroom observations, student feedback) should be demonstrably related to student achievement gains 
• Third, the measure should include feedback on specific aspects of a teacher’s practice to support teacher growth and development. 

NB: "Achievement gains" are edu-jargon for increases in standardized test scores.  There are so many problems with this, I don't know where to begin.  For one, there is the obvious: these standardized tests DO NOT MEASURE what students are learning.  But a more important issue to me is that: THESE TESTS DO HARM TO STUDENTS.  And I'm not talking just about "they get stressed when they take tests."  I'm also talking about the WEEKS of instructional time lost to testing throughout the school year, and the MONTHS of instructional time lost to test-preparation throughout the school year.  I'm talking about the science classes, the history classes, the art classes, which ARE NOT TAUGHT so that reading and math test scores can improve.

This is just a little slice of the Test-Mania inflicting the schools where I make my rounds.   I wonder what the kids make of this poster, as they pass it in the hallway every day.  And I wonder how it makes them feel.
I know what I think when I pass it: 58.3% is SOARing?? 

See, the biggest damage done is not from the 5-hour-long sessions of sitting at a desk to take these tests; it is in the life-long damage to the students done by the test-mania they are subjected to in school.  At the heart of the issue is the damage done to students' conceptions of what it means to learn something.

As a science educator, I am most concerned about how the tests distort students' views on what it means to learn and to do science.  The  students take away such distortions from this test-crazed school culture when it is working as it is supposed to.  That means under Gates' ideal conditions, students' conceptions of science (and who knows what else!) will be destroyed, or at least distorted beyond recognition.  I have seen this first hand in my time in the classroom as an instructor, and as a researcher.

The fundamental principle of educational reform should be the same as it has been in medicine: DO NO HARM.  Gates' program, despite its best intentions, is a way of institutionalizing harm to children.  This is what happens when you jump from your own biases to institutionalizing them as recommendations.  Which brings me to my next wag-of-the-finger:

#3 Gates is jumping right from making assumptions to making recommendations
It's one thing to do descriptive statistics.  It's another to make causal claims.  But causal claims must be substantiated BEFORE making recommendations.  And the research that's already been done must be addressed first.

Yet somehow, Gates decided that he can simply dismiss all the research that shows the positive correlation between small class sizes and student learning (one of the most robust findings in educational research).  His recommendation: INCREASE class sizes, so we can force teachers to do more for less, and with less resources to help them do it.

Again, if this were just Uncle Bill ranting at a party it would be one thing.  But this is a person who is determining the future of the educational system with billions of dollars of investment in harmful and misguided policies and their proliferation.

#4 He wants traffic cameras in the classroom...
...except instead of being used to issue speeding tickets, they will be used to punish teachers.  Big brother, anyone?  What a great way to encourage teachers to enter into the profession and stay there (which, by the way, is really the key issue, if you ask Uncle Luke).  And by "great" I mean "idiotic."

TEACHERS:

Gates knows when you've been boring, Gates knows when you've been late...

Gates knows when kids are snoring, so give them tests for testing's sake!

Okay, enough ranting.  Here is something good I think Uncle Bill is bringing to the table, although he is horribly misusing it: using videos of classrooms to improve instruction & learning.  Video of classroom practice can be extremely helpful for teachers, UNDER THE RIGHT CONDITIONS.  Larry Ferlazzo has written a wonderful article on how video can be used productively to improve teaching.  Mr. Ferlazzo *voluntarily* used video of his teaching in order to have an open discussion with an external evaluator *and his students* about his teaching *in that video* (not to summarily characterize his teaching).  That sort of practice has great promise, if you ask Uncle Luke.

What are the lessons to learn from Columbus?

Was Columbus a hero or a villain?  

We all know that Columbus' legacy is a controversial one.  Many history books have painted him as an intrepid explorer and overlooked the facts that would paint him in a negative light.  Some Columbus scholars have admitted that he encited a devastating genocide, but dedicated no more than a sentence to that fact (see, for example, Samuel Eliot Morison).  


So which is it--was Columbus a hero or a villain?  And how do we decide?  One thing that would be important to determine is what Columbus himself thought he was doing.  Perhaps he was trying to do good.  Perhaps he did not mean to exploit and kill all those natives...maybe it was his lower officers that took things into their own hands and got out of control.  


Fortunately, we have Columbus' log, as well as the log of several of his viceroys, and so we can find some answers to this question.  This, for example, is what Columbus wrote about his first encounter with the natives:


They ... brought us parrots and balls of cotton and spears and many other things, which they exchanged for the glass beads and hawks' bells. They willingly traded everything they owned... . They were well-built, with good bodies and handsome features.... They do not bear arms, and do not know them, for I showed them a sword, they took it by the edge and cut themselves out of ignorance. They have no iron. Their spears are made of cane... . They would make fine servants.... With fifty men we could subjugate them all and make them do whatever we want.


Well, he pretty much just comes out and says that he is intentionally subjugating them and making them do whatever they wanted.  And, also according to Columbus' own words, they wanted them for two things: gold and slavery.  So he took many as slaves and set everyone else to the grueling work of looking for gold where there wasn't any to write home about.   The working conditions for finding the gold were miserable, and the penalty for not meeting one's gold quota was chopping off the hands and bleeding them to death.  

The situation was written about extensively by one of Columbus' appointed governors, Bartolome de las Casas, a young priest who initially took part in the conquest and held slaves and such, but became disgusted by the cruelty of the Spaniards.  Here he describes the working conditions for the Arawaks faced under Columbus' rule:


Thus husbands and wives were together only once every eight or ten months and when they met they were so exhausted and depressed on both sides ... they ceased to procreate. As for the newly born, they died early because their mothers, overworked and famished, had no milk to nurse them, and for this reason, while I was in Cuba, 7000 children died in three months. Some mothers even drowned their babies from sheer desperation.... in this way, husbands died in the mines, wives died at work, and children died from lack of milk . .. and in a short time this land which was so great, so powerful and fertile ... was depopulated. ... My eyes have seen these acts so foreign to human nature, and now I tremble as I write. ...


When Las Casas arrived in the Bahamas in 1508 he documented the unbelievable scale of the devastation:


"there were 60,000 people living on this island, including the Indians; so that from 1494 to 1508, over three million people had perished from war, slavery, and the mines. Who in future generations will believe this? I myself writing it as a knowledgeable eyewitness can hardly believe it...."


And so the question of whether Columbus' behavior was villainous seems pretty settled, based on his own writings as well as accounts from his officers.  What is not yet settled, for me at least, is how Columbus justified his behavior to himself.  With his reports to the King and Queen of Spain he could talk of subjugation without needing to explain how that is a good thing.  But what was going through his head when he went to sleep each night?  Was there any recognition of the evil actions let alone remorse?  Did he think he was being a hero?  Did he, as a devout Christian, think he was saving the souls of these natives?  If so, did he somehow twist this reasoning to render his maniacal methods as somehow forgivable, even noble?  Is there a way we can ever find this out?


I don't know the answer to these questions, perhaps nobody does and nobody ever will; but I think it is an extremely important set of questions with which to struggle.  You see, Columbus is not the only instance of such a horrible turbulence between two cultures as they newly meet.  If anything, subjugation and genocide seem to be the norm of two intersecting cultures, especially in the Americas.  The same sort of despicable treatment of human beings, from slavery to torture and genocide, accompanied the missions of Cortes in Mexico, Pizarro in Peru, and English settlers in English Settlers in Virginia and Massachusetts with the Powhatans and Pequots.


The lessons we learn (or do not) from such conquests could make or break the survival of the Earth, if extraterrestrial beings ever pay us a visit.  Is there a way for two cultures to intersect and mutually reinforce each other, or is war and death the only inevitable outcome?  Or maybe we will one day venture out to the stars, and we could end up being Avatars, i.e., Columbus 2.0.  These are big IF's, of course, but I think it is worth thinking about how we might do things better next time, whichever end of the ordeal we end up on.


Columbus apparently went down a slippery slope, thinking it his spiritual duty to convert these natives and save their souls, which let him to thinking, how better to convert people than by the club, and what makes a better club than a sword?  By turning to the sword, Columbus ultimately succumbed to blind and arrogant self-righteousness which nothing--not the absence of gold nor the decemation of an entire people--could snap him out of.  Let's learn to avoid this in the future, what do you say, fellow humans?

Electrons have their cake and eat it too...

A zen monk named Yogi Berra once said, "If you see a fork in the road, take it."  Quantum mechanics has shown us that elementary particles, such as electrons and photons, seem to take Yogi's advice.  That is, when an experimental physicist gives a quantum particle such as an electron or a photon a choice between two paths, it can take both at once.  This is evidenced by an interference pattern that results when you recombine the paths at the other end of the experimental apparatus.  The interference pattern shows that not only does the particle take both paths, but it actually "gets in its own way" as it does so! 

But it gets weirder.  The electron does not always take both paths.  Sometimes it takes one path or the other.  But this only happens when you try to find out which path it took!  In fact, the more you know about the path of the electron, the less likely it is to show an interference pattern.  In other words, the electron seems to respond how much we *know* about it!  If we set up our experiment to get any "which path" information, it will only take one path.  But if we set up our experiment so that we do not know which path it took, it will give an interference pattern showing that it took both paths.  So we can decide, based on how we set up our experiment, whether an electron took one path or both paths. 

But it gets EVEN weirder!  Not only can the experimental physicist decide whether it took one path or both paths by changing how they set up the experiment, but they can do so *retroactively*, i.e., after the electron has made its way through the path(s)!!  This is called the delayed-choice experiment.  Here is a description from John Wheeler, who came up with the idea:

In the 1970's, I got interested in another way to reveal the strangeness of the quantum world. I called it "delayed choice." You send a quantum of light (a photon) into an apparatus that offers the photon two paths. If you measure the photon that leaves the apparatus in one way, you can tell which path it took.

If you measure the departing photon in a different way (a complementary way), you can tell if it took both paths at once. You can't make both kinds of measurements on the same photon, but you can decide, after the photon has entered the apparatus, which kind of measurement you want to make.

Is the photon already wending its way through the apparatus along the first path? Too bad. You decide to look to see if it took both paths at once, and you find that it did. Or is it progressing along both paths at once? Too bad. You decide to find out if it took just one path, and it did.

The delayed-choice experiment may be weird, but it is not mere science fiction.  It was first carried out by physicists at the University of Maryland, where I go to school.  Actually one of the physicists who did the experiment works across the hall from the office where I spent most of my time here, Dr. Alley. 

Shih & Alley carried out the delayed-choice experiment in the late 1980's using photons, and it has been replicated several times since then.  They decided, retroactively, whether the photon took one path or both paths by shifting the experimental arrangement after the photon was well on its way along the path(s), several nanoseconds after it would have had to "choose" one path or the other.

But wait, it gets EVEN WEIRDER!!  In principle, as Wheeler has pointed out, this experiment could be carried out using astronomical sources.  A photon from a distant quasar, for instance, could have the option of taking two paths towards Earth due to an effect called gravitational lensing.  The photon could go straight to Earth or it could be pulled around another path by the strong gravitational force by a galaxy along the way.  Since we can still decide whether the photon took one or both paths by how we set up the experimental apparatus on Earth to measure "which path" information or to find an interference pattern, we can decide which path(s) the photon took BILLIONS OF YEARS AFTER it had to have taken them!

Good luck getting to sleep tonight.

A nifty little use of big binder clips...

It both keeps the toothpaste squeezable and also holds it upright.

I imagine someone more artsy than I could think of ways to improve the aesthetics...maybe some designs with white-out on the black part?

And yes, I am a total nerd.

- Posted using BlogPress from my iPhone

A Little Rule That Could Change Your Life Forever

So, I am such a big dork that I am proud of the way I organize my folders, both real as well as the folders on my computer.  If you're like me, your folders have way too many things in there to keep track of visually.  It may looking something like this:

Ugh, that is visually daunting.  It's hard to see any details or structure for how things relate to each other, and frankly it just gives me a knot in my stomach looking at all the things I'm supposed to be keeping track of in my life.  In fact, I'm crying right now.

BUT THERE IS HOPE!  I have gotten my files and folders in order, and you can too if you follow one simple rule.

That's right, folks, you heard it here.  My organizational system follows one rule, and one rule only.  It is a rule that is based on empirically grounded psychological principles of how the mind works.  In fact, it is based on perhaps the most robust result in the study of human memory.

Now there is long term memory (memories of childhood, memories of alien abductions, etc.) and there is short term memory (memory of what you just read literally a second ago, weren't you paying attention??).  Long term memory is a mystery as wide as the ocean.  But short term memory--the memory underlying your attention--is not so daunting.  It's at least something we can explore experimentally without having to wait a long time.  So, it is attentional memory that is the critical factor here.


Speaking of which, I'm probably losing your attention, so here is the rule: 7+/-2

This is the number of things you can store in your short term memory.  And therefore it should also correspond with the number of things in an open folder.  Any more than that, it's time to organize it down to 7+/-2.  (That's anywhere between 5 and 9, for you mathematically disabled folks).

So here goes the principle in action.  Above, you got to see my "2011 Articles" folder (and don't you feel a little closer to me now??) which is way too cluttered.  At the bottom of the Finder on my Mac, it actually tells me how many items there are, in this case 25.  Sheessh 25 things to keep track of!  Too much.  So, that made me organize so that there were only 7+/-2 items.  And here's the result:

And it took me like 5 minutes, tops.  (don't ask how long blogging about it took me...)  I just decided to consolidate.  First I noticed that several folders could be considered "Discourse Analysis" and so I put them into, of couse, the Discourse Analysis folder that was already there.  And then I even realized that I'm really only keeping Discourse Analysis stuff because it relates to my dissertation.  SO, I put it in the Dissertation folder.  And so on, and so on. 


There it is.  When your life is feeling full to the brim and hard to keep track of, chances are, your folders are too.  And here's the simple rule to fix both: open folders should have only 7+/-2 things in them!

Thank you, goodnight.

Design principle: don't break the stream of the user unless you mean it

Design principles are often most noticeable when they are violated. You may personally experience frustration as the result of design flaws, and/or on a larger scale you may notice that nobody follows the design.

This came to my mind as I exited a bathroom of a coffee shop in Portland after washing my hands. On the door hangs a sign telling me to use a paper towel to turn off the water.



Uh, too little, too late!

It also tells me to use a paper towel to open the door as I leave. Now, I could either go back to the paper towel dispenser or I could do what I normally do--use my foot or elbow or try to touch the door where nobody else has. Based on the wear and tear around the door handle this is what other people have done, too.



Lastly, it tells me to throw out the paper towel in the trash can. Only problem is, there's no trash can anywhere nearby. That there are no paper towels on the ground therefore suggests that nobody bothers to get them in the first place.

They apparently want the bathroom users to get a paper towel to turn on the water, then go get another one to turn off the water, then another to open the door, then go back in to throw it out. Then another to leave after throwing the first one out. But then go back in to throw the second one out. But then another to leave again...maybe they don't want anyone to leave.

At least, that would explain why there were 37 very confused people in the bathroom spinning around in circles...


- Posted using BlogPress from my iPhone

Location:NE Holladay St,Portland,United States

Grilling at the heart of the world

We tend to think of modern scientists in the reductionist tradition to have thought more deeply about the world than ancient thinkers. Thomas Kuhn, at his most extreme, was convinced that ancient theories were no more or less true than modern theories, just different. Sometimes, when I'm standing under a big tree, with birds chattering, and the moon just as aloof now as it was 1,000,000 years ago, I can convince myself of the same thing. But then I remember it's time to flip over the pork chops on the grill.

- Posted using BlogPress from my iPhone

Location:My backyard

Where Have all the Flowers Gone?

Watching the Olympics this past week has conjured up a lot of memories of various moments in sport that I have found particularly moving. One of my favorite moments was one you probably do not remember.  It was 1994, at the Nagano Winter Olympics.  This was the much-anticipated Olympics of the Nancy Kerrigan-Tanya Harding drama, when skating had reached new high in the amount of attention from the public by hitting a new low morally and emotionally. 

Under the radar was two-time Olympic champion Katarina Witt, who had just come back to figure skating that year.  Coming into the long program, she -stood in 6th place.  Witt dedicated her long program performance to the city of Sarajevo, where she had won her first gold medal 10 years before.  (Sarajevo in 1994 was under siege in the midst of the genocidic Bosnian war.)  In an elegant and simple dress (in contrast to a lot of the gaudy sparkle-fests worn by her competitors) Witt skated her program with soul, grace, and fluidity:

http://www.youtube.com/watch?v=RjB17Cn_Hd8

I especially love the ending, 4min into the video--I find it visually stunning and powerful.  I think it is noteworthy that the crowd was so taken by the performance, they were throwing flowers onto the ice.  Even more telling are the boos and hisses from the crowd when Katarina's abysmal scores were announced.  She came in eighth in the long program, because she just didn't do enough triples to impress the judges, like her upstart competitors did. 

Why has this moment stuck with me for so long?  I think it is because even then, when I was 16, I could sense the irony expressed by Katarina's performance.  There was the explicit message that in an age of war and aggression, we should seek peace and beauty.  There was also the implicit message sent to the sport of figure skating--in an age when skating had become little more than a triple-axle competition mixed with a reality TV show, Katarina was expressing that it had come at the expense of honesty and elegance. 

I think the sport of figure skating has tried harder and harder to become an "objective" sport, under the assumption that the more objective it is, the more you can prove through measurement that one performance was better than another, or that one skater is better than another.  I think Katarina Witt's performance at the Olympics in 1994 was one of the most telling reminders for me that the most important things cannot be measured.

I would vote Coakley on Monday, if I were still in Massachusetts…

…and here’s why. 

Of course there’s the health care reform, but we have to remember that this vote for a senate seat, not merely health care reform.

An issue of equal importance, in my book, is education.  Coakley’s stances are well-thought out and will make positive changes within the currently wretched policy environment.  Brown’s stances are backwards and will only take things from bad to worse.

Being a doctoral student in education, I am particularly passionate about the importance of good education in fostering a stronger nation and a better life for its citizens.  Through my studies and experiences, I have come to believe that our nation’s educational policies (ahem, NCLB) have had a lasting negative impact on our nation’s schooling that only promises to get worse unless something drastic happens.

I have been working in schools over the last 10 years as a teacher, as a teacher supervisor, and as a professional developer fostering innovative teaching techniques.  I started teaching in 2000, before NCLB was passed, and I felt the winds change.  These winds brought in some dark clouds: my efforts at improving education have been continually (and continue to be) thwarted by the current policy environment.  And making positive changes has only gotten more difficult over the past 10 years. 

The whole premise of NCLB is misguided, however well-intentioned its writers may have been.  The whole idea is that all students, 100%, every single one, will score “proficient” or above on a standardized test by 2016.  This is regardless of whether they are: bad-test-takers, severely mentally disabled, rich, poor, recent immigrants (legally or illegally), attend a good or a bad school, have good or bad teachers, have an f’d up home life, etc.  This would be a laudable goal, albeit a bit pie-in-the-sky, if only the standardized test had anything to do with what we would really want to call learning and thinking.   It does not.

The worst, most idiotic, and most damaging part of NCLB is the “Adequate Yearly Progress” clause.  Not only must schools get all students to 100% proficiency on the standardized test, but they must also get better and better scores each year.  Highlighting the short-sightedness of this policy, Bush in 2001 ended up awarding both the Blue Ribbon of excellence and also the ‘failing school’ condemnation to the very same schools!  There was a USA Today article on it at the time; you can check it out here.

School systems, because of NCLB, are addicted to proving “Adequate Yearly Progress” (AYP), because this determines the federal funding for the school, and the employment of its administrators and teachers.  This prevents any adoption of new curricula or teaching methods, unless they are likely to greatly improve test performance.  And guess what greatly improves test performance?  That’s right: learning test-taking strategies.  So, instead of learning to think, or learning to do science or music or art, or math, or learning to read or right, students are pushed to learn how to take standardized tests.  And the problem is, the test-taking strategies are in fact improving their test scores!  But at what cost?

Research in education is uncovering a scary picture of how NCLB has affected what goes on in classrooms.  Researchers at the University of Maryland happened to be closely studying the activities of the classroom, when right in the middle of their study NCLB was passed and implemented.  They were tracking, with PDA’s, the minute-by-minute goings-on in the classroom.  They found that, in every classroom they were monitoring, the amount of high cognitive demanding questions went significantly down, and the amount of low cognitively demanding questions and tasks went way up. Now THAT’S scary.  NCLB, and the high-stakes testing environment, apparently lowers the standards.  How’s that for ‘accountability’?  (BTW: This research is reported in the book Test Driven, but be forewarned that it’s very research-y!) 

Accountability is a buzz-word that has nearly lost all of its meaning in education, and when a politician mentions it it is because they are trying to sell you something.  (Thanks, George Bush!)  So, it makes me cringe when Scott Brown makes that the centerpiece of his education platform.  He also

vows to fight for standardized testing as a measure of accountability:

Scott Brown’s Education policy statement: I am passionate about improving the quality of our public schools. Accountability and high standards are paramount. I support choice through charter schools, as well as the MCAS exam as a graduation requirement. I have worked to ensure that all children have access to a quality education. I am a strong advocate for the METCO program, which provides lower income students with broader educational opportunities.

Martha Coakley, on the other hand, is looking forward.  Not only is education a more important issue to her, but she has sensible plans for actually improving it.

Martha Coakley’s Education policy statement: Martha is deeply committed to public education. As Senator, she will fight to improve teacher compensation, fund programs that connect students to innovative technology and industries, and implement education reform that fosters and rewards innovation.

I encourage you to go to her site and read more about her education policy stances (I would tell you to read more about Brown's stances, but what I pasted was all he had to say.)  Here’s my favorite part of Coakley's statement:

Martha supports efforts to move away from measuring adequate yearly progress (“AYP”) based on standardized testing.  These tests fail to recognize that all children do not learn in the same way or at the same rate, especially in high-risk schools.  By holding schools accountable to this one-size-fits-all standard, many are improperly labeled as underperforming and subject to unfair and counter-productive federal sanctions. Martha supports the use of growth models and indexing systems to focus on tracking the progress of individual students over time.

If you want a senator working for positive change in educational policy, I suggest all you massholes vote for Coakley!!

What’s really happening

A story about stories

There is a fundamental paradox that we are all vaguely aware of, even if we haven’t quite articulated it to ourselves.  Unlike the paradoxes of physics and philosophy, which we may never personally encounter, this paradox resides right under our noses.  More specifically, it resides right at the tip of our tongue.  It also buzzes incessantly right between our ears, being the fabric out of which even our internal monologue is woven.    It is the paradox of storytelling—the holy trinity of the story, its teller, and its audience. 

When I say storytelling you probably think of the sorts of storytelling done by professionals such as Twain or Poe, or the kind that is performed to a group sitting around a campfire or a dinner table.  And I do mean those; but I don’t mean only those.  I mean storytelling as grand as telling the story of our cosmic origins, or as minute as silently but persistently telling ourselves what it is we are thinking about at the moment…and everything in between.

We are all storytellers.

Historians compose stories about civilization, the ideologies and innovations that compete and collaborate to form periods of stability, progress, and revolution.

The press and its journalists compose stories that amount to the history of “now”—events at the intersection of people, their roles, and the motivations that drive them to act according to their roles.

Biologists tell same sorts of stories as historians and journalists; the differences amount to ones of scope, with roles played by very different sorts of characters, the innovations of a much less teleological nature, and the motivations largely being those of survival.  But really these are not such dramatic differences after all.

Physicists tell causal stories about particles and their interactions.

Your mind tells stories about you, what you’re doing, what you have done, and what you plan to do.

How many stories are there?

We like to think of history as a continuous stream of goings-on.  So much so that we each tend to decide on one story and stick with it, quickly forgetting, ignoring or even deleting versions that don’t jive with it.  We all know it’s the winners that write the history books; this is true of the shared history written down in books as well as our personal histories written down in our stream of consciousness.  But if you’re really observant, you can sometimes spot multiple drafts of the same story before one get chosen and the other swept under the carpet. 

Case in point: the recent protests in Iran (video).  There are two major versions of the same events.  I’d like you to suspend judgment, if just for a moment, which version you believe.  (btw I’m going off this NY Times article)

Version #1: The Iranian government says that western countries helped orchestrated the protests, and that shots from the crowd struck and killed several people, including Ali Mousavi, the nephew of the opposition leader.

Version #2: The people in the street says that the protests were peaceful, but that revolutionary guard soldiers violated the rules of the holy day by shooting into the crowd, possibly even assassinating the nephew of the opposition leader.

These two versions of the story seem completely incompatible.  How can one person ever believe both at the same time?  How can it be decided which version is a “factual” account of the events?  Most likely what will happen is that one group of people will believe one version, and another will believe the other.  Whichever story gets believed by more people in the end will survive and become the “official” account, the other will pretty much die away.

What’s the real story, and who gets to tell it?

And now for the paradox. 

We all know that there are many sides to a story.  And so it makes sense to say that there is no one real story of what really happened.  There are only versions of stories, which are unavoidably colored by who is telling them and who they are being told to. 

But on the other hand, to say that there is no privileged version of what really happened—there is no plain and simple truth, no bare fact of the matter—seems totally crazy. 

I think this paradox, just like any paradox worth its mettle, is inherently unresolvable.  But that does not make it a dead end.  Keeping this paradox in mind helps us remember that we may always be wrong about even the things we’re most certain of.  I think this is a crucial step—perhaps THE crucial step—towards the peaceful resolution of conflict.

viewing the world through googl-y eyes

Google Scholar search results for "since september 11"

before 9/11/01: 85
since 9/11/01: 9,910

Voting ≠ Democracy (part I)

What is democracy? I was brought up to think it meant that people got to elect their leaders. But we don't live in that kind of dreamworld. There are so many assumptions that get broken down in the real world.

 
 

First of all, who votes? Not everyone. Therefore there is a selection effect. The poorest, which coincides at all times with the racial minority, get left out of the decision making. Furthermore, it is not our vote that determines the most important political position (the president). We vote for members of the electoral college, who then verbally promise that they will vote for who we told them to. And the primaries really mess with the idea of a pure democracy as well.

 
 

Second of all, what does your vote DO? The idea is to vote for a leader who will make decisions representative of the people's best interest. But WHICH people--not all the population has the same best interests. And who gets to decide what actions will serve our best interests? The leader determines how to act, and therefore determines WHICH peoples' interests to serve, and HOW to serve them. But these things can seriously diverge from the public's view of their own best interest. George Bush's 27% approval rating is indicative of this. "History will vindicate me" he says. What if it doesn't?? Mugabe in Zimbabwe only legitimizes the votes of the people that are in line with his own best interests--whatever doesn't do that is due to the "influence of the west." How do we draw the line?

 
 

Third of all, who do we vote FOR? It's not the president, as I said, it's the electoral college. But for whom do they vote? Not the president, because its not the president who makes all the decisions and policies. It's the presidential cabinet--his advisors such--that really make the policies. The further away from the vote these people are, the more they can diverge from the people's best interests.

 
 

Fourth of all, WHY do we vote for them? It's not really their policies and beliefs. It's their name. It's their appearance. It's their soundbites. It's their verbal miscues. There is data to back this all up. Are these really indicators of the best interests of the people?

 
 

No, voting does not mean democracy. Voting is one way of getting at the greater principle at stake here, which is the coupling between the voiced needs of the people and the actions of their leaders. Voting is supposed to do this in two ways. (1) it selects leaders that are pre-aligned with the perspectives of the majority of the people, and (2) it puts pressure on the leaders to keep listening and acting for the interests of the people. This latter point is an often-overlooked component these days. In Iraq, for example, the U.S. only paid attention to (1).

 
 

We have to ask if voting is the only way of implementing (1) and (2). The answer is no. (1) can be fulfilled by a revolution, for example (see U.S., France, Cuba). Therefore, the U.S. should not consider a country to be a part of the "axis of evil" just because their leader was not elected. China, for example, has elections and they have no regard for the interests of the people. The reason is largely the lack of free press. A free press can carry out (2) more effectively than even voting can in certain circumstances. The lack of free press undermines the principle of democracy in very serious ways. For one, it convinces the people of what their best interests are. One way it does that is it selects and therefore distorts the facts by only presenting one point-of-view; that of the government who are trying to preserve their own best interests. This prevents the public from having the proper grounding in the present to determine for themselves what their best interests are.

 
 

Voting and free press I'm sure are not the only aspects of democracy, I'm thinking justice system, educational system, and army and such, but I'll have to come back to those because I am hungry and late for school.

Norton AntiVirus is a Virus

There is a program that has gained access to my computer without me knowing or wanting it, regularly disrupts my computer's normal functioning, eats up tons of memory, and resists being erased. It could happen to you, too, so I want to warn you to watch out for this horrible, senseless malware. Its name? Norton AntiVirus.

Ironically, Norton AntiVirus was designed to find and destroy programs with just these qualities. I believe the cliché applies here, that you become what you hate.

If Norton AntiVirus now wants to save its own credibility, it must remove itself from my computer.

I'm not holding my breath.

Bass Jam #1

I was simultaneously testing my microphone and my bass, and I can up with this little improv...how does it sound to you?

coincidence?

Thou Shalt Not Take the Bible Literally…

…not if you want to avoid some severe epistemological conundrums, that is.

Some things can't be true

Many people claim to take the Bible "literally," but besides the problem of defining just what "literally" means, there are many reasons to believe that this is not possible—let alone desirable—even for the deeply religious. Here I will lay out a few of the problems you have to grapple with if you claim to take the Bible literally.

Epimenides was a Cretan philosopher whose claim to fame was his declaration that "Cretans are always liars." For centuries, scholars have wondered whether Epimenides, himself a Cretan, was telling the truth when he said that. Paul, in his epistle to Titus, did not seem affected by the paradox since he simply stated that Epimenides' statement is true:

¹⁰For there are many rebellious people, mere talkers and deceivers, especially those of the circumcision group. ¹¹They must be silenced, because they are ruining whole households by teaching things they ought not to teach—and that for the sake of dishonest gain. ¹²Even one of their own prophets has said, "Cretans are always liars, evil brutes, lazy gluttons." ¹³This testimony is true. (Titus 1:10-1:12)

This is a problem. For if it is true that Cretans are always liars, then Epimenides is always a liar, and so he must have been lying. In sum, if Epimenides' statement is true, then he must have been lying and so it must be false...which makes it true again because he said they always lie, which makes it a lie, etc. etc. etc.

So, is it true or not? Philosophers tend to say it is neither, preferring instead to call such paradoxical statements "undecidable."

Paul's statement adds another layer to this problem. Is everything in the Bible literally true? Well, if so, then Paul's statements also have to be true. If Paul's statements are true, then his statement "This testimony is true" is true. If this testimony (i.e. that Cretans are always liars) is true, then Epimenides was always a liar. If Epimenides was always a liar, then he lied when he said Cretans are always liars. 
So then Paul is wrong. So then the Bible contains things that are not literally true.  Even if you concede that "Cretans are always liars" is not false—it's just undecidable—then Paul is still wrong to say it is true.

Some things aren't supposed to be true (literally)

Maybe you're worried at this point, but don't be. It's okay. The Bible literally says not to take the Bible literally. For example, Jesus admittedly taught much of his important messages metaphorically, in parables. He would explain the meanings of these parables more straightforwardly to his 12 apostles:

And His disciples asked Him, saying, "What might this parable mean?"   And He said, "Unto you it is given to know the mysteries of the Kingdom of God; but to others in parables, that `seeing they might not see, and hearing they might not understand.' " (Luke 8:9-10, 21st Century King James Version)

So, if you want to take the Bible literally, it seems you are going against what the Bible literally says to do.

So You Think You Can Philosophize: Episode 2

This week's contestants, Destro and Cobra Commander, consider whether there can be any critical experiments in science. That is, until their boss catches them.

	There can be no critical experiments in science, if you believe in structural realism.
	There can't be any critical experiment, no matter what your theory, if you ask me.
	Well, that depends on what you mean by critical experiment.
	So what do you mean then?
	I mean an experiment that, if it comes out a certain way, proves your theory wrong. An example would be the 1919 test of Einstein's theory of relativity by observing how far the distant starlight was deflected by the curvature of spacetime around the Sun. If there was no deflection, Einstein would have been proven wrong. That's a critical experiment.
	So it sounds like critical experiments in general have to be defined counterfactually.
	Hmm, I never thought of it that way, but it would be an interesting thing to explore. What do you mean?
	Well, if a theory is successful, it has passed all the experiments, or at least all the trusted experiments, that have been done to test it. If they were critical experiments, then they can only be described as such counterfactually, . I.e. had they come out differently, the theory would have had to be abandoned.
	Okay, but that doesn't preclude critical tests of the theory in the future, does it?
	How do you mean?
	Well, the tests it has passed in the past may have to be counterfactually shown to be critical tests, but there is still the future to look forward to. The theory will be put to more tests. And if it makes predictions that differ from reality then it ruled out. In that case, it was a critical experiment, not counterfactually.
	Okay, yes. But still any passed test can only be defined as a critical test artifactually, right? Can we agree on that?
	Well, it seems so right now, so I'll go with it. But it may happen in the future that something comes to light that would rule it out. Moving on.
	Point noted. So, what was that you were saying about structural realism? I'm afraaid I don't know quite what that is.
	Oh, structural realism? It's a nifty way of looking at progress in science. You see, there is a strange tension in the progression of science. Our numerical predictions are getting more and more precisely verified by experiment. Therefore, some reasonable people say that science is getting us closer and closer to the truth. Or, rather, that science gives us the truth, in ever more fine grained detail.
	Yeah, that seems right to me.
	Ah, but then you have the problem of scientific revolutions. As Einstein put it, "no amount of experiments can prove me right, but a single one can prove me wrong". Now, what do you think he meant by that?
	Well, it sounds to me like he's talking about critical experiments.
	That's right, I think he was talking about crucial experiments in the last clause. But the first clause is curious, isn't it? "no amount of experiments can prove me right."
	He was a very humble man.
	Well, I don't know about that. He also was trying to figure out if God had any choice in creating the universe…not so humble if you ask me.
	Alright, alright. But he's just saying in that quote that his theory will never gain 100% precision. There will always be some uncertainty, so if certainty is your criterion for his theory being "right", then you are out of luck. But that is a very stringent criterion for a theory to be considered "right". Clearly the theory is right, to the extent that your GPS unit has to use his theory to account for your correct coordinates.
	Okay, I see you point. That is one way of interpreting his statement, and now I see why you think he is being humble by saying so. His theory is obviously right to some extent, but he is taking the high road but not claiming to be settled completely. Well, there's another way of interpreting his statement that you may want to hear.
	Let's hear it.
	Okay, so he's saying that no amount of experiments can prove him right, and that one can prove him wrong because he knows that someday his theory will be overturned. He has said as much elsewhere.
	Huh.
	Right. But think about it: his theory was overturning Newton's in a sense, a system of laws that had been taken as gospel for hundreds of years. And yet a single experiment, the eclipse observation of 1919, was sufficient to overturn it. This has happened time and time again in the history of science. A theory is thought to be "right" but then at some point an experiment proves it wrong. So, if it can always be proven wrong at some point, then what does that say about it's chances of being right? Those chances are apparently zero.
	Unless you have the correct theory of everything.
	And that only makes sense if you are a unificationist, I think.
	Huh?
	Nevermind. So, do you see the tension now? On the one hand it seems that are theories are getting us the truth, more and more precisely. Even when a theory is overthrown, its in a regime where the old theory wasn't designed to tread anyway, and the mathematics are continuous by design. Quantum mechanics mathematically reduces to classical physics in the limit of h bar being very, very small.
	I see that.
	But on the other hand, there are radical revolutions of theories, in which the old theory is not continuous with the new. Newton's law of gravitation explained the motions of the planets in terms of gravitational force, which emanated from the center of massive bodies and acted over a cosmic distance. In Einstein's theory of gravity, there is no gravitational force. There is only the local curvature of spacetime that massive bodies follow along in the straightest line that they can. Entities such as gravitational forces that were the main players in one theory are completely absent in another.
	But their roles are still present. Something is still present that makes the planets move as they do.
	In a sense, yes, I think I agree with that. Although a little nagging doubt thinks about Wheeler's book "Spacetime Physics" which says that the natural state of motion in GR is free-float, and it's deviations from the geodesic path that need to be explained. But I'll leave that issue aside for now and just say that I agree with you. For this is what I think structural realism is all about. Science gets at the truth in that we are discovering the true roles, the true structure of the universe. But we may, in individual scientific theories, be getting the players of those roles wrong.
	So scientists are writing a play, and their first performance may have had a bad cast, but the screenplay is still great if we can only find the right actors to play the parts.
	Something like that.
	So back to your original point--how does this preclude critical experiments?
	Well, to follow the play analogy, how can we ever really know if it's the actors that are bad, and not the script? If it's really hard to find an actor that does a role justice, is it a problem with the actors or with the role?
	What do you think?
	Well, I don't know. There may not even be any fact of the matter. But for now, I will assume that there is a fact of the matter and keep running with the metaphor. The director can decide to tweak the script to find a balance with the actor that he's got. Or, more radically, he may take that role out entirely.
	But then you have to worry about whether its even the same play anymore.
	That's true, depending on the role. If the play were Hamlet, and you took out the role of Hamlet, it seems clear that it's no longer the same play. But if the roles were Rosencrantz and Guildenstern? Then it's not so clear. Perhaps it's the centrality of the role removed that determines to what extent the play has changed. But you agree that it's not an on/off thing?
	Well, I don't know. If you change the main character, for whom the play is named, that seems pretty on/off. What if you took King Lear out of King Lear? Godot out of Waiting for Godot? The silence out of "2:00 of silence"?
	But on the other hand, if you change the other roles there seems to be varying amounts of grey area. What if you took Brutus out of Julius Ceasar? Or just the chorus?
	Okay, so I'm having trouble seeing how this gets back to crucial experiments in structural realism. I got a little lost in the metaphor.
	Fair enough. I can see how that might be the case. I am, after all addicted to metaphor, but that's a discussion for another day. If structural realism says that we have the roles correct, as expressed in the explanatory and mathematical structure, but we get the details wrong about ontological entity filling those roles, then I suppose a critical experiment would be one that puts to the test one of the roles in question. And if all we are ever changing in practice is the actors that fill the roles (gravitational force vs. curvature of spacetime) rather than the roles themselves, then we are never doing critical experiments.
	Wow, that seems pretty weird.
	So if we never put roles on the chopping block, then maybe that means we've had all the roles all along. Which makes me worry that we are just filling out theories constrained by the very structures of our brains.
	Well, you are a worrier...I think that's a big leap.
	How so?
	Well, I'm not sure yet, but I'm trying to work that out. For one, we can't have had all the roles all along. There are new roles introduced by theories all the time.
	How so?
	Well, quarks, for instance. Higgs particles. Fields. We didn't even know atoms had a nucleus until the last 150 years, so how could the role of keeping the nucleus together been around before that?
	That's a good point, but I'm not sure we're talking about the same level as being roles. We might be though. But maybe what I mean by roles is an explanans--quarks play the role of keeping together something that otherwise shouldn't be together. If we didn't think like charges repel then we might never have needed the role that quarks play.
	What about astronomical observations? What role is played by black holes, quasars, things we can observationally detect that we wouldn't have dreamed of before?
	Well, I'm not sure. Perhaps you make a good point. So maybe my worry was misplaced after all.
	I'll give you something to worry about! What is this insubordinance?! Get back to work, you slimes…this, I command!
	Serpentor! I should have smelled you coming.
	Destro, the tricky details of your thesis have to be done by showing when roles were introduced and by showing to what extent they were really put on the line. But that is a task for another day, my friend.
	Long live Cobra Commander!
	Cobra!!