I’ve had a set of “bad science movies” on my Netflix queue for a while, and every once in a while I dip into it.  Each time it feels a bit risky, like trying some weird new combination, like cherry dip on my mint chocolate chip ice cream cone.  Sometimes it’s OK.  Sometimes it’s not the best use of my money, so I cut my losses and go surf the internet.  But this time, it all worked out, it all worked out great. On the other hand, my brain was rather fried from a long day slogging through snow covered peaks (see picture below). 

Climbing Mt. Neva. Photo by Brian Moore.

So, after a day like this, this kind of dumb was just what I wanted. Of course I knew that the whole premise of “The Core” would be laughingly stupid.  (The earth’s magnetic field has stopped!  We have to drill down to the center of the earth and jump-start it!).  But, even allowing for the whole “flawed premise” (after all, being a writer is about being creative, so we can cut them some slack to create the storyline, I guess).

But I was still giggling here and there.  Even simple stuff — the pigeons go beserk and start crashing through storefront windows (c’mon, birds fly into windows all the time and don’t smash them to smithereens), was just silly.  And while the movie writers were careful to provide at least pseudoscientific explanations of how most things worked, I guess they knew that it was going to be beyond their ability to come up with a decent explanation of how Mission Control could manage to communicate (instantaneously!) with the ship as it burrowed through hundreds of miles of molten metal.  So they didn’t even try.

But I needn’t bother to spend the time to roast this movie in the pan that it so richly deserves, it’s been done far beyond my ability on Intuitor’s Insultingly Stupid Movie Physics.  (They have a bunch of other wonderful reviews of popular movies).

Here’s a zinger from that site:

Keyes proceeds to demonstrate the effects of losing the magnetic field by lighting the aerosol from a can of hair spray and flaming a peach representing Earth. He makes his explanation simplistic since he’s talking to military brass who can’t grasp complexity, even though they lead one of the most complex and high tech organizations in the world.

Whether Earth did or didn’t have a magnetic field would make no difference….

Not only does Keyes not know the difference between forces and energy but he apparently believes that electromagnetic radiation such as microwaves can be deflected by a magnetic field. Here’s a quick experiment, try using a magnet to deflect the electromagnetic (EM) radiation emitted by a flashlight. The EM radiation is a beam of visible light and, although we hate to spoil the experiment, nothing will happen.

Whether Earth did or didn’t have a magnetic field would make no difference as far as microwave radiation is concerned. First, the magnetic field doesn’t affect it, and second, there’s very little of it in the first place. The Sun emits lots of electromagnetic radiation but most of it is visible light. It sends very little microwave radiation. At its worst, the Sun’s microwave radiation can cause interference with radio or cellphone transmissions but poses no significant health hazard.

Ouch.  Of course, the plot also has plenty of loopholes, scientific or not:

The cast is rounded out by DJ Qualls who plays a stereotypical convicted computer hacker called Rat. He is brought on board for the critical task of preventing anyone on the Internet from precipitating a worldwide panic by posting theories about the impending disaster. Apparently, dead pacemaker patients, berserk window-smashing pigeons, bizarre space shuttle crash landings, monstrously powerful thunderstorms, the Golden Gate bridge collapse, unexpected nightly displays of the aurora borealis, and the total destruction of Rome, all in around three months, aren’t enough to generate concern.

Besides, no TV, newspaper or radio news organization would ever speculate on such matters, let alone ask reporters or high-priced consultants to find answers. No televangelist would see anything Biblical in these signs of impending judgment nor would any private citizen be panicked without input from a webpage.

Bottom line:  rent “The Core.”  Go, do it now.  If you’re a science teacher, assign your students to watch it, and then come up with 5 examples of “what’s wrong with this picture.”  What a fun assignment.

Incidentally, I got much of my list of bad (and good) science movies from Sidney Perkowitz’s Hollywood Science book, which reviews early to recent movies and explains the good, bad, and ugly in the science in these films.  It also has a list of the all-time best (and the all-time worst) science movies.  Worth a look.

One good outcome of this movie (which really is a hoot, and not a terrible movie if you like this sort of thing, which I do), is that it was purportedly the impetus to start the Science and Entertainment Exchange (run partly by Cocktail Party Physics blogger Jennifer Ouellette), which connects scientists with the folks in the entertainment industry so that stuff like this won’t happen again.  They have a blog too.

You can also see Blick on Flicks at the National Science Teachers Association for some more blogging on movie science (and how to use it in your classroom).

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OK, I wouldn’t let it run quite as long as these bored college students did, but it DOES look REALLY cool (and it’s a great use of those annoying AOL CD’s, or the romantic mixes that your old boyfriend made for you):

And another really pretty one (gotta love the Darth Vader-esque breathing in the background), with an extra bonus:  aluminum foil!

You can play around to see if it matters if there are images on the CD, if it looks different printed side up or shiny side up, etc.  This site claims that it works best label-side up, and that the less ink on them, the less they smoke.

As you know, it’s not supposed to be good to microwave metal.  That’s because the microwaves can push the electrons around in the metal.  (Electrons in non-metal, or non-conductive material are kind of glued in place, so they can’t be pushed around).  That can make the metal heat up (just like a metal wire will heat up when it’s conducting a current) and do all sorts of bad things to your microwave.  You can read more about microwaves and what they do to metals here.

So, CD-ROM’s have a thin aluminum layer.  And the microwaves push the electrons around in the aluminum, making big currents, which heat up the aluminum so much that it vaporizes (turns into steam)!  The electric current is still there, though, so it jumps across the vaporized aluminum (making a pretty light show) to get to another section of aluminum.  There is a little bit of similar science between this and the Microwave a Grape activity I posted earlier, in that you’re seeing air glow as electrons jump through it (a phenomenon called arcing).  You’ll see a bunch of little paths burned into the aluminum after a while.   An interesting observation from this site:

Some of the islands will be shaped so that they make very good microwave antennas. These spots will focus the microwave energy, and get very hot. Now you will see just a few bright spots spewing a lot of smoke. The good part of the light show is over, turn off the oven.

Here is a lovely image of a CD post-microwave, showing beautiful fractal trees where the electrical arc made its way across the aluminum.

I’m still a little confused as to why the patterns burned in the CD follow these circumferential patterns.  I imagine that the CD data is originally etched in circumferential patterns, making the aluminum thinner in these regions, and thus channeling the electricity in these circles.

For extra fun, if you happen to have a Tesla Coil lying around, here is what happens when you place the microwaved CD on top of the Tesla coil.  I got this from ElectricStuff.co.uk, which has even more pictures.

I believe what’s happening is that the electric current from the Tesla is flowing just through the parts of the CD that still have aluminum on it, generating high heat and arcing in lovely patterns.

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So, I’ve got this bumper sticker, which has sort of become my little badge of fame, “Flirt harder. I’m a physicist.” I love it — I’ve had motorists pull up beside me, motion to roll down my window, and yell “What kind of physicist?” I once saw the driver of the car behind me taking a picture of it while we were both stopped at a stoplight. I’ve had numerous pedestrians stop to ask me about it. Several don’t get it, like this blogger:

the confusing ones say “flirt harder. i’m a physicist.” i really don’t get that one. do i have to be a physicist to understand it? i’ve only taken high school physics so i have no idea what flirting has to do with anything physics related.

I’ve had some guess that it means that physicists are more desireable, so you should flirt harder to get one (I don’t mind that interpretation). But Jen Oullette gets it:

One of my favorite physics buttons/bumper stickers reads, “Flirt Harder — I’m a Physicist.” There’s a certain degree of truth to this stereotype, although it must be said, most physicists, computer geeks, etc., seem to end up married or in relationships at some point, so they can’t be as clueless as they’re generally believed to be.

The reason I love this bumper sticker, for myself, is partially its irony (I’m known to be an incurable flirt, and certainly not among the clueless when it comes to picking up on romantic signals). I’ve also often wondered how much of people’s confusion about its meaning comes from the fact that it’s on a woman’s car. The stereotyped clueless physicist/geek is a guy — women aren’t generally known for being socially inept. The opposite — we’re supposed to be the ones holding the fort together. So, is it a bit of cognitive dissonance to think “geek” along with “woman”? The two words hold some conflicting stereotypes.

Which brings me to the real reason for this post, which is to comment on a very interesting thread over at Cocktail Party Physics on what happens for women occupying the overlapping states of smart & sexy? This was in response to the 81 (and counting!!) varied comments on Phil Plait’s posting about Nerd Girls. Jennifer says:

Phil Plait is taking some heat from commenters over at Bad Astronomy after posting about the Nerd Girls: a Website, blog, and collection of curricula aimed at celebrating “smart-girl individuality” and challenging “stereotypes and myths about women in science and engineering.” … Apparently this site is controversial because it depicts smart women who are pretty, have a sense of style, and like to wear heels and a nice dress in the evenings when they go out dancing (at least a couple of them do). … The audacity! How dare smart women engage in such frivolous matters! They’re supposed to be dour, humorless, scruffy dressers, I guess, in keeping with their seriousness of purpose, so they can prove to the world that they don’t care what people think of them. Or something. Who knew that wearing makeup and wanting a pair of nice shoes automatically made you shallow and a slave to our appearance-obsessed society, no matter what your other brainy accomplishments

In graduate school, I worked in a lab full of other women.  I wanted to put up a website called “chicks in science” and have us all wearing short little lab coats with plunging necklines, posing coquettishly with erlenmeyer flasks.  I was the only one who seemed to get a kick out the idea.  (Now, of course, it sounds like the Nerd Girls site capitalized on a great idea).

I personally have always liked romping in this fun little playspace between girly and geeky. I certainly revel in all things science, and play up that part of my personality. And I wore my hear in pigtails for years, and had fuzzy little pigtail holders with stars on them. I use glittery nail polish. My cell phone case (which drew a gasp from my ex) has little blue and pink hearts on them. I like a good manicure, though I’ve also had sort of wimpy tomboy tendencies since I was a kid. I have a giggly bubbly side to me, and often times I get that sort of wide-eyed “really?” when folks find out that I’m a physicist. Of course, that’s not necessarily gender specific (plenty of physicists, male and female, are too familiar with the “hush in the conversation” that follows the admission of one’s profession).

But guys (of course, I surround myself with nerdy guys) are generally not dismayed to find out the “smart + sexy” equation applies to me — there’s generally this sort of “hey cool, that’s hot” look that passes over their face. But one thing that strikes me is that my smartness seems to play second fiddle. I can’t think of a single time when a man has looked deeply into my eyes and said breathlessly, “Stephanie, you’re so smart!” But they have said that I’m beautiful. Plenty of times. I look at them all googly-eyed and croon about how smart they are. Why this seeming double standard, even among men who value the fact that I’m smart? I’m with Phil Plait on this one — how can we expect ourselves to “rise above” millions of years of evolution? Men are attracted to me for the traits that we’ve been bred to be attracted to — those which signify fertility and health. You know, big hips, rosy lips, symmetric facial features, etc. I’m attracted to them because it seems they can outsmart the antelope. We’ve got these big ponderous brains that let us think about the nature of consciousness, the universe, and gender differences. But that doesn’t mean those brains can completely override those gender differences, even if we’re aware of them.

The unfortunate result is that I’m much more confident of my looks than my brains. I accept compliments about my appearance much more gracefully than those about my smarts, where I tend to minimize, “Oh, I don’t really know physics that much.” Internally, I know I attribute my successes in science to extrinsic factors (”the exam was easy,” “I talked my way into graduate school,” or even “They let me in because I’m a woman”) than to intrinsic factors (”I’m smart”), though I do admit that I worked hard. I don’t see guys do this. I’m not blaming them (or anyone), it just seems a shame. I do feel angry that I’ve gotten so much more positive feedback (interpersonally) over my life for being cute than for being smart. I even know that being cute has probably helped my career (research shows that attractive women have many advantages in career, as do tall men.)

Jennifer’s post continues:

The mistake many people make, however, is to over-compensate too far in the other direction, wherein anything remotely “girly” is somehow exerting undue pressure on young girls, with no thought to the possibility that maybe some girls genuinely like this stuff. Maybe this is part of who they are. Maybe they also like science and math. Ergo, we are putting a whole different kind of peer pressure on them that also squelches their individuality, by insisting they simply can’t be both interested in science and in clothes and makeup. (”Accessorizing is evil and will turn you into a bubblehead! Put down that Coach handbag and back away slowly! Do it for science!”)

That attitude is showing up a lot in Phil’s comment thread; I’ve heard it before. Danica MacKellar was sharply criticized when Math Doesn’t Suck was published last year for using math problems involving, say, shopping for school clothes.

I’ve seen this too, this “girly stuff is demeaning” attitude. It bothers me. A lot. Because “boyish” stuff, like trains and hunting and barbeques, doesn’t have that same negative connotation. To me, the embarrassment we’ve got about girly stuff has to do with our negative attitudes towards women. Period. We think that handbags and high-heels don’t belong in a textbook (or anywhere serious) because they’re related to women, and we don’t value women.   I don’t usually state such strong opinions, but there it is!

Back to guys’ interest in the “sexy+smart” coincidence. One thing that’s curious is that they often seem to cling to this hope that I’ll “get” them, that I “speaka their language.” Which, to some degree, I do. I speak geek. I like talking about this stuff. But to a large degree, I DON’T understand guys any more than any other girl. Stereotypically speaking, I have a woman’s desire to talk deeply about how I feel, to examine issues from many sides, to seek connection and to listen and to build community and all that crud. And I still have all the communication problems with men than most other women do. And yet, men talk about topics that I find much more interesting, in general. I straddle these two worlds — of nail polish and emotional conversations, versus differential equations and debunking astrology.

Where’s a geekgirl to call home?

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[[AAPT Millikan Lecture: Eric Mazur]]

Eric Mazur (Harvard) was awarded the Millikan prize this year, and this blog post is a detailed account of the marvelous keynote lecture he gave for the occasion. You can download the entire presentation on his website, and I recommend that you do so, because, well, it was marvelous!

The AAPT Press release on the award has this to say:

“Professor Eric Mazur’s Peer Instruction technique has altered the landscape of physics teaching. Numerous teachers have adopted Peer Instruction, enlivening their classes by turning passive students into active learners. AAPT’s Robert A. Millikan Medal recognizes Eric Mazur’s outstanding scholarly contributions to physics education,” says Harvey S. Leff, Chair, AAPT Awards Chair, as well as the 2008 AAPT Past President, and Professor Emeritus of Physics, California State Polytechnic University.

Here’s the content of the lecture.

He opened up with this poem from the “Dear Professor” collection of poems based on emails sent to a real live physics professor and compiled by his wife.

Dear Professor,
I still don’t believe heavy
and light things fall at the same speed.
A feather and a stone, for example.
You kept saying I’d get it
if I lived in a vacuum.
Do you live in a vacuum?

One stark moment in Mazur’s career came when one of his students, taking a concept quiz about force and motion, asked him,

“How should I answer these questions? According to what you taught me? Or according to the way I usually think about these things?”

Why is there this difference, asks Mazur, between the world of physics and the real world? He wanted to know, so he went to Harvard square and undertook to find out. He asked people there who hadn’t taken a physics course whether physics had anything to do with the regular world. Their response?

“Yeah”

“Sort of”

“I’m sure in some way it does”

“Yes, definitely. I’m just not sure it applies to what I do everyday.”

So, while there was some hesitation, generally people were pretty positive about the connection between physics and real life. But studies have shown that generally after taking introductory physics, students believe physics is less relevant to the real world than they did when they entered the class! There is something about the way we’re teaching physics that is divorcing it, in students’ minds, from the stuff of everyday experience.

Why?

Mazur’s answer is that “spherical cows endanger physics.”

(Don’t know what a spherical cow is? From Wikipedia:

Spherical cow is a metaphor for highly simplified scientific models of reality. The phrase comes from a joke about theoretical physicists:

Milk production at a dairy farm was low so the farmer wrote to the local university, asking help from academia. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the farmer received the write-up, and opened it to read on the first line: “Consider a spherical cow. . .

Mazur argues that — mostly through our textbooks — we paint a picture of physics that is

• Really weird
• Different from the real world
• Truly confusing

Physics is Weird

You’re an introductory physics student. You buy your big fat tome of a physics textbook and crack it open to see what this stuff is all about. What do you see? Really weird pictures, says Mazur. Elephants sitting on tables (with the force of gravity clearly labeled), a tightrope walker walking a rope slung between two capacitor plates, a huge wrench trying to lever the earth (to illustrate torque), a catapult set up to slingshot stones at a sunbather. “I wish I was making this stuff up,” he said, as he showed us one hilarious image after another — monkeys pulling themselves up a pulley, a periscope allowing a penguin to look underwater, a man standing in a box floating in the ocean (Be sure to download the whole presentation if you want more examples — I don’t want to pirate his presentation any more than necessary to make the point).

These textbook pictures are meant to make the content interesting or funny or engaging for students, but they just come across as strange and silly. They certainly don’t suggest that physics has anything to do with the real world. Silly art makes us look weird, he says.

Physics is Different

Image from M. McCloskey, Intuitive Physics, Scientific American 248 (1983), pp. 122-130

Think about the above image for a moment. Which path is right? If you’re a physics teacher or know something about physics, chances are you chose the parabolic path — path C. That’s what all Mazur’s Harvard colleagues chose — he showed us videotape of them.

But what about when he asked the everypeople out on Harvard square? They all chose path B. Why? Things fall straight down. When he asked them what they’d say if he told them that most physicists chose path C, they said

“I’d take their word for it, but I’d want to know why”

“I’d have to see it.”

“I’d be concerned for the world of physics.”

“I wouldn’t believe you.”

“I’m sure you know what you’re talking about, but why would it go so far forward if you weren’t throwing it?”

He then showed us a video of someone running while they drop a ball. And would you believe it? Path B is the closest to what really happens! The runner would have to be running at 25 miles per hour in order to have the ball drop to the ground where his foot falls at the end of his stride. Or, he’s running on some tiny planet where g is 1/100th that on earth. But as physics folk, we choose the path that fits our model, even if the representation of that model is wrong! None of the professional physicists he asked mentioned that the picture was exaggerated — they were even a little offended that he asked them the question! When he asked them what they would say if he said that path B was actually the most correct, they asked him, “In what sense?” The model overrides our personal experience. No wonder people feel physics doesn’t represent the real world. Illustrations like this are really problematic. They look realistic, but the trajectory of the ball is unrealistic. So there is this unrealistic image projected on a realistic background. How confusing! He showed us about 5 pictures just like this one, taken from physics textbooks.

To make matters worse, in an attempt to make pictures interesting and “real world” textbook artists put all sorts of distracting elements in pictures: hikers, baseball players, bridges, trees. He showed us, for instance, one picture of a boy throwing a ball from a bridge, with trees in the background. The parabolic path of the ball was marked on the diagram. He then showed us results from an eye-tracking study of that image, showing what parts of the picture people looked at. Where did they look? The boy, the ball, the trees, the text showing the height of the bridge. Do they look at the parabolic trajectory at all — the whole point of the diagram? Not really.

These realistic renderings of images are a distraction, he argues, not a help. These are unnecessary elements.

Physics is Confusing

In this part of the talk, he pointed out errors in textbooks, including his own. He asked us, first, are the components of a vector (eg., the x and y components) themselves vectors? There was some disagreement in the audience. There appears to be some disagreement in the textbooks too, as he showed us pages within the same textbook that first showed the components to be vectors, and then scalars, and then vectors again. In his own textbook, he found he was using confusing language to talk about whether “momentum was conserved” versus “the total momentum is constant”. He argued that because we know what we mean when we say something, we’re unconscious of the errors. We’ve become blind to what is actually written because we know what we intend to say. To the physicist it all makes sense, but the students are confused.

To Sum it all up:

Mazur summed up his main points thusly:

Silly art makes us look weird

Misplaced realism makes physics different

Lack of precision confuses

We need to be more careful in our representations, he says.

An audience member asked him what he thought the simplest concept in physics was. He thought for a while but finally answered that no concept is simple. “Sometimes I’m surprised at how we manage to learn,” he said. No wonder these things are difficult, we’ve taken thousands of years to develop our discipline.

Another interesting story, for those familiar with peer instruction. This illustrates just how much faculty can be set in their ways. He gave a talk to faculty and gave them a challenging question that he knew would be a struggle. Their responses showed that there was not a consensus on the right answer. He asked them to turn to their neighbor and discuss the answer. Generally in his classes, this results in an in lively discussion which results in most students choosing the correct answer because they are able to understand the answer as argued by a neighbor. With the faculty, fistfights almost broke out, they argued so vehemently. When he asked them to revote, the results were exactly the same — nobody changed their mind!
Thank you Dr. Mazur for such a wonderful talk!

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I’ve just posted a new episode of my Science Teaching Tips podcast — Which is Closest?

Which is farthest away from the earth, the stars or Pluto? The answer may be obvious to you, but a lot of people get this wrong.  Here’s the task — arrange these in the order from closest to furthest from the earth:  moon, sun, Pluto, stars, and clouds.  Think about it first, and then listen… listen carefully!  It can be easy to miss the mistakes that people make.

We went out and harassed the employees at the Exploratorium with this little survey.  I was astounded by what we found.  Many teachers are.  Linda explains why people (even highly educated people!) answer as they do, and what this means for teaching about science.

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Wikimedia Commons - Gnu license

There’s a delightful post on crackpot science (in particular crackpot physics) from Twisted Physics this week.

For some reason, physics has more than its fair share of crackpots fringe scientists: those misunderstood tormented souls whose genius goes unnoticed by mainstream physicists… The receipt of any missive beginning, “EINSTIEN WAS WRONG AND MY THEORY PROVES IT!!!” invariably causes most physicists to discard said missive in the nearest trash receptacle. But what about the rest of us? How do we know if Harry Brained’s new theory is bogus, or a

Fortunately, a handful of enterprising physicists offer some helpful online advice. The best-known resource is John Baez’s “A Simple Method for Rating Potentially Revolutionary Contributions to Physics,” affectionately known around the science-minded blogosphere as “The Crackpot Index.”

Mis-spelling “Einstien,” for instance, will earn you 5 points on the crackpot index, along with each word in ALL CAPS, although Baez is willing to make an exception if your keyboard happens to be malfunctioning — perhaps after you spilled your can of soda over it in your excitement at finding that fatal flaw in relativity’s Teflon (TM) armor. (Hey, it could happen to anyone.)

Another great resource is Bob Park’s Seven Warning Signs of Voodoo Science

Bob Parks is a physicist at the American Physical Society and he’s written a lot of stuff about how to be skeptical about such claims. He’s got a book called Voodoo Science. I was lucky enough to interview him when I was at NPR, and he said something I never forgot. He was telling the story of when the controversial experements on cold fusion came out and there was a lot of excitement in the public about it even though the scientists were quite certain it couldn’t have happened. When people want something to be true, he said, it’s very compelling for them to believe it. When he said that the cold fusion experiment didn’t jibe the physical principles, a woman asked him, “But it would be so very important for the world. Couldn’t you try just a little bit harder?” Of course, the cold fusion scenario was very different from the type of crackpot science we’re talking about here, but that woman’s reaction does go a long way to explaining why it’s hard for many of us to let go of ideas that we should be more skeptical about.

Here’s Bob Parks 7 warning signs of voodoo science:

1. A discovery is pitched directly to the media, bypassing peer review, e.g., Pons & Fleischmann’s claims about cold fusion and Dennis Lee’s claims about free energy.

2. A powerful “establishment” is said to be suppressing the discovery.

3. An effect is always at the very limit of detection.

4. Evidence for a discovery is anecdotal.

5. A belief is said to be credible because it has endured for centuries, i.e., commits the fallacy of appeal to tradition. E.g., acupuncture and Ayurvedic medicine.

6. An important discovery is made in isolation (the “lone genius”).

7. New laws of nature are proposed to explain an incredible observation. A common lament of parapsychologists.

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I just had to repost from the Deep Sea News blog, which points out an alarming 300% increase in the number of shark attacks in the last year in a particular town in Mexico:

Aren’t statistics wonderful things? That’s why when you read something in the medical news about “50% fewer heart attacks” or some such due to XYZ drug, your first question should be “but what was the number to begin with”?

In this case, a 300% increase means 3 attacks instead of one. That’s hardly a statistically robust difference. But the local papers surmised that Sharks are hunting humans. Blogger CR McLain writes in Deep Sea News:

Thankfully the Mexican Navy has been called on to track down and kill these death wielding beasts.

PLEASE PEOPLE! Although tragic, three attacks and two deaths is not extraordinary that searching for pattern or cause is necessary. You don’t see people freaking out about pigeon related deaths. An increase of one to three is hardly a pattern. In four tosses of a penny this morning I just got 1 head and 3 tails…it happens. The fact that the media is in a frenzy combined with Mexico actually spending money on searching for causes and using sophisticated Naval ships to exterminate the sharks is nothing short of absurd. Let’s get a bit of perspective…

Americans killed by guns in the U.S. each year: 30,000

Americans killed by tobacco in the U.S. each year: 418,000

Americans killed after being struck by police Tasers in 2004: 40

U.S. murder rate: 5.9 per 100,000

U.S. traffic fatalities each year: 39,000

People injured/killed by lightning each year in the U.S.: Struck: 700, Killed: 70

Deaths from obesity per year in the USA: 112,000

I will take a shark any day over a Twinkie, lighting strike, the flu, a tsunami, Taser, cigarette, hand gun, war, or a car any day.

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This myth appears in a bunch of textbooks, so it’s not surprising that it’s persisted. The myth is that we mostly taste sweetness, bitterness, saltiness, and sourness at different areas of the tongue. While it’s true that we do have different taste sensations on different areas of the tongue, the exact distribution of sensitivity depends on the particular person doing the tasting. Try this out with a few friends — make your own taste maps and see if they coincide or not. The original myth stems back to the early 1900’s when a German reseacher named Hanig published data on taste sensitivity of different areas of the tongue. The differences in sensitivity he reported were real — but they were so slight as to be of no practical significance. Nobody bothered to check or refute it until many years later, when the idea was already firmly rooted in our popular consciousness, and textbooks.

Some other interesting tidbits about taste:

- These four basic “tastes” have been expanded to five. The fifth is called “umami” which loosely translates from Japanese to “deliciousness.” It’s the flavor of amino acides (such as meat broth, aged cheese, or glutamate, as in monosodium glutamate, or MSG; ) which explains why things with MSG taste so good. There’s also some debate about a sixth receptor for fat.

- Your nose plays a huge role in what you taste. If you plug your nose it can be difficult to tell the difference between a potato and an apple. That’s why things taste bland when you have a cold and your nose is stuffed up.

- Taste buds are clusters of taste receptors. The taste buds themselves are too small to see, but they live on the end of little protrusions of tissue called papillae. You can see your papillae easily by dropping a few drops of food coloring on your tongue (blue works best). The pale dots are the papillae. Taste receptors are activated when chemicals in food bind to them, the taste receptor then fires and sends a message to your brain. Within a few seconds the taste receptor adapts to the flavor and fires much less strongly.

- Your taste sensations depend on the temperature of your tongue! That’s why Ben & Jerry’s serves its ice cream slightly warm in its tasting room, to enhance its sweetness.

For more information, see:

Bartoshuk, L. M. 1993. The biological basis of food perception and acceptance. Food Qual. Pref. 4:21-32

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No, the myth isn’t that airplane fly at all — we know they do, but how do they do it? This is one that really bothered a bunch of us when we were in graduate school in physics. How does an airplane fly? I have a substantial investment in knowing that the physics of these big metal monsters is sound. The reason we were worried is the Bernouilli effect. The Bernouilli effect is what sucks papers out of your car window when you’re speeding down the highway — it says that the faster a fluid (e.g., air) moves, the lower its pressure. That’s why the papers get sucked out of the window — they’re drawn towards the lower pressure outside the window, where the air is moving quickly.

For airplanes, the Bernouilli argument goes that the air moving over the top of the wing (where it’s curved, see below) must travel farthe than that moving under the wind (where it’s flat). So, the lift is caused by the lower pressure on the top of the wing relative to the bottom of the wing.

Fine. But then how do planes fly upside down?

The Bernouilli argument above is flawed. There is no reason why two air molecules which hit the front of the wing at the same time must rejoin each other at the trailing edge, which is what the above argument suggests with its “air must go faster along the top of the wing because it’s traveling further than if it had gone below the wing.”

The key lies instead in the “angle of attack” shown in the above diagram. The wing is slanted upward slightly. As the wing moves forward, it pushes air in front of it, which “piles up” under the wing, becomes compressed, producing high pressure on the underside of the wing. At the same time, the upper surface is being pulled away from the air behind it as the plane moves forward. This leaves a low pressure area along the upper surface of the wing. This produces lift.

Another force lifting the wing is that the lower surface of the wing hits air molecules downward as it moves. Every action produces an equal and opposite reaction, so just as when two balls hit each other and move off in opposite directions, the wing hits air downward and this throws the wing upward slightly. This gives some more lift.

This post was adapted from Kenneth Fuller’s website.

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Gosh, I’d like to believe this one, it’s just such a “cool” idea. One argument against this idea is that if you take thousands of pictures of snowflakes, it’s still not a very good statistical sample. Kenneth Fuller writes about this, and other modern myths taught as science. He hypothesized that this myth arose from the publication of a wide sample of snow crystals by Wilson Bently in 1931. Bently only published his very best pictures, which were taking from a specific type of storm. While the final result was astounding (6000 photographs), this is not a very good sample when you consider all the snowflakes that have ever existed in the world.

A counter-argument (which Fuller rejects) is that on the molecular level, no two snowflakes will ever be quite the same, because some of the water molecules will be slightly different from the others (e.g., they’ll contain an isotope of hydrogen or oxygen). Fuller poo-poos this idea, since it also says that no two drops of water are exactly alike, which begs the question of whether or not the beautiful symmetrical crystal, above, might be replicated from one snowflake to the next.

However, the math of combinatorics comes into play when you consider all the different ways that a snow crystal might form. By that, I mean that as each snow crystal forms, it has several different “choices” about how to continue its growth. There are many crystal structures available, and different paths that each crystal may take as it continues its growth. So, there is a huge number of different crystal structures that could arise. Snow researcher Kenneth Librecht from Caltech claims at Snowcrystals.com that it’s statistically unlikely that two snowflakes might be exactly the same (even though we could never actually check them all to make sure).

See some beautiful (public domain) pictures of snowflakes at Wikimedia Commons.

Find out how to preserve a snowflake for 30 years with superglue on a later post.

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