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how evolution was proved to be true

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The origin of species is a natural phenomenon

Jean-Baptiste Lamarck

The origin of species is an object of inquiry

Charles Darwin

The origin of species is an object of experimental investigation

Hugo de Vries

(quoted in The Gene: an intimate history, by Siddhartha Mukherjee)

Gregor Mendel

I’ve recently read Siddhartha Mukherjee’s monumental book The Gene: an intimate history, a work of literature as well as science, and I don’t know quite where to start with its explorations and insights, but since, as a teacher to international students some of whom come from Arabic countries, I’m occasionally faced with disbelief regarding the Darwin-Wallace theory of natural selection from random variation (usually in some such form as ‘you don’t really believe we come from monkeys do you?’), I think it might be interesting, and useful for me, to trace the connections, in time and ideas, between that theory and the discovery of genes that the theory essentially led to.

One of the problems for Darwin’s theory, as first set down, was how variations could be fixed in subsequent generations. And of course another problem was – how could a variation occur in the first place? How were traits inherited, whether they varied from the parent or not? As Mukherjee points out, heredity needed to be both regular and irregular for the theory to work.

There were few clues in Darwin’s day about inheritance and mutation. Apart from realising that it must have something to do with reproduction, Darwin himself could only half-heartedly suggest an unoriginal notion of blending inheritance, while also leaning at times towards Lamarckian inheritance of acquired characteristics – which he at other times scoffed at.

Mukherjee argues here that Darwin’s weakness was impracticality: he was no experimenter, though a keen observer. The trouble was that no amount of observation, in Darwin’s day, would uncover genes. Even Mendel was unable to do that, at least not in the modern DNA sense. But in any case Darwin lacked Mendel’s experimental genius. Still, he did his best to develop a hypothesis of inheritance, knowing it was crucial to his overall theory. He called it pangenesis. It involved the idea of ‘gemmules’ inhabiting every cell of an organism’s body and somehow shaping the varieties of organs, tissues, bones and the like, and then specimens of these varied gemmules were collected into the germ cells to produce ‘mixed’ offspring, with gemmules from each partner. Darwin describes it rather vaguely in his book The Variation of Animals and Plants under Domestication, published in 1868:

They [the gemmules] are collected from all parts of the system to constitute the sexual elements, and their development in the next generation forms the new being; but they are likewise capable of transmission in a dormant state to future generations and may then be developed.

Darwin himself admitted his hypothesis to be ‘rash and crude’, and it was effectively demolished by a very smart Scotsman, Fleeming Jenkin, who pointed out that a trait would be diluted away by successive unions with those who didn’t have it (Jenkin gave as an example the trait of whiteness, i.e. having ‘white gemmules’, but a better example would be that of blue eyes). With an intermingling of sexual unions, specific traits would be blended over time into a kind of uniform grey, like paint pigments (think of Blue Mink’s hit song ‘Melting Pot’).

Darwin was aware of and much troubled by Jenkin’s critique, but he (and the scientific world) wasn’t aware that a paper published in 1866 had provided the solution – though he came tantalisingly close to that awareness. The paper, ‘Experiments in Plant Hybridisation’, by Gregor Mendel, reported carefully controlled experiments in the breeding of pea plants. First Mendel isolated ‘true-bred’ plants, noting seven true-bred traits, each of which had two variants (smooth or wrinkled seeds; yellow or green seeds; white or violet coloured flowers; flowers at the tip or at the branches; green or yellow pods; smooth or crumpled pods; tall or short plants). These variants of a particular trait are now known as alleles. 

Next, he began a whole series of painstaking experiments in cross-breeding. He wanted to know what would happen if, say, a green-podded plant was crossed with a yellow-podded one, or if a short plant was crossed with a tall one. Would they blend into an intermediate colour or height, or would one dominate? He was well aware that this was a key question for ‘the history of the evolution of organic forms’, as he put it.

He experimented in this way for some eight years, with thousands of crosses and crosses of crosses, and the more the crosses multiplied, the more clearly he found patterns emerging. The first pattern was clear – there was no blending. With each crossing of true-bred variants, only one variant appeared in the offspring – only tall plants, only round peas and so on. Mendel named them as dominant traits, and the non-appearing ones as recessive. This was already a monumental result, blowing away the blending hypothesis, but as always, the discovery raised as many questions as answers. What had happened to the recessive traits, and why were some traits recessive and others dominant?

Further experimentation revealed that disappeared traits could reappear in toto in further cross-breedings. Mendel had to carefully analyse the relations between different recessive and dominant traits as they were cross-bred in order to construct a mathematical model of the different ‘indivisible, independent particles of information’ and their interactions.

Although Mendel was alert to the importance of his work, he was spectacularly unsuccessful in alerting the biological community to this fact, due partly to his obscurity as a researcher, and partly to the underwhelming style of his landmark paper. Meanwhile others were aware of the centrality of inheritance to Darwin’s evolutionary theory. The German embryologist August Weismann added another nail to the coffin of the ‘gemmule’ hypothesis in 1883, a year after Darwin’s death, by showing that mice with surgically removed tails – thus having their ‘tail gemmules’ removed – never produced tail-less offspring. Weismann presented his own hypothesis, that hereditary information was always and only passed down vertically through the germ-line, that’s to say, through sperm and egg cells. But how could this be so? What was the nature of the information passed down, information that could contain stability and change at the same time?

The Dutch botanist Hugo de Vries, inspired by a meeting with Darwin himself not long before the latter’s death, was possessed by these questions and, though Mendel was completely unknown to him, he too looked for the answer through plant hybridisation, though less systematically and without the good fortune of hitting on true-breeding pea plants as his subjects. However, he gradually became aware of the particulate nature of hereditary information, with these particles (he called them ‘pangenes’, in deference to Darwin’s ‘pangenesis’), passing down information intact through the germ-line. Sperm and egg contributed equally, with no blending. He reported his findings in a paper entitled Hereditary monstrosities in 1897, and continued his work, hoping to develop a more detailed picture of the hereditary process. So imagine his surprise when in 1900 a colleague sent de Vries a paper he’d unearthed, written by ‘a certain Mendel’ from the 1860s, which displayed a clearer understanding of the hereditary process than anyone had so far managed. His response was to rush his own most recent work into press without mentioning Mendel. However, two other botanists, both as it happened working with pea hybrids, also stumbled on Mendel’s work at the same time. Thus, in a three-month period in 1900, three leading botanists wrote papers highly indebted to Mendel after more than three decades of profound silence.

Hugo de Vries

The next step of course, was to move beyond Mendel. De Vries, who soon corrected his unfair treatment of his predecessor, sought to answer the question ‘How do variants arise in the first place?’ He soon found the answer, and another solid proof of Darwin’s natural selection. The ‘random variation’ from which nature selected, according to the theory, could be replaced by a term of de Vries’ coinage, ‘mutation’. The Dutchman had collected many thousands of seeds from a wild primrose patch during his country rambles, which he planted in his garden. He identified some some 800 new variants, many of them strikingly original. These random ‘spontaneous mutants’, he realised, could be combined with natural selection to create the engine of evolution, the variety of all living things. And key to this variety wasn’t the living organisms themselves but their units of inheritance, units which either benefitted or handicapped their offspring under particular conditions of nature.

The era of genetics had begun. The tough-minded English biologist William Bateson became transfixed on reading a later paper of de Vries, citing Mendel, and henceforth became ‘Mendel’s bulldog’. In 1905 he coined the word ‘genetics’ for the study of heredity and variation, and successfully promoted that study at his home base, Cambridge. And just as Darwin’s idea of random variation sparked a search for the source of that variation, the idea of genetics and those particles of information known as ‘genes’ led to a worldwide explosion of research and inquiry into the nature of genes and how they worked – chromosomes, haploid and diploid cells, DNA, RNA, gene expression, genomics, the whole damn thing. We now see natural selection operating everywhere we’re prepared to look, as well as the principles of ‘artificial’ or human selection, in almost all the food we eat, the pets we fondle, and the superbugs we try so desperately to contain or eradicate. But of course there’s so much more to learn….

William Bateson

Written by stewart henderson

June 14, 2017 at 5:42 pm

an intro to chemistry for dummies by dummies

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orbitals – one day we may understand

Jacinta: Well, in ‘researching’ – I have to put it in quotes cause what I do is so shallow it barely counts as research – the last piece, I came across a reference to Philip Ball’s choice of the top ten unsolved mysteries in science, at least chemical science.

Canto: Philip Ball, author of Curiosity…

Jacinta: Among other things. His list was published in Scientific American in 2011, the official ‘Year of Chemistry’ – which passed unnoticed by supposedly scientific moi. The actual article is largely unavailable to the impoverished, but at least I’ve been able to access the list here. So I thought we might have fun discussing it in our quest to self-educate autant que possible before we die.

Canto: Yes I don’t know enough about chemistry to say whether this is a bog-standard list or an eccentric one, but there are no quibbles about the first mystery – the origin of life. But have we already covered that?

Jacinta: Not really. Ball’s mystery number 1, to be exact, is ‘How did life begin?’ – by which he presumably means life as we know it. And, as Jack Szostak puts it, the answer lies with ‘chemistry plus details’. Putting the right chemistry together in the right order under the right conditions, which they’ve managed to do in a ‘small way’ in the lab, synthesising a pyrimidine nucleotide, as noted in our last post.

Canto: Yes it seems to me we’re never going to solve this mystery by somehow stumbling upon the first life on Earth, or even a trace of it. How will we ever know it’s the first? Then again creating different kinds of conditions – gases and pressures and molecular bits and pieces – and mixing and shaking and cooking, that may not solve the mystery either, because we’ll never know if it happened like that, but it might show how life can begin, and that would be pretty awesome, if I may use that word correctly for once.

Jacinta: Usage changes mate, live with it. So what’s Ball’s second mystery?

Canto: ‘How do molecules form?’ Now we’re really getting into basic chemistry.

Jacinta: But isn’t that a known known? Bonding isn’t it? Like O² is an oxygen atom bonding with another to create a more stable configuration… I don’t know.

Canto: Well let’s look into it. What exactly is a chemical bond and why do they form? Molecular oxygen is common and stable, but what about ozone, isn’t that just oxygen in a different molecular form, O³? Yet in different molecular form, oxygen has different qualities. Ozone’s a pungent-smelling gas, whereas standard oxygen’s odourless. So why does it have different molecular forms? Why does it have any molecular form, why doesn’t it just exist as single atoms?

Jacinta: But then you could ask why do atoms exist, and why in different configurations of protons and neutrons, etc? Best to stick to how questions.

Canto: Okay, I’d like to know how, under what conditions, oxygen exists as O³ rather than O².

Jacinta: So we have to go to bonding. This occurs between electrons in the ‘outer shell’ of atoms. In molecular oxygen, O2, the two oxygen atoms form a covalent bond, sharing four electrons, two from each atom. The water and carbon dioxide molecules are also covalently bonded. Covalently bonded molecules are usually in liquid or gas form.

Canto: What causes the atoms to form these bonds though?

Jacinta: There are two other types of bonds, ionic and metallic. As to causes, there are simple and increasingly complex explanations. I’m sure Ball was after the most complex and comprehensive explanation possible, which I believe involves quantum mechanics. For a very introductory explanation to the types of bonds, this website is useful, but this much more complex, albeit brief, explanation of the O2 bond in particular will leave you scratching your head. So I think we should do a sort of explication de texte of this response, which comes from organic chemist David Shobe:

If you mean the molecule O2, that is actually a complicated question.  It is a double bond, but not a typical double bond such as in ethylene, CH2=CH2.  In ethylene, each carbon atom has a sigma orbital and a pi orbital for bonding, and there are 4 electrons available (after forming the C-H bonds), so each bonding orbital (sigma and pi) has 2 electrons, which is optimal for bonding.  Also, since each orbital has a pair of electrons, one gets a singlet ground state: all electrons are in pairs.

In O2, there are 1 sigma orbital and 2 pi orbitals for bonding, but 12 valence electrons.  Four electrons, 2 on each oxygen atom, are in lone pairs, away from the bonding area.  This leaves 8 electrons for 3 bonding orbitals.  Since each orbital can only hold 2 electrons, there are 2 electrons forced into antibonding orbitals.  This is just what it sounds like: these electrons count negatively in determining the type of bond (technical term is bond order), so 2 sigma bonding electrons + 4 pi bonding electrons – 2 pi antibonding electrons, divided by 2 since an orbital holds 2 electrons, equals a bond order of 2: a double bond.

However, there are *two* pi antibonding orbitals with the same energy.  As  a result, one electron goes into each pi antibonding orbital.  This results in a triplet ground state: one in which there are two unpaired electrons.

That may be more answer than you wanted, but it’s what chemists believe.

Canto: Wow, a tough but interesting task. So a very good place to start is the beginning. By double bond, does he mean covalent bond?

Jacinta: Well according to this clearly reliable site, ethylene, aka ethene (C2H4) is the simplest alkene, that is an unsaturated (??)  hydrocarbon with double bonds – covalent bonds – between the carbons. So I think the answer to your question is yes… or no, there are triple covalent bonds too.

Canto: Okay so I’d like to know more about what a covalent bond is, and what valence electrons are, and then we need to know more about orbitals – pi and sigma and maybe others.

Jacinta: Well guess what, the more you dive into molecular bonding, the murkier stuff gets – until you familiarise yourself I suppose. There are different types of orbitals which lead to different types of covalent bonds, single, double and triple. The term ‘covalent’ means joint ownership, sharing, partnering, as we know, of valence. So how to describe valence? With great difficulty.

Canto: Just watched a video that tells me that covalent compounds or molecular compounds only exist between non-metallic elements, whereas ionic compounds are made up of non-metallic and metallic elements, and ionic bonds are quite different from covalent bonds. And presumably metallic bonds join only metallic elements. Don’t know if that helps any.

Jacinta: Well yes it does in that it tells us we really need to start from scratch with basic chemistry before we can get a handle on the molecule problem.

Canto: Okay, time to go back to the Khan academy.

Jacinta: Yes and we’ll do so always bearing in mind that fundamental question about the formation of molecules. So our chemistry lesson begins with elements made up of atoms so tiny that, for example, the width of a human hair, which is essentially carbon, can fit a million of them.

Canto: And the elements are distinguished from each other by their atomic numbers, which is the number of protons in their nuclei. They can have different numbers of neutrons, but for example, carbon must always have six protons.

Jacinta: And neutral-charge carbon will have six electrons buzzing about the nucleus, sort of. They keep close to the nucleus because they’re negatively charged, we don’t know why (or at least I don’t), and so they’re attracted to the positively charged protons in the nucleus.

Canto: More fundamental questions. Why are electrons negatively charged? Why are positively charged particles attracted to negatively charged ones? And if they’re so attracted why don’t electrons just fall into the nucleus and kiss their attractive protons, and live in wedded bliss with them?

Jacinta: Let’s stick to how questions for now. Electrons don’t fall into the nucleus but they can be lost to other atoms, in which case the atom will have a positive charge, having more protons than electrons. So with the losing and the stealing and the sharing of electrons between atoms, elements will have changed properties. Remember oxygen and ozone.

Canto: So it’s interesting that, right from the get-go, we’re looking at that ancient philosophical question of the constituents of matter. And though we now know that atoms aren’t indivisible, they do represent the smallest constituents of any particular element.

Jacinta: But as you know, that smallest constituent gets weird and mathematical and quantum mechanical, with electrons being waves or particles or probability distributions, with the probability of finding them or ‘fixing’ them being higher the closer you get to the nucleus. So this mathematical probability function of an electron is what we call its orbital. Remember that word?

Canto: Right, that’s a beginning, and it gives me an inkling into types of orbitals, such as antibonding orbitals. Continue.

Jacinta: We’ll continue next time. We’ve only just entered the darkness before the dawn.

Written by stewart henderson

May 23, 2017 at 1:27 am

the strange world of the self-described ‘open-minded’ part two

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  • That such a huge number of people could seriously believe that the Moon landings were faked by a NASA conspiracy raises interesting questions – maybe more about how people think than anything about the Moon landings themselves. But still, the most obvious question is the matter of evidence. 

Philip Plait,  from ‘Appalled at Apollo’, Chapter 17 of Bad Astronomy

the shadows of astronauts Dave Scott and Jim Irwin on the Moon during the 1971 Apollo 15 mission - with thanks to NASA, which recently made thousands of Apollo photos available to the public through Flickr

the shadows of astronauts Dave Scott and Jim Irwin on the Moon during the 1971 Apollo 15 mission – with thanks to NASA, which recently made thousands of Apollo photos available to the public through Flickr

So as I wrote in part one of this article, I remember well the day of the first Moon landing. I had just turned 13, and our school, presumably along with most others, was given a half-day off to watch it. At the time I was even more amazed that I was watching the event as it happened on TV, so I’m going to start this post by exploring how this was achieved, though I’m not sure that this was part of the conspiracy theorists’ ‘issues’ about the missions. There’s a good explanation of the 1969 telecast here, but I’ll try to put it in my own words, to get my own head around it.

I also remember being confused at the time, as I watched Armstrong making his painfully slow descent down the small ladder from the lunar module, that he was being recorded doing so, sort of side-on (don’t trust my memory!), as if someone was already there on the Moon’s surface waiting for him. I knew of course that Aldrin was accompanying him, but if Aldrin had descended first, why all this drama about ‘one small step…’? – it seemed a bit anti-climactic. What I didn’t know was that the whole thing had been painstakingly planned, and that the camera recording Armstrong was lowered mechanically, operated by Armstrong himself. Wade Schmaltz gives the low-down on Quora:

The TV camera recording Neil’s first small step was mounted in the LEM [Lunar Excursion Module, aka Lunar Module]. Neil released it from its cocoon by pulling a cable to open a trap door prior to exiting the LEM that first time down the ladder.

Neil Armstrong, touching down on the Moon -an image I'll never forget

Neil Armstrong, touching down on the Moon – an image I’ll never forget


the camera used to capture Neil Armstrong's descent

the camera used to capture Neil Armstrong’s descent

As for the telecast, Australia played a large role. Here my information comes from Space Exploration Stack Exchange, a Q and A site for specialists as well as amateur space flight enthusiasts.

Australia was one of three continents involved in the transmissions, but it was the most essential. Australia had two tracking stations, one near Canberra and the other at the Parkes Radio Observatory west of Sydney. The others were in the Mojave Desert, California, and in Madrid, Spain. The tracking stations in Australia had a direct line on Apollo’s signal. My source quotes directly from NASA:

The 200-foot-diameter radio dish at the Parkes facility managed to withstand freak 70 mph gusts of wind and successfully captured the footage, which was converted and relayed to Houston.


Needless to say, the depictions of Canberra and Sydney aren’t geographically accurate here!

And it really was pretty much ‘as it happened’, the delay being less than a minute. The Moon is only about a light-second away, but there were other small delays in relaying the signal to TV networks for us all to see.

So now to the missions and the hoax conspiracy. But really, I won’t be dealing with the hoax stuff directly, because frankly it’s boring. I want to write about the good stuff. Most of the following comes from the ever-more reliable Wikipedia – available to all!

The ‘space race’ between the Soviet Union and the USA can be dated quite precisely. It began in July 1956, when the USA announced plans to launch a satellite – a craft that would orbit the Earth. Two days later, the Soviet Union announced identical plans, and was able to carry them out a little over a year later. The world was stunned when Sputnik 1 was launched on October 4 1957. Only a month later, Laika the Muscovite street-dog was sent into orbit in Sputnik 2 – a certain-death mission. The USA got its first satellite, Explorer 1, into orbit at the end of January 1958, and later that year the National Aeronautics and Space Administraion (NASA) was established under Eisenhower to encourage peaceful civilian developments in space science and technology. However the Soviet Union retained the initiative, launching its Luna program in late 1958, with the specific purpose of studying the Moon. The whole program, which lasted until 1976, cost some $4.5 billion and its many failures were, unsurprisingly, shrouded in secrecy. The first three Luna rockets, intended to land, or crash, on the Moon’s surface, failed on launch, and the fourth, later known as Luna 1, was given the wrong trajectory and sailed past the Moon, becoming the first human-made satellite to take up an independent heliocentric orbit. That was in early January 1959 – so the space race, with its focus on the Moon, began much earlier than many people realise, and though so much of it was about macho one-upmanship, important technological developments resulted, and vital observations were made, including measurements of energetic particles in the outer Van Allen belt. Luna 1 was the first spaceship to achieve escape velocity, the principle barrier to landing a vessel on the Moon.

After another launch failure in June 1959, the Soviets successfully launched the rocket later known as Luna 2 in September that year. Its crash landing on the Moon was a great success, which the ‘communist’ leader Khrushchev was quick to ‘capitalise’ on during his only visit to the USA immediately after the mission. He handed Eisenhower replicas of the pennants left on the Moon by Luna 2. And there’s no doubt this was an important event, the first planned impact of a human-built craft on an extra-terrestrial object, almost 10 years before the Apollo 11 landing.

The Luna 2 success was immediately followed only a month later by the tiny probe Luna 3‘s flyby of the far side of the Moon, which provided the first-ever pictures of its more mountainous terrain. However, these two missions formed the apex of the Luna enterprise, which experienced a number of years of failure until the mid-sixties. International espionage perhaps? I note that James Bond began his activities around this time.

the Luna 3 space probe (or is it H G Wells' time machine?)

the Luna 3 space probe (or is it H G Wells’ time machine?)

The Luna Program wasn’t the only only one being financed by the Soviets at the time, and the Americans were also developing programs. Six months after Laika’s flight, the Soviets successfully launched Sputnik 3, the fourth successful satellite after Sputnik 1 & 2 and Explorer 1. The important point to be made here is that the space race, with all its ingenious technical developments, began years before the famous Vostok 1 flight that carried a human being, Yuri Gagarin, into space for the first time, so the idea that the technology wasn’t sufficiently advanced for a moon landing many years later becomes increasingly doubtful.

Of course the successful Vostok flight in April 1961 was another public relations coup for the Soviets, and it doubtless prompted Kennedy’s speech to the US Congress a month later, in which he proposed that “this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth.”

So from here on in I’ll focus solely on the USA’s moon exploration program. It really began with the Ranger missions, which were conceived (well before Kennedy’s speech and Gagarin’s flight) in three phases or ‘blocks’, each with different objectives and with increasingly sophisticated system design. However, as with the Luna missions, these met with many failures and setbacks. Ranger 1 and Ranger 2 failed on launch in the second half of 1961, and Ranger 3, the first ‘block 2 rocket’, launched in late January 1962, missed the Moon due to various malfunctions, and became the second human craft to take up a heliocentric orbit. The plan had been to ‘rough-land’ on the Moon, emulating Luna 2 but with a more sophisticated system of retrorockets to cushion the landing somewhat. The Wikipedia article on this and other missions provides far more detail than I can provide here, but the intensive development of new flight design features, as well as the use of solar cell technology, advanced telemetry and communications systems and the like really makes clear to me that both competitors in the space race were well on their way to having the right stuff for a manned moon landing.

I haven’t even started on the Apollo missions, and I try to give myself a 1500-word or so limit on posts, so I’ll have to write a part 3! Comment excitant!

The Ranger 4 spacecraft was more or less identical in design to Ranger 3, with the same impact-limiter – made of balsa wood! – atop the lunar capsule. Ranger 4 went through preliminary testing with flying colours, the first of the Rangers to do so. However the mission itself was a disaster, as the on-board computer failed, and no useful data was returned and none of the preprogrammed actions, such as solar power deployment and high-gain antenna utilisation, took place. Ranger 4 finally impacted the far side of the Moon on 26 April 1962, becoming the first US craft to land on another celestial body. Ranger 5 was launched in October 1962 at a time when NASA was under pressure due to the many failures and technical problems, not only with the Ranger missions, but with the Mariner missions, Mariner 1 (designed for a flyby mission to Venus) having been a conspicuous disaster. Unfortunately Ranger 5 didn’t improve matters, with a series of on-board and on-ground malfunctions. The craft missed the Moon by a mere 700 kilometres. Ranger 6, launched well over a year later, was another conspicuous failure, as its sole mission was to send high-quality photos of the Moon’s surface before impact. Impact occurred, and overall the flight was the smoothest one yet, but the camera system failed completely.

There were three more Ranger missions. Ranger 7, launched in July 1964, was the first completely successful mission of the series. Its mission was the same as that of Ranger 6, but this time over 4,300 photos were transmitted during the final 17 minutes of flight. These photos were subjected to much scrutiny and discussion, in terms of the feasibility of a soft landing, and the general consensus was that some areas looked suitable, though the actual hardness of the surface couldn’t be determined for sure. Miraculously enough, Ranger 8, launched in February 1965, was also completely successful. Again its sole mission was to photograph the Moon’s surface, as NASA was beginning to ready itself for the Apollo missions. Over 7,000 good quality photos were transmitted in the final 23 minutes of flight. The overall performance of the spacecraft was hailed as ‘excellent’, and its impact crater was photographed two years later by Lunar Orbiter 4. And finally Ranger 9 made it three successes in a row, and this time the camera’s 6,000 images were broadcast live to viewers across the United States. The date was March 24, 1965. The next step would be that giant one.

A Ranger 9 image showing rilles - long narrow depressions - on the Moon's surface

A Ranger 9 image showing rilles – long narrow depressions – on the Moon’s surface

the strange world of the self-described ‘open-minded’ – part one

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my copy - a stimulating and fun read, great fodder for closed-minded types, come moi

my copy – a stimulating and fun read, great fodder for closed-minded types, comme moi

I’ve just had my first ever conversation with someone who at least appears to be sceptical of the Apollo 11 moon landing of 1969 – and, I can only suppose, the five subsequent successful moon landings. Altogether, twelve men walked on the moon between 20 July 1969 and December 10 1972, when the crew members of Apollo 17 left the moon’s surface. Or so the story goes.

This conversation began when I said that perhaps the most exciting world event I’ve experienced was that first moon landing, watching Neil Armstrong possibly muffing the lines about one small step for a man, and marvelling that it could be televised. I was asked how I knew that it really happened. How could I be so sure?

Of course I had no immediate answer. Like any normal person, I have no immediate, or easy, answer to a billion questions that might be put to me. We take most things on trust, otherwise it would be a very very painstaking existence. I didn’t mention that, only a few months before, I’d read Phil Plait’s excellent book Bad Astronomy, subtitled Misconceptions and misuses revealed, from astrology to the moon landing ‘hoax’. Plait is a professional astronomer who maintains the Bad Astronomy blog and he’s much better equipped to handle issues astronomical than I am, but I suppose I could’ve made a fair fist of countering this person’s doubts if I hadn’t been so flabbergasted. As I said, I’d never actually met someone who doubted these events before. In any case I don’t think the person was in any mood to listen to me.

Only one reason for these doubts was offered. How could the lunar module have taken off from the moon’s surface? Of course I couldn’t answer, never having been an aeronautical engineer employed by NASA, or even a lay person nerdy enough to be up on such matters, but I did say that the moon’s minimal gravity would presumably make a take-off less problematic than, say, a rocket launch from Mother Earth, and this was readily agreed to. I should also add that the difficulties, whatever they might be, of relaunching the relatively lightweight lunar modules – don’t forget there were six of them – didn’t feature in Plait’s list of problems identified by moon landing skeptics which lead them to believe that the whole Apollo adventure was a grand hoax.

So, no further evidence was proffered in support of the hoax thesis. And let’s be quite clear, the claim, or suggestion, that the six moon landings didn’t occur, must of necessity be a suggestion that there was a grand hoax, a conspiracy to defraud the general public, one involving tens of thousands of individuals, all of whom have apparently maintained this fraud over the past 50 years. A fraud perpetrated by whom, exactly?

My conversation with my adversary was cut short by a third person, thankfully, but after the third person’s departure I was asked this question, or something like it: Are you prepared to be open-minded enough to entertain the possibility that the moon landing didn’t happen, or are you completely closed-minded on the issue?

Another way of putting this would be: Why aren’t you as open-minded as I am?

So it’s this question that I need to reflect on.

I’ve been reading science magazines on an almost daily basis for the past thirty-five years. Why?

But it didn’t start with science. When I was kid, I loved to read my parents’ encyclopaedias. I would mostly read history, learning all about the English kings and queens and the battles and intrigues, etc, but basically I would stop at any article that took my fancy – Louis Pasteur, Marie Curie, Isaac Newton as well as Hitler, Ivan the Terrible and Cardinal Richelieu. Again, why? I suppose it was curiosity. I wanted to know about stuff. And I don’t think it was a desire to show off my knowledge, or not entirely. I didn’t have anyone to show off to – though I’m sure I wished that I had. In any case, this hunger to find things out, to learn about my world – it can hardly be associated with closed-mindedness.

The point is, it’s not science that’s interesting, it’s the world. And the big questions. The question – How did I come to be who and where I am?  – quickly becomes – How did life itself come to be? – and that extends out to – How did matter come to be? The big bang doesn’t seem to explain it adequately, but that doesn’t lead me to imagine that scientists are trying to trick us. I understand, from a lifetime of reading, that the big bang theory is mathematically sound and rigorous, and I also know that I’m far from alone in doubting that the big bang explains life, the universe and everything. Astrophysicists, like other scientists, are a curious and sceptical lot and no ‘ultimate explanation’ is likely to satisfy them. The excitement of science is that it always raises more questions than answers, it’s the gift that keeps on giving, and we have human ingenuity to thank for that, as we’re the creators of science, the most amazing tool we’ve ever developed.

But let me return to open-mindedness and closed-mindedness. During the conversation described above, it was suggested that the USA simply didn’t have the technology to land people on the moon in the sixties. So, ok, I forgot this one: two reasons put forward – 1, the USA didn’t have the technological nous; 2, the modules couldn’t take off from the moon (later acknowledged to be not so much of an issue). I pretty well knew this first reason to be false. Of course I’ve read, over the years, about the Apollo missions, the rivalry with the USSR, the hero-worship of Yuri Gagarin and so forth. I’ve also absorbed, in my reading, much about spaceflight and scientific and technological development over the years. Of course, I’ve forgotten most of it, and that’s normal, because that’s how our brains work – something I’ve also read a lot about! Even the most brilliant scientists are unlikely to be knowledgeable outside their own often narrow fields, because neurons that fire together wire together, and it’s really hands-on work that gets those neurons firing.

But here’s an interesting point. I have in front of me the latest issue of Cosmos magazine, issue 75. I haven’t read it yet, but I will do. On my shelves are the previous 74 issues, each of which I’ve read, from cover to cover. I’ve also read more than a hundred issues of the excellent British mag, New Scientist. The first science mag I ever read was the monthly Scientific American, which I consumed with great eagerness for several years in the eighties, and I still buy their special issues sometimes. Again, the details of most of this reading are long forgotten, though of course I learned a great deal about scientific methods and the scientific mind-set. The interesting point, though, is this. In none of these magazines, and in none of the books, blogs and podcasts I’ve consumed in about forty years of interest in matters scientific, have I ever read the claim, put forward seriously, that the moon landings were faked. Never. I’m not counting of course, books like Bad Astronomy and podcasts like the magnificent Skeptics’ Guide to the Universe, in which such claims are comprehensively debunked.

The SGU podcast - a great source for exciting science developments, criticism of science reporting, and debunking of pseudo-science

The SGU podcast – a great source for exciting science developments, criticism of science reporting, and debunking of pseudo-science

Scientists are a skeptical and largely independent lot, no doubt about it, and I’ve stated many times that scepticism and curiosity are the twin pillars of all scientific enquiry. So the idea that scientists could be persuaded, or cowed into participating in a conspiracy (at whose instigation?) to hoodwink the public about these landings is – well let’s just call it mildly implausible.

But of course, it could explain the US government’s massive deficit. That’s it! All those billions spent on hush money to astronauts, engineers, technicians (or were they all just actors?), not to mention nosey reporters, science writers and assorted geeks – thank god fatty Frump is here to make America great again and lift the lid on this sordid scenario, like the great crusader against fake news that he is.

But for now let’s leave the conspiracy aspect of this matter aside, and return to the question of whether these moon landings could ever have occurred in the late sixties and early seventies. I have to say, when it was put to me, during this conversation, that the technology of the time wasn’t up to putting people on the moon, my immediate mental response was to turn this statement into a question. Was the technology of the time up to it? And this question then turns into a research project. In other words, let’s find out, let’s do the research. Yay! That way, we’ll learn lots of interesting things about aeronautics and rocket fuel and gravitational constraints and astronaut training etc, etc – only to forget most of it after a few years. Yet, with all due respect, I’m quite sure my ‘adversary’ in this matter would never consider engaging in such a research project. She would prefer to remain ‘open-minded’. And if you believe that the whole Apollo project was faked, why not believe that all that’s been written about it before and since has been faked too? Why believe that the Russians managed to get an astronaut into orbit in the early sixties? Why believe that the whole Sputnik enterprise was anything but complete fakery? Why believe anything that any scientist ever says? Such radical ‘skepticism’ eliminates the need to do any research on anything.

But I’m not so open-minded as that, so in my dogmatic and doctrinaire fashion I will do some – very limited – research on that very exciting early period in the history of space exploration. I’ll report on it next time.

Written by stewart henderson

February 25, 2017 at 12:34 pm

So why exactly is the sky blue? SfD tries to investigate

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Canto: Well, Karl Kruszelnicki is one of our best science popularisers as you know, and therefore a hero of ours, but I have to say his explanation of the blueness of our daily sky in his book 50 Shades of Grey  left me scratching my head…

Jacinta: Not dumbed-down enough for you? Do you think we could form a Science for Dummies collaboration to do a better job?

Canto: Well that would really be the blind leading the blind, but at least we’d inch closer to understanding if we put everything in our own words… and that’s what I’m always telling my students to do.

Jacinta: So let’s get down to it. The day-sky is blue (or appears blue to we humans?) because…?

Canto: Well the very brief explanation given by Dr Karl is that it’s about Rayleigh scattering. Named for a J W Strutt, aka Lord Rayleigh, who first worked it out.

Jacinta: So let’s just call it scattering. What’s scattering?

Canto: Or we might call it light scattering. Our atmosphere is full of particles, which interfere with the light coming to us from the sun. Now while these particles are all more or less invisible to the naked eye, they vary greatly in size, and they’re also set at quite large distances from each other, relative to their size. The idea, broadly, is that light hits us from the sun, and that’s white light, which as we know from prisms and rainbows is made up of different wavelengths of light, which we see, in the spectrum that’s visible to us, as Roy G Biv, red orange yellow green blue indigo violet, though there’s more of some wavelengths or colours than others. Red light, because it has a longer wavelength than blue towards the other end of the spectrum, tends to come straight through from the sun without hitting too many of those atmospheric particles, whereas blue light hits a lot more particles and bounces off, often at right angles, and kind of spreads throughout the sky, and that’s what we mean by scattering. The blue light, or photons, bounce around the sky from particle to particle before hitting us in the eye so to speak, and so we see blue light everywhere up there. Now, do you find that a convincing explanation?

Jacinta: Well, partly, though it raises a lot of questions.

Canto: Excellent. That’s science for you.

Jacinta: You say there are lots of particles in the sky. Does the size of the particle matter? I mean, I would assume that the light, or the photons, would be more likely to hit large particles than small ones, but that would depend on just how many large particles there are compared to small ones. Surely our atmosphere is full of molecular nitrogen and oxygen, mostly, and they’d be vastly more numerous than large dust particles. Does size matter? And you say that blue light, or blue photons, tend to hit these particles because of their shorter wavelengths. I don’t quite get that. Why would something with a longer wavelength be more likely to miss? I think of, say, long arrows and short arrows. I see no reason why a longer arrow would tend to miss the target particles – not that they’re aiming for them – while shorter arrows hit and bounce off. And what makes them bounce off anyway?

Canto: OMG what a smart kid you are. And I think I can add more to those questions, such as why do we see different wavelengths of light as colours anyway, and why do we talk sometimes of waves and sometimes of particles called photons? But let’s start with the question of whether size matters. All I can say here is that it certainly does, but a fuller explanation would be beyond my capabilities. For a start, the particles hit by light are not only variable by size but by shape, and so potentially infinite in variability. Selected geometries of particles – for example spherical ones – can yield solutions as to light scattering based on the equations of Maxwell, but that doesn’t help much with random dust and ice particles. Rayleigh scattering deals with particles much smaller than the light’s wavelength but many particles are larger than the wavelength, and don’t forget light is a bunch of different wavelengths, striking a bunch of different sized and shaped particles.

Jacinta: Sounds horribly complex, and yet we get this clear blue sky. Are you ready to give up now?

Canto: Just about, but let me tackle this bouncing off thing. Of course this happens all the time, it’s called reflection. You see your reflection in the mirror because mirrors are designed as highly reflective surfaces.

Jacinta: Highly bounced-off. So what would a highly unreflective surface look like?

Canto: Well that would be something that lets all the light through without reflection or distortion, like the best pane of glass or pair of specs. You see the sky as blue because all these particles are absorbing and reflecting light at particular wavelengths. That’s how you see all colours. As to why things happen this way, OMG I’m getting a headache. The psychologist Thalma Lobel highlights the complexity of it all this way:

A physicist would tell you that colour has to do with the wavelength and frequency of the beams of light reflecting and scattering off a surface. An ophthalmologist would tell you that colour has to do with the anatomy of the perceiving eye and brain, that colour does not exist without a cornea for light to enter and colour-sensitive retinal cones for the light-waves to stimulate. A neurologist might tell you that colour is the electro-chemical result of nervous impulses processed in the occipital lobe in the rear of the brain and translated into optical information…

Jacinta: And none of these perspectives would contradict the others, it would all fit into the coherence theory of truth…

Canto: Not truth so much as explanation, which approaches truth maybe but never gets there, but the above quote gives a glimpse of how complex this matter of light and colour really is…

Jacinta: And just on the physics, I’ve looked at a few explanations online, and they don’t satisfy me.

Canto: Okay, I’m going to end with another quote, which I’m hoping may give you a little more satisfaction. This is from Live Science.

The blueness of the sky is the result of a particular type of scattering called Rayleigh scattering, which refers to the selective scattering of light off of particles that are no bigger than one-tenth the wavelength of the light.

Importantly, Rayleigh scattering is heavily dependent on the wavelength of light, with lower wavelength light being scattered most. In the lower atmosphere, tiny oxygen and nitrogen molecules scatter short-wavelength light, such as blue and violet light, to a far greater degree than long-wavelength light, such as red and yellow. In fact, the scattering of 400-nanometer light (violet) is 9.4 times greater than the scattering of 700-nm light (red).

Though the atmospheric particles scatter violet more than blue (450-nm light), the sky appears blue, because our eyes are more sensitive to blue light and because some of the violet light is absorbed in the upper atmosphere.

Jacinta: Yeah so that partially answers some of my questions… ‘selective scattering’, there’s something that needs unpacking for a start…

Canto: Well, keep asking questions, smart ones as well as dumb ones…

Jacinta: Hey, there are no dumb questions. Especially from me. Remember this is supposed to be science for dummies, not science by dummies

Canto: Okay then. So maybe we should quit now, before we’re found out…


‘Why is the sky blue?’, from 50 shades of grey matter, Karl Kruszelnicki, pp15-19

‘Blue skies smiling at me: why the sky is blue’, from Bad astronomy, Philip Plait, pp39-47

Written by stewart henderson

December 15, 2016 at 4:35 am

Proxima b

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Quote of the day/week/month/post:

Better to have questions you can’t answer than answers you can’t question – Max Tegmark (and many others)


Jacinta: So while astrophysicists argue over the likelihood of life elsewhere in our tiny but massive universe, some are focusing on our nearest star neighbour. Some wobbling of the red dwarf known as Proxima Centauri has revealed, upon lengthy observation, that it has a closely orbiting planet, which considering the relative coolness of the star – way too dim to be seen with the naked eye – and the proximity of its satellite, is very much in the habitable zone. While it’s too early to say so much for the naysayers, the discovery of a planet in the Goldilocks zone of our nearest star in a galaxy of billions of possibilities must surely raise hopes and expectations of life abundant.

Canto: This closest possible exoplanet was only discovered in August this year, so we’re desperate to find out more about it. Being in the habzone is one thing, habitability is another. Obvious questions we have no current way of answering are: does it have an atmosphere? Any possibility of water? Is it tidally locked? And of course we’d love to know if we could launch some sort of robotic mission to our nearest star neighbour. Meanwhile is there any other way of gleaning more info from this tantalising object?

Jacinta: It’s not likely to be habitable though. Solar winds are estimated to be some 2000 times those experienced on Earth, though we can’t be too sure. Researchers are trying to work out the size of the planet…

Canto: How do they know about those solar winds?

Jacinta: Oooh, that’s a horribly good question. It’s due to the closeness of the orbit, where you would expect the solar winds to be much stronger, as they are in our solar system. It’s believed that Mercury’s magnetic field, which should be stronger than it’s been measured to be because of its heavy metallic core, is dampened massively by our solar wind. So basically they would’ve inferred Proxima Centauri’s wind by our own. As to how they came up with the figure of 2000 times that experienced on Earth, I’ve no idea, but strong solar winds make it hard to maintain an atmosphere, which is vital for life. You’ve also talked about tidal locking, which is a feature of close orbits, such as the Moon’s orbit of the Earth. So you’ll have a permanently hot day side and a permanently cool night side, and this can be problematic for the creation of an atmosphere, according to modelling.

Canto: Now, all of this sounds very negative, but basing exo-planetary activity on what’s been the case, as far as we can work it out, in our solar system, has been really problematic hasn’t it?

Jacinta: Definitely, that’s why we need to go beyond modelling, if we can, and collect some real data. So we’re looking to the James Webb Space Telescope (JWST), the very exciting successor to Hubble to be launched around November 2018, to garner more info, which it’ll be perfectly equipped to do.

Canto: If by some near-miraculous combination of circs there is an atmosphere on Proxima b, or a reasonable quantity of liquid water, that would help distribute the heat around the planet. With no atmosphere, the difference between day side and night side would be stark.

Jacinta: Exactly, and that’s what the JWST should be able to detect, as the best way to detect the atmosphere is to measure the planet’s infrared heat signature. If the JWST finds a decisive and fixed difference between the planet’s day and night sides, it’s a safe bet that no atmosphere is present. The JWST will be equipped to measure this IR signature on both sides of the planet, and if it doesn’t find that stark difference, that’ll be when we can start speculating about an atmosphere and its constituents.

Canto: Though of course they’ve already started with the speculation. But really, whatever they find – and I don’t expect that everything will line up for life – the fact that we’ve found an exoplanet well worth investigating on the nearest star outside our solar system, with billions of stars yet to be homed in on, one by one – doesn’t that say something to those who argue for the Fermi paradox – where are they? Okay, Fermi and Hart were talking about intelligent life, and that may well be orders of magnitude more difficult to develop than life itself, but I’m sure that Fermi would be unsettled in his skepticism, if he was alive today, by the vast numbers of exoplanets, in other words possibilities for life, we’re discovering now, with so many to come in the near future.

Jacinta: Yes, bliss in this time it is to be alive, but to be young, that would be very heaven!




Cosmos issue 71, pp9-10



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Written by stewart henderson

December 4, 2016 at 9:38 pm

the renewable energy juggernaut

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There is more global investment in solar power today than there is in fossil fuels. We’re talking about hard-headed investment for profit by business and governments worldwide, not greenies or special interest groups. And another interesting factoid: China today is generating more energy from wind power than the whole of Australia’s energy production. Not to mention the Chinese government’s massive investment in other renewables. That’s info I got from a recent ABC Science Show podcast. Renewable energy really is making inroads, and this is most encouraging for those around the world fighting the damaging environmental effects of mining and fracking in their regions, though it’s clear that such operations are dying hard.

I remember some time ago at a meeting of skeptics (not climate change ‘skeptics’, just regular sciencey anti-quackery, anti-UFO-type skeptics), when I was spruiking the virtues of wind power, so successfully taken up here in South Australia, being told dismissively that it was too expensive to be really viable. However, wind-power only really has establishment costs. Ongoing costs are quite minimal. Furthermore, a research group conducted by the Carnegie Institution for Science’s Global Ecology Department has recently conducted the most wide-ranging expert survey on wind (or any other) energy. Sure, it was a survey of those already heavily invested in wind, but that does make them the experts in the field. Predictions about the cost of wind energy into the future were based on two approachess. First, a projection into the future of falling costs over the past three decades or so – what they call the ‘learning curve’. One would assume those projections would vary from ‘most optimistic’ to ‘most pessimistic’, with consensus somewhere in between. The second approach involved a ‘bottom-up engineering assessment’, looking at the costs of individual turbine components into the future. Science Daily has summarised the findings:

On average, the participants expected wind power costs to continue falling for the next several decades, for three major classes of wind turbines, both onshore and offshore, with prices falling by 24-30% by 2030, and 35-41% by 2050.

Meanwhile governments worldwide are getting on board in a determined effort to drive down the cost of solar. Vox Energy & Environment reports on the US target:

…the US Department of Energy has a program, the SunShot Initiative, devoted entirely to driving down the cost of electricity generated by solar panels — the target is solar power with $1 per watt installed costs by 2020, a 75 percent reduction in costs from 2010.

It’s hard to get the head around the growth of solar energy worldwide since about 2007. It’s been a whirlwind ride, but starting from an extremely low level. And in the US since 2012, large or utility-scale solar has been growing faster than domestic, rooftop solar, and with falling prices and increasing module efficiency, the growth trend in big and small solar should continue well into the future. Yes, there’s government stimulus, but solar is being seen more and more as a sound investment on its own terms. Solar’s steady growth also makes for sound investment against the high volatility of the natural gas market. And this of course is just as relevant for many regions outside the US.

I’ll be taking another look at Australia’s situation, while many of our governments bicker and focus elsewhere, in an upcoming post.


Written by stewart henderson

September 16, 2016 at 8:57 am