Outlier Week: Camera Man

Human abnormality is, quite frankly, fascinating. In the past, to get their fill, people attended freak shows advertising seven-foot-tall 'giants' and parasitic twins. Now in the age of the internet it's even better: we have instant access to information about the most unusual people on the planet. This week will be dedicated to the outliers on various bell curves representing human abilities and behavior. After all, as well as morbid fascination, a lot of science is to be found at the edges.

First up is Stephen Wiltshire, an austistic man who can draw incredibly detailed cityscapes from memory, after viewing them out the window of a helicopter for just a few minutes:

How does Wiltshire do it? How do all savants do what they do, such as counting huge numbers of objects almost instantly or knowing that August 18, 1953 was a Tuesday? How did a three-year-old savant named Nadia draw this picture of a horse?

Recent research leads us to believe that such skills come down to a malfunctioning front temporal lobe. This part of the brain allows most of us to process the sensory information we take in and turn it into concepts. When the front temporal lobe doesn't work, though, no processing occurs and you're left with only the raw data itself.

So Wiltshire simply lays on a page the visual data he gathered while in the helicopter. The data hasn't been compressed, conceptualized, or manipulated in any way.

A physicist named Allan Snyder thinks we all have savant capabilities within us, and that our front temporal lobes are the only impediment to this particular type of genius. There is evidence to support his view. People who suffer from frontotemporal dementia, for example, sometimes show drastic improvement in artistic and musical ability as their condition degenerates. One recent study found that when the front temporal lobes of volunteers were shut off (using a non-invasive technique called transcranial magnetic stimulation), a certain number of them showed improvement in drawing, date-day matching, and multiplying.

To learn more about Snyder's theory and your inner savant, read this very good Discover article by Douglas S. Fox.

Hmm... I guess I wouldn't mind being a savant for a day or so.

Secular Weeping Icon

Every so often I learn about a geological structure that is so amazing I have to wonder: how can I have gone my whole life without knowing this existed on the same planet as me?! One such site is Blood Falls, where oozing red liquid gushes forth from Taylor Glacier in Antartica.

Boingboing blogger Maggie Koerth-Baker recently described this eerie spot as "a secular version of one of those crazy weeping Virgin Mary statues" - and I agree. How miraculous it seems to see what looks like blood tumbling five stories over the edge of a mountain of ice!

Since secular miracles don't exist, here's the explanation. The red liquid emerges from deep beneath the glacier, where an ancient colony of microbes has been trapped for several million years without oxygen or sunlight. They glean energy by breaking down iron and sulfur compounds in the rocks buried in their midst. Freed iron and sulfur are then released into the water, turning it into a red ooze. This bursts up through a fissure in the glacier and tumbles down in an epic "bloodfall."

So striking!

Blood, Sweat, and Eyes

The chemical basis of love is well-known. When you see the face of the person you're in love with, your brain floods with a surge of dopamine. Doses of this happy-drug can become addicting to the point that being apart from your beloved feels torturous, and induces symptoms of chemical withdrawal.

Dopamine addiction explains why people tend to stay in love once they've become so, but it doesn't account for why they fall in love in the first place - or who with. Those matters seem too multi-faceted to be fully addressed by MRI scans. In fact there are so many factors involved in the love plunge that we might never sort them out in a scientifically rigorous manner. Nevertheless, certain key pieces have been identified by psychologists and neuroscientists. Here are two particularly interesting findings.

We each have a set of genes, called the major histocompatibility (MHC) locus, that determines which type of immune system we have. To investigate how MHC genes correlate with sexual attraction in humans, Swiss zoologist Claus Wedekind conducted an experiment modeled on one done with mice. He had 44 men of varying immune system types each put his sweaty t-shirt in a box. 49 women with diverse MHC genes subsequently smelled the boxes of t-shirts and rated the sexual attractiveness of the sweat smells.

It was found that the more different a man's immune system genes were from a woman's, the more sexually attractive she found his smell. This makes a great deal of sense: our offspring are more likely to outlast diseases if they're pooling a diverse set of MHC genes from their parents. Furthermore, if one parent dies of a disease, it's best for the kid if the other one does not. Our senses of smell are attuned to who would be the best other parent.

In 1998, psychologist Art Aron conducted a study in which he had (straight?) participants of opposite sexes pair up and engage in various "icebreaker" activities together. One task required the couples to silently gaze into each others' eyes for 2 minutes. The couples reported that this made them feel extremely close; in fact one pair who did it went on to get married six months later.

Follow-up neuroscience studies on the effect of eye contact on attraction were done. It was found that more dopamine is released in the brain when we look at pictures of a person looking at us than when the person is looking away. (By the by, it's weird to think about how our brains can simultaneously know and not know that a photograph isn't a real person, don't you think?)

A participant's rating of the pictured person's attractiveness was correspondingly higher if he or she appeared to be making eye contact. The study's authors surmised that it was the feeling of being valued and attended to themselves that participants found so attractive in onlookers.

Though feeling attraction isn't falling in love, it often plays a significant part in it. And it's the part we're closest to making scientific.

(Still) Sick

Sorry everyone. I think I'll be better by tomorrow.

Brazil Nuts Rising

While gazing out his window most professorially, a chaos theorist once asked me, "Natalie: when you shake a bowl of mixed nuts, why do the Brazil nuts always rise to the top?"

We hadn't been talking about nuts so I was slightly caught off guard. But that's the thing with chaos theory. "Um... hmm." (Silence.)

I seldom knew the answers to questions this physicist asked me, but it turned out that in matters of rising nuts my ignorance was somewhat forgivable. The so-called "Brazil nut effect" is a major unanswered question in many-body physics.

Among an assortment of objects (such as nuts), the larger ones tend to work their way upwards through the mix in spite of their greater gravitas. Most of us have probably noticed this phenomenon in our bowls of nuts or breakfast cereal, and yet, believe it or not, it totally confounds physicists.

Why should bigger nuts rise? The answer is probably - but not definitely - some combination of the following:

1) Small nuts can trickle down through the nooks and crannies of a pile while big ones cannot.

2) Because small nuts pack together more tightly than big ones, they can achieve higher densities. Gravity requires these to sit lower in a pile.

3) Convection currents exist in containers which push particles up through the center and pull them down the sides. Though Brazil nuts get pushed up by convection, there isn't enough wiggling room for them to be dragged back down around the edges.

4) Nuts of certain mass-to-diameter ratios condense together and sink.

No one can figure out to what extent each explanation plays a part, and so no very successful simulations can be made. It's a difficult problem but a surprisingly important one. Manufacturers of all kinds of inhomogeneous materials (mixed nuts included), as well as pharmacologists, geologists, astronomers, and many others would benefit from a solid understanding of the effect.

Aside from the applications it also just seems like something we ought to know about, and I think that's the main scientific appeal. Physicists aren't always contemplating the cosmos when they gaze thoughtfully out of windows. They're asking questions about everything... even their endearingly old-fashioned snacks.

No More Colors

Today's post is a quick follow-up on yesterday's fact. There are many philosophically interesting questions associated with color and our perception of it. One question that I contemplate now and again is what it would mean for there to be more colors.

The color wheel is a circle, a cycle, a complete set whose start and end points connect. The colors move seamlessly through ROY G BIV and back to red again. If you imagine centering this color wheel at the origin of an X-Y plane, there would be lines pointing outward from the center in infinite directions, all the way around, and each line would have a color associated with it. There could be no more lines, and no more colors; in physics and math terminology, one could say that the set of all lines (and all colors) "spans the space" of the X-Y plane.

Most light is invisible to us: for example infrared light, ultraviolet, X-rays, gamma rays. Our eyes are only sensitive to a small range of wavelengths, from about 350 nanometers for violet light to 700 nanometers for red. The set of colors (of which there could be no more in my conception) have been coordinated by our brains to exactly cover the visible range. If we could see a broader range of wavelengths, it seems likely that our brains would have simply spread the set of colors out over the broader range. I don't know what it would mean for there to actually be more colors. What do you think?

And if there can't be more colors, why are there the ones that there are? Could there be a totally different set of colors? What are colors?

Feynman discusses color vision and perception in Volume I, Chapters 35 and 36 of his Lectures. (I can't find a PDF of Ch. 36 - if you do, let me know.) Well worth reading.

Seeing True Colors

If you ask just about anyone, they'll tell you that red, blue, and yellow are the primary colors. The reason people give is that red is not blue-ish or yellow-ish, nor is blue red-ish or yellow-ish, or yellow, blue-ish or red-ish. The three form a “triad” on the color wheel, which means they are as far away from each other as they can get. All other colors are blends of those three, and are located in between them on the color wheel.

But if you shift around the wheel and choose another triad to think about, you'll find that it could provide a set of equally valid primary colors according to our definition. Take orange, purple, and green for example: none of the three is similar to the other two. But red, blue, and yellow definitely seem more primary than orange, purple, and green – why?

Well it has to do with the way we see. In our eyes we have three different types of cells that are sensitive to color, called cones. One cone is most receptive to blue light, another to red, and the third, to green - not yellow. See, where light is concerned, green is a better primary than yellow because if you add red and green light you can create a good yellow, but you can't create green very easily from yellow and blue light like you can with paint. The picture to the right makes this clear. So according to our eyes the primary colors are red, blue, and green.

Three types of cones allow us to see a huge variety of colors. The process is similar to the way that three coordinates can specify any point in space. Light that comes into our eyes stimulates each type of cone cell to a different extent, and based on how much each cone is stimulated, our brain can figure out what color the original light was.

For example, imagine you're looking at a flower. If it stimulates both red and blue cone cells in your eyes, then your brain adds those signals together and figures out that the flower must be purple. If the green cone cells are a little bit stimulated as well, then the flower must be a slightly lighter purple than if the green cones weren't. Because, of course, white light is made up of all the colors.

Since our light cones are centered on green, red, and blue, these are quite simply the easiest colors to look at. Our brains don't need to do any calculating to come to terms with them, for they each only stimulate a single light cone. This is why they feel primary. The reason why we say yellow, though, and not green, is because in all practical purposes such as art making, yellow forms the third color in the triad with red and blue.

Like all matters in biology, there are variants to this story of color vision. People who are colorblind only have two fully functional light cones. Consequently, they can't properly distinguish between colors that stimulate the two working cones equally, but would have stimulated the malfunctioning cone to different extents.

On the other end of the spectrum, it is speculated that there are some human females who are tetrachromats: they possess four types of cones. The newly-evolved fourth cone is sensitive to a different shade of red light than the red cone we all have. This additional sensitivity makes these women better able to distinguish between similar colors. If you think you're more sensitive to color, then you might have a fourth cone. You lucky dog, you!

The End of the Line

Our cells are constantly replacing themselves, but they cannot do so forever. Cells of each type are alloted only a certain number of replications before they can divide and conquer no more. This so-called Hayflick limit places an upper bound on our longevity.

How does mortality set in on the cellular level? Well, attached to the end of DNA are segments called telomeres. Each time a cell replicates its DNA in order to divide, a piece of telomere gets chopped off and discarded. Every generation of cells has a shorter telomere segment than the one before, and eventually, when all the telomeres are gone, no more divisions are possible for that particular cell line.

Lets just say it's like the opposite of the punch card at your favorite sandwich shop.

There is one particular type of cell, though, which has figured out a way to shed this mortal coil, and the result isn't pretty. Cancer cells contain an enzyme that can build telomeres. Every time cancer cells replicate, a piece of telomere gets rigged up by the enzyme and tacked on the end of the new strand of DNA. This enables cancer cells to replicate over and over indefinitely.

The most famous line of immortal cancer cells have recently been further immortalized by the bestselling book The Immortal Life of Henrietta Lacks. "HeLa cells" are particularly aggressive self-replicators that originated in a fatal tumor belonging to Mrs. Lacks in the 1960s. Since that time, they have become the cells most commonly used in biomedical research. There are freezers full of HeLa cells in labs all over the world.

How many cells are we talkin'? If all the cells that have ever been cultured from Mrs. Lacks's original cell sample could be piled onto a scale, they would weigh more than 100 Empire State Buildings!

So I suppose the Hayflick limit is a good thing. As much as I'd like to live forever, I'm glad there aren't skyscraping stacks of ancient people piled up all over the planet.

Beautiful Number

Those most attuned to aesthetics, such as architects and artists, have given preference to a certain proportion in their designs since ancient times. They tend to create rectangles in which the ratio of the length to the width is about 1.6 to 1. Indeed when asked to choose a favorite rectangle from among an array of options, there is evidence that most people feel an inclination toward that particular shapeliness as well.

What makes the golden rectangle more beautiful than the others? How could a rectangle - so plain, so stark - be "beautiful" at all? Such an aesthetic preference may seem irrational, but in fact it is anything but that. Quite to the contrary, the so-called "golden ratio," approximately equal to 1.61803.., is dictated in the language of logic itself. When our searching eyes settle upon the golden rectangle as our favorite, it is the math underlying its proportions that our brains find beautiful.

The golden ratio arises from what is known as the Fibonacci sequence. In this set of numbers, adding each number to the number before it gives the next number in the sequence. As the numbers grow bigger and bigger, the ratio of each number to the number before gets closer and closer to 1.61803.. the golden ratio.

The ratio that defines an iterative progression as simple as the Fibonacci sequence shouldn't surprise anyone by appearing all over the natural world - and yet it never fails to do so. The graphic art film below gives a taste of the way the golden ratio, Fibonacci sequence, and other mathematical elements serve as blueprints for the construction of nature. It is a truly wonderful video.

As well as shells, flowers, symmetric faces, and other things we find most beautiful, how amazing that even our sense of beauty itself may be tied to the mathematics of the golden ratio!

Oil Eaters

Paul Stamets thinks that mushrooms can save the world, and he does a fair job making the case in the following video. Specifically in minutes 8:00 through 9:40, Stamets demonstrates that land which is saturated with diesel, oil, and petroleum waste can be utterly rejuvenated by fungi.

As Stamets explains, the part of a fungus called mycelium, which permeates the soil as a branching network of filaments, is able to break down hydrocarbons in oil and uses the biproducts to grow mushrooms. These then serve as a gateway for the development of flourishing ecosystems.

In light of the current oil spill disaster in the Gulf, the transformative power of fungi is no niche subject, but rather a valuable and possibly highly consequential discovery.

Yardsticks and Spacetime

Possibly Einstein's main contribution to physics was his realization that measurements of space and time are not absolute; they depend on who's doing the measuring.

Imagine two lightbulbs flashing. You see the flashes alternating in time, and spaced a mile apart. Meanwhile your friend who is zooming by on a spaceship sees the lights flashing simultaneously, and thinks they are closer together than a mile. Neither you nor your friend are wrong in your measurements. The difference comes down to the speed of your friend's spaceship.

This idea lies at the heart of Einstein's theory of special relativity, and it has completely changed the way we understand the Universe. We used to think of space and time as objective, constant, rigid things. Now we know that there is interplay and give-and-take between them, and that together they make up a single entity known as spacetime.

If you are moving through spacetime at an extremely high speed - some significant percentage of the speed of light - then the length of objects in your direction of travel get contracted (compared to measurements made by someone who isn't moving). For example, if you're zooming along a football field, holding out a yardstick, then you'll measure the length of the field to be much less than 100 yards. And again, it's not that you're wrong. The length of the football field really is shorter than regulation size in your frame of reference.

But if you could somehow extend your yardstick out sideways, the width that you would measure for the football field would be the same as if you were at rest. Length is only contracted in your direction of travel.

Einstein was a talented employer of such "thought experiments", in which he imagined scenarios (which would be quite difficult to create in reality) and deduced the way events would play out in them. As long as you don't make any wrong assumptions, you can accept the implications or results of thought experiments to be like those of real experiments. Here is a thought experiment having to do with what I've told you about length contraction which illustrates the curvature of spacetime.

Imagine an enormous circular disc sitting in space. "Euclidean geometry", which describes flat surfaces, tells us that the ratio of any circle's circumference to its diameter is exactly pi. You and your friend walk around and across the disc, measuring its circumference and diameter with a yardstick, and you confirm that this is true.

Now, imagine that the disc is spinning at a constant speed. The very center of the disc will be stationary. The outer edge is always accelerating in toward the center, always changing direction such that it moves around in a circle. This is what is meant by centripetal acceleration. It is an equivalent motion to the Moon orbiting the Earth, or any object orbiting in a gravitational field.

Imagine you are sitting at the stationary center of the disc, and your friend sits on the edge holding the yardstick. Because of special relativity, when you look out at your friend zooming around in circles, the yardstick looks contracted - much shorter than a yard. You see more of the yardsticks fitting into the disc's circumference, so you measure the circumference of the circle to be bigger than before, when the disc was at rest.

Now your friend extends the yardstick inward toward you to measure the disc's diameter. Remember - length doesn't get contracted in that direction since your friend isn't moving inward. The value you and your friend measure for the diameter is thus the same as it was before.

Clearly, then, the ratio of your new measurement of the circumference of the disc to its diameter won't be pi at all - it will be some greater value. It is as if the surface of the spinning disc is now curved!

In his wonderful book Relativity: The Special and the General Theory, A Clear Explanation that Anyone Can Understand, Einstein concluded from this thought experiment: "This proves that the propositions of Euclidean geometry cannot hold exactly on the rotating disc, nor in general in a gravitational field."

Massive objects create gravitational fields, which cause objects to accelerate. They do this, he realized, by curving spacetime itself.

Objects of Affection

Love knows no bounds. The best proof of this that I've ever heard comes in the form of a rare condition called objectum sexuality. Individuals who identify as objectum-sexual (OS) feel intense love, attraction, and commitment to inanimate objects - and they believe that their feelings are reciprocated.

The objectum-sexual community includes two-time world archery champion Erika Eiffel, who married the Eiffel Tower in 2007 and has become somewhat of a spokesperson for the 40-member worldwide community. She is surprisingly well-spoken, in fact, and as one journalist noted, "appears extraordinarily ordinary."

Another German objectum-sexual woman has had a 30-year marriage to the Berlin Wall that has obviously outlasted its felling. Relationships with a garden fence, an amusement park ride, and a sword are other famous cases of this unusual brand of sexuality.

Most OS individuals are women; they are more likely than not to have Asperger's syndrome. Though their condition is speculated to be linked to past sexual abuse or abandonment, most objectum-sexuals insist they are happy with the form of love they have discovered. And who's to judge?

You'll want to watch this video, which is fascinating (but may make you feel uncomfortable):

Clips from documentary called Married to the Eiffel Tower

United We Stand

Since the 12th century, the aristocratic Borromeo family of Northern Italy has used this symbol as its coat of arms. If you study it carefully, you'll see that cutting any one of the rings would cause all three to come apart. Now known as the Borromean rings, they stand for strength in unity.

As well as adorning marble vaults in Florence, Borromean rings of a kind can also be found in a rather different place: inside atoms. Certain gatherings of protons and neutrons which don't coexist in the usual form, all packed together in the nucleus, are stable in an unexpected arrangement known as Borromean halo nuclei.

In such atoms, most of the neutrons and the protons are packed together in a traditional nuclear core. But outside the core, spaced far away from it, hover two extra neutrons.

The nuclear core and the two "halo neutrons" all depend on each other for stability. If any of the three pieces were to be displaced or removed, the whole structure would break apart.

This strange configuration exists for a heavy form of Lithium, which has 3 protons and 6 neutrons in the core and 2 halo neutrons, and also for a form of Carbon with 6 protons, 14 core neutrons, and of course 2 halos.

There are many questions to be asked about these atoms, not the least of them being: why are they stable? The halo neutrons are spaced far enough from the core (~6 femtometers) as to be beyond the range of the strong nuclear force. This is the force that binds particles together in the nucleus under normal circumstances. But if the halo neutrons don't feel the effects of this force where they are, then what is binding them to the core at all?

Only quantum mechanics explains it. The interdependencies of the particles in this Borromean state are so complicated that physicists are not able to model them exactly, but quantum mechanical calculations have yielded approximate results.

The idea of three pieces all being crucial to the stability of a structure, whether they are interlocked Borromean rings or the particles of a surprising type of atom, is a most familiar one. It calls to mind some of our oldest colloquialisms. (Strength comes in numbers; the whole is greater than the sum of the parts; united we stand, divided we fall.)

Musical Scale

Why do we understand what it means for a statue to be 10 feet tall, while that same height described as 0.002 miles means nothing? Why is a distance of 10 miles understandable but not the equivalent 52,800 feet?

Quite simply, a unit of measurement must be reasonably close to the scale of the object being measured. A unit is like a frame of reference. You probably have a good idea of the length of a foot (I think of a wooden ruler every time), so by using that as a reference you can easily imagine 10 such rulers stacked end to end. But it is difficult to clearly imagine a huge number of them, or a very small fraction of one.

As with distance, so it is with sound. Our ears understand speech, or the tick-tock of a clock, or music because their patterns exist on the same temporal scale as our own, defined by our heartbeats. If musical beats were many times slower or many times faster than our heartbeat, such that heartbeats were inappropriate units of measure of the music, our ears would lose their grasp of the patterns. And, I suppose, the music would not be music at all.

Or would it be? To explore this question, artist Leif Inge created a recording called "9 Beet Stretch" that is Beethoven's 9th Symphony stretched out to a duration of 24 hours. Each second of music played at a normal speed lasts 16 seconds in his version. The piece was played in 2004 in San Francisco at a day-long event, and has since been streamed continuously at the website linked to below. Please check it out. Though the melody is stretched beyond recognition, the music remains beautiful.

9 Beet Stretch

143 (I Love You)

The times they are really, really a-changin'. Not only do kids these days not know what the previous sentence refers to, they don't even care. They're 2BZ TXTNG.

This year's National Texting Champion was 15-year-old Iowan Kate Moore. Her knowledge of text message acronyms, ability to text blindfolded, and most importantly, unbelievable speed won her the title and $50,000 prize.

There is little mystery to her success: Moore said she sends around 500 text messages a day. In 16 waking hours that comes out to a text sent every 2 minutes. Every 2 minutes, all day long, in school and out!

Ok, ok, so Moore isn't typical - she's their champion. Surely the average number of text messages teens send per day is some far saner value... but no, not really. It's 80. That's a text every 20 daytime minutes. Think about an hour-long class period in school: the average student is sending and receiving altogether six texts during that time.

To avoid carpal tunnel syndrome and (worse still) the confiscation of phones by teachers, brevity is key. Texting has developed its own pidgin language of sorts, known as txtese, made up of phonetics, shorthand, and acronyms that are more familiar to some young people than grammatical English.

Fortunately the anxiety and fear for the future that I feel when I think about teenagers texting constantly, as well as playing video games, chatting online, and watching an average of 5 hours of tv each day, has its own text message acronym: TARFU (things are really f***ed up).

Which leads me to the contemplation: BHIMBGO (bloody hell, I must be getting old).

Temporal Editing

Our brains keep two different measures of duration: one that corresponds to the actual passage of time, and another, "tidied up" version of the first, which gets delivered to our conscious minds like a debriefing to the President.

An example of this process in action is the following:

Say the wiring in your room is such that there is a 200 millisecond delay between the moment you flip the light switch and the moment the light actually comes on. After a while, your brain recognizes the pattern and edits out the delay. From then on, even though your subconscious brain still registers the 200 millisecond delay, you perceive the lights coming on instantaneously at the flip of the switch.

Then you move houses. In your new room, the real-time delay between switch-flipping and light-on is only 100 milliseconds. But your subconscious brain is still stuck in the old editing mode where it cuts 200 milliseconds off the time you think it takes for the light to come on. So it seems like the light comes on 100 milliseconds before you flip the switch!

The confusion this causes in your brain leads you to quickly recalibrate with the new pattern. But until then you get to time travel in a small way! I'd be interested to hear if anyone has actually experienced this phenomenon.

God, It's Happening Again

In Going Rogue, Sarah Palin discusses why she never went in for evolution, rogue or otherwise. Palin "didn't believe in the theory that human beings - thinking, loving beings - originated from fish that sprouted legs and crawled out of the sea." I guess it is hard to believe that fish would have done such a crazy thing... except for the fact that they're at it again.

According to a February Gallup poll, only 39% of Americans believe in the theory of evolution. And yet so many of them watch Youtube!

"Fact"

You've probably heard this meme: We eat an average of eight spiders a year in our sleep. There may have been a time when a younger, more gullible version of yourself believed that statistic, and if you haven't thought about it since, it may still feel true (because you thought it was true last time you thought about it). But give it a moment's consideration using your adult brain. Yep, it's ridiculous.

How in the world could it be proven that every month or two a spider crawls into each of our mouths and gets swallowed? Why would they go for our mouths, knowing what all creatures know about mouths much larger than themselves? Do we always eat them when they crawl in our mouths or are there ten spit-outs for every one gulp? No, there has never been a study on the nighttime ingestion of spiders. Erase that latent childhood belief from your brain once and for all.

Why, then, is the Internet simply swarming with references to the eight-spider fact? According to Snopes.com, a myth debunking website, and according to the millions of websites that now quote Snopes on the matter:

This "statistic" was invented as an example of the absurd things people will believe simply because they come across them on the internet. In a 1993 PC Professional article, columnist Lisa Holst wrote about the ubiquitous lists of "facts" that were circulating via email and how readily they were accepted as truth by gullible recipients. To demonstrate her point, Holst [made up] her own list of equally ridiculous "facts," among which was the statistic ... about the average person's swallowing eight spiders a year ... In a delicious irony, Holst's propagation of this false "fact" has spurred it into becoming one of the most widely-circulated bits of misinformation to be found on the Internet.

Many people have heard about this debunking, and one could say it's the new meme on the subject of spider ingestion. Since I started this blog, several people have told me the story. BUT THE DELICIOUS IRONY CONTINUES. It's all a lie. PC Professional magazine doesn't exist! Lisa Holst doesn't exist! No such investigation of chain mail gullibility was done in 1993. And there's no rhyme or reason as to why Snopes.com says what it says.

In summary, the original midnight spider snack "fact" is not a fact at all, and the widely-referenced explanation of how we know it's not a fact is also not a fact. For God's sake don't believe everything you read.

Not even here (I write reluctantly).

Dark Energy: What Facts We Have

The other day I found myself coffee-shopping next to cosmologist Saul Perlmutter. As I blogged light-heartedly, he hypothesized about the nature of dark energy just a few feet away. I have no idea what his latest speculations on the subject might be (and probably wouldn't understand them anyway), but here are the basics of what we know about dark energy, and how we know it.

The Universe is expanding. What's more, it's expanding faster and faster all the time. Perlmutter and others figured this out ten years ago by looking at light coming from stars exploding in the distance (called "supernovae").

Loosely speaking, as light travels toward us through expanding space, it gets stretched. This causes it to become 'redshifted', or redder in color. Light coming from supernovae explosions that are far away is redshifted more than light from closer ones, since the former has traveled a greater distance through the expanding Universe, and for a longer time.

However, light from nearer supernovae is disproportionately redshifted; it has undergone more than its fair share of stretching. Since this light left its source more recently, this implies that the Universe is now expanding faster than it was long ago. In other words, the expansion of the Universe must be accelerating.

The supernova data was corroborated by other evidence, so that we now know the Universe is definitely accelerating. All the stars, galaxies, and galaxy clusters are moving faster and faster apart. But why? If gravity alone were acting between the matter in the Universe, we wouldn't expect expansion to speed up, since gravity pulls massive objects toward each other. Apparently there is another effect in place. Something exists that is driving space (and the matter within it) apart.

This is the something we call "dark energy". We don't know what it is, only how it influences the things we can see. From what we can tell, dark energy permeates all space and has a uniform density everywhere. It has negative pressure, which causes space to expand away from it. And when space expands, growing larger in volume, more dark energy emerges to occupy the enlarged space. And the presence of more dark energy drives space apart even more.

Based on the observed rate of expansion, we know that the sum of all the dark energy inherently built into space must make up 74% of the total energy in the Universe. An almost equally mysterious material called dark matter makes up another 22%, and visible matter - everything we can actually see, all that we've ever known to exist - composes only 4% of the total.