A Schooner of Science

The physics of pink – why it isn’t in the rainbow

// November 14th, 2011 // 1 Comment » // Science Communication

“Did you know there’s no pink in the rainbow?” my brother asked in the car.

“Yeah, it always used to bug me in playschool. ‘Pink and yellow and purple and green?’ Why couldn’t they just put them in order of wavelength!’ I said. “Or teach the Richard of York gave battle in vain acronym so kids don’t just yell ‘It’s a RAINBOW!’ when they see a bunch of random colours.”

“Do you know why there’s no pink?”

“No…”

“It’s because it doesn’t have a wavelength at all. It’s a non-colour, we should call it minus-green.”

“What are you talking about?” I said, and he put me onto this youtube vid, “there is no pink light,” one-minute physics from New Scientist.

Nifty, but I was still confused after watching it, so I did some digging.

The colours in the rainbow can be called monochromatic colours, or spectral colours. They have a single, dominant wavelength that trigger receptors in our eyes that send a message to the brain. We have red, blue and green receptors called cones… though it’s not quite that neat and tidy.

Light colours mix together differently then paint does. In light, all the colours together make white (and on the flip side, sunlight contains all colours), while no colours, and no light, makes black. Red and green make yellow, green and blue make cyan, and blue and red… wait for it… make magenta, or pink.

We see pink when our eyes register a mixture of red and blue light. However, there’s no wavelength corresponding to pink, because the spectrum of light (or electromagnetic radiation) is more like a long line stretching from really low energy radio waves which carry our favourite TV shows, to microwave, infrared, red …your favourite rainbow acronym… violet… ultraviolet, x-rays etc. There’s no red-pink-violet, only red-orange-yellow-green-cyan-blue-violet.

(I actually found this part of the video confusing. It sounded like we could perceive non-visible electromagnetic radiation as pink, and we can’t. We don’t see pink x-rays or pink radiowaves, and most of us are still blind to UV light. Though if you want to see the world through bee-eyes, you should check out flowers under ultraviolet light. These white flowers show a bullseye pattern, invisible to us, that directs pollinators to the centre.)

Back to the rainbow. Those spectral colours, the ones with wavelengths, are found on a Planckian locus below by following the outside curve. The pink colours are in the middle of the bottom, and are non-monochromatic colours, ones without a wavelength of their own, made by seeing two different colours at once. Hey presto, red and blue (and no green) make pink.

There’s another colour left out of the rainbow club. Where does brown come from? A dark colour, we perceive it when we see low levels of light, with a dominance towards red. It’s a dark, dirty red.

Did I hear you right? McGurk and other illusions

// November 4th, 2011 // 2 Comments » // Science at Home

The other day I was chatting about muddled senses. Do we really see what’s around us, or do we just assume it’s the same as yesterday and fill in the blanks. How do we understand half-uttered mumblings we don’t properly hear, and when we think we’ve understood, have we actually listened to the other person or just heard what we want to hear?

It lead us to talk about some illusions that show how intertwined and untrustworthy our senses can be.

Case one: The McGurk Effect

What you see changes how you hear. Take the sound “ba”. When an audio recording of “ba” is dubbed over a silent video of someone saying “fa” – then “fa” is what you hear.

If the video silently mouths “ga” or “da”, while playing a “ba” audio – it turns into the harder sound “da.”

Close your eyes and the effect stops. Open them and it starts right back up again. No matter how much you try to hear “ba”, the visual information overrides the audio. Check it out.

Try it with your eyes open, then watch it again with them shut. Whaaaaa???

This BBC video has more of an explanation and the ba/fa illusion.

Nice, but what are the applications? Firstly, I should move my mouth more clearly when I talk to people instead of my usual pirate mumble-slur.

Second, if speech recognition software uses video as well, it could possibly become more accurate.

University of Adelaide research week begins

// October 28th, 2011 // No Comments » // Science Communication

Today marks the start of Research Week at the University of Adelaide, so if you’re SA based like me, might be worth heading in for a look.

Monday 5pm there’s a seminar on wind energy that looks good. We’re always spotting turbines when we road-trip to Melbourne.

On my way to Whyalla for a science show earlier this year we stopped in the infamous bodies-in-the-barrels Snow Town. A turbine blade fell off a truck years ago and, damaged, they put it on show in a fenced outdoor spot. They are MASSIVE!!! The bank where the bodies were found, in barrels of acid, so the killers could receive their government payments from what I heard, was all boarded up.

Wednesday evening it’s a toss-up between African Research Safari, where directors of the Joanna Briggs Institute talk about challenges and success stories to evidence-based health research in Africa, and a Meet the Researchers event, with a short introduction from ten world-class researchers and a chance to chat with them over tea and cake. Both sound really good!

Though it’s not super sciencey, I’m keen to go to the History of Emotions workshop on Thursday 12 – 5 (if I can justify taking the afternoon off.) There’s Shakespeare, which I freaking love to be honest, and discussions on how shifting cultures change emotional regimes over time. Sounds difficult to research – is historical evidence different because the emotions are different, or because the writing style and language was different? On the other hand, without the language to describe emotion, can we even experience the emotion… maybe not. And how could we tell? Takes me back to my philosophical Theory of Knowledge days.

Click here for the full event calendar.

Prehistoric kraken lair with fossilised ‘self-portrait’? Probs not.

// October 14th, 2011 // No Comments » // Just for Fun

It would be remiss of me not to write about this wonderful, but rather unlikely story, given its about a subject close to my heart – giant squids.

Within Nevada’s Berlin-Ichthyosaur State Park are nine fossilised remains of ichthyosaurs, marine reptiles that looked a little like dolphins, but much bigger. Nine remains all in one spot! How did they die? Why were they all found in one place? And don’t they resemble, just a little, the suckers of an octopus, a squid or a GIANT KRAKEN!

At least, that’s an idea presented to the annual meeting of the Geological Society of America on Monday. Here’s the press release and the presentation blurb.

According to the blurb, the fossil remains are from a giant cephalopod midden, a collection of bones arranged by a huge prehistoric squid, octopus, or the mythological Kraken. Perhaps this fearsome beast of the sea hunted ichthyosaurs like the epic, iliad-worthy battles of giant squid versus sperm whale. Powerful tentacles curling about the undulating reptilian body, a lover’s embrace turned fatal attraction, tightening, strangling until still and dragging to the depths of the ocean.

The arrangement of the bones resembles suckers because, according to the blurb, they are a particularly grisly self-portrait. An intentional arrangement of the vertebra to resemble the creature’s own suckers. Imagine it – An introspective kraken rising up from the deep and looking deeply at its tentacles with saucer-eyes. Did it want a friend? Was it an homage to the suckers on which its lonely life depended? Was it not a self-portrait, but a picture of a friend, a lover, a child? We simply don’t know.

Granted, these ichthyosaur vertebra do look a lot like suckers, but a self-portrait is a big call.

The media release has received a lot of attention, not all of it good. There’s a rather scathing report from the brilliant fossil-blogger Laelaps and a reply of (sarcastic) support from Deep Sea News.

Unfortunately, cephalopods are soft-bodied and don’t fossiise well, so there’s no evidence of the prehistoric kraken, and certainly none that it created self-portraits. Still, it’s a nice story.

(Just to be clear, I’m not giving this guy a hard time. I think it’s great he has the opportunity to discuss his ideas publicly. It would take some bravery, and I respect that. I wouldn’t agree with a reporting of the presentation as if it were widely accepted fact, though. But even then, I don’t think it’s particularly harmful to readers. That’s my humble opinion, and I love a good giant squid story.)

Crocheting a coral reef

// October 4th, 2011 // 2 Comments » // Science Art

It was my birthday last week, and to celebrate I went to a crochet workshop at the Royal Institution of Australia to whip up an addition to their artistic coral reef.

I was lucky to nab some chunky bright orange yarn and made the piece pictured in about two hours.

It was good times – a glass of wine and nibbles, plenty of wool and spare crochet hooks and a group of thirty or forty people creating a hum of conversation and creativity.

My friends grabbed a spot on the floor (the tables were taken, and I prefer floor-sitting anyway) and started talking. A couple of the group were beginners, and I’m not much better, but they picked it up in about forty minutes.

The hyperbolic shapes, curvacious and wiggly, are made by frequent increases on each row. It’s kind of a funky shape, and it might look good as a scarf or fascinator, even a cuff. What do you think?

The RiAus Adelaide Reef in their downstairs gallery has closed over spring to make room for a new art installation Energy landscapes, a new frontier. It opens again over the holiday period from early December to the end of January.

I saw the exhibition a few months ago and it’s HUGE! A large room is full of pieces, handmade by people in Adelaide. They’ve linked the crochet to environmental problems plaguing the Great Barrier Reef, like coral bleaching.

I’m keen to go to the next workshop, which is on Thursday 17 November 6-8pm. You can register here. It’s free.

The project is a satellite of the worldwide Hyperbolic Crochet Coral Reef project created by Margaret and Christine Wertheim of the Institute For Figuring in Los Angeles.

Tales of the demon core

// September 21st, 2011 // 3 Comments » // Poisons

On August 21, 1945, the demon core claimed its first victim. Harry K. Daghlian, Jr. was at Los Alamos, a secret laboratory in New Mexico where scientists worked feverishly on the equally secret Manhattan Project. To the outside world, at least those with sufficient security clearance, it was known simply by the mailing address – postbox 1663.

This particular night, Harry was working alone in the lab, stacking heavy blocks of tungsten carbide bricks around a core of plutonium. The bricks were to act as a neutron reflector, which would hopefully cause plutonium to reach the critical threshold at a much lower mass.

Criticality was, well, critical to making a nuclear bomb. It was that particular point when moments of nuclear fission supply the energy for more fission. At that point and beyond, fission runs away with itself and becomes self-sustaining, exuding radiation as it goes.

Just as he was about to place the final brick, intent on the delicate construction like a small child building their first block tower, the neutron counters sounded a warning. He froze. The numbers showed that if he added that one last brick, the plutonium would become supercritical. Slowly, heart pounding in his ears, he moved his hand back. As he did, the brick slipped through his fingers, fell, landed right in the center with a thud like a nail in a coffin.

What was it that made him drop that brick? Was it the beads of sweat that coated his hands as he realised what could happen? Was it that infallible fear-fulfillment that sends learning bicyclists directly to the obstacle they want to avoid? Or was it indeed a demon?

Either way, that final brick flipped the system into a critical reaction and radiation began bursting forth.

Harry panicked and tried to knock the brick off. No luck, it was a good four kilos. With a deep, shaky breath and a sour taste in his mouth, he disassembled the bricks as fast as he could until the reaction stopped.

By that time, Harry had received about 510 rem of neutron radiation, resulting from 1016 fissions. Unfortunately he became the first known fatality resulting from a criticality accident, and died less than a month later from acute radiation poisoning.

The demon core smiled.

Nine months later to the day, physicist Louis Slotin was tickling the dragon’s tail. It was an extremely high risk experiment to find the point when a sphere of plutonium, the same one which claimed Harry’s life, would become critical from the position of neutron reflectors – in this case, two half-shells of beryllium. Plutonium was placed inside one half, like a yolk inside an eggshell.

As the top half was raised and lowered, machines measured the activity from the core. Louis was showing seven other scientists how it was done.

“Lift it up and the activity is reduced,” said Louis, demonstrating. His thumb was crooked inside the thumbhole of the beryllium, allowing him to hold it rather like a bowling bowl. “Watch as I carefully lower the beryllium.” He slowly moved it down, down, down. The scintillation counters started to beep faster. Louis had done this almost a dozen times before, and had helped assemble the Trinity core, the first detonated atomic bomb. It never failed to amaze him, but he didn’t particularly like his work with bombs, and was training a replacement, Alvin Graves, to take over while he went back to biophysics.

“If you allow the beryllium spheres to close completely, the plutonium will reach critical mass,” he cautioned, brandishing a flathead screwdriver with his other hand but keeping both eyes on the core. “To get it as close as possible to that point, I have found a simple screwdriver does the job quite well.” He put the screwdriver tip between the beryllium as he lowered his hand further, until only a tiny space separated the two halves.

At that point, the unseen demon flexed. The screwdriver slipped.

The watching scientists later described a blue light and a wave of heat, and Louis tasted something sour in his mouth. Immediately, as if on reflex, he jerked his hand back to break the beryllium sphere and end the reaction. His body, crouched over as it had been during the experiment, had shielded the other scientists from most of the radiation.

At once they all left the building, Louis vomiting as soon as he was outside. He was rushed to hospital, but even numerous blood transfusions couldn’t save him.

Louis had received the equivalent radiation of someone standing one and a half kilometres from an atomic bomb blast and died nine days later in the presence of his parents.

After the accident, all future criticality testing was ‘hands off’ and scientists worked through machines like the Godiva devices.

As for the demon core, it was detonated later that year during Operation Crossroads testing at Bikini Atoll, which remains uninhabited to this day.

Green potatoes are poisonous

// September 9th, 2011 // 1 Comment » // Science at Home

So I was cooking dinner tonight and had a hankering for potato wedges. Unfortunately, in a fit of nonsense I had put my potato in the fruit basket to ripen. Ridiculous. So it had turned greenish.

Now I’m a pretty frugal, food-saving kinda person and hate throwing stuff out, but I had a feeling that this was one of those times. One of those “better safe than sorry” times, so I checked the interwebz and then threw it out.

If you’re ever in a similar quandary, here’s why not to eat green potatoes.

Potatoes make glycoalkaloids, chemicals that protects them from insects and fungi. They are especially fond of these chemicals when they are damaged or growing new plants, when they go green and sprout from their eyes.

One of these chemicals is called solanine, a poison made by deadly nightshide (a member of the same family, Solanaceae, along with tomatoes).

Solanine poisoning resembles gastroenteritis, so vomiting, pooping, and generally upsetting symptoms. The CSIRO says that, seeing as the symptoms are the same, some undiagnosed cases of gastro might be due to green potatoes. (So glad I didn’t eat them.)

I usually keep potatoes in the fridge, which is apparently also bad. At the chilly 2-6 degrees celsius of a fridge, the starch turns quickly into high levels of sugar, causing them to brown quickly during frying. So you’re supposed to keep them in a paper bag in a dark cupboard.

So much dinner-time learning! Oh – and the replacement meal, curried roast vegetable couscous, was delicious.

Photographs from the first day of spring

// September 2nd, 2011 // 1 Comment » // Science at Home

Spring has sprung here in South Australia, bees buzz in the blossoming trees and the air is warm and sweetly scented. So I took my camera for a stroll around my neighbourhood and took some pictures to capture the first day of spring.

Wattle – nothing says Australian spring so much as the smell and sight of these fuzzy yellow coated trees. The picture doesn’t do justice to the sound of all the bees collecting nectar and pollen overhead. Try to imagine the buzzing.

Trees which line a street just around the corner from my house. Gorgeous days like this remind me of a line from Moby Dick, Herman Melville, my favourite book:

The warmly cool, clear, ringing, perfumed, overflowing, redundant days, were as crystal goblets of Persian sherbet, heaped up—flaked up, with rose-water snow.

In among some rocks, I noticed a colony of ants going nuts! It was queen day, as I like to call it. When young princess ants fly away to start a colony of its own. There were a few drones, fertile male ants with wings who were smaller than the princesses. It was their nuptial flight.

A worker ant helps a princess prepare for a nuptial flight.

Hen mothers for ducklings, cross-fostering species

// August 25th, 2011 // 1 Comment » // Sex and Reproduction

When I was young and living on a small farm in the Adelaide Hills, we used to raise ducklings under chickens. The hens were more inclined to sit and warm the eggs, and once hatched were better at protecting their young from rats. So we took duck eggs, placed them under brooding hens, and everything was cheery.

Those hens loved them little ducks, at least, they looked after them just as well as they did their own chicks. They’d go out foraging together, chattering away in their different tongues at a handful of scattered grain. But there was one place where their differences became obvious. The pond.

At the first sight of water, the ducklings would be in and swimming, having a great time duck-diving underwater and eating duckweed. Meanwhile, mother hen would be going absolutely spare! You could almost hear the concerned clucks saying “now get out of that water at once! Don’t you know you can’t swim? Oh heavens, what have I done to deserve such unruly children?”

What she’d done, somewhat unintentionally, was to be a cross-foster mother. A species which raises children of another species.

Chicago’s Brookfield Zoo recently raised two clutches of guineafowl chicks with peahen mothers. The parents protected their brood from hawks, and showed them the ropes of living free-range in the zoo – such as how to avoid pedestrians.

From the press release:

“‘Zoogoers may not notice anything unusual between the moms and chicks, but there are definitely differences and several barriers that they needed to overcome, including language and behaviors,’ said Tim Snyder, curator of birds for the Chicago Zoological Society, which manages Brookfield Zoo. ‘The first two weeks were a little precarious because the chicks needed to learn what the peahens’ vocalization meant and adapt to different behaviors that are not instinctual to them.’

“For instance, Guineafowl chicks naturally scatter and hide when frightened or threatened, while peachicks run toward their mother. Additionally, Guineafowl moms and chicks move as a group and help care for each others’ young, which is the opposite of independent peafowl.”

Cross-fostering for conservation helped bring Black Robins from the brink of extinction. In 1980, only five survived in the wild on Little Mangere island in New Zealand, including a just one fertile female called Old Blue.

Each Spring, the first clutch of eggs was raised under a Chatham Island tit, giving Old Blue time to breed twice in the season.

Bit by bit the population has crawled back and is now a relatively comfortable 250 individuals. The fostering program has been used as a model for other endangered bird species.

My picks for National Science Week 2011 (dinosaurs, quizes and citizen science)

// August 16th, 2011 // 2 Comments » // Science Communication

So it’s that time of the year again – National Science Week (which now spreads across the whole month) is already upon us. See what’s on in your area.

Apparently there are dinosaurs in towns across Australia, at least, virtual ones. I haven’t seen them myself, but I’ve seen similar augmented reality exhibitions and its fun technology. If you see one of these yellow symbols, and you own a smartphone, then you can do some phone magic science and hunt for dinosaurs through your phone’s camera. Sah-weeet! I’m going to hunt me some dinosaurs. I’m watching Stand By Me right now, which feels like Jurassic Park for some reason…

If, like me, you enjoy a good quiz night and have left it too late to jump on someones team at the last minute (and have no expertise in history, sport or music – but an embarrassing enthusiasm for biology and chemistry) then this might appeal. The CSIRO have a DIY quiz with questions and answers for download. You can host your own, and ensure an appropriate balance of alcohol, dips and science.

For the past few years, National Science Week have organised a citizen science project. In 2009 it was a National Star Hunt. In 2010 it was a Big Sleep Survey. This year they want to know if you are any good at multitasking. It’s a fair question. I was once a proud multitasker myself, until I read research that showed it was far less efficient than just picking one job and doing it properly. Want to help? Take the test.