Cocktail Party Physics

karma chimera

When I was just a wee young thing, my grade school teacher assigned us all reports on a specific animal. I got the duckbilled platypus. Can I just say? I thought my teacher was having me on at first. I mean, come on: it had a bill like a duck, a body like a beaver, and it was venomous like a snake! It could have popped right from the pages of the fantasy stories and ancient myths I devoured so regularly at that tender age. Among other tales, I was fascinated by the myth of the Chimera, a Greek fire-breathing monster described in Homer's Iliad as having a lion's head, goat's body, and serpent's tail, and the platypus seemed eerily similar in concept, if not appearance. But I dutifully did my library research -- this was pre-Internet, so we had to actually look stuff up on paper and use old-fashioned, musty card catalogs and everything -- and sure enough, the animal was very real indeed. I've had a fondness for the platypus ever since. Its very existence made the world seem that much more magical.

My old friend the platypus made for big science news this past week: scientists have just completed the full sequence of the platypus genome. It's a lazy Sunday, and I'm still mulling over all the excellent comments on my last post, so I'll let Juan Nunez-Iglesias, another New Voice from K.C. Cole's science writing class, weigh in with his own thoughts on the matter:

Last year I attended the 2007 conference on Research in Computational Molecular Biology (RECOMB) in Oakland, California. By far the most entertaining talk was given by Jennifer Marshall Graves of the Australian National University in Canberra. Graves talked about the platypus and how weird it is, not just in its appearance, but in its genetics.

For example, one of the first principles of genetics is that of independent assortment of chromosomes. We have two full copies of our genome in every cell in our bodies: one from our father, and one from our mother. Each copy consists of 23 chromosomes, separate pieces of DNA. When a germ cell divides, it splits our own double-copy genome in two and places each half into one daughter cell -- to pass on half of our genome (per offspring) to the next generation. The principle of independent assortment states that each of our 23 chromosomes has a 50% chance of ending up in one or the other daughter cell, independent of where the other 22 end up.

This principle was first formulated by Gregor Mendel in the 19th century, and has been shown to hold for every organism ever tested -- save the platypus. The platypus has 5 sex-determining chromosomes from each parent, and all its sex chromosomes stay together generation after generation. A platypus's young will inherit all the sex chromosomes from that platypus's father or from its mother. But never a mix of the two, as happens with all the other chromosomes.

Well, the weirdness doesn't stop there. Researchers announced [last week] the release of the complete sequence of the platypus genome, publicly available online. [Jen-Luc Piquant notes that this would be a fine time to create your own cloned pet platypus, boys and girls!] Down at the single-base pair level, the platypus continues to be weird. Half of its genome looks like a reptile's, half like a mammal's. It also has genes to make venom, which not surprise you after hearing the reptile thing, but... surprise! The platypus venom genes evolved independently of the reptile ones; they are completely unrelated and unique. You can read all this and much more in this excellent article in Nature News. Definitely an exciting time to study genomics.

That sounds suspiciously like a chimera-like creature at the genetic level, doesn't it? Except it isn't. Let me just say that right up front before PZ Myers gets all medieval on my ass. Seriously, PZ's frustration with the media coverage of our friend the platypus inspired him to write this terrific post explaining why the platypus is not the the same as a chimera:

"Over and over again, the newspaper lead is that the platypus is 'weird' or 'odd' or worse, they imply that the animal is a chimera.... No, no, no, a thousand times, no; this is the the wrong message.... What's interesting about the platypus is that it belongs to a lineage that separated from ours approximately 166 million years ago, deep in the Mesozoic, and it has independently lost different elements of our last common ancestor, and by comparing bits, we can get a clearer picture of what the Jurassic mammals were like, and what we contemporary mammals have gained and lost genetically over the course of evolution."

Got that? The platypus is not a chimera. Take it from someone who really knows this stuff. Okay, but do chimeras really exist? I'm so glad you asked. Certainly the mythological Greek monster isn't real, but there is a genetic anomaly that gives rise to a rare condition known as chimerism. Per Wikipedia, "A chimera is an animal that has two or more different populations of genetically distinct cells that originated in different zygotes." (Genetically distinct cells originating from the same zygote produce a related condition called mosaicism.) In humans, it's long been believed to be an exceedingly rare condition, with fewer than 40 reported cases.

One of the most famous is Lydia Fairchild, the subject of a documentary called The Twin Inside Me. She separated from her husband while pregnant with her third child, and took a DNA test to prove her husband's paternity, as required to qualify for welfare support. He was, indeed, the father, but according to the test, she wasn't the children's mother. She was taken to court for fraud. She was only exonerated when she gave birth to her third child, with a judge-ordered witness present to take blood samples from mother and infant for testing. And those DNA tests revealed she wasn't the mother of that child either. Except she was. I mean, court-appointed eye witnesses watched her give birth. If she was a fraud, she was a damned good one, on a par with the world's best illusionists. (This gorgeous bit of artwork, BTW, is the creation of Sandro Castelli.)

A similar thing happened (without the charges of fraud) to Karen Keegan in 1998, a Boston-area teacher who needed a kidney transplant. She had three grown sons who were tested to see if they could be donors, but the DNA showed that two of them weren't her biological children. This time doctors did additional testing on Keegan, drawing samples from other areas of the body, and discovered she had two sets of cell lines with two separate sets of chromosomes -- a mix of two individuals, fraternal twin sisters who fused in the womb and developed into a single infant. Fairchild's lawyers heard about the case, and arranged for their client to undergo more testing as well. She, too, turned out to be a chimera. For instance, the DNA in Fairchild's skin and hair didn't match that of her children, but the DNA from her cervix did.

Now that's weird -- weird enough to inspire episodes of both House and C.S.I. In "Cane and Abel," House treats a young boy who suffers from seizures and believes he was abducted by aliens; the hallucinations turn out to be caused by the "alien" brain tissue from the twin brother who had merged with the boy in the womb. The C.S.I. episode ("Bloodlines") involved a rape victim who correctly identifies her attacker, only to have him exonerated by DNA evidence, although it demonstrated her rapist was related to the original suspect, who had many brothers -- none of whom proved to be a positive match. The suspect turns out to be a chimera: two different sets of DNA. Grissom discovers the suspect's unique condition when he notices visible Blaschko's lines while photographing said suspect's torso for evidence.

Bizarre though it sounds, according to this 2003 article in New Scientist, chimerism might not be as rare as previously believed; in fact, some researchers are beginning to think there might be a little bit of the chimera in all of us. Most cases simply aren't detected. Usually, there aren't many outward signs or symptoms: eyes of slightly different coloration, for example, hair growing differently on opposite sides of the body, even hermaphroditism (having both male and female genitalia -- the subject of another memorable House episode in which a beautiful young female model turned out to have testicular cancer). Male tortoiseshell tabbies are examples of chimerism. It takes a DNA test to reveal the chimerism, and usually more than one, with samples taken from different parts of the body.

A more common variant is blood chimerism, when fraternal twins share part of the same placenta and exchange blood, which settles in the bone marrow, so each twin is genetically separate -- except for their blood which has two distinct sets of genes and two distinct blood times. Some 8% of fraternal twins are blood chimerism, and the number could rise given the increase in multiple births, thanks to in vitro fertilization. Fairchild and Keegan are much rarer cases.

Of course, it was only a matter of time before scientists started creating chimeras in the lab -- yes, just like the infamous South Park episode where the local mad scientist created creatures with multiple derrieres. Okay, not like that, but in 1984 scientist combined a embryos from a goat and sheep to form a "geep." Others have made rat/mouse and rabbit/human chimeras (2003), as well as pigs with human blood flowing through their bodies. Most were created not with the intention of creating living hybrids, but for the purpose of harvesting stem cells for further research. And in 2007, scientists at the University of Nevada's School of Medicine created a sheep with 15% human cells. In the UK, researchers are attempting to insert human DNA into a cow's egg using the same technique that successfully cloned Dolly the Sheep. Last I heard, they hadn't yet succeeded.

Sheesh. Truth really is stranger than fiction sometimes. A creature from Greek mythology has a counterpart in modern 21st genetics. Next scientists will be telling us that vampires and werewolves are real. Which means we might be in need of a Slayer or two. Any takers?

picture this

It's been an incredibly busy week, so I'm just now getting around to writing about Chad's post about how it's not science without graphs. Basically, in a fit of procrastination, he plotted his latest blog traffic stats into a nice little graph, drew a line through the data points, and analyzed the results. It's all very meta of him. But who am I to point fingers? Chad's post made me realize that I am officially an uber-geek. See, back in late January, I got sidelined by the flu and spent a couple of days with a high, spiking fever, unable to do much except moan in between gulps of Theraflu. Bored with flipping channels and the meager offerings of daytime television, I started checking my temperature every hour and recording it, with the aim of plotting it onto a graph when I was done. I had some vague, drug-fogged notion of finding the slope of the tangent curve and thereby practicing my calculus by taking a derivative using a "real-world" example: the rate of change of my body temperature as the fever ran its wicked course.

It didn't quite work out that way: that particular calculus trick only works if the graph gives you a smooth curve. I had so few data points that the result was a series of spiked lines. If I took my temperature every 5 minutes and plotted it out, the end result might have been closer to a curve -- or not. Given the relative crudeness of my digital thermometer, the differences at that point would be so minimal that it probably would have just looked like a straight line. Still, before I started my amateur dabbling into self-taught calculus, I would not have realized that the closer one gets to an infinite number of ever-smaller data points, the more like a curve the resulting graphed data will appear. And it would never have occurred to me to try to create my own real-world calculus problem tracking the rate of change of my own body temperature. Maybe I ended up somewhere other than where I'd intended when I started my little sickbed exercise, but I learned something quite valuable from the experience -- and I'm not likely to forget the "lesson," either.

Real-world examples while learning abstract mathematical principles work for me, despite the recent findings by researchers at Ohio State University that this widespread assumption among educators may be wrong. Ed Yong at Not Exactly Rocket Science has an excellent summation of the study specifics, accompanied by a thought-provoking comment thread. For instance, more than one person said that the so-called "real world" problems one finds in, say, calculus textbooks bear very little resemblance to anything most students would want to solve -- like that silly train analogy that leads off both the New York Times article and Ed's blog post on the study's results. (Jen-Luc Piquant  has her own snide response to when Train A, departing at 6 PM and traveling at 40 MPH toward Station B, will pass Train B, departing at 7 PM and traveling at 50 MPH toward Station A: "When everyone on board is long past caring.") Far from making math "come alive," it's just one more way to make students' eyes glaze over in boredom.

I do not, however, conclude from this that "real world examples don't work." I think it depends on which examples you choose, and how you use them. They are a useful starting point for piquing student interest, but you still have to make the critical connection -- "This relates to that abstract principle, which can be broadly applied to other situations" -- and put in the work to grasp the abstractions.

Jennifer Kaminski, the OSU researcher who spear-headed the study, thinks such an approach obscures the underlying mathematical principle, rather than illuminating it, and actually hinders students' ability to transfer their knowledge to new problems. "They tend to remember the superficial, two trains passing in the night," she told the New York Times. "It's really a problem of our attention getting pulled to superficial information." I can see how that might happen, but I think it's more of a translation problem. Honestly? I sucked at textbook story problems in my K-12 math classes, and received excellent grades in high school geometry and algebra.

But here's the thing: I didn't actually understand the abstractions; I was just blindly following the "rules," manipulating meaningless symbols. And it bored me. I needed some kind of context, just not the equally pointless exercises routinely used in classrooms. The real world examples in textbooks don't really correspond to our daily experiences, or how we might typically approach such a problem. As one of Ed's commenters put it: "If I wanted to know Frankie's and Johnny's ages, I'd ask them, not work out some weird algebra problem." Yet another commenter observed, "'Real-world examples may be treated by students as confusing symbolic concepts that look like real things they know about but act like abstract notions that are defined by the teacher."

I was pleased to read that Kaminski isn't suggesting that we eliminate all real-world examples in classrooms; rather, she thinks that they should augment the abstract principles -- which should be taught first -- rather than being deeply grounded in one specific context. I agree this might increase a student's chances of extrapolating the general principles and applying them to new problems as they arise. Perhaps letting the students choose a real-world problem they'd like to solve -- like my little experiment plotting out my changing rate of body temperature -- is a better way of incorporating a practical context.

You're more likely to pique their interest if they're involved in creating the problems and then figuring out how to solve them -- the "lessons" they learn along the way are more likely to "stick," plus it's a lot more similar to what a working scientist actually does for a living. Is it a calculus problem? A statistical one? How does one go about "translating" that situation into a meaningful mathematical format? This is more of a ground-up approach, akin to taking apart an alarm clock and putting it back together to gain a more comprehensive understanding of how it works. Personally, Jen-Luc would like to see more LOLCats in math and science classes:

This kind of choose-your-own-problems approach also might address the perennial problem of over-generalization -- we all learn differently, and suggesting there is only one correct way to teach a subject like math or physics is likely to leave behind as many students as such a pedagogical approach would advance. And sometimes teachers under-estimate the difficult of new concepts because it's been so long since they learned the material for the first time themselves. As commenter Sam C. said, "Once one has learned something, it's difficult to appreciate what it looks like to someone who hasn't learned it." Something that seems perfectly obvious to the teacher, probably needs to be spelled out, step by step, for many of his/her students.

Case in point: I started my informal calculus "studies" with a DVD lecture series from The Teaching Company. The lectures were pretty good, conceptually: visual elements, real-world examples, but tying them to the abstract principles and then showing how they could be broadly applied. The first thing I learned was how I could (a) use the derivative to figure out the speed of my car from the car's position, and (b) use the integral to figure out how far I'd traveled in my car based on speed. The two are flip sides of the same coin, two different approaches to solving the same problem, depending on the information at one's disposal. And there's a handy real-world context: this is basically what's going on in your car's speedometer and odometer all the time.

Frankly, finding the integral is a labor-intensive process of multiplication and addition take to ridiculous extremes (i.e., infinity). There is a short-cut to the much-harder integral however: if I know both my beginning and ending position, for example, I could just subtract the first from the second to figure out how far I'd traveled. What if I don't know my ending position (and my odometer is broken), just my speed (the velocity function)? Per my DVD instructor, "all" I have to do is figure out which position function generates the known velocity function, and voila! I can do a bit of math-y hocus-pocus to essentially "retrace my steps" backward and use the easier derivative approach. Fair enough, but he never once explained how one goes about finding that position function. There's a lot of them. Still, he insisted it was a simple matter, and silly me -- I believed him.

My DVD instructor lied. It's actually a non-trivial thing for someone just starting out, and/or a bit rusty in their basic algebra and geometry. Don't take my word for it; listen to Johann Bernoulli, a contemporary of Newton and Leibniz who made significant contributions to then-brand-new field of calculus in the 17th century: "But just as much as it is easy to find the differential (derivative) of a given quantity, so it is difficult to find the integral of a given differential," he wrote. "Moreover, sometimes we cannot say with certainty whether the integral of a given quantity can be found or not."

Fortunately, I know a lot of physicists and a smattering of mathematicians, most of whom are happy to weigh in now and then with their own insights and "tricks" for the kind of road-block described above. And I'm persistent. I only bring it up because I think it's always interesting to see where different people get hung up when learning new mathematical concepts. Sometimes it's just a language problem, mixing up terminology, or not realizing that you do know what a particular term means -- you just didn't realize that's what your mental concept was called. You hadn't made the connection. Sometimes the instructor has inadvertently left out a step, or doesn't realize that some of his/her students need to be walked through something a bit more carefully.

Because we all learn and think differently -- newsflash: even scientists don't all think and learn alike! -- I'm interested in hearing from readers about similar experiences in their math and science education -- or even their humanities education. I admit, I have an "intuitive" feel for words and writing, and have been guilty in the past of just not understanding why someone couldn't grasp some "trivial" aspect of composition. I've noticed that many "gifted" math sorts can make similar intuitive leaps with numbers. What were your most significant roadblocks? Have you ever stopped to really analyze what happened? How did you overcome them? What are some of the "tricks of the trade" you find useful when applying abstract math principles to "real world" problems?

I think it's a conversation worth having....

crime scene craziness

Last year, the Spousal Unit and I attended a friend's 40th birthday party here in Los Angeles. Among the many guests was one of the writers for Bones -- one of my favorite current TV shows, as regular readers may know. We exchanged the usual pleasantries, I said how much I liked the show, and then he asked what I did for a living. As soon as I said "science writer," he tensed up, with a slightly panicked, hunted look in his eye, and launched into a litany of his supposed "sins against science": "I know, I know, we take liberties with the science, DNA testing can't be done in just a few hours, Angela's holographic system for recreating faces doesn't exist...." I quickly interrupted his impromptu "confessional" to assure him I wasn't one of those sorts who constantly feel compelled to nitpick science-themed fictional TV shows for --basically -- not being science-themed documentaries.

Personally, I think it's quite telling, and more than a little sad, that this man's first reaction to encountering a science-oriented person (even one who admitted to being a Bones fan) was to recoil and start defending himself. I can only imagine how often he's encountered such individuals who dispensed with the usual pleasantries and simply attacked him for doing his job: producing a compelling, entertaining crime drama. It reflects quite poorly on scientists, frankly. Scientists mean well, but all the  judgmental finger-wagging gets pretty old, pretty darn fast. And soon, they're just not being heard because people have stopped listening. Who likes to be nagged and nitpicked all the time? Would it kill the scientific community to hand out a few kudos once in awhile, to offset the constant griping?

So in today's monster blog post, I come not to bury science-themed TV shows (death by nitpicking?) but to praise them -- specifically, to praise Thursday night's new episode of C.S.I., or, as Jen-Luc Piquant has dubbed it, "the episode that launched a thousand Google searches." Maybe it was because of May Sweeps, or perhaps the whole writing staff got exposed to laughing gas that made them collectively giddy, but the episode ("The Theory of Everything") managed to cram together a record number of weird, stranger than fiction forensic oddities. (The writers of House are probably seething with envy; extremely rare and bizarre medical anomalies are their stock in trade.) And as I discovered when I Googled the relevant terms, they're all pretty solidly based on scientific fact. [SPOILER ALERT! The rest of this post gives away key plot points -- solely in the interests of science -- so if you didn't catch the episode, you might want to hold off reading further until you've checked it out: it's available on the CBS official Website.]

We get an inkling of the craziness to come in the opening sequence, set in the Vegas police station, where Detective Brass is questioning a suspect while, in the main room, a mentally disturbed homeless woman named Evelyn expounds on string theory and the coming alien invasion. We quickly discover that the suspect is in jail for killing a deer with a bolt from a cross bow and, um, putting a dress on it. He's recently divorced, drunk as a skunk (blood alcohol level of 2.8!), and suddenly makes a break for it, bolting through the station until he's cornered. The assembled officers use pepper spray to subdue him, but he's too smashed for it to have much effect. So Brass gives the order to tase him, using the unfortunate phrase, "Light him up." As if on cue, the suspect bursts into flames. Soon he joins the dead deer in the morgue for autopsy, and Brass is taking heat for having a suspect die in custody.

First, a brief word about tasers. I tend to think of them in terms of those smaller handheld electroshock devices, but the kind more commonly used by law enforcement -- and depicted in the episode -- are a bit more complicated. A taser fires two small darts (electrodes) connected to the main unit by conductive wire, with a maximum range of about 35 feet. The darts are pointed to penetrate clothing and touch the skin. Earlier models required them to pierce the skin, but today's version uses a "shaped pulse" that is more effective in penetrating clothing. The handheld devices are more commonly marketed to the general public these days. In fact, Jen-Luc Piquant was thrilled to discover a surprisingly large number of pretty pink tasers for women, from a standard issue model, to a taser disguised as a couple of pink tampons, to this adorable pink seal taser -- and yes, it was made in Japan, along with the infamous Hello Kitty "personal massage wand." (Think I'm kidding? Think again! A Hello Kitty taser is practically inevitable.) Jen-Luc totally covets her own pink seal taser.

Anyway, tasers, or stun guns, are fairly controversial, since there have been several cases of suspects dying, ostensibly as a result of being tased -- the most recent case was last year, involving a Polish immigrant in Canada who died after being tased by police in Vancouver's airport. That man didn't burst into flames, however. Combustion isn't typically one of the risks. Nick Stokes figures it has to be either the moonshine the man had been consuming, the pepper spray, or some chemical in the man's shirt, but a controlled experiment involving three Jell-O Men shows that none of those could account for the poor man's sudden immolation.

Eventually, Stokes discovers that there is more than one type of pepper spray. This is quite true. All types contain the same active ingredient: capsaicin, a chemical derived from the fruit of plants like chilis. But the episode is correct that the sort used by the police is water-based and hence non-flammable -- precisely because of the growing use of tasers by police officers. Some consumer brands have alcohol-based propellants, however, which are highly flammable.

In the case of Burning Man, the officer at fault had used a consumer version after his girlfriend accidentally took his pepper spray with her to work. Nick repeats the experiment with the other type of pepper spray, and voila! The Jell-O Man bursts into flame. And yes, that was the Mythbusters looking on approvingly from behind the glass as Nick performs his final test -- an uncredited cameo to keep obsessive fans happy. (Obsessive? Moi? Jen-Luc is the one who writes Mythbuster-themed slash fanfic. And if that doesn't take you to a scary mental place, I shudder to think what it would take to do so.)

Really, that's weird enough for one episode right there, but when  police finally track down the unfortunate Evelyn, she's dead, the victim of a collision with a semi. The truck driver was temporarily blinded by the sun reflecting off her tinfoil costume, and didn't even see her. The clincher: she's bleeding green blood -- yes, just like Mr. Spock; perhaps she really was in touch with aliens. (Or not; certain species of lizards known as skinks also have green blood, along with some marine worms.) The whole green blood thing turns out to be a mini-epidemic: two more victims soon show up: another homeless man, dead from blunt force trauma to the head, and his killer: a pest control specialist named David Bohr, a.k.a. "Atomic Dave" (one of several cheeky nods to physics).

Bohr is alive when they find him, but not for long: he soon starts seizing and the same green blood, um, oozes out of his face. He joins the other victims in the county morgue, where we have the added twist of all his internal organs being various shades of green, including his brain. It turns out that all the green blood victims suffered from migraines and were taking massive doses of a medication without a prescription -- supplied by Bohr the exterminator, who was taking the stuff himself in enormous quantities. Except Bohr thought he was suffering from migraines, when in fact, he had a massive brain tumor -- hence the headaches, crazed behavior, and hemorrhaging. That's the danger of self-medication: what if your original diagnosis is wrong?

Hodges and Wendy (who is emerging as his unlikely love interest) conclude -- along with Grissom -- that the culprit is high levels of sulphur in the blood, caused by the large doses of migraine medication the victims had been taking. (The drug is identified as thiocyte, but this might be a fictional version -- perhaps for legal reasons? -- since the only Google hits that showed up on that drug name were related to this particular episode of C.S.I.) And naturally, they invoke Mr. Spock, although Wendy rightly reports that Spock's green blood, according to the series, arose from copper instead of iron in the hemoglobin. She knows a whole bunch else about Star Trek, as it happens, prompting Hodges to observe, "You're like a geeky nerdy guy trapped in a woman's body." Not to be outdone, Wendy zings back, "So are you."  Yeah, those two are made for each other....

This "Vulcan Blood" phenomenon isn't fictional. In fact, it's ripped right from last year's science headlines, when an article appeared in The Lancet describing a very odd case of a 42-year-old Canadian man (why are they always Canadian?) who appeared to have dark-green blood coursing through his arteries. The case was already a bit strange before the whole Vulcan-blood thing. The patient had fallen asleep in a chair for so long, and in such a position, as to severely restrict the blood flow to his limbs, resulting in localized tissue and nerve damage that required surgery to correct, before he lost his legs. The man also suffered from chronic migraines and had been prescribed sumatriptan to treat them. Apparently he'd been consuming a whopping 200 milligrams of the stuff per day, giving rise to a rare condition called sulfhaemoglobinaemia, in which high levels of sulphur wind up up in the oxygen-carrying compound hemoglobin, found in red blood cells.

Meanwhile, Catherine Willows gets called to a nearby home where a 60-something couple has been found dead in their sleep. The husband was a physics professor, and they named their cat Schroedinger -- except poor Schroedinger in this case isn't in a superposition of states, but very much dead and buried in the back yard, which is littered with the bodies of dead squirrels.

Initially, Willows surmises the exterminator's equipment -- which employs electromagnetic pulses to chase away the squirrels -- interfered with the couple's matching pacemakers, but lab tests definitively rule that out: the pulses were too weak to have any effect on the pacemakers' operation. It's a very real health risk, however: most Websites concerned with pacemakers warn those considering the surgery to avoid MRIs altogether afterward, and use with caution such devices as cell phones, iPods microwave ovens, metal detectors, industrial welders, and electrical generators.

A tox screen reveals that both the squirrels and the couple died of cyanide poisoning, the squirrels via ingested pellets, and the couple by inhaling a hydrogen cyanide gas. Victims of foul play? Yes for the squirrels; the jewelry-maker next door admitted to using cyanide in her electroplating (a common application for cyanide) and dosing the pesky squirrels (not to mention the unfortunate Schroedinger, by accident), but as for the elderly couple -- not so much. Turns out the cyanide that killed them came from the old carpet -- since overlaid with a new one -- which contained polyvinyl chloride as a flame retardant. A fire broke out when a fleeing squirrel chewed through some electrical wiring, the old carpet kept things to a low smolder and the chemicals in the carpet fibers, when burnt, produced hydrogen cyanide gas. At least the couple died peacefully in their sleep.

All of the above is pretty scientifically accurate, give or take the occasional liberty for Purposes of the Plot -- at least as far as I could tell from my hour of Googling. If one were going to nitpick on the cyanide front, one might note that Hodges is credited with the rare gift of being able to smell the bitter almond odor associated with hydrogen cyanide. It's true that not everyone can do so, but those that can't are in a minority (one out of four). Three out of four people can detect the telltale odor; if anything, it's surprising that Hodges is the only person in the Vegas lab who can do so. Then again, Hodges is known for exaggerating his gifts, so constantly proclaiming the uniqueness of his ability is entirely in keeping with his character.

Recapping the day, the C.S.I. team marvels at the unlikely string of coincidences that connected the various cases. First, a suspect goes up in flames while in police custody, and the last person he came into contact with -- Tinfoil Evelyn -- ends up dead and oozing weird green blood from migraine medication she'd copped from Atomic Dave, hired by the elderly couple to get rid of the squirrels. The late, great Immolated Deer-Killer turns out to be the ex-husband of the couple's next-door neighbor. The Deer Killer only ended up in police custody (and thus, dead) because he was so upset about the end of his relationship with the jewelry maker. Grissom says there's no such thing as coincidences and attributes the phenomenon to (wait for it!) string theory -- thereby tying him to crazy Tinfoil Evelyn.

Okay, citing string theory as an explanation for a series of unlikely coincidences is stretching things very far indeed -- in fact, unlikely coincidences do arise quite frequently, and they are rarely (if ever) evidence of anything more than that. But the brief layperson's sound-bite summation that Grissom gives of the essence of string theory is dead-on. The writers did their due diligence, even if they added their own fanciful metaphorical embellishment. And that's good enough for me.

NEW VOICES: love bytes

For the last eight months or so, I've been encouraging various aspiring young science writers I encounter to submit the occasional guest post to Cocktail Party Physics. First, sometimes I just get tired of the sound of my own voice, or need a break. Second, I think it's critically important to encourage fresh new voices in the science writing sphere -- because they will become the voices of "authority" tomorrow. Maybe they're not quite ready to take the plunge with their own blog, but I try to make this blog a place where it's okay to take the occasional creative risk, and receive helpful feedback from a (mostly) receptive audience so that they can keep refining their science writing skills.

Frankly, many of the aspiring science writers I've approached have been a bit intimidated about venturing into an admittedly rowdy (at times) public forum, but I'm finally optimistic that at least a few brave souls will be coming on-board for my little project over the next few months. So on this May Day, I inaugurate a new, occasional series called "New Voices." Today we welcome back Brian Frank, a student in KC Cole's science writing class at the University of Southern California, who guest blogged a couple of weeks ago about "Doomsday Physics." In this post, he shares the result of an in-class assignment on imagining a unique story-telling approach to a scientific topic -- the workings behind a simple email -- aimed at a very general target audience, for our consideration. Without further ado, we present "Love Bytes: A Fantasy of Networks and Bits." (Jen-Luc Piquant thinks we should all forward the post to any members of Congress -- *cough* Ted Stevens *cough* -- who remain mystified by how these Intertubes actually work.)

Johnny's sitting there, trying to decide how to sign his email to Liz. He taps out "-- Johnny." He reconsiders, hits the Backspace key, and taps a few more keys. There it is: "Love, Johnny." He pauses. The cursor darts erratically around the screen as he wobbles the mouse. Then it hovers over the Send button. There's still time to change the signature line, but he's certain now. He clicks.

Normally, Johnny wouldn't think twice about what happens next to his message, but he's in a rather sentimental mood. With a modest background in computer science, he knows how that message will cross the nearly 3000 miles of networked wires from his apartment in Los Angeles to Liz's in New York. Through the filter of his romantic brooding, though, that electrical transmission seems as grand and romantic as some lone adventurer crossing the Sahara to reach his beloved. He imagines the L that started the one word that seemed to convey the whole of his message.

L is exactly one byte, but he isn't traveling alone. Each letter, each comma, each period of the message amounts to a byte. In Johnny's imagination, time is compressed, and L and all his compatriots are about to embark on an odyssey that in fact occurs countless times every second on the Internet.

But first, they have to wait while the E-mail program gets them in proper order. This gargantuan application (from L's point of view) works like a factory, padding the message with extra information in the form of even more bytes. These extra bytes will travel at the head of the pack (in the header, no less), delivering special instructions on how to handle everything that comes after them. It's like sending a company representative ahead of a shipment to explain to the people on the receiving end how to unpack the freight trucks and reassemble the contents into a house.

With the header finished, the E-mail application prepares L and all the other bytes for travel. First, L is turned into something that can be easily read by computers. He gets crunched into bits -- not smashed, really, but assigned "bits," the 0s and 1s that, in clusters of eight, make one byte. L translates to "01001100" in bits (which is binary, the universal language of computers). In a sense, that string of digits will act like L's identification tag.

Now properly identified, L gets crammed together with his neighbors into a long stream of digits. It's impossible to tell where one byte ends and another begins, really. All those letters and commas and periods blend together until they look like this: 01001100101011101010110100100101, and so on.

L and the other bytes are now ushered down to the network card, where they find their seats, as it were, on one of a caravan of buses -- the packets that make it more efficient to send information across a network. These packets come in various sizes, but many hold up to 4000 passengers, which are bytes just like L. That seems like a lot of characters for one message, but actually a substantial portion of those bytes are part of the header that will tell the receiving computer what to do with all these 0s and 1s.

The packets line up in an orderly fashion and point to the cable that connects Johnny's computer to the Internet and ultimately to Liz's computer. But here's the beauty of it for L. The bytes are sent in groups, one packet at a time, but they don't actually have to travel at all. The computer just reads the information on the identification tags, and in a kind of Morse code, calls out the 0s and 1s across the network. Instead of using the blips of light or sound characteristic of traditional Morse code, the computer will send electromagnetic pulses. Each 1 is a pulse. Each 0 is a pause. With the perfect rhythm of a clock, the computer will either pulse or pause.

The packet in front of L's moves forward and all its bytes have their identification tags read and relayed down the line. L's packet has to wait briefly before it follows, because if all the packets went in a row, the line would be tied up too long, preventing other computers from sending other heartfelt messages.

Finally, L's packet has its turn. Each byte in front of his has its 0s and 1s transmitted. Then L's ID is read: "01001100." The computer measures out the beats like this: wait, pulse, wait, wait, pulse, pulse, wait, wait.

The pulses and pauses travel in their packets for hundreds of miles at a time -- Los Angeles to Houston, Houston to Denver, Denver to Detroit, and so on until they reach New York. At each hub, a computer receives the signal and records it as bytes in a packet. It signals the next hub and so on down the line. When a line is temporarily busy, the computer hub holds the packet for a short layover. And they don't all have to travel together. Part of the job of that header was to tell the receiver, "Hey, there are 100 packages en route, so don't try reassembling all this stuff until you have all of them."

Eventually all the packets arrive in New York, in Liz's computer, in fact. The computer watches for pulses and pauses, keeping the same rhythm as the sender. For each pause it records a 0, and for each pulse a 1. Gradually it has a long string to work with. It snips every eighth bit and reads the subsequent string as a byte. All those bytes are sent up to Liz's E-mail application, where the factory transforms the digits back into characters. At some point, the application comes across the by-now-familiar byte "01001100," and shoots an L onto her screen. And at last, the journey is complete.

Of course, all this happens in a matter of seconds. Johnny and Liz have already traded numerous email messages today. This time, Liz sees the "Love, Johnny," panics, and sends a quick reply. Her message takes the same fantastic route, all the characters changing to bits and then pulsing across the Web to Johnny's computer. Unfortunately for Johnny, preceding Liz's name is not the "01001100" that would start the L word. Instead, he message reads, "I think we're better off as friends. -- Liz."