Archive for the ‘Chemistry’ Category

the-universe-in-100-key-discoveries-by-giles-sparrowThe Universe in 100 Key Discoveries, Giles Sparrow (Quercus 2012)

Possibly the best book I’ve ever read on astronomy: text and images complement each other perfectly. Even the solidness of the book was right. It’s a heavy book about heavy ideas, from the beginning of the universe to its possible endings, with everything astronomical in between.

And everything is astronomical, if it’s looked at right. The elements vital for life were cooked in stars before being blasted out by supernovae. We are star-stuff that has the unique privilege – so far as we know – of being able to understand stars.

Or trying to. This book was first published in 2012, so it’s inevitably out of date, but many of the mysteries it describes are still there. And when mysteries are solved, they sometimes create new ones. Even the behaviour and composition of a celestial body as close as the Moon is still impossible for us to explain. But sometimes it’s easier at a distance: the interior of the earth can harder to study than galaxies millions of light years away, as I pointed out in “Heart of the Mother”.

In every case, however, understanding depends on mathematics. Astronomers have been building models of the heavens with shapes and numbers for millennia, but the models had to wait for two things to really become powerful: first, the invention of the telescope; second, the development of modern chemistry and physics. Whether or not there is life out there, celestial light is full of messages about the composition and movement of the stars and other bodies that generate it.

But visible light is only a small part of the electromagnetic spectrum and modern astronomy probes the universe at wavelengths far above and below it. The more data astronomers can gather, the more they can test the mathematical models they’ve built of the heavens. The best models make the most detailed predictions, inviting their own destruction by ugly facts. But when predictions fail, it sometimes means that the observations are faulty, not the models. Cosmological models predicted much more matter in the universe than we can see. Is the gap accounted for by so-called “dark matter”, which “simply doesn’t interact with light or other electromagnetic radiations at all”? (ch. 98, “Dark Matter”, pg. 396)

Dark matter is a strange concept; so is dark energy. Astronomy may get stranger still, but the cover of this book is a reminder that human beings inhabit two kinds of universe. One is the universe out there: matter and radiation, moons, planets, stars, galaxies, supernovae. The other is the universe in here, behind the eyes, between the ears and above the tongue. The cover of this book offers a vivid contrast between the swirling complexity and colour of a star-field and the sans-serif font of the title and author’s name. But the contrast is ironic too. The stars look complex and the font looks simple, but language is actually far more complex and difficult to understand than stars.

Consciousness may be far more complex still. In the end, is the value of science that it expands consciousness, offering new physical and mental sensations of discovery and understanding? The powerful and beautiful images and ideas in this book could only have been generated by science, because the universe is more inventive than we are. But without consciousness, the universe might as well not exist. Without language, we’d never be able to try and understand it. Then again, the universe seems to have invented language and consciousness too.

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journey-to-the-centre-of-the-earth-by-david-whitehouseJourney to the Centre of the Earth: A Scientific Exploration into the Heart of Our Planet, David Whitehouse (Weidenfeld & Nicolson 2015)

Can you touch anywhere on your body with your right hand? Replying quickly, you might say you can. But what about your right elbow? You can’t touch that with your right hand. Science is like that, because distant things are often easier to study and understand than close things. We have a good understanding of how stars work, for example, but not of how the earth’s magnetic field is generated.

And while we’ve been able to predict solar eclipses for millennia, we still can’t predict earthquakes or volcanic eruptions. Understanding the deep earth is difficult, so there are a lot of mysteries and conjectures in this well-written and compelling book about the interior of our home planet. Scientists have landed probes on Mars, millions of kilometres away, but the “deepest hole ever drilled on earth – the Kola Superdeep borehole in northern Russia” reached only 12,262 metres. That’s a mere pinprick by comparison with the radius of the earth. To get beyond that, scientists have had to study the shockwaves generated by earthquakes. The medium is the message: as the waves pass through or hit different regions and materials, they behave in different ways.

For example, when the Croatian scientist Andrija Mohorovičić (1857-1936) “studied the records from several seismometers” after an earthquake near Zagreb, “he realised that some of the shockwaves […] were being reflected back to the surface from a boundary region between the crust and mantle.” (pg. 82 of the 2016 paperback) The region is now called the Mohorovičić discontinuity. But that discovery was made before the First World War and deep geology hasn’t advanced very much in the intervening century. This book borrows the title of a Jules Verne novel published in 1864. If Verne came back to life, he would be pleased to see that his work is still popular, but he would be disappointed to see that the human race was no nearer reaching the centre of the earth.

Or would he? The American geologist Don Anderson says: “Almost everything known or inferred about the inner core from seismology or indirect inference is controversial.” (pg. 211) Deep geology is a difficult science, but that’s part of what makes it so interesting. Something else that makes it interesting is that the inner earth can visit catastrophes on the outer earth and the film of the life that clings there:

The big question is: can we see mass extinction events on the way up? Some scientists believe that we can by looking for the plumes [i.e., giant plumes of rising magma]. Such a thing is seen in the south-west Pacific near the Fiji Tonga subduction zone. It’s 700 km deep, has a structure consistent with a massive temperature anomaly and may be rising. It could render the earth uninhabitable for humans and it will reach the surface in an estimated 200 million years. (ch. 17, “Plumes”, pg. 146)

Asteroid impact and gamma-ray bursts are not the only catastrophes that threaten the continued existence of the human race. They may not even be the most likely. The film of life on the surface of the earth is fragile and one day it won’t be there any more.

But there’s also life deep inside the earth, living in conditions of extreme pressure, heat and darkness. We still know little about this “deep biosphere” and it may hold some big surprises. The rest of the deep earth almost certainly does. And the deep earth is just the beginning: as Whitehouse describes in chapter 26, there are “Other Worlds, Other Journeys” to come, including the even more extreme conditions at the heart of Jupiter, where the temperature is a “staggering 37,000 degrees C” and the pressure is “over ten times that found at the centre of the Earth.” (pg. 239)

Or so scientists estimate. Will scanners be invented to prove their theories? Will probes ever get there and find out for real? We can hope so. In the meantime, this book is an excellent introduction to the ideas, the pioneers and the modern researchers into mysteries that are right beneath our doorsteps. Whether it’s discussing diamonds, demons or “Double-D-Prime”, Journey to the Centre of the Earth is popular science that’s interesting, entertaining and informative all at once.

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Rocks and Minerals by Ronald Louis BonewitzRocks and Minerals, Ronald Louis Bonewitz (Dorling Kindersley 2012)

When you read a book, you read your own brain. Somehow the chemicals inside your skull turn electrical signals into conscious experience. Colour is one of the most powerful examples: the difference between the red of cinnabar, the yellow of orpiment and the blue of hemimorphite is ultimately a difference in the firing-rate and strength of nerve-signals. But that’s true of the differences between sight and smell, smell and hearing, hearing and touch, and so on. The nerve-signals are essentially the same: it’s the encoding that changes, but the encoding is quantitative, not qualitative. So how do quanta turn into qualia?

This book brings these questions home very strongly, because its images are so powerful. Minerals can be beautiful or ugly, crystalline or formless, dazzling or dull. Yet all those differences, so sharp in the mind, arise from differing arrangements of the same set of subatomic particles. Smooth blue turquoise has the chemical formula CuAl6(PO4)4(OH)8•4H2O; the orange-red crystals of vanadinite have the formula Pb5(VO4)3Cl. Those very different formulas involve different elements, so it’s not surprising that turquoise and vandanite have very different appearances and chemical behaviour.

But all elements are built of three things: protons, neutrons and electrons. On every page of this book you’re just seeing variations on a threme – a theme of three. But “just” isn’t right for the vastness of what’s going on. The differences between minerals are numerical: the three particles are arranged differently and come in different quantities. Of course, there are sub-atomic forces involved too and smaller units at work in the three particles, but the fundaments of matter are far simpler than the shapes, colours and textures that can be produced by mixing those fundaments in varying proportions.

As you’ll see here: variety is the spice of this book. The geologist Ronald Louis Bonewitz discusses basic chemistry, crystallography and collecting techniques, then works his way systematically through the many families of mineral: native elements, sulphides, molybdates, arsenates, and so on, plus organics like coral and amber. Then there’s a shorter section on rocks: igneous, metamorphic and sedimentary, plus meteorites. Each distinct mineral and rock has an individual page with a colour photograph, a formula, a key of its identification features, and a short text discussing its name, chemistry and uses:

Scorodite FeAsO4•2H2O3

A hydrated iron arsenate mineral, scorodite takes its name from the Greek word scorodion, which means “garlic-like” – an allusion to the odour emitted by the arsenic when specimens are heated. Scorodite can vary considerably in colour depending on the light under which it is seen: pale leek green, greyish green, liver brown, pale blue, violet, yellow, pale greyish, or colourless. It may be blue-green in daylight but bluish purple to greyish blue in incandescent light; in transmitted light it may appear colourless to pale shades of green or brown. Crystals are usually dipyramidal, appearing octohedral, and may have a number of modifying faces. They may also be tabular or short prisms. Drusy coatings are common. Scorodite may also be porous and earthy or massive. Scorodite is found in hydrothermal veins, hot spring deposits, and oxidized zones of arsenic-rich ore bodies. Associated minerals may be pharmacosiderite, vivianite (p. 157), adamite (p. 160), and various iron oxides. (“Minerals: Arsenates”, pg. 165)

There’s a lot here to delight the eye, stimulate the mind and twist the tongue, but chemistry always makes me think of consciousness. It’s a fundamental science and it’s been spectacularly successful in both explaining and altering the material world. This book is a triumph of chemistry both as an object and as an exposition.

But chemistry isn’t all-conquering: it’s helpless to explain the mental aspect of the world. My brain is made of the same basic particles as both this book I’m reading and the minerals it’s describing and depicting. But I’m conscious and they’re not. Science has absolutely no idea how to cross the chasm between matter and mind.

This book wasn’t intended to raise that question, but it does for me. And the better it succeeds in its obvious purpose – portraying, describing and explaining matter – the more strongly it knocks on that stubbornly closed metaphysical door.

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30-Second Elements ed by Eric Scerri30-Second Elements: The 50 Most Significant Elements, Each Explained in Half a Minute, ed. Eric Scerri (Icon 2013)

Pythagoras thought the world was governed by whole numbers and their ratios. He was wrong, but you could still call chemistry a Pythagorean subject. The huge difference between, say, the noble gas neon and the alkali metal sodium is actually based on a tiny difference in protons. Neon has ten, sodium has eleven. That’s why the two of them behave so differently. As Hugh Aldersey-Williams says on page 64: “Neon is so inert that it forms no chemical compounds at all.” But Brian Clegg says this of sodium on page 16:

This soft, silver-tinted alkali metal is known for its reactivity. Drop a small piece into water and it will fizz energetically as it converts to sodium hydroxide and hydrogen, giving off plenty of heat.

The atomic weight of an element, or the number of positively charged protons it has, affects the number of negatively charged electrons it has. Electrons and their arrangement determine how an element reacts with itself and with other elements. So one proton extra can make a huge difference: it can tip the balance between one configuration of electrons and another, between the inertness of neon and extreme reactivity of sodium.

And sodium obviously isn’t something you’d want to put in your mouth. Except that it is. Sodium is essential for life and isn’t dangerous when ingested as part of the compound NaCl, a.k.a. sodium chloride, a.k.a. table salt. The other half of the compound, chlorine, is also dangerous in its free state: when breathed in, it “burns away the lining of the lungs, leaving victims drowning the fluid that oozes out” (pg. 54).

Elsewhere, carbon and oxygen are the opposite: benign or essential for life when they exist as free elements, but potentially deadly in combination as CO, carbon monoxide, or CO2, carbon dioxide. Chemistry is a complicated business, but there is an underlying simplicity in the whole numbers that represent sub-atomic particles: protons, electrons and neutrons.

This simplicity is laid out in the periodic table, which was proposed and perfected by the Russian chemist Dmitri Mendeleev (1834-1907) in the nineteenth century. As explained in the introduction to this book, the table arranges elements in columns and elements in the same column share chemical properties. Neon is in the column of noble gases, on the far right, while sodium is in the column of alkali metals, on the far left. An extra proton turns helium into lithium, neon into sodium, argon into potassium, krypton into rubidium, and so on. A small change in atomic weight translates into a huge change in chemical behaviour.

An extra proton also turns platinum into gold and gold into mercury. But the transitions in behaviour aren’t as sharp in the inner columns of the periodic table: all of those elements are metals, even though mercury is liquid at room temperature. It’s also poisonous and when it was used to “treat animal fur in hat-making”, it inspired “the phrase ‘mad as a hatter’ and the character of the Hatter in Lewis Carroll’s 1865 novel Alice’s Adventures in Wonderland” (pg. 90). The double-page elemental biographies discuss culture as well as chemistry and chemists, but they’re all brief and this is a primer, not a proper scientific text.

And one page of each biography is occupied by an image: 30-Second Elements is a book for the internet age and its short attention spans. But the images are colourful and inventive – a glowing skeleton dancing amid seashells for “Calcium”; diamonds surrounding a cut-away earth for “Carbon”; the Statue of Liberty atop coils of tubing for “Copper” – and they capture the spirit of chemistry, both as a subject and as a phenomenon. Chemistry is rich, exuberant and endlessly fascinating. All its big names and big discoverers are here, from Lavoisier, Mendeleev and Humphrey Davy to William Ramsey, Marie Curie and Glenn Seaborg.

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