A Cultural Backlash

There seems to be a cultural backlash against science. Some of my liberal friends blame science for the evils of neonicotinoids, GMOs, and vaccines. They are wrong, of course. My conservative friends decry science for promoting Darwinism, the Earth’s real age, and critical reasoning. They are wrong, too. So often, it seems, rational thought is trashed in favour of emotion, tradition, or politically motivated goals.

However, it also seems that science is slowly winning the war. Today, there are very few troglodytes advocating for a flat Earth occupying the centre of the universe, even though that had been the religious status quo for over a thousand years. (Although they still exist, as attested in the painful video to your left.) Hard to believe, but as recently as the 1800s, an Irish intellectual named Richard Kirwan believed that all matter consists of just the basic Aristotelian elements.  Fire, said Kirwan, is an element liberated from matter when it’s burnt. He spent years trying to prove the idea, but died as the last scientific phlogistonian on Earth. Aristotle’s basic elements of Earth, Wind, Fire, and Water were replaced by about 100 elemental elements. Sometimes our brains stubbornly resist the wooing of science, but critical examination of nature relentlessly chips away at the thinning veneer of traditional thought.

Science is not always “right”. But that’s the wonderful thing about it, isn’t it? Put a new idea out on the block (along with your neck) and you have the chance to have it cut off or a chance to fly into Oslo to give an acceptance speech. Science is not static. It is alive and constantly changing. Yesterday’s truth about stationary continents became today’s truth about plate tectonics. And one day something new may replace the way that we imagine tectonics works.

Although there is a cultural backlash against science, it might not be so different from the general tendency to resist change of any sort. A staid vested interest group sees little advantage in rejecting the world they built and maintained, even if they see the walls of their towers crumbling. It takes a brave and bright soul to rebel against the frozen inherited truths of former generations.

One scientist who understands this very well is Jason Morgan. It was Morgan who first explained the rigid plates of plate tectonics and described them mathematically by drawing upon Euler’s theorem of rotation of surface fragments upon a sphere. In the 1960s, when his papers were being hailed as the harbinger of the new paradigm, Morgan became world-renowned for his mathematical description of plate motion. A colleague once asked Morgan what he could possibly do about plate tectonics to make an even greater name for himself. “I don’t know. Prove it wrong, I guess.”

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The Billion Year Discovery

All that sparkles is not gold. It could be zircon.

All that sparkles is not gold. It could be zircon.

About a century ago, a college student figured out that the Earth has rocks over a billion years old. Until Arthur Holmes’ experiments at Imperial College in London, geologists could only guess at the age of various rock formations. Geologist knew that Devonian rocks are older than Jurassic, for example, but they did not have any real idea if the age difference was tens or hundreds of millions of years. Fossils of jawless fish  embedded in Devonian layers were definitely more primitive than bipedal Jurassic dinosaurs. And Devonian rocks are buried under younger Jurassic. So, there was never an argument that Devonian was older. But how much older?

Arthur Holmes, 1912

Arthur Holmes, 1912

21-year-old Arthur Holmes came up with the answer. He used the simple fact that the element lead rarely appears in the common zircon mineral, but uranium frequently does. And uranium transforms into lead at a fixed speed. By counting the number of lead atoms in a sample, and comparing that with the amount of uranium, he realized he could figure out the age of the zircon. Before we get into the nuts and bolts of the calculation, let’s follow young Holmes from his home in north England to his lab in London.

From the book, The Mountain Mystery:

Arthur Holmes was born in Gateshead, England, a gloomy and remote coastal town in the northeast, a spare place of windswept barren bogs and heaths.  Reverend John Wesley, the first Methodist, arrived there in a blizzard in 1785, and described it as a pathless waste inhabited mainly by “tinkers, gypsies, pitmen, and quarrymen.”  In bringing his good news to Gateshead, Wesley must have been at least partly successful – Holmes grew up in a Methodist family. Of that, Holmes says he was puzzled, as a child, to read the Earth’s Creation date printed in the family Bible. It appeared at the beginning of the book’s summary of the world’s chronology – 4004 BC – the year Bishop Ussher had calculated. “I was puzzled by the odd ‘4.’ Why not a nice round 4000? And how could anyone know?” Holmes would prove the Earth’s age was in the billions, not thousands, of years. At 17, he escaped dreary Gateshead and studied physics and geology at Imperial College in London. For food, lodging, and class fees, he survived on a scholarship of £5 per month – about $300 today.

Holmes performed the world’s first uranium radiometric dating. The rock he tested was an astounding billion years old. He published his results in 1911, as “The association of lead with uranium in rock-minerals, and its application to the measurement of geologic time.” It was revolutionary. Barely past his teenage years, Holmes created a brilliant geological technique still used a hundred years later.

Until Holmes’s experiments, few guessed the planet might be over a thousand million years old. Nor had they ever had an actual number, a nearly precise value, rather than a vague notion of timelessness. Holmes continued to refine the way radioactive decay revealed deep time. By 1927, he revised his estimate to three billion years. By the early 1940s, Holmes figured the Earth had had a solid crust for about 4.5 billion years. With a minor correction, this is still considered valid. The reason for Holmes’ revisions is related to the way radioactive isotopes were becoming understood and the way measuring techniques and equipment became increasingly accurate.

In the early days, radioactive dating was like using an ancient grandfather’s clock, tinkering to get the time right, knowing it will be somewhat reliable, but never perfectly accurate.  The nuclear clock has been steadily ticking away ever since elements coalesced. Physicists found it works like this: Radioactive materials change with time at a steady, predictable rate. They lose their radio-activity as their unstable bits shed energy and become stable forms of matter. For example, uranium can be dangerously radioactive, emitting cancer-causing rays or exploding in nuclear bombs. Inside the Earth, radiation releases enormous amounts of energy, keeping our planet’s interior hot with energetic material slowly transforming into permanent forms. Once uranium has shed some of its mass as energy and settled into a life of lead, it is stable and non-radioactive. In a rock sample, a comparison of the amount of uranium with the amount of lead yields its age. A specimen with quite a bit of uranium and virtually no lead is young. As it ages, there is more and more lead.

Given enough time, a considerable portion of the unstable uranium ends up as the stable element lead. Physicists cannot predict when any individual atom will spontaneously transform, but a lump of granite has billions of unstable atoms, so scientists predict the percentage of material that will undergo the change each second.

Even though the transformation of any single uranium atom is unpredictable, the average rate is precisely known. Half of the unstable isotope U-235 becomes lead (Pb-207) in 704 million years. In twice the time period, 1,408 million years, three-quarters of the original U-235 is Pb-207. For this particular kind of uranium, geologists simply compare the proportions of lead and uranium. You may wonder how they account for any lead already in the lump of granite when the rock first formed. It is easy – there wasn’t any.

Uranium is sometimes found in the mineral zircon. Zircon is a common mineral, plenty is found in ancient crustal rocks. Pure zircon has one zirconium, one silicon, and four oxygen atoms stitched together in a molecule. When zircon molecules form, uranium frequently sneaks in, replacing the zirconium atom. Then you have a molecule with one uranium, one silicon, and four oxygen atoms. Lead never combines this way during zircon’s formation – there is never a newly formed zircon molecule with a lead atom replacing the zirconium atom. Geologists inspecting zircon minerals in igneous rocks realize every bit of  lead in the mix is there only because in its former life, the lead was uranium, and then radioactively decayed into lead. They can be certain that a bit on zircon with equal amounts U-235 and Pb-207 is 704 million years old.

With this technique, Holmes was able to show that jawless Devonian fish fossils were about 400 million years old while Jurassic dinosaurs were common 150 million years ago. At last, a real number, in years, rather than the former “very old” and “very, very old” that geologists had use before Arthur Holmes gave them the dates.

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The Bright Side of Solar Flares

Northern Lights over Calgary

Northern Lights over Calgary

Electronics destroyed. Skin radiated. Mutations. Cancer. And if the GPS is down, how will anyone find their way home? But there is a bright side to solar flares. And that would be last night’s light show. For those of us in Canada, a bit of spark in the air adds to the atmosphere of the place. Here’s how the Aurora works.

The sun has a lot of weird stuff going on. It occasionally erupts with solar flares that spit out coronal mass ejections. Some times those head directly towards the Earth. This week, according to the Space Weather Prediction Center, a G3 geomagnetic storm resulted when two flares from sunspot AR2158 flung their charged particles our way. A G3 is about midpoint on the mag-storm scale. A “Strong” blast, but not the worst we’ve ever seen. Lucky for us, the Earth’s magnetic field does a pretty fair job of trapping the energy. Our only real problem with such storms are burnt power grids and disrupted satellite radio and navigation equipment. In 1989, a geomagnetic storm knocked out the Hydro-Québec electric grid.  Millions were without power for half a day.

On the lighter side, the aurora, or northern lights, were reportedly brilliant in parts of Canada and the northern states. I have seen the display spectacularly only a few times – once as a child, in Pennsylvania when the whole family stood in the orchard, marveling at “Whatever the hell that is,” as my father called it. Later, as a youngster in northern Saskatchewan, I was driving a truck at 2 in the morning, hauling some equipment across the province, when I realized the sky was on fire. Curtains of red and green and yellow and orange hung there, as if a draper were selling me his wares. The fabric slowly changed shapes, angles, and colours. I am sure I heard the fizzy snapping of the storm – sort of like a poorly connected fluorescent light tube. It was so fascinating that I powered down the truck, stretched out on the hood, and stared at the heavens for a full hour.

The northern lights mean more than a dazzling light show. They mean you should hold on to your stock portfolio. As far back as astronomer William Herschel (1738-1822), the German-born English composer who discovered the planet Uranus, economics, sunspots, and the aurora have been inexplicably and incorrectly linked. Herschel said the price of wheat is correlated to the number of sunspots – the more spots, the higher the price. It may have been a brief correlation at the time, but there is no causative connection. And no justification for the lingering belief that sunspots (which can created northern lights) make people happy. Which make them buy more junk which improves markets which raises stock prices. People believe the most interesting things.

Last night, here in Calgary, we poked our heads out the door every few minutes, hoping the clouds would clear. But alas, no luck. Calgary has lousy stargazing weather. This is a dry part of the world, nearly desert, and we are at 3,000 metres elevation. So, one would expect mostly clear skies. But almost invariably, clouds build each evening, obscuring our view of anything but the undersides of those growing clouds. In the late evening, there was a brief clearing, but not much aurora to report. When I awoke at 4 this morning (geophysicists start their day early), the sky was completely obscured. Time to sell my Celestron shares.

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What’s that Smell?

Bardarbunga, photo in Creative Commons by Peter Hartree

Bardarbunga, photo in P.D. by Peter Hartree

Yesterday’s odoriferous eruption of Iceland’s Bárðarbunga volcano got me thinking about the nasty stuff just below our feet. The volcano has begun gassing smelly poisons and the scent of Iceland’s rotten eggs has been whiffed as far away as Finland. Why are volcanoes so often sulphur-tinged?

Well, sulphur is pretty universal. Astrophysicists figure it is cooked up in the deeper ovens of the larger stars. Or anywhere that temperatures exceed 2 billion degrees and pressure is sufficient to fuse silicon and helium into elemental sulphur. Once formed, expelled, and extruded into nascent solar systems, naturally occurring sulphur seems tame – yellowish and often crystalline. At its most pleasant, it looks like the sample in the picture on this page. If there sulphur-smwas ever an industrial element, sulphur would be it. Almost all the sulphur produced in the world comes to us as a by-product of oil refining and its commercial uses include gun powder, matches, fireworks, insecticides, fungicides, and fertilizer for agribusiness. Sulphur is one of the essential elements of life, both animal and plant – which is why the biggest commercial use for sulphur is in fertilizer.

This stuff is frequently distilled and concentrated by heat, water, and the pressure of blossoming volcanic buds.  Then it is blasted into the atmosphere. Its reeking odor can permeate the cabin of a passing plane. If accompanying volcanic ash doesn’t bring the craft down, inhalation of sulfur dioxide, even at low concentrations, can make most people sick. Or worse.  And when sulfur dioxide joins water, sulphuric acid is formed. Its an acid that can damage aircraft windows, build up sulphate deposits in engines and strip the paint off the once shiny surface of wings. Sounds grim. Earth is not the only place that deals with volcanic sulphur.

Jupiter’s closest Galilean satellite, Io, is the most geologically active object in the solar system. Tidal pressure from its nearby mother planet generates enormous heat. This creates volcanoes known to spew sulphur 500 kilometres above Io’s surface, which is mostly volcanic mountains and plains coated with yellow sulfur and sulfur dioxide frosting. With all that heat and sulphur, Io may be the refuse pile for lost souls.

God's Wrath, by John Martin, 1852

God’s Wrath: Destruction of Sodom and Gomorrah, painted by John Martin, 1852

Brimstone is an old word for sulphur. Means exactly the same thing. You’ve heard of fire and brimstone. Maybe you’ve even attended a weekend morning lecture on the subject. There are places all around our town that offer introductory lessons on the downside of ending up in pits of fire and brimstone. The Torah authors knew how to sometimes describe the foul and frightful. Ever wonder what God’s breath smells like? Not coffee. Isaiah 30:33: “The breath of Jehovah is like a stream of brimstone.” In 1712 BCE, God destroyed Sodom and Gomorrah with fire and brimstone. Probably with his angry morning breath.

Which brings us back to Bardarbunga (sometimes called Bunga-Bunga by geologists in the know). What has Iceland been up to that it has been getting smacked by the personal breath of God? Whatever it is, the Bunga-Bunga eruption within the Holuhraun lava field has been emitting smelly volcanic gases (sulfur dioxide, carbon dioxide and hydrogen sulfide) for weeks. For years. For many centuries, actually. This is just the latest gasp in a very long Icelandic saga.

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Signs of Plate Tectonics on Europa – Ice Plates, that is.

An iced martini - not unlike the surface of Europa

An iced martini – not unlike the surface of Europa

There is a lot to like in this next story. Life may exist on an ice-world that glows red in the light of Jupiter’s torch. This is an interesting idea derived from NASA data that had been sitting on a shelf for ten years. It just took hard work and keen minds to connect some dots, but the idea that Jupiter’s satellite Europa has tectonics transforming its ice-clad surface is important.

Europa has been getting some attention as a potential lively spot in the solar system. Lively in the sense that the remote moon may harbor life. Microbes, not Spocks – but life, nevertheless. Europa has an oxygen-rich atmosphere and a smooth, shiny surface that seems to be ice. Not methane ice or frozen nitrogen, but good, old-fashioned martini-cooling ice. Last December, scientists observed a huge geyser that was spraying water far into the atmosphere. Europa has ice covering seas of water. And the water can be geysered right through the ice. How cool is that?

Scientists have puzzled over Europa’s smoothness. Europa is thought to have the least interesting surface of any (observed) orb in the solar system. It is interesting because it is so uninteresting. Having the smoothest surface means a lack of volcanoes and mountains – if any exist, they are below the ice sheets. But researchers also think that the lack of really old craters from meteor bombardment is also strange. The oldest are perhaps 60 million years in age. What happened to the craters from meteors that hit Europa in the days before Earth’s dinosaurs? Subducted, say geologist Simon Kattenhorn and planetary scientist Louise Prockter. They reported this in Nature Geoscience yesterday.

The two scientists pored through pictures from NASA’s Galileo spacecraft, which orbited Jupiter from 1995 to 2003. Not all of the old photos were sharp, so they concentrated their efforts on an area where some high-resolution imagery existed. Then, in the fashion of earthly tectonics advocates of the 1960s, they slid around jigsaw-puzzle pieces of what they saw. From that, the scientists reconstructed ice sheet movement, mimicking plate tectonics.

Europa's ice-plate system (NASA photo from the Galileo mission)

Europa’s ice-plate system (NASA photo from the Galileo mission)

“We looked at an area about the size of Louisiana,” says Kattenhorn, “and there was a missing piece the size of Massachusetts.” That missing piece is assumed sub- merged under the global ice, taking old meteor craters with it. This would only work if the underlying material – just below the ice – was warm liquid water. There is some evidence of cryolava (partially melted, slushy ice that flows like hot-0-lava) on one side of inferred subduction zones, but not on the other. We see something like this on Earth, where volcanoes appear on one side of a subduction boundary (such as along an island-arc) but not on the other.

Other scientists have noted that Europa has signs of extension with surface patches that seem to widen with time. If the surface is widening, then distal areas must be piling up the excess that is moving away from the spreading center. But, Europa lacks mountains of ice. So, there has been a long standing hunch (since at least way back in 2006) that subduction is taking place on Europa. Kattenhorn and Prockter have possibly identified the visual evidence.

Europa has a smooth bald surface without old craters;
Earth has smooth ocean crust without truly ancient fossils.

Europa has cracks that resemble subduction zones with cryolava on one side;
Earth has trenches with island arc subduction zones with hot lava on the island side.

Europa has a crusty ice surface that appears to change with time.
Earth has plate tectonics.

Does Europa have ice tectonics? Probably. Most geo-biologists point out that plate tectonics played a big role in the evolution of life on Earth. Astro-biologists are suggesting that subduction and accompanying implied convecting warm water may have created a microbe-friendly environment in the seas of Europa by distributing salts and minerals to hungry little organisms.

Europa's geysers with Jupiter watching. (NASA)

Europa’s geysers with Jupiter watching. (NASA)

By the way, you may have been wondering how Europa could have liquid water when it is so far from the sun. Shouldn’t the satellite be an icicle from surface to sea floor? The little world’s heat source seems to be gravitational pressure – tidal forces – caused by Jupiter. The massive planet exerts enormous mechanical energy on Europa. That energy is translated into heat, keeping the water melted.

“We propose that Europa’s ice shell has a brittle, mobile, plate-like system above convecting warmer ice. Hence, Europa may be the only Solar System body other than Earth to exhibit a system of plate tectonics,” Kattenhorn and Prockter wrote in Nature. Now, that’s exciting!

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Sunday, September 7, 2014: Will it be Armageddon Day?

This Sunday, nature is throwing an unexpected surprise our way. Scientists have just discovered that an asteroid the size of a house will narrowly miss striking the Earth. If it should hit us, it would almost certainly spoil your weekend. It is expected to pass closer than some of our communications satellites, but it is not likely to take an earthwards plunge.

Meteor Crater, Arizona

Meteor Crater, Arizona

The Earth has had a long history of attracting over-sized meteors. When the Solar System was young, enormous amounts of rock and debris filled the Earth’s orbit. These materials regularly collided with our planet, heating it red hot, and adding to its mass. Scientists are fairly certain that an early collision with a planetoid created the Moon. Other impacts caused mass extinctions, likely including the demise of the dinosaurs. This photo, which I took in 1999, shows the rather tame Arizona crater that formed from a rock about 3 times larger than the one approaching the Earth today. We are told it released 10 megatonnes of energy.  (Whatever that means – I have trouble visualizing things in terms of detonated nuclear bombs.)

Astronomers are calling it a good-news-bad-news event. Good it will miss striking us; bad that we didn’t see it coming. Until today. Not that we would have sent Bruce Willis and a team of roughnecks from an oil rig to blast the rock apart. It’s just that we would have had more time to consider joining one of the world’s many doomsday religions that are actively seeking converts.

endofworld

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Into Subduction

xkcd's take on subduction

xkcd’s take on subduction

On some level, we are all into subduction. But not many of us apply for the license. If you sometimes follow Randall Munroe’s creative web comic xkcd, then you may have seen this comic. What does it mean? I’d like to drone on philosophically, but I have to admit that I’m not sure what xkcd has in mind with this one. For me, it is funny just because it is unexpected. It is like a photo I used in my book, The Mountain Mystery. The picture shows of the back of guy at an outdoor concert wearing a T-shirt with “STOP PLATE TECTONICS” in big bold letters. You don’t expect geological anarchists at music festivals, nor do you expect the next guy coming into your office to have a subduction license in his hand.

And what of subduction? Does it work like Munroe’s comic suggests? Or is it more like an unlicensed train wreck? (Not that licenses are actually issued for train wrecks.) If you remember your introductory geology courses (or grammar school lessons as plate tectonics is now taught in Grade 3) then you were shown that the Earth has plates that are moved by convection currents in the mantle and if two plates are headed to the same place, there is likely to be a messy collision. The heavier plate will eventually sink – or subduct – below the lighter one and cause quite a lot of damage in the process.

Maybe this is what you actually get with a subduction license.

          Maybe this is what you actually get to do with your subduction license.

The subducting crust bends sharply and plunges deeply into the mantle. It will melt and merge and circulate and . . . well, it’s still all rather fuzzy with a lot of unknowns. How deep does the crustal material actually go; what temperature does it reach; how much do the materials mix; and how long will it take before it re-emerges are among the hotly contested questions. What we do know is that the subduction thing is probably more accurately described by this diagram than the drawing that began this blog entry.

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