Humans, despite having originated in hot parts of the world, have long looked for ways to make buildings more comfortable in hot weather. The first attempts in the 19th century involved circulating air over blocks of ice, but modern air conditioning first had to await the invention of mechanical refrigeration.

Liquids absorb heat from their surroundings when they evaporate or boil, and you can control the temperature at which that happens by controlling the pressure: the higher the pressure, the higher the boiling point.

William Cullen first demonstrated refrigeration using this principle in Glasgow in1748, but it was 86 years before Jacob Perkins of London patented the first practical ice-making machine, and it wasn’t until 1911 that Willis Carrier invented a practical air-conditioning system.

In both a refrigerator and an air conditioner, a liquid is boiled in an evaporator. It absorbs heat as it expands, and the warmed vapour is then compressed (which makes it even hotter) and run through pipes that allow it to radiate that heat away (which is why the back of your refrigerator is so hot). In other words, both refrigeration and air-conditioning boil down to (sorry) transferring heat from whatever you want cooled to a place where you don’t mind that heat being released.

The most common refrigerants for the last 80 years have been chlorofluorocarbons. Although later implicated in the erosion of the ozone layer, they were actually developed as a safe alternative to the much nastier refrigerants that preceded them, such as sulfur dioxide. Stable, incombustible and non-toxic, CFCs made air conditioning practical in office buildings, hospitals, apartments, trains and buses, and, by 1950, automobiles.

There are new ozone-friendly refrigerants in use today, but refrigeration-based air conditioning still has its problems. For one thing, it’s energy-intensive, as those with central air conditioning well-know from their sky-high electricity bills in hot weather.

But now comes word that the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) has invented a new kind of air conditioner that could potentially use anywhere from half to a whopping 90-percent less energy than standard systems.

The new system, called DEVap, is based on evaporative cooling rather than refrigeration. In a really dry climate that doesn’t get too hot or too humid (say, Denver), you can cool and humidify air simply by flowing water over a mesh and then blowing air through the mesh.

Unfortunately, evaporative coolers don’t work well enough to cool really hot air to a pleasant temperature, and in a humid climate they actually make things more unpleasant by increasing humidity while hardly cooling the air at all.

DEVap combines an evaporative cooler with desiccants, chemicals that absorb water from the air (you know, like those “Do Not Eat” packages you find in electronics packaging). It uses highly concentrated syrupy solutions of salts such as lithium chloride and calcium chloride that can create very dry air.

One challenge with desiccant-based cooling systems has been their complexity. DEVap has simplified things immensely by using thin membranes that are hydrophobic–water beads on them instead of soaking through them. This allows the membranes to control the flow of liquid within the cooling core, keeping the water and the desiccant separated from the air stream.

What that means in practice: hot, humid air flows into the core and in a fraction of a second becomes cool, dry air that can then be directed into the space to be cooled.

The NREL has patented the DEVap process, and will be refining it over the next couple of years with the goal of eventually licensing it to manufacturers.

It won’t help this season. But in a few years, you may be able to enjoy a cool, comfortable house without any heart-stopping power bills, all summer long.

Later, I was crossing a street downtown when a van went through the yellow in front of me. It looked to me like the driver had plenty of time to stop—but no doubt he had his own excuse.

It’s a rare driver who doesn’t run through a yellow light on occasion, and in most cases it’s barely even a conscious decision. You have a split second to decide to brake, keep going…or even speed up.

So how do we make that decision?

A transportation engineering graduate student at the University of Cincinnati recently decided to see what he could learn about the factors influencing the decision to run a yellow light.

In cooperation with the Ohio Department of Transportation and with the help of his advisor, Professor Heng Wei, Zhixia Li conducted research in Akron, Cleves and Fairfield, Ohio. The results were set forth in a paper called “Analysis of Drivers’ Stopping Behaviors Associated with the Yellow Phase Dilemma Zone—An Empirical Study in Fairfield, OH,” and were presented at the 2010 American Society of Highway Engineers National Conference held last week in Cincinnati.

Unfortunately the paper itself is not yet online, but a press release about his findings was put out a few days ago.

According to the release, Li found that lane position, type of vehicle, travel speed, speed limit and the timing of the light all figure in the running of yellow lights.

For example, he found that people in the right lane are 1.6 times more likely to speed through a yellow light than drivers in the left lane.

Drivers in heavy trucks are more likely to pass through a yellow light than drivers of automobiles, SUVs, vans or pickup trucks. I suspect that’s a matter of momentum: it takes a heavy vehicle longer to stop than a lighter one, and once it’s stopped, it’s harder to get going again.

I also suspect, though Li’s research has nothing to say on the matter, that in Saskatchewan in the winter time the incidence of people running yellow lights increases dramatically because suddenly all of us are dealing with the problem of momentum: brake too hard on an icy road and you’ll skid through the intersection, possibly out of control. Even if you do manage to stop, you may find it almost impossible to get going again. In effect, winter turns us all into heavy trucks.

(Er, turns our vehicles into heavy trucks. Although, after a month of Christmas goodies…)

Travel speed is a pretty obvious factor: the faster a vehicle is travelling at the onset of the yellow light, the more likely it is to pass through it. And that naturally means that the higher the posted speed limit, the more likely vehicles are to pass through the yellow light at an intersection.

Finally, there’s the timing of the light.

Yellow lights are typically set to last somewhere from three to five seconds. Drivers coming to an intersection with a longer yellow light are more likely to pass through it (presumably because they’re familiar with the intersection and know how long the light is going to be).

In fact, Li found that for every additional second a yellow light persists, drivers are three times more likely to pass through the intersection under yellow. In other words, drivers are three times more likely to pass through a four-second yellow than they are a three-second yellow, and three times more likely than that to pass through a five-second light, which if my math is right means that they’re a whopping nine times more likely to pass through a five-second yellow than a three-second one.

This kind of empirical data should be of great use to traffic engineers attempting to make better, smoother and safer the flow of traffic through cities.

It might even, the press release suggests, “help drivers consider their own actions when in the yellow-light dilemma zone.”

But that, I’ll believe when I see.

In the U.S., the Memorial Day weekend at the end of May is seen as prime barbecuing time, which is probably why LiveScience, one of the science sites I frequent, recently answered that burning (sorry) question: “Why does grilled food turn black?”

But in order to build suspense, I’m going to refrain from answering that this early in the column in favor of reminding you of a few other interesting facts about barbecue.

First up: what we call barbecuing ain’t technically barbecuing at all. According to LiveScience, the Memphis in May World Championship Barbecue Cooking Contest defines barbecue as “pork meat (fresh or frozen and uncured) prepared only on a wood and/or charcoal fire.” Since we cook a lot more things on our “barbecues” than just pork, and most people these days have propane “barbecues,” we’re not really barbecuing at all by the strictest definition of the word.

Then there’s the fact that authentic barbecue is actually cooked at a low temperature, which means it rarely blackens, though soot from the fire may turn it brown.

What we call “barbecue” is really grilling: and with grilling, you most definitely do get meat turning black. It’s because—

No, wait, not yet! Let me keep you in suspense a little longer.

How about some background? As I noted in a previous column on barbecuing, the word “barbecue” comes to us from the Caribbean. (Interestingly enough, so does the word “cannibal.” You can make your own connections.)

My family rarely barbecues, partly because we don’t have a slick propane-fueled unit but only one of those classic round grills that you fill with charcoal briquettes: lumps of fuel formed from scrap wood and sawdust that’s first burned to carbon, then compressed with a starch binder and ground coal.

The tightly compressed nature of the briquettes means it’s hard for oxygen to penetrate them, which is why they burn so slowly. Their uniform shape means they give a nice, even heat, too; but the binder and the coal can sometimes give food an off-taste. A better choice for wood-based backyard cooking is hardwood lump charcoal, wood that has been left to smolder without oxygen until it turns to carbon (which burns hotter and more slowly than wood).

Or you can break down and get a propane grill like probably everyone else on your block has. Propane, of course, doesn’t provide any smoke for flavor, and the even heat takes some of the excitement out of cooking because everything is cooked evenly all the way through—although the excitement of finding your chicken breast is half-raw in the middle is one I personally could do without.

Alas, grilling, associated in our memories with carefree summer days, does pose certain health risks. A study presented at the 2006 American Association for Cancer Research meeting contained evidence that the chemicals in charred meat can raise the risk of prostate cancer in rats.

The reason? Carcinogenic compounds called hererocyclic aromatic amines, or HAAs, produced whenever meat is cooked at high temperature.  And burned meat—that is, blackened meat—is particularly high in HAAs.

Which brings me, finally, to the reason meat turns black.

Essentially, it’s because the heat breaks down amino acids and sugars, burning them away until all that’s left behind is blackened, partially combusted carbon. As anyone who watches Star Trek knows, our planet is full of “carbon-based life forms,” and so when you burn a terrestrial life form—whether a tree being turned into charcoal, or a piece of chicken over an open flame—without burning it up completely, you get carbon.

If you’re worried about HAAs, you might consider scraping that carbon off your meat before you eat it…or you might consider going in for “real” barbecue and cooking a long time at a slow temperature.

Head on down to Memphis. I’m sure they’d be happy to show y’all how it’s done.

Ask someone on the street to name a particularly deadly disease, and there’s a good chance he’ll say “Ebola.” Yet of the diseases I wrote about, the biggest killer by far is meningitis, the bacterial form of which kills some 170,000 people every year, according to the World Health Organization. (And if you want even bigger killers, in sub-Saharan Africa alone tuberculosis kills some 5,000 people a day, and yearly in that region malaria kills 700,000 and simple diarrhea 900,000.)

Ebola has captured the public imagination, however, because unlike most diseases, it’s gotten a foothold in pop culture, through books like Richard Preston’s 1994 best-seller The Hot Zone and the 1995 movie Outbreak.

I admit it also captured my imagination as I wrote my own book, not least because Ebola (which, by the way, is named after a river near Yambuku, Democratic Republic of the Congo, site of the first recognized outbreak), begins with fever, weakness, muscle pain, headache and sore throat—in other words, “flu-like symptoms.” Which I experienced while I was writing the book, since I was, after all, writing in Saskatchewan in the winter. Oh, sure, I knew intellectually I didn’t have Ebola, but still…

The symptoms get a lot worse than that, of course. Eventually, vomiting, diarrhea and rash develop, the kidneys and liver may stop functioning, and, in fatal cases, uncontrollable internal and external bleeding begins, resulting in the vomiting of blood and bleeding from the eyes, ears, nose and other orifices. And the most deadly of three different strains of Ebola, Ebola-Zaire, is fatal in up to 90 percent of cases.

(Fortunately, human-to-human transmission is via direct contact with blood or other bodily secretions, or contact with contaminated objects: no airborne transmission of Ebola has been documented in humans, which makes breaking the chain of transmission relatively easy with proper isolation and sterilization procedures.)

Ebola is frightening not only because it’s an awful way to die, but because there has been no effective treatment. But that may be changing, and a B.C. biotech firm is involved.

In a proof-of-concept study just published in the medical journal The Lancet, scientists report that they used tiny particles of genetic material to interfere in the replication process of the Ebola virus, and by doing so successfully prevented monkeys exposed to that virus from dying of hemorrhagic fever.

The scientists used particles called small interfering RNAs (siRNAs) to target a protein essential for Ebola virus replication. The process is similar to a natural mechanism used by all cells to silence genes.

Three rhesus macaques were given anti-Ebola-Zaire siRNAs intravenously half an hour after they were exposed to the virus, and again on days one, three and five. A second group of four macaques was given the treatment after half an hour and then for six consecutive days. The technique used to deliver the siRNAs is called SNALP (for “stable nucleic acid-lipid particles”), and was developed by Tekmira Pharmaceuticals Corporation of Vancouver.

Two of the three animals in the first group survived, and all four of the second group survived. The treatment itself seemed to produce no complications.

The results were so encouraging that lead author Dr. Thomas W. Geisbert of the Boston University School of Medicine says the work “justifies the immediate development of Ebola SNALP as a countermeasure to treat Ebola-infected patients.”

Of course there’s further research to be done: further studies in monkeys are needed to figure out dosing, toxicology and other issues before the treatment can be licensed for human use.

Still, it’s wonderful to think there may actually be hope for an effective treatment for Ebola at last…and what’s even more exciting is the fact that this approach to treating Ebola could also be used to combat other deadly viral diseases.

Even if it does make my books obsolete.

But that’s exactly what’s happening this month. Next week (Saturday, May 15, to be precise) marks the 50th anniversary of the invention of the laser. And what follows is (with some slight revisions) the column I wrote to celebrate its 30 anniversary back in 1990. (But it’s OK: I promise not to trot it out again until the centennial.)

On May 15, 1960, a cylindrical rod of synthetic ruby placed inside a spiral flashlamp by American physicist Theodore H. Maiman in his laboratory at Hughes Aircraft Company in California momentarily produced light 10 million times more powerful than sunlight: the first laser, an acronym for Light Amplification by Stimulated Emission of Radiation.

To understand how lasers work, you have to go to the basics–atoms. Every atom has a nucleus surrounded by electrons. These electrons reside in discrete energy levels, or electron orbits, around the nucleus. The further out from the nucleus they are, the more energetic they are.

Sometimes an electron from a high-energy level drops to a lower energy level. To do that it must lose energy, which is released as a photon of light. This is called spontaneous emission.

When a photon comes into contact with an atom that has two energy levels with an energy difference exactly equal to the energy of the photon, then the photon may be absorbed, and an electron at the lower level moves up to the higher. The atom is now said to be in an excited state, but it only lasts for a tiny fraction of a second. Then it throws off a photon, or “decays,” and relaxes again.

In 1917 Albert Einstein suggested that if a photon from one atom came into contact with a similar atom that was in an excited state, it could cause another photon identical to itself to be emitted. This is called stimulated emission.

Lasers basically consist of three items: a material which acts as a light amplifier (the ruby rod in Maiman’s original laser), a source of energy (Maiman’s flashlamp) and two mirrors. The energy source excites the atoms in the light amplifier (called the active medium) so they can produce stimulated emission. The energy source has to be strong enough to excite the atoms faster than they can decay back to their normal state, so that soon you have more excited atoms than non-excited ones. This is called a population inversion.

Initially a few atoms emit photons spontaneously, which induce other atoms to emit. The light intensity quickly grows in all directions. Some of the photons go out the sides of the active medium and are lost, but some travel the length of the medium, inducing still more atoms to emit–and when they reach the end of the active medium, they bounce off one of the mirrors and return to stimulate still more atoms. In this way a single photon can produce millions and millions of others exactly like itself.

Although one mirror is a regular, fully reflecting mirror, the other, at the far end of the active medium, is only partially reflecting. The light that passes through this mirror is the laser beam.

This light is special in several ways. First, it is monochromatic–all one, pure colour. That’s because all the photons in the laser are identical copies of each other, all with the same wavelength.

Laser light is also coherent: those identical light waves are exactly in step with each other. (You can have monochromatic light that is incoherent, where the waves aren’t in step with each other, but then it’s not a laser.)

Although synthetic ruby was first, many different materials can be made to “lase.” In 1961 the first gas laser was constructed, using a mixture of helium and neon. Nowadays we have tuneable lasers, using solutions of organic dyes that can produce laser light of any colour.

Today, lasers are everywhere, used to play DVDs, print letters, transmit messages, cut and weld metal, repair eyes, target weapons, and liven up rock shows. New research even suggests ultra-fast pulses from powerful lasers could be used to create water droplets out of thin air, creating rain on demand.

Not bad for what originally seemed only a scientific curiousity…and well worth a rousing rendition of “Happy Birthday.”

Consider it sung.

Oh, sure, it’s conceivable you could be a talented entertainer and also have an informed, thoughtful opinion that adds more light than heat to the debate surrounding a contentious issue, but just because something is possible it doesn’t mean it’s likely. And let’s face it, the mere fact you’re pretty good at pretending to be somebody else in front of a camera does not give you any special insight the rest of us lack.

I also resent lectures from affluent millionaires who use private jets like we use cars and have just expended vast amounts of energy making Pocahontas In Outer Space with blue people telling the rest of us we should be cutting back on vacation trips to Moose Jaw to reduce our environmental footprint.

It is therefore gratifying to hear scientific evidence that celebrity endorsements do not, by and large, persuade people…at least not when it comes to whom to vote for.

Two studies carried out at North Carolina State University revealed that young voters—the ones one might expect would be most susceptible to the rush of hot air from Hollywood—are not swayed by celebrity endorsements of political candidates.

Results of the studies were outlined in a paper entitled “Seeing Stars: Are young voters influenced by celebrity endorsements of candidates?”, co-authored by Michael Cobb, an associate professor of political science, and undergraduate Kaye Usry and presented April 22 at the 68th Annual Conference of the Midwest Political Science Association in Chicago.

“The positive effects of a celebrity endorsement are minimal for politicians,” says Cobb. “I began to observe this kind of sentiment among my own students—particularly my conservative students—who were continually commenting about how much they disliked celebrities wading into politics, and I knew there was some research to be done.”

In the studies, he used theoretical voting scenarios and invented headlines about Hollywood partisanship to evaluate whether more than 800 college students, in two separate studies, would let endorsement from celebrities—including George Clooney, Angelina Jolie and Madonna—influence their voting behavior.

They not only found that celebrity endorsements do not help candidates, they can actually hurt them, with some young people less likely to vote for a candidate after a celebrity endorsement than before.

This echoes the finding of a Pew Research Centre survey conducted during the 2008 presidential campaign that found that endorsements by Jay Leno, Bill Gates, Kanye West, Angelina Jolie, Jon Stewart, Donald Trump, among others, mad no difference in the voting plans of fully three-quarters of the voting public.

And while endorsing a political candidate may make little difference in the number of people who vote for that candidate, it holds risks for the celebrity. In the study, students were asked to rate both the credibility and trustworthiness of the stars mentioned. Students who identified themselves as Democrats had a lower opinion of George Clooney when told he had endorsed a Republican; students who identified themselves as Republicans had the same reaction when told Clooney had endorsed a Democrat.

In the real world, data suggest Oprah Winfrey became less popular after endorsing Barack Obama in the 2008 presidential election.

Celebrity endorsements, then, are of little use to candidates and hold dangers for the celebrities, who risk alienating large sections of their public whichever party they publicly support.

Cobb is willing to grant one way in which a celebrity endorsement can help a candidate: a celebrity putting in an appearance at a rally can boost attendance. As he says, “Are you more likely to attend a political event if the candidate is slated to appear by him- or herself, or if the candidate is going to appear with Madonna?”

In the U.S. in particular, where candidates have to win over large numbers of the voters in their own party in primaries before being presented to the general electorate as a candidate, a celebrity endorsement can also help candidates stand out in a crowded field.

But once they’re actually up for election, the celebrities would be doing the candidates and themselves a favor by fading into the woodwork.

Alas, that seems about as likely as a Hollywood movie that portrays former President George W. Bush in a favorable light.

Could happen, I suppose, but on the day such a film is released, I plan to keep my head low.

Those flying pigs pack a mean wallop.

Have you ever wondered why?

A German researcher at the University of Bamberg with the unlikely-yet-oddly-appropriate name of Claus-Christian Carbon did, and the results of his study were recently published in the journal Acta Psychologica under the title “The cycle of preference: Long-term dynamics of aesthetic appreciation.”

Carbon suggests that two basic but somewhat conflicting human tendencies influence our reaction to automobile designs: a natural inclination to prefer curved objects, and a fascination with the new.

Normally, humans avoid sharp objects, because sharp objects—fangs, claws, knives, thorns—can hurt us. Rhinoceroses are more alarming than hippos, for example.

Indeed, MRI studies have found that the amygdala, a brain structure activated by fear-inducing stimuli, “lights up” more when sharp-edged objects are in view than when rounded ones are.

But we have another natural inclination, which is to take notice of the new and unexpected. Place a black obelisk like the one in 2001: A Space Odyssey in a field full of tulips, and our attention will be drawn to the sharp-edged obelisk rather than the flowers.

The ebb and flow of curviness and sharpness in car design vocabulary (“Formensprache” is the wonderful German word) is a result of these conflicting impulses, Carbon suggests.

For his research, he had four different groups of participants rate car models from 1950 to 1999, but he primed each group a little differently. In the first study, participants, who were asked to rate curvature, complexity, quality, innovation and security, were given no historical context: they didn’t know when the cars were built.

In the second study, historical context was provided, so the viewers knew what era the cars originated from, the goal being to identify what Carbon calls “Zietgeist-dependent” effects. In a third study, before being shown the cars from 1950 to 1999, participants were first shown futuristic concept cars; in the fourth, participants were first shown highly angular historical cars.

In the third study, where the participants were first shown futuristic cars before being shown models from the past 50 years, the “shock of the new” influenced their opinion: they rated cars from the past 15 years as being lower in innovation and also didn’t like them as much as participants who weren’t first shown concept cars. “We experience similar cognitive processes when coming back from influential international motor shows in Frankfurt, Tokyo or Detroit,” Carbon says:  suddenly everyday cars look old-fashioned…no matter what their curvature.

So: our natural preference for curvy cars can be overcome by the novelty factor of sharp-edged cars. But after a few years of boxy cars, curvy ones, which we naturally prefer anyway, begin to look fresh again…and so car designers and buyers move back toward them.  As Carbon puts it, “The evolutionary program (favouring curves) is always running, but on top of it can be running a cultural program,” which favors innovation.

Interestingly, that cultural program seems to be running faster: Carbon says the cycle in car design between curvy to sharp and back again is speeding up. He says that while it used to take 50 years for car designs to swing between rounded and boxy, now it’s more like 20 years: in fact, he predicts an increase in sharply angled cars in the coming decade.

Oddly enough, sharp-edged designs’ association with things that can hurt us may be part of their appeal. The amygdala lights up, warning us, but we know there’s not really anything to fear from a car’s sharp edges: it becomes a safe thrill, like the thrill we get on a rollercoaster.

Ultimately, this explains more about human nature than just how we like our cars to look, of course. As Carbon puts it, “although humans might generally be pre-shaped by evolution to prefer specific properties preventing them from danger, they are specifically shaped to explore innovative and challenging properties.”

And, he adds, the push-and-pull between those conflicting impulses may ultimately explain why humans are both so successful in designing objects, and in adapting to them.

Funny thing, though: once you break one, it’s hard to think about anything else.

When first I wrote about bones, back in a 1993 instalment of this column, I told the story of my own broken-bone experience, for which I blame my big brother, Dwight (mainly because it was his fault).

I was seven years old and he was 12. We were both inside a big cardboard box that had held a refrigerator. For some reason, we’d decided it was fun to roll down the back steps inside this box. And it was fun, right up until Dwight’s friend from down the street jumped on top of the box. Inside, my brother was on top of my arm, which was up against the steps, and I was suddenly the startled owner of an L-shaped wrist.

My indignant initial reaction (I tried to say, “Now look what you’ve done,” but it came out more like “Glubbleulp!”) gave way to an intensely personal curiosity about bones. “Someday,” I vowed, “I will write science columns about them!”

This particular vow-fulfillment column was prompted by the report of a new procedure to turn blocks of wood, of all things, into artificial bones.

Developed by scientists at the Instituto di Scienza e Technologia dei Materiali Ceramici in Faenza, near Bologna, Italy, the wood-derived bone substitute promises to allow live bones to heal faster and more securely after a break than the metal and ceramic implants that are currently used.

It makes sense, because if you’ve ever seen a cross-section of a bone—there’s one at the Saskatchewan Science Centre, if you’d like to run down and have a look—you will have noticed that, far from being solid, it’s quite porous.

As I noted in that original column all those years ago, “We think of bones as hard, dead matter, like hair or fingernails, but they’re actually organs consisting of living cells embedded in a matrix of calcium phosphate and other calcium minerals, held together by collagen, the tough fibrous protein we also use to make ligaments, tendons and skin. Bone tissue constantly renews itself…dissolving old tissue and…depositing new tissue.”

That’s why broken bones can heal themselves. But when titanium is used as a bone implant, bone can’t interact with it. Instead, the titanium is simply encapsulated in fibrous tissue. Nor is it practical to introduce pores into the titanium: that weakens it to the point where it could break, inflicting more damage.

Wood, however, like bone, is porous. Bone tissue can interact with the new wood-based substitute bone, growing right into it, along with blood vessels, nerves and more.

Titanium and ceramic implants can also damage bone simply because they’re so much harder than it. Whereas natural bone flexes slightly (and that stress actually strengthens the bone), the harder, less flexible implants can apply so much stress to a particular area that the bone snaps.

So how do you go about turning wood into something approximating bone?

The process begins with a block of wood (rattan works best). It’s heated until nothing remains of it but pure carbon (i.e., charcoal). The charcoal is then sprayed with calcium, which creates calcium carbide, then heated further under intense pressure and treated with a phosphate solution. After about 10 days, the wood has become a bone-like material.

The cost? About $850 per block, which provides enough material, on average, for one bone implant. Virtually any size or shape can be created.

Dr. Anna Tampiere, leader of the research team, says the new material is strong enough to take the heavy loads bodies place on it, and durable enough that, unlike existing bone substitutes, it will never need replacing.

The bone substitute has been implanted into a flock of sheep. X-rays show that, indeed, the sheep’s bones have migrated into the wood substitute. With time, says Tampiere, “you don’t even see the join.”

Human tests are probably still about five years away, but so far there has been no sign of the sheep’s bodies rejecting the new material, raising hope that this new process could give us a natural, cheap and effective replacement for bones.

Bonus: these implants won’t set off metal detectors at airports.

And one of the most baffling is the Mpemba Effect.

You may not know it by that name—I didn’t until I read an article on New Scientist’s website last week—but you’ve probably heard about it. Heck, you may even have gotten in an argument about it.

The Mpemba Effect is the proper name of the counterintuitive fact that sometimes hot water freezes faster than cold water.

As New Scientist explains, Aristotle remarked on this phenomenon in the 4th century B.C., and Francis Bacon wrote about it in 1620. Just 17 years after that, in the very same year in which he famously wrote “Cogito ergo sum” (“I think, therefore I am”), René Descartes took time out from philosophical musings to note that, “Experience shows that water that has been kept for a long time on the fire freezes sooner than other water.”

Still, the phenomenon didn’t even have a name until the 1960s, when Erasto Mpemba, a Tanzanian schoolboy, told his science teacher that he could make ice cream faster than usual by putting a heated mixture in a freezer. His classmates laughed at him, but a school inspector in Dar es Salaam successfully repeated the experiment.

Why should something that’s hot to start with freeze faster than something that’s already cold? There have been numerous attempts at explanations, but they’re frustrated by the fact that the effect is unreliable. While hot water will, indeed, sometimes freeze faster than cold water, it doesn’t always freeze faster than cold water. In fact, cold water is just as likely to freeze first.

Over the past 10 years, James Brownridge, radiation safety officer for the State University of New York at Binghamton, has carried out hundreds of experiments on the Mpemba effect (in his spare time, not as part of his duties), and he believes he has the answer.

According to Brownridge, the effect is based on another phenomenon called supercooling, the fact that even though we all know zero degrees Celsius is the freezing point of water, water hardly ever freezes right at zero degrees. Usually it cools below that point before it begins to freeze.

The actual freezing point depends on impurities in the water. These impurities—which can range from dust particles to bacteria to dissolved salts—serve as “seeds” for the formation of ice crystals, and different types of impurities trigger freezing at different temperatures. The impurity that causes freezing at the highest temperature determines when the water will start to freeze.

In his experiments, Brownridge starts with two samples of water at the same temperature in covered test tubes. He cools them in a freezer. One will freeze first, presumably because of its random mix of impurities. Brownridge then takes the sample with the higher natural freezing temperature and heats it to 80 degrees Celsius, warming the other only to room temperature. Then he puts them back in the freezer. If, in the initial test, the hot-water sample’s freezing temperature was at least five degrees Celsius higher than the other sample, it will always freeze first.

Why does that five degrees make such a difference when the hot-water sample has a full 60 degrees of extra temperature to shed compared to the room-temperature sample? Because the higher the temperature difference between an object and its surroundings, the faster it cools. That means the hot sample sheds all of its extra heat and reaches its five-degrees-higher freezing point of, say, minus-two, before the room-temperature sample, cooling more slowly, reaches its lower freezing point of, say, minus-seven.

Is it a matter of case solved, then? Not hardly. As New Scientist points out, Jonathan Katz of Washington University in St. Louis, for one, doesn’t buy it. In his theory, heating raises the freezing point of water by driving off solutes such as carbon dioxide, which means heating water increases the chance that it will freeze first, rather than it being purely random as Brownridge suggests.

It may all seem rather unimportant, as scientific debates go, but it’s a fascinating reminder that the world is a very complex place about which there’s always more to discover…even in our own kitchens.

Our moral judgment feels so integral to who we are, so much a part of our personality, that it’s a bit disturbing to discover, as MIT researchers reported this week, that it can be disrupted by magnets.

Rebecca Saxe, an assistant professor of brain and cognitive sciences at MIT, has focused her research on social cognition: how we interpret other people’s thoughts. She wants to understand how the brain gives rise to things like moral judgments, belief systems and language.

The challenge, of course, is that we have no way to observe people’s thoughts and beliefs directly. Nevertheless, we do have tools with which to see which parts of the brain are active when we think about other people’s thoughts, which we do whenever we’re trying to figure out why others are behaving the way they are.

I’ve referred in many previous columns to functional magnetic resonance imaging, or fMRI, which measures blood flow, and hence activity, in various regions of the brain. Using that tool, Saxe has discovered that an area called the right temporo-parietal junction (TPJ), is highly active when we think about people’s intentions, thoughts and beliefs.

In the new study, Saxe and her fellow researchers used a non-invasive technique called transcranial magnetic stimulation (TMS) to selectively interfere with brain activity in the right TPJ: in other words, they applied a strong magnetic field to a small area of the skull. The magnetic field created weak electrical currents that made it hard for nearby brain cells to fire normally. (Fortunately, the effect is temporary.)

They ran two experiments. In one, they exposed the right TPJ of volunteers to TMS for 25 minutes, then had the volunteers take a test in which they read a series of scenarios and made moral judgments on the actions of the characters in the scenarios, using a scale of one to seven, with one being “absolutely forbidden” and seven being “absolutely permissible.”

In the second, they applied TMS in 500-millisecond bursts just at the moment when the volunteer was asked to make a moral judgment, such as how permissible it is for a man to let his girlfriend walk across a bridge he knows to be unsafe, even if she makes it across unharmed.

(That’s a common kind of scenario in morality studies, because people who have the normal capacity to infer other people’s thoughts would typically judge the man as morally wrong because something bad could have happened and he knew it, whereas those without that capacity, such as those with certain kinds of brain damage, judge his action to be morally acceptable because nothing bad actually happened.)

In both experiments, the researchers discovered that, when the right TPJ was subjected to TMS, the subjects were more likely to judge the man’s action as morally permissible. That seems to indicate that when brain activity in the right TPJ is disrupted, people are less able to interpret other’s intentions, leaving them with only the outcome on which to make their judgment.

“You think of morality as being a really high-level behaviour,” says the study’s lead author, Liane Young. “To be able to apply (a magnetic field) to a specific brain region and change people’s moral judgments is really astonishing.”

That’s not to say that the disruption completely reversed people’s moral judgments, but it definitely biased them. As Saxe points out, there’s more to moral judgment than merely understanding other people’s intentions. We also take into account their desires, previous record and any external constraints, and it’s all guided by our own concepts of loyalty, fairness and integrity.

Moral judgment, Saxe says, even though it feels like one uniform thing, is “actually a hodgepodge of competing and conflicting judgment, all of which get jumbled into what we call moral judgment.”

As the MIT researchers continue their research, I can’t help but think there’s a germ of a science fiction story here, one in which a villain uses technology to disrupt the brain activity of a law-abiding citizen, turning him into a savage, murderous animal. I even have a title: “Animal Magnetism.”

OK, maybe not.