Category Archives: Science
Relative dating from sedimentology dates back some 200 years, as beautifully explained here by my friend, field geologist and Anglican priest, Michael Roberts, with illustrations from what he has seen himself, while we have now had absolute radiometric dates for over a century. Index fossils are used only to establish that rocks are the same age, and the way creationists manage to forget this fact is indeed miraculous.
This piece gains added interest because of its first-hand accounts, both of geological exploration, and of attempts to persuade creationists to accept the results.
This incredibly duplicitous meme appeared on my twitter feed today. Fri 13th Jan 2017
Evolution is wrong as it is a circular argument from the age of fossils worked out from evolution
Yes, it is the old chestnut of Young Earthers that the age of rocks is based on a circular argument from evolution. It took me back to 1971 when I made the felicitous mistake of going to L’Abri to sit at the feet of the evangelical guru Francis Schaeffer. I arrived ther all bright-eyed and bushy tailed thinking of all the wondrous things I would learn in the next four weeks. I learnt much but not what I had expected.
On my first morning i was sent to Shaeffer’s son-in-law Udo Middlemann to discuss what I would study. I explained that I was going into the Anglican ministry and had just returned from 3 years working as an…
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I had the pleasure of hearing Abdus Salam give a talk in Oxford, sometime around 1960. I naïvely asked why a neutron would decay into a proton and electron, rather than an antiproton and positron, and he gently explained to me the concept of baryon number, which I would have known about by that point if I had been paying proper attention to his talk. Both prose and neutron have baryon (heavy particle) number +1, while their antiparticles have baryon number -1. They also have lepton (like particle) number 0, which is why the neutron decays into a proton, and electron, and an antineutrino.
The Washington Post recently ran a story about the late Abdus Salam, a physicist who won the Nobel Prize almost 40 years ago. The piece concerns the politics of naming a building at a Pakistani university in honour of a man from a religious minority background. Salam’s family belonged to the Ahmadiyya community – followers of a Muslim faith deemed heretical by Pakistan’s dominant Sunni Muslims. The religion was formally declared ‘non-Islamic’ by the Pakistani government in 1974. Before the new decree, extremists sometimes attacked and burned Ahmadi businesses, mosques and schools; after the decree, members could be imprisoned for their beliefs. In protest and for safety, Dr Salam moved to London.
Salam from Pakistan
Before leaving Pakistan, Salam had been the chief science advisor to Pakistan’s president, had contributed to theoretical and particle physics, was the founding director of the Space Research Commission (SUPARCO), and had…
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Creationists argue that historical science is different from, and more uncertain than, present-day observational science. But their choice of examples shows that they themselves don’t really believe this.
The difference between what young earth creationists like to term “operational” or “observational” science and historical science doesn’t have the sharp distinction they like to project to their audience. I was reminded of this recently when I had an opportunity to hear Tommy Mitchell speak at a local Answers in Genesis conference a few weeks ago. One particular talk was entitled: Jurassic Prank: A Dinosaur Tale. In it Mitchell presents the young-earth case that dinosaurs lived with man as recently as a few thousand years ago. The “tale” of course is that scientists have been telling us that dinosaurs died out millions of years before man existed. You could say the punchline to the entire talk was that the public has been punked with regards to the truth about dinosaurs.
There are many lessons to be learned from this talk but I want to focus on one seemingly simple observation that Mitchell makes. Below is a YouTube version…
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This by my friend the geologist, historian, and Anglican priest Michael Roberts, reminding us that the acceptance and active participation of clergymen and other believers in the emerging sciences of biology and evolution dates back more than three centuries.
If you read many historical studies of Britain in the 19th century, you will read that a major conflict was over science. That claim is overstated. Here is a brief overview.
Geology (Deep Time) and Evolution?
From reading many books on church history, general history or popular science, it is easy conclude that advances in geology in the eighteenth and early nineteenth centuries and then evolution after 1859 had gradually been undermining belief in God as Creator as well as an almost official literal reading of the early part of the book of Genesis. The actuality is rather different.
Genesis 1 from a 1611 copy of the KJV
So often the work of Archbishop James Ussher is cited as the “official” view of the churches. In 1656 he published his Annales Veteris Testamenti (Annals of the Old Testament) which gave the famous date of creation as 4004BC. (Actually, it has…
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Homage to Jack Chick, (April 13, 1924 – October 23, 2016); repost of How to lie about radiometric dating, evolution, and even nuclear physics
Now that he is dead, let us play Jack Chick the compliment of treating his ideas as seriously as we did when he was alive. I am sure he would not have wished otherwise.
And so, in his memory (he died on Sunday) I am reposting my analysis of one of his pieces that I found particularly interesting [update: Americans United for the Separation of Church and State have also reviewed his life and work, here]:
How to lie about radiometric dating, evolution, and even nuclear physics
Have you heard the one about the live snail with a carbon-14 age of 3000 years? Or the lava erupted in 1800 in Hawaii with a potassium-argon age in the millions? It’s all true, true I tell you. But does this signify a major problem with radiometric dating?
I don’t know who first dug up these examples, but they were popularised by the creationist comic-book writer Jack Chick, in a publication called “Big Daddy”. The first page, available here, shows a well-primed creationist student arguing with a singularly ill-informed biology professor. The professor has been leading such a sheltered life that he’s never met these creationist arguments before. And he doesn’t understand anything about evolution or dating of rocks or embryology or indeed anything else. Surprise! the student wins! A skilled cartoonist, Jack Chick manages to squeeze the largest number of fallacies into the smallest number of words. There is a crib sheet at the end of this post, listing all the fallacies I spotted myself; I just reached double figures but there may be more.
Of course, it doesn’t help that the Professor doesn’t know anything about whale ancestors:
Or that the student is allowed to make the most absurd statements unchallenged, on the basis of a video by Kent Hovind:
But there’s more! At the end of page 1, which is also the end of your free sample I’m afraid, the student converts the Professor by pointing out that no one has ever actually seen gluons:
But fear not; an answer is at hand, in the very next frame:
So Jesus must be the force that holds the atomic nucleus together. Convinced by this reasoning, the Professor accepts Jesus, announces that as a result he can no longer teach evolution, and is sacked.
Jack Chick, by the way, has just published another comic book at the age of 92. In it, a bright young man from a good Christian (i.e. creationist) home is seduced by Satan into believing in evolution, and when we last see him is heading straight for damnation. In the words of one of Satan’s many horned helpers, “Joe trusted evolution, not God, and became a jobless party animal.” And a criminal and a drug addict, and covered himself with tattoos, and died and went to hell. Tragic, and so easily avoidable.
I never managed to get to Page 13 of Big Daddy, which is what we really need; link (if it works for you) here. It didn’t work for me, but you’ll find a description of the contents by someone called Honus at talkorigins, and I’ve seen some of the relevant cartoons reproduced elsewhere. So you can either take Honus’s and my word for it, or go online to Chick Publications and buy 25 copies (minimum purchase) of the tract, which I am not about to do.
The really remarkable thing about the tract is that it actually gives the primary literature references to the results that is discussing. And the briefest perusal of this primary literature will show why the papers that Chick refers to, far from undermining radiometric dating, actually reinforce it.
That snail was not 3000 years old, but that really was its apparent radiocarbon age, because it was exchanging calcium carbonate in its shell with mineral calcium carbonate. And that makes all the difference, so you need to take such features of the environment into account.
Many readers will be familiar with the principle of carbon-14 dating. Carbon-14 decays with a half-life of 5730 years. Nonetheless, the fraction of carbon-14 in the atmosphere stays roughly constant (or did before we started adding to it by nuclear weapons testing, and diluting it with carbon dioxide from fossil fuels). That is because the upper atmosphere is bombarded with cosmic rays, which cause nuclear reactions that convert nitrogen-14 (stable) to carbon-14. Mixing distributes this radiocarbon through the atmosphere, where it is taken up by plants and, in due course, animals. As long as you are alive, you are part of the circulating pool of carbon, but as soon as you die, the carbon-14 in your body starts decaying. Of course, cosmic ray intensity is not really constant over a long period, but we can calibrate carbon-14 dates by comparison with carbon in tree rings (dendrochronology). The tree ring correction is small for most purposes, but matters for things like precise dating of Egyptian dynasties.
The point, of course, is that the carbon in the lettuce being fed to the snails is part of the general pool, but the carbon in calcium carbonate minerals is radiochemically dead, having been out of circulation for a long time. What the paper really showed was that the snail exchanges carbonate in its shell with carbonate from dissolved minerals, giving a spurious depletion of radiocarbon in the snail. You will find the story in Science, 1963, p. 637 (paywall, sorry, but summary here).
What about these rocks in Hawaii? Here again the paper is behind a pay wall, but if you follow this link it will take you to the title and abstract, which is all you need. In fact, the title alone is all you need: “Radiogenic helium and argon in ultramafic inclusions from Hawaii”. Inclusions. And in case that’s not clear enough, the abstract tells you that the work is all about the dating of xenoliths. Xeno- foreign, as in xenophobia; lith rock, as in monolith. Look at the paper in more detail, if you can get access to it, and you will find that the excess argon is only found in bubbles of fluid within the rock, that bits of rock that aren’t bubbly don’t show any, and that there is circumstantial evidence that the argon comes from deep within the Earth’s mantle, not radioactive decay in the lava itself.
Anomalies happen all the time in geology. They are, in the original sense of the expression, exceptions that prove the rule; if there were no rule, we would not consider them exceptional. Uranium-lead and potassium-argon dates of rocks usually agree, but not if the rock has been so strongly heated that argon gas can escape. Whole rock dates can be misleading, as in the example of the Hawaiian volcano, if the rock has been contaminated from some source, in this case fluid from the mantle. So far from undermining the method, these anomalies add further information about the sample. In much the same way, radiocarbon dates will be anomalous if some of the carbon comes from inorganic sources, as in the case discussed above, and the anomaly might even be used to tell us something about the specimen’s history and diet.
Now here’s the bit that I really don’t understand. What is going on in Jack Chick’s mind, when he gives us this stuff? I assume that he is an honest person of goodwill, who is doing his best. He really believes that because I and most readers here accept the fact of evolution, we are going to be punished in hell for ever. Being a kindly man, he really doesn’t want that to happen, so he is doing his very best to convince us of the error of our ways.
So why does he do it by pointing us towards papers that say the very opposite of what he says they say? I can only speculate that this is the result of what psychologists call confirmation bias, which leads to interpreting new information, however perversely, in a way that supports what you already think. And when we come to creationism, the motivation for bias is extreme. Remember that we are talking about people who really believe (a) that if you don’t accept salvation through Jesus you are going to go to hell, and (b) that the doctrine of salvation through Jesus only makes sense if the biblical Fall is a historical fact. The papers I’ve mentioned above show that under certain rather special circumstances, radiometric dating will give you the wrong answer unless you take those circumstances into account. Young Earth creationists, knowing that their entire worldview depends on refuting radiometric dating, pounce on these examples as evidence that the method is unreliable. Which of course it is, if you don’t do it right. So what?
All of which gives me uncomfortable pause for two reasons. If creationists are so blinded by confirmation bias, what hope is there of reasoning with them? And if I see my intellectual opponents displaying confirmation bias, completely oblivious to what they are doing, what makes me think that I am any different?
h/t Sensuous Curmudgeon for tip-off about Jack Chick’s latest. Whale ancestors illustrated (Ambulocetus and Pakicetus) copyright JGM Thewissen; may be reproduced for non-commercial educational purposes.
Crib sheet: Definition as obfuscation. Misdefinition of science to exclude all indirect inference (although even Young Earth creationists accept the fact of an Ice Age on geological evidence). Macroevolution, if the word means anything, means major change, and this takes more time than we have been watching. So of course we’ve never seen it. Similar fossils do indeed imply similar ages, but the order of these ages has been known for nearly 200 years on the basis of stratigraphy, and absolute ages established for over 100 years now by radiometric dating. Polystrate fossils were explained in 1868; the explanation is much the same today. New Scientist really did point out in 1997 that it is silly to carry on using Haeckel’s highly questionable drawings, as some still do, when we now have a much more detailed information. But, as explained in Alice Roberts’s Incredible Unlikeliness of Being and many other places, the gill folds on the human embryo really are homologous to the folds on that of a fish. They just develop rather differently, explaining such oddities as the tortuous path of our vagus nerves. As for the whale’s pelvis having “nothing to do with walking on land”, by 1999 we already had extensive series of fossils linking whales to their terrestrial ancestors; there is an excellent review here by one of the scientists involved in Evolution Education and Outreach (free download), and whales evolution also features in an excellent video here . The development of secondary functions (exaptation) is commonplace. Thus mammals’ ear bones are vestigial relics of reptiles’ rear jawbones. Creationists often argue, as here, that natural selection can only remove, and not add. This riddle was solved 120 years ago, with the discovery of mutation. Mutations supply novelty; selection winnows it. Creationists agree in explaining away pre-modern human fossils, such as Lucy and numerous others already known by 1999, as being either apes, or humans. Unfortunately, they can never agree on which is which. And, something that I think believers in particular should find offensive, the theological absurdities of the final frame.
This post originally appeared here in January, at https://paulbraterman.wordpress.com/2016/01/08/how-to-lie-about-radiometric-dating-evolution-and-even-nuclear-physics/
Part 1 of this series, “Atoms Old and New: Atoms in Antiquity” can be read here.
The transition to modern thinking
“It seems probable to me, that God in the beginning formed matter in solid, massy, hard, impenetrable, movable particles… even so very hard, as never to wear or break in pieces; no ordinary power being able to divide what God Himself made one in the first creation.” So wrote Sir Isaac Newton in his 1704 work, Opticks. Apart from the reference to God, there is nothing here that Democritus would have disagreed with. There is, however, very little that the present-day scientist would fully accept. In this and later posts, I discuss how atoms reemerged as fundamental particles, only to be exposed, in their turn, as less than fundamental.
The scientific revolution and the revival of corpuscular theory – 1543–1687
In 1543, on his death-bed, Nicholas Copernicus received a copy of the first edition of his book, On the Revolutions of the Heavenly Bodies, in which he argued that the Sun, not the Earth, was thecentre of what we now call the Solar System. In 1687, Isaac Newton published his Mathematical Principles of Natural Philosophy, commonly known as the “Principia”. With hindsight, we can identify the period between these events as a watershed in the way that educated people in the West thought about the world, and number the political revolutions in America and France, and the economic revolutions in agriculture and industry, among its consequences.
Before this scientific revolution, European thinking about nature still followed that of Aristotle. The Earth lay at the centre of the Universe. Objects on Earth moved according to their nature; light bodies, for instance, containe, air or fire in their makeup, and these had a natural tendency to rise. Earth was corrupt and changeable, while the heavens were perfect and immutable, and the heavenly bodies rode around the centre on spheres within spheres because the sphere was the most perfect shape. By its end, Earth was one of several planets moving round the Sun in elliptical orbits, the movements of objects were the result of forces acting on them, the laws of Nature were the same in the heavens as they were on Earth, and all objects tended to move in straight lines unless some force deflected them from this path. The Universe ran, quite literally, like clockwork. This mechanical world-view was to last in its essentials until the early 20th century, and still remains, for better or worse, what many non-scientists think of as the “scientific” viewpoint.
Left: manuscript where Galileo records his observations of the motion of the moons of Jupiter, dethroning Earth from its special position as centre of celestial motion. Below right, Gallileo demonstrates the telescope to the Doge of Venice, fresco by Bertini. Click to enlarge
In 1611, Galileo turned the newly-invented telescope on the heavens, discovered sunspots, and moons round Jupiter, and realised that the belief in a perfect and unchanging1 celestial realm was no longer sustainable. Earlier, he had studied the motion of falling bodies. In work that he started in 1666, Newton showed how the laws of falling bodies on Earth, and the movement of heavenly bodies in a Copernican solar system, could be combined into a single theory. To use present-day language, the Moon is in free fall around the Earth, pulled towards it by the same force of gravity as a falling apple. This force gets weaker as we move away from Earth, according to the famous inverse square law, which says that if we double the distance, the force falls to a quarter of its value. Then with a certain amount of intellectual effort (involving, for example, the invention of calculus), Newton was able to work out, from the acceleration of falling bodies on Earth, and from the Earth-Moon distance, just how long it should take the Moon to go round the Earth, and came up with the right answer. He was also able to work out just how long it would take satellites at different distances to go through one complete orbit. Of course, at that time, Earth only had one satellite (the Moon), but six were known for the Sun (Mercury, Venus, Earth, Mars, Jupiter, Saturn), and his theory correctly predicted how the length of the year of these different planets would vary with their distance from the Sun (the answer is a 2/3 power law; an eight-fold increase in distance gives a fourfold increase in time). Celestial and terrestrial mechanics were united.
It was around this time that a Dutchman, Anthony van Leeuwenhoek, began an extensive series of microscope studies, using single lens instruments of his own devising. Among the first to observe spermatozoa, he also described bacteria, yeast, the anatomy of the flea, and the stem structure of plants. He communicated his results to the Royal Society in London. Formally established around 1660, under the patronage of Charles II, this was and remains
Image from Arcana Naturae Detecta, 1695, Leeuwenhoek’s collected letters to The Royal Society. Click to enlarge
among the most prestigeful of learned societies. Here they caught the attention of Robert Boyle (of Boyle’s Law for gases). Boyle tried to explain such properties of matter as heat, and the pressure of gases, in terms of the mechanics of small particles, or “corpuscles”, and hoped that the other aspects of matter could be explained in the same kind of way. This was, after all, simply an extension downwards of the mechanical system that Newton had so successfully extended upwards. It is instructive to consider how far this hope was fulfilled. Atoms and molecules are in some ways similar in their behavior to small objects obeying the everyday laws of mechanics, but in others they are very different, and it is these differences that must be invoked if we are to understand the forces involved in the chemical bonding.
Early modern theory – 1780-1840
Between 1780 and 1840, chemistry underwent a revolution, that transformed it into the kind of science that we would recognise today. It is no accident that this was the same period as the beginning of the industrial revolution in Europe. Materials were being mined, and iron and steel produced and worked, on a larger scale than ever before. By the end of the period, mineral fertilisers were already in large scale use to feed the growing population. Demand for machinery led to improvements in engineering, and this in turn made possible improvements in the precision of scientific instruments. Much of the new interest in chemistry grew out of mining, mineralogy, and metallurgy, while improvements in manufacture and glass-blowing led to the precision balance, and to new apparatus for handling gases.
Here I will summarise some of the most important discoveries, as seen from our present point of view, and using today’s language. This means running the risk of creating a misleading impression of smoothness and inevitability. Inevitability, perhaps yes; the world really is what it is, and once certain questions had been asked, it was inevitable that we would eventually find the right answers. Smoothness, no; the very concept of atoms, let alone bonding between atoms, remained controversial in some circles way into the 20th century. Outsiders sometimes criticise scientists for taking their theories too seriously, but more often they are reluctant to take them seriously enough.
Overall, mass is conserved; the mass of the products of a reaction is always the same as the mass of the reactants. This is because atoms are not created or destroyed in a chemical reaction.2 Single substances can be elements or compounds, and the enormous number of known compounds can be formed by assembling together the atoms of a much smaller number of different elements. We owe our distinction between elements and compounds to Lavoisier (“The banker who lost his head“). Boyle had come close a hundred years earlier, but was so taken with the transformations of matter that he rejected the notion that its fundamental constituents were immutable.3
The combustion of carbon (its reaction with oxygen) gives a gas, the same gas as is formed when limestone is heated. But there is no chemical process that gives carbon on its own, or oxygen on its own, by reaction between two other substances. So we regard carbon and oxygen as elements, whereas the gas formed by burning carbon (what we now call carbon dioxide) is a compound of these two elements. The production of this same gas, together with a solid residue, by the heating of limestone, shows that limestone is a compound containing carbon, oxygen, and some other element.4 To us, using today’s knowledge, limestone is calcium carbonate, and decomposes on heating to give carbon dioxide and lime (calcium oxide). In Lavoisier’s time, there was no way of breaking down calcium oxide into simpler substances, so he considered it to be an element.
A short philosophical digression (and every scientist has a working philosophy, whether they realise it or not): Lavoisier could make as much progress as he did because he had introduced an operational definition of an element, referring not to some inner essence but to observationally defined properties. And implicit in this was the principle of fallibilism; conclusions are always in principle revisable in the light of further observation, as the example of calcium oxide shows.
Air is a mixture, and burning means reacting with one of its components, which we call oxygen. Metals in general become heavier when they burn in air. This is because they are removing oxygen from the air, and the weight (more strictly speaking, the mass) of the compound formed is equal to that of the original metal plus the weight of oxygen. (Mass is an amount of matter; weight is the force of gravity acting on that matter. Atoms are weightless when moving freely in outer space, but not massless.)
Different elements combine with different amounts of oxygen; these relative amounts are a matter of experiment. In modern language, when some typical metals (magnesium, aluminium, titanium, none of which were known when Lavoisier was developing his system) react with oxygen, they form oxides with the formulas MgO, Al2O3, TiO2.
About one fifth of the air is oxygen, and if we burn anything in a restricted supply of air, the fire will go out when the oxygen has been used up. Nothing can burn in (or stay alive by breathing) the remaining air. Some materials, like wood and coal, appear to lose weight when they burn, but this is because they are in large measure converted to carbon dioxide and water vapour, which are gases, and we need to take the weight of these gases into account.
It was also shown during this period that the relative amounts of each element in a compound are fixed (Law of Definite Proportions). For instance, water always contains 8 grams of oxygen for each gram of hydrogen. Moreover, when the same elements form more than one different compound, there is always a simple relationship between the amounts in these different compounds (Law of Multiple Proportions). Thus hydrogen peroxide, also a compound of hydrogen and oxygen, contains 16 grams of oxygen for each gram of hydrogen. Similarly, the gas (carbon dioxide to us) formed by burning carbon in an ample supply of oxygen contains carbon and oxygen in the weight ratio 3:8, but when the supply of oxygen is restricted, another gas (carbon monoxide) is formed, in which the ratio is 3:4. Carbon monoxide is intermediate in composition between between carbon and carbon dioxide, but it is not intermediate in its properties. For a start, it is very poisonous; it sticks to the oxygen-carrying molecules in the blood even more strongly than oxygen itself, thus putting them out of action. It is formed when any carbon-containing fuel, not just carbon itself, burns in an inadequate supply of air, That is why car exhaust fumes are poisonous, and why it is so important to make sure that gas-burning appliances are properly vented. It is also one of the components of cigarette smoke, which helps explain why cigarettes cause heart disease and reduce fitness.
Left: Dalton’s table of the elements, with relative weights, based on H = 1. The correct value for oxygen is 16. Dalton’s value is based on an assumed formula HO for water, together with experimental error; likewise for other elements
All these facts can be explained if the elements are combined in molecules that are made out of atoms, the atoms of each element all have the same mass,5 and each compound has a constant composition in terms of its elements. For instance, each molecule of water contains two atoms of hydrogen and one of oxygen (hence the formula H2O); hydrogen peroxide is H2O2; carbon dioxide is CO2; carbon monoxide is CO; and the masses of atoms of hydrogen, oxygen, and carbon are in the ratio 1:16:12. Using these same ratios, we can also explain the relative amounts of the elements in more complicated molecules, such as those present in octane (a component of gasoline), C8H18, and sucrose (table sugar), C12H22O11. Why C8H18 and not C4H9, which would have the same atomic ratio? This can be inferred from the density of the vapour, using Avogadro’s hypothesis (see below).
Thus, by the early 19th century, chemists were in the process of developing consistent sets of relative atomic weights (sometimes known as relative molar masses). However, there was more than one way of doing this. For instance, John Dalton, the first to explain chemical reactions in terms of atoms, thought that water was HO and that the relative weight of hydrogen to oxygen was one to eight. This uncertainty even led some of the most perceptive to question whether atoms were real objects, or merely book-keeping devices to describe the rules of chemical combination.
Evidence from the behavior of gases (to around 1860)
A French chemist, Joseph Gay-Lussac, noticed that the volumes of combining gases and of their gaseous products, were in simple ratios to each other. In 1811, the Italian Count Amadeo Avogadro explained this by a daring hypothesis, that under the same conditions of temperature and pressure equal volumes of gases contain equal numbers of molecules. We now know this to be (very nearly) true, except at high pressures or low temperatures.
Avogadro’s Hypothesis, as we still call it, gives us a way of directly comparing the relative weights of different molecules, and of inferring the relative weights of different atoms. For example, if we compare the weights of a litre of oxygen and a litre of hydrogen at the same temperature and pressure, we find that the oxygen gas weighs sixteen times as much as the hydrogen. (This is not a difficult experiment. All we need to do is to pump the air out of a one litre bulb, weigh it empty, and then re-weigh it full of each of the gases of interest in turn.) But Avogadro tells us that they contain equal number of molecules. It follows that each molecule of oxygen weighs sixteen times as much as each molecule of hydrogen.
One litre of hydrogen will react with one litre of chlorine to give two litres of the gas we call hydrogen chloride. Thus, by Avogadro’s Hypothesis, one molecule of hydrogen will react with one molecule of chlorine to give two molecules of hydrogen chloride. So one molecule of hydrogen chloride contains half a molecule of hydrogen, and half a molecule of chlorine. It follows that the molecules of hydrogen and of chlorine are not fundamental entities, but are capable of being split in two. Making a distinction between atoms and molecules that is obvious to us now but caused great confusion at the time, each molecule of chlorine, must contain (at least) two separate atoms.6 By similar reasoning, since 2 litres of hydrogen react with 1 litre of oxygen to give 2 litres of steam, water must have the familiar formula H2O, and not HO as Dalton had assumed for the sake of simplicity.
Avogadro’s hypothesis was put forward in 1811, but it was not until 1860 or later that his view was generally accepted. Why were chemists so slow to accept his ideas? Probably because they could not fit it into their theories of bonding. We now recognise two main kinds of bonding that hold compounds together – ionic bonding and covalent bonding. Ionic bonding takes place between atoms of very unlike elements, such as sodium and chlorine, and was at least partly understood by the early 19th century, helped by the excellent work of Davy and Faraday in studying the effect of electric currents on dissolved or molten salts. They showed that sodium chloride contained electrically charged particles, and inferred, correctly, that the bonding in sodium chloride involved transfer of electrical charge (we would now say transfer of electrons) from one atom to another. But, as we have seen, Avogadro’s hypothesis implies that many gases, hydrogen and chlorine for instance, each contain two atoms of the same kind per molecule, which raises the question of what holds them together. These are examples of what we now call covalent bonding or electron sharing, a phenomenon not properly understood until the advent of wave mechanics in the 1920s.
Physicists, meanwhile, were developing the kinetic theory of gases, which treats a gas as a collection of molecules flying about at random, bouncing off each other and off the walls of their container. This theory explains the pressure exerted by a gas against the walls of its container in terms of the impact of the gas molecules, and explains temperature as a measure of the disorganised kinetic energy (energy of motion) of the molecules. The theory then considers that this energy is spread out in the most probable (random) way among large numbers of small colliding molecules. It can be shown that molecules of different masses but at the same temperature will then end up on average with the same kinetic energy, and it is this energy that at a fundamental level defines the scale of temperature. This is a statistical theory, where abandoning the attempt to follow any one specific molecule allows us to make predictions about the total assemblage.
The kinetic theory explains the laws (Boyle’s law, Charles’ law) describing how pressure changes with volume and temperature. Avogadro’s hypothesis can also be shown to follow from this treatment. Many other physical properties of gases, such as viscosity (which is what causes air drag) and heat capacity (the amount of heat energy needed to increase temperature), are quantitatively explained by the kinetic theory, and by around 1850 the physicists at least were fully persuaded that molecules and, by implication, atoms, were real material objects.
Structural chemistry, 1870 on
Kinds of isomer. The nature of optical isomers was established by Pasteur. Simple rotamers, such as the pair shownbottom right in diagram, readily interconvert at room temperature, giving an equilibrium mixture. The other kinds shown generally do not
Chemists were on the whole harder to convince than the physicists, but were finally won over by the existence of isomers, chemical substances whose molecules contain the same number of atoms of each element, but are nonetheless different from each other, with different boiling points and chemical reactivity is. This only made sense if the atoms were joined up to each other in different ways in these different substances. So atoms were real, as were molecules, and the bonding between the atoms in a molecule controlled its properties. This is what we still think today.
Einstein and Lucretius The piece of evidence that finally convinced even the most skeptical scientists came from an unexpected direction, from botany. In 1827, a Scottish botanist called Robert Brown had been looking at some grains of pollen suspended in water under the microscope, and noticed that they were bouncing around, although there was no obvious input of energy to make them do so. This effect, which is shown by any small enough particle, is still known as Brownian motion. Brown thought that the motion arose because the pollen grains were alive, but it was later discovered that dye particles moved around in the same way. The source of the motion remained a mystery until Albert Einstein explained it in 1905. (This was the same year that he developed the theory of Special Relativity, and explained the action of light on matter in terms of photons). Any object floating in water is being hit from all sides by the water molecules. For a large object, the number of hits from different directions will average out, just as if you toss an honest coin a large number of different times the ratio of heads to tails will be very close to one. But if you toss a coin a few times only, there is a reasonable chance that heads (or tails) will predominate. and if you have a small enough particle there is a reasonable chance that it will be hit predominantly from one side rather than the other. Pollen grains are small enough to show this effect. But this is only possible if the molecules are real objects whose numbers can fluctuate; if they were just a book-keeping device for a truly continuous Universe, the effects in different directions would always exactly cancel out. And if molecules are real, then so are atoms. It is just as Lucretius said, looking at dust in the air two thousand years earlier:
So think about the particles that can be seen moving to and fro in a sunbeam, for their disordered motions are a sign of underlying invisible movements of matter.
1 In fact (see earlier post), the Arabs had already recognized the variability of the star Algol
2 We cheat. There are, of course, processes (radioactive decay, nuclear fusion) where the number of atoms of each kind is not conserved because one element is transformed into another. We simply decide to call these physical processes, so that our statement remains true by definition. Nonetheless, it is useful, because it is usually pretty obvious whether a process should be called “chemical” or “physical”, on other grounds, such as whether or not it involves the formation of new bonds between atoms.
3 The Architecture of Matter, S. Toulmin and J. Goodfield, Hutchinson, 1962
4 In present-day notation,
C + O2 = CO2 and CaCO3 = CaO + CO2
5 This is not quite true. Most elements are a mixture of atoms of slightly different mass but very similar properties. The relative atomic masses of the elements as they occur in nature are an average of the masses of these chemically identical isotopes
6 So we can write the reactions as H2 + Cl2 = 2HCl and 2H2 + O2 = 2H2O
An earlier version of some of this material appeared in my From Stars to Stalagmites, World Scientific. Leeuwenhoek material via Buffalo Library. Dalton’s table of elements and their symbols via Chemogenesis. Isomers image by Vladsinger via Wikipedia
This post originally appeared on 3 Quarks Daily.
Young Earth Creationism is not just a belief, but proof of allegiance to a very special group, the Real Christians (or, I now fear, Real Jews or Real Muslims). Once a belief assumes this function, rational criticism is counter-effective.
(Of course you and I, dear reader, are not as others are, and would never allow our allegiances to shape our beliefs.)
It baffles many people whether Christian or not why some Christians are Young Earth Creationist, with a belief in a 10,000 year old earth and rejection of evolution. It cannot be denied that Young Earth Creationism has caused bad relationships among Christians, influenced education and results in much mockery from some. A major reason for the friction is that YEC’s claim explicitly or implicitly that the majority of Christians who accept modern science with the vast age of the earth and evolution are at best naughty or heretical Christians.
With YEC making inroads into churches (including the Church of England) and trying to call the shots over education in all parts of the world, it is best to know what they believe and why they do as they go against all scientific teaching and what most churches actually believe.
WHAT YOUNG EARTH CREATIONISM IS;
As YEC attracted so much more heat than…
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Reposted from 3 Quarks Daily:
Michael Gove (remember him?), when England’s Secretary of State for Education, told teachers
Never have I seen so many major errors expressed in so few words. But the wise learn from everyone,  so let us see what we can learn here from Gove.
From the top: Newton’s laws. Gove most probably meant Newton’s Laws of Motion, but he may also have been thinking of Newton’s Law (note singular) of Gravity. It was by combining all four of these that Newton explained the hitherto mysterious phenomena of lunar and planetary motion, and related these to the motion of falling bodies on Earth; an intellectual achievement not equalled until Einstein’s General Theory of Relativity.
In Newton’s physics, the laws of motion are three in number:
1) If no force is acting on it, a body will carry on moving at the same speed in a straight line.
2) If a force is acting on it, the body will undergo acceleration, according to the equation
Force = mass x acceleration
3) Action and reaction are equal and opposite
So what does all this mean? In particular, what do scientists mean by “acceleration”? Acceleration is rate of change of velocity. Velocity is not quite the same thing as speed; it is speed in a particular direction. So the First Law just says that if there’s no force, there’ll be no acceleration, no change in velocity, and the body will carry on moving in the same direction at the same speed. And, very importantly, if a body changes direction, that is a kind of acceleration, even if it keeps on going at the same speed. For example, if something is going round in circles, there must be a force (sometimes, confusingly, called centrifugal force) that keeps it accelerating inwards, and stops it from going straight off at a tangent.
Then what about the heavenly bodies, which travel in curves, pretty close to circles although Kepler’s more accurate measurement had already shown by Newton’s time that the curves are actually ellipses? The moon, for example. The moon goes round the Earth, without flying off at a tangent. So the Earth must be exerting a force on the moon.
And finally, the Third Law. If the Earth is tugging on the moon, then the moon is tugging equally hard on the Earth. We say that the moon goes round the Earth, but it is more accurate to say that Earth and moon both rotate around their common centre of gravity.
All of this describes the motion of single bodies. Thermodynamics, as we shall see, only comes into play when we have very large numbers of separate objects.
The other thing that Gove might have meant is Newton’s Inverse Square Law of gravity, which tells us just how fast gravity decreases with distance. If, for instance, we could move the Earth to twice its present distance from the Sun, the Sun’s gravitational pull on it would drop to a quarter of its present value.
Now here is the really beautiful bit. We can measure (Galileo already had measured) how fast falling bodies here on Earth accelerate under gravity. Knowing how far we are from the centre of the Earth, and how far away the moon is, we can work out from the Inverse Square Law how strong the Earth’s gravity is at that distance, and then, from Newton’s Second Law, how fast the moon ought to be accelerating towards the Earth. And when we do this calculation, we find that this exactly matches the amount of acceleration needed to hold the moon in its orbit going round the Earth once every lunar month. Any decent present-day physics student should be able to do this calculation in minutes. For Newton to do it for the first time involved some rather more impressive intellectual feats, such as clarifying the concepts of force, speed, velocity and acceleration, formulating the laws I’ve referred to, and inventing calculus.
But what about the laws of thermodynamics? These weren’t discovered until the 19th century, the century of the steam engine. People usually talk about the three laws of thermodynamics, although there is actually another one called the Zeroth Law, because people only really noticed they had been assuming it long after they had formulated the others. (This very boring law says that if two things are in thermal equilibrium with a third thing, they must be in thermal equilibrium with each other. Otherwise, we could transform heat into work by making it go round in circles.)
The First Law of Thermodynamics is, simply, the conservation of energy. That’s all kinds of energy added up together, including for example heat energy, light energy, electrical energy, and the “kinetic energy” that things have because they’re moving.  One very important example of the conservation of energy is what happens inside a heat engine, be it an old-fashioned steam engine, an internal combustion engine, or the turbine of a nuclear power station. Here, heat is converted into other forms of energy, such as mechanical or electrical. This is all far beyond anything Newton could have imagined. Newton wrote in terms of force, rather than energy, and he had been dead for over a century before people realized that the different forms of energy include heat.
There are many ways of expressing the Second Law, usually involving rather technical language, but the basic idea is always the same; things tend to get more spread out over time, and won’t get less spread out unless you do some work to make them. (One common formulation is that things tend to get more disordered over time, but I don’t like that one, because I’m not quite sure how you define the amount of disorder, whereas there are exact mathematical methods for describing how spread out things are.)
For example, let a drop of food dye fall into a glass full of water. Wait, and you will see the dye spread through the water. Keep on waiting, and you will never see it separating out again as a separate drop. You can force it to, if you can make a very fine filter that lets the water through while retaining the dye, but it always takes work to do this. To be precise, you would be working against osmotic pressure, something your kidneys are doing all the time as they concentrate your urine.
This sounds a long way from steam engines, but it isn’t. Usable energy (electrical or kinetic, say) is much less spread out than heat energy, and so the Second Law limits how efficiently heat can ever be converted into more useful forms.
The Second Law also involves a radical, and very surprising, departure from Newton’s scheme of things. Newton’s world is timeless. Things happen over time, but you would see the same kinds of things if you ran the video backwards. We can use Newton’s physics to describe the motion of planets, but it could equally well describe these motions if they were all exactly reversed.
Now we have a paradox. Every single event taking place in the dye/water mixture can be described in terms of interactions between particles, and every such interaction can, as in Newton’s physics, be equally well described going forwards or backwards. To use the technical term, each individual interaction is reversible. But the overall process is irreversible; you can’t go back again. You cannot unscramble eggs. Why not?
In the end, it comes down to statistics. There are more ways of being spread out than there are of being restricted. There are more ways of moving dye molecules from high to low concentration regions than there are of moving them back again, simply because there are more dye molecules in the former than there are in the latter. There is an excellent video illustration of this effect, using sheep, by the Princeton-based educator Aatish Bhatia.
The Third Law is more complicated, and was not formulated until the early 20th century. It enables us to compare the spread-out-ness of heat energy in different chemical substances, and hence to predict which way chemical reactions tend to go. We can excuse Gove for not knowing about the Third Law, but the first two, as C. P. Snow pointed out a generation ago, should be part of the furniture of any educated mind.
So if you don’t immediately realize that Newton’s laws and the laws of thermodynamics belong to different stages of technology, the age of sail as opposed to the age of steam, and to different levels of scientific understanding, the individual and macroscopic as opposed to the statistical and submicroscopic, then you don’t know what you’re talking about. Neither the science, nor its social and economic context.
R, a fluyt, typical ocean-going vesselof Newton’s time. Below, L, the Great Western, first trans-Atlantic steamship, designed by Isambard Kingdom Brunel, on its maiden voyage
(Disclosure: I taught Boyle’s Law for over 40 years, and it gets three index entries in my book, From Stars to Stalagmites.)
Bottom line: Boyle’s Law is not basic. It is a secondary consequence of the Kinetic Theory of Gases, which is basic. The difference is enormous, and matters. Anyone who thinks that Boyle’s Law is a principle doesn’t know what a principle is. (So a leading Westminster politician doesn’t know what a principle is? That figures.)
Mathematically, the Law is simply stated, which may be why Mr Gove thinks it is basic: volume is inversely proportional to pressure, which gives you a nice simple equation, as in the graph on the right:
P x V = a constant
that even a Cabinet Minister can understand. But on its own, it is of no educational value whatsoever. It only acquires value if you put it in its context, but this appeal to context implies a perspective on education beyond his comprehension.
Now to what is basic; the fundamental processes that make gases behave as Boyle discovered. His Law states that if you double the pressure on a sample of gas, you will halve the volume. He thought this was because the molecules of gas repel each other, so it takes more pressure to push them closer together, and Newton even put this idea on a mathematical footing, by suggesting an inverse square law for repulsion, rather like his Inverse Square Law for gravitational attraction. They were wrong.
The Law is now explained using the Kinetic Theory of Gases. This describes a gas as shown on the right; as a whole lot of molecules, of such small volume compared to their container that we can think of them as points, each wandering around doing their own thing, and, from time to time, bouncing off the walls. It is the impact of these bounces that gives rise to pressure. If you push the same number of molecules (at the same temperature) into half the volume, each area of wall will get twice as many bounces per second, and so will experience twice the pressure. Pressure x volume remains constant; hence Boyle’s Law.
Actually, Boyle’s Law isn’t even true. Simple kinetic theory neglects the fact that gas molecules attract each other a little, making the pressure less than what the theory tells you it ought to be. And if we compress the gas into a very small volume, we can no longer ignore the volume taken up by the actual molecules themselves.
So what does teaching Boyle’s Law achieve? Firstly, a bit of elementary algebra that gives clear answers, and that can be used to bully students if, as so often happens, they meet it in science before they have been adequately prepared in their maths classes. This, I suspect, is the aspect that Gove finds particularly appealing. Secondly, some rather nice experiments involving balancing weights on top of sealed-off syringes. Thirdly, insight into how to use a mathematical model and, at a more advanced level, how to allow for the fact that real gases do not exactly meet its assumptions. Fourthly, a good example of how the practice of science depends on the technology of the society that produces it. In this case, seventeenth century improvements in glassmaking made it possible to construct tubes of uniform cross-section, which are needed to compare volumes of gas accurately. Fifthly … but that’s enough to be going on with. Further elaboration would, ironically, lead us on to introductory thermodynamics. Ironically, given the interview that started this discussion. The one thing it does not achieve is the inculcation of a fundamental principle.
There are mistakes like thinking that Shakespeare, not Marlowe, wrote Edward II. There are mistakes like thinking that Shakespeare wrote War and Peace. And finally, there are mistakes like thinking that Shakespeare wrote War and Peace, that this is basic to our understanding of literature, and that English teachers need to make sure that their pupils know this. Then Education Secretary Gove’s remarks about science teaching fall into this last category. Such ignorance of basic science (and education) at the highest levels of government is laughable. But it is not funny.
1] Ben Zoma, MishnahChapters of the Fathers, 4a. “Chapters of the Fathers” may also be interpreted to mean “Fundamental Principles”.
2] It is often said that Einstein’s famous equation,
E = mc2
means that we can turn mass into energy. That puts it back to front. The equation is really telling us that energy itself has mass.
3] There are lots of situations (steam condensing to make water, living things growing, or indeed urine becoming more concentrated in the kidney) where a system becomes less spread out, but this change is always accompanied by something in the surrounds, usually heat energy, becoming more spread out to compensate.
Newton as painted by Godfrey Keller, via Wikipedia. Gove image via Daily Telegraph, under headline “Michael Gove’s wife takes a swing at ageing Education Secretary”. Solar system image from NASA. Steam turbine blade Siemens via Wikipedia. Dye diffusing in water from Royal Society of Chemistry. Fluyt imge from Pirate King website. Great Western on maiden voyage, 1938, by unknown artist, via Wikipedia. Boyle’s Law curve from Krishnavedala repllot of Boyle’s own data, via Wikipedia. Kinetic theory image via Chinese University of Hong Kong
The Leave campaign used brilliant iconography; a pampered Old Etonian disguised as an ordinary bloke, either wearing a hard hat or at the wheel of a Labour red London bus carrying a mendacious advertisement, despite the fact that both Labour and London supported Remain. Its more disreputable wing also used emotional linkage between East European immigrants and immigrants from the Muslim world, as in the notorious Daily Mail front page showing Afghans intercepted in a people-smuggling lorry under the headline “We’re from Europe; let us in”.
For decades, Progressives like Lakoff (“Don’t Think of an Elephant”) have been telling us of the importance of framing our arguments. The point has been well taken, unfortunately, not by his intended audience but by their opponents. It is time we woke up.
A comment on the Remain campaign. I am a scientist, a strong Remain supporter, and take some trouble to keep myself reasonably well-informed. Yet I did not know, until I read Wandering Gaia’s post below, that 17 Nobel Prize scientists had come out for Remain. Something is wrong.
And an uneasy comment on how some of my Remain friends have reacted to the vote; insulting those whom you have failed to convince is not necessarily the most constructive response.
There’s been a trend over the past decade in translating forgotten Eastern European plays from the 1930s and 40s, resetting them in a contemporary Britain and staging them to new London audiences. The problem I’ve always found with these adaptations is that the plays – often satires – only really make sense in the context of the time and place for which they were written. Emerging into a relaxed 21st century London after curtainfall, stretches the “it could happen here” premise too far.
The events of of the past week have undone this certainty – have undone me.
As I write, Britain faces a deep economic recession with cuts areas already struggling in the wake of years of austerity policy, including our cherished National Health Service, social care, transport and infrastructure, housing, regeneration for deprived areas, education and environmental services. Food, energy, oil prices are set to rise. Jobs will…
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