1
CHAPTER TWO
TURNING POINTS IN SCIENCE
Before we set off in quest of the Promethean Fire we ought to be clear what we will be searching for. Equally we need to demolish some beguiling myths that could otherwise lead us seriously astray. And what better way to do this than to recall some fundamental scientific discoveries and try to identify the primary mental tactics that were used to make them. If the folklore is true, that is to say that science is an experimental, deductive affair very largely advanced by geniuses, then this will become apparent. But if that lore is nonsense, or a gross distortion of the truth, then that should emerge too.
I hope you will find each episode absorbing in itself, though it is not the particular discovery, nor the individual protagonist, nor even its significance to mankind, that will interest us, but the underlying mental tactics employed. Are those tactics familiar to us, or extraordinary? Were they deductive, or inferential? Were they mathematical or indeed quantitative at all? Was the discoverer a lone genius – or did he or she have rivals or precursors? Could the discovery have been made long before, or were the preconditions for it of recent origin? At the end of the chapter we look back to see if history has supplied answers to these questions. And we shall conclude, with Einstein, that “The whole of science is nothing more than a refinement of everyday thinking”. If that is so then we shall be ready to track down those refinements and try to domesticate them to our everyday use.
At the end of each episode you might like to pause and ask yourself two questions:
“Have I thought along the same lines, but in a different context, myself?”
and
“If I have not, then could I usefully add this tactic to my box of mental tools for future use?”
So let us begin, heading each episode with the mental tactic employed.
1 RECOGNISING THERE IS A PROBLEM
“Why is the sky dark at night?” To most of us it would never occur to ask this question. We might suppose, “It just is – so what’s the problem?” or if we thought a little harder we might come up with “Darkness is an absence of light, surely it is the presence of something, not its absence, that we have to explain”. Johannes Kepler a boy from Wurtumburg thought otherwise, and so founded the subject of scientific cosmology – the study of the heavens in their entirety. He was stimulated to think about the matter after reading “The Starry Messenger” a pamphlet put out by Galileo Galilei in 1610 describing the sensational discoveries he had just made with his first astronomical telescope. Galileo reported that the instrument “set distinctly before the eyes other stars in myriads which have never been seen before…….” And of the Milky Way he said “…….it.is nothing else but a mass of innumerable stars plastered together in clusters. Upon whatever part of it you direct the telescope straight way a vast crowd of stars presents itself to view………..”
Struck by this last remark Kepler noted that nevertheless the sky remained dark – very dark. If it were true that wherever you cast an eye or telescope in the heavens it were to fall upon a star, then the whole heavens should burn with the furnace heat of a typical stellar-surface – such as the Sun. That it does not, implied to Kepler that the Milky Way, and indeed the entire firmament of stars must somewhere, somehow come to an end. Whatever else it might be, the Universe could not be infinite.
This was a profound thought – and not one that man has found it easy to explain. Or rather it was one we found all too easy to explain – using unsound arguments.
First it was supposed that there was absorbing smoke in interstellar space that obscures the distant stars in an infinite universe. The snag with that explanation is that any conceivable smoke particles would evaporate after absorbing so much luminous energy. Next theoretical cosmologists came up with two elaborate calculations to prove that either a spatially finite cosmos, or later an expanding one, would explain Kepler’s so called “Dark Sky Paradox”. Both very complex calculations turned out eventually to be wrong. Today we suppose the way out is connected with “The Big Bang” ie the idea that the Universe began in a titanic explosion ten billion years ago. For the sky to be bright the universe would have to be vastly older than that, old enough for the light of truly distant stars to have the time to reach us and fill up our local sky.
The important point here is not whether there is a solution, but to recognise that there is a problem. Kepler did, whereas lesser men either did not, or dismissed it with some facile explanation. When the ancients saw the mast of a distant vessel sink below the horizon, or picked up the fossil of an extinct creature, only a very rare few were prepared to confront the issues being raised .
It is fascinating to wonder if there are other problems as fundamental as Kepler’s still staring us in the face but being ignored today. The Origin of Inertia may be one such. How does a massive body know when it is being accelerated, and thus resist the forces acting on it? Think of Foucault’s pendulum, a massive weight swaying back and forth on a long wire suspended from a ceiling far above. Foucault hung his giant pendulum from the dome of the Pantheon in Paris in 18 . Too immense to be affected much by air resistance, such a pendulum will beat back and forth for days. If you suspend it above a large sand-tray the pendulum will etch a mark on the sand each time it swings by. As the Earth turns, with the sand-tray resting upon it, so the pendulum cleaves to a fixed constant plane with regard to the distant stars. Over the course of 23 hours and 56 minutes, precisely the time it takes the Earth to turn once in relation to those distant stars, the marks in the sand tray make one exact revolution.[Because of the curvature of the earth the period is different at different latitudes being 23hours and 56 minutes only at the poles]. The cathedral has turned, the continent upon which it is built has turned, the massive Earth has turned but the pendulum has ignored them all, preferring to mark its beat by the distant Universe. Why, or rather how? It is apparently an effect without a cause? What forces unknown connect the pendulum, and indeed all accelerated masses to the distant constellations? Most scientists do not appear to care, do not see it as more than a “philosophical problem”, but a few of us do.
2 RECOGNISING A COINCIDENCE
Over the history of mankind no individual has saved as many lives as Dr. John Snow. In 1848 he was called in to a cholera epidemic raging at Soho in the heart of London. Within 10 days 500 people died in a very localised area around Golden Square and Broad Street. In some households everybody died, whereas in the ones to either side no one was affected. For instance only 5 out of the 535 inmates of the Poland Street Workhouse were affected whereas the neighbouring buildings were devastated. From the odd pattern of the disease Snow began to suspect the water from the Broad Street pump (there was no piped water in those days). The workhouse for instance had its own well while the inhabitants in unaffected houses drew their water from elsewhere. His suspicions were definitely confirmed by the sporadic cases that occurred in distant parts of London, all of which could be traced to drinking some water from the Broad Street Pump. After Snow had the pump-handle removed the epidemic died out.
Snow’s observations led soon afterwards to a huge public-works program, to the laying of sewers and the supplying of truly clean water across the civilized world. Not only cholera was banished but a host of other agues and dysenteries which dragged down those living in urban stews everywhere. Mankind’s enormous population growth and increased longevity owes more to the discovery of John Snow’s coincidence than to anything else.
3 SPOTTING A CONNECTION BETWEEN TWO PREVIOUSLY UNRELATED PHENOMENA.
Hans Christian Oersted was employed by the Danish government to study meteorological records. He was given the task of looking through ships logbooks to find out about storms at sea. Time and again seamen reported that during electrical storms their compasses went haywire. This was inexplicable because at the time (1820) no one suspected that electricity and magnetism were in any way were related. But Oersted could hardly avoid that inference, and so decided to do a simple experiment. Luckily for him the battery had just been invented. Passing a current through a wire he was able to map its indubitable effect upon any compass placed nearby.
News of this discovery spread like wildfire through the laboratories and academies of Europe. In particular Ampere in Paris and Faraday in London were able to tease out the precise relationship between two hitherto unrelated phenomena. Electromagnetism was born, and with a small addition from James Clark Maxwell 30 years later, so was the bulk of the modern world. After Oersted’s discovery, Faraday, Marconi and Einstein were inevitable. The radio demagogues, television, code-breaking, computers, Relativity and mobile phones were all waiting in the wings of history.
Associating two previously unrelated observations has been one of the most widely productive tactics across all of science. Perhaps it explains why so many great scientists have exhibited omnivorous curiosity. If you know only 10 things there are only (10 times 9)/2 = 45 possible connections between them [the 2 enters because otherwise you will count the same connection twice]. But if you know a hundred there are (100 times 99)/2 or nearly 5000 possible connections to explore.
4 NOTICING A NUMERICAL COINCIDENCE
From the sight of a falling apple – in conjunction with the Moon seen in the sky above the apple-tree – the young Isaac Newton was led in 1665 to suspect that the force of the Earth’s gravity extended so far as the Moon. But how? Years later, with an accurate distance to the Moon before him, Newton was able to calculate its acceleration toward the Earth, the acceleration that keeps it in its orbit instead of straying off to infinity. He found the acceleration to be 3,600 times less than the falling apple’s. Why 3,600? Newton noticed that 3,600 is the square of 60 precisely [ie 60 times 60] and that 60 is the ratio of the Moon’s distance from the centre of the Earth, to the apple’s. He had his famous ‘Law of Universal Gravity’ . He guessed that gravitation, an attractive force between any two bodies in the Universe, must fall away as the inverse square of the distance between them – at twice the distance it is four times as weak When he tried it out on the planets he found he could explain exactly all three of Kepler’s Laws of Planetary Motion, to say nothing of the comets, the tides and the complex trajectory of the Moon.
Another singular numerical coincidence astonished the Scottish physicist James Clerk Maxwell when he was working on electromagnetism at Kings College London in 1864. He was trying to cast into differential equations the laboratory work of men like Oersted and Faraday. To his consternation he found that his equations allowed for electric charge to disappear, something never observed in Nature. Realizing that some effect must be missing from his equations he guessed it must be the “displacement current”, the transient pulse of current observed in open circuits when they are first switched on. The addition of this new current term sufficed to conserve electric charge in his equations. Satisfied, he went on to explore the consequences.
In perhaps the greatest moment of epiphany in the history of science Maxwell discovered that the equations predicted that electromagnetic waves would propagate through empty space. Furthermore they predicted the speed of these waves in terms of two obscure electric and magnetic constants of nature, previously measured in the laboratory by Kohlsrausche and Weber. Filling in their numbers Maxwell found that the wave speed would be 300,000 km/sec. But that was precisely the speed of light, long known to science from observing the moons of Jupiter. Maxwell must have been flabbergasted. Light, electricity and magnetism must be one and the same phenomenon, otherwise the numerical coincidence in their velocities would be inexplicable. He said: “………………….”. Intriguingly other such numerical coincidences have been found in physics, which are still totally unexplained. For instance the ratio of the electric to the gravitational forces between elementary particles appears to be equal to the square root of the number of protons in the observable Universe.
5 RECOGNISING A PATTERN
The apparent fit between the opposite shore-lines of the Atlantic Ocean had long intrigued map-makers. Had the two sides once been parts of a super-continent which had split, leaving the halves to drift apart? The first man, to seriously entertain this hypothesis of ‘Continental Drift’ was the German meteorologist Alfred Wegener. He reasoned (1912) that if there was anything to it then the detailed geology on opposing sides of the ocean ought to correspond. When he looked into the geological libraries he indeed found an uncannily good correspondence. Rocks thousands of miles apart matched so uncannily well that it seemed there could be no doubt about the matter.
Unfortunately Wegener, a man of many parts, died a heroic death out on the Arctic ice in 1930. This enabled the theoretical geophysicists, led by Harold Jeffries at Cambridge, of whom more later, to dismiss the awkward facts, and to prove with the aid of a string of equations that the idea of solid continents drifting about was preposterous.
It took another 30 years to discover these theorists in their delusions when even more striking patterns appeared in geomagnetic measurements of the ocean floor. The bed of the sea was indubitably spreading outwards on both sides from the Mid-Atlantic Ridge at several centimetres a year. Rock was far more plastic than Jeffries and the theoreticians had been able to imagine. Wegener’s pattern-recognition argument, albeit in a modified form, was far too strong to be gainsaid by any number of partial differential equations. Some solids, such as the andesite rock underlying the continents, are rigid in the short term but can flow plastically over geological time. Likewise the glass in ancient Egyptian tombs had visibly ‘dripped’ by the time it was unearthed.
6 FOLLOWING UP A CHANCE OBSERVATION
– is one of the classic high-roads to discovery. Thus in 1899 Henri Becquerel was experimenting with a compound called potassium uranyl sulphate which fluoresces, that is to say continues to glow after it has been exposed to sunlight. It is the kind of substance that enables you to see the hands of your watch in the dark. Unfortunately, in the middle of his experiments, the sky clouded over and Becquerel put away in a light-tight drawer the packet of unexposed photographic plates that he was using to detect the fluorescence. When, several days later, he resumed his experiments he was disconcerted to find out that the plates were all fogged over – as if they had been exposed to light. Instead of throwing them away as defective – which is what most of us would probably have done, Becquerel tried to find out how the plates could have become blackened in an apparently light- tight package within a light-tight drawer.
He traced the source of the problem to a dusting of the aforesaid potassium uranyl sulphate compound left by accident on the surface of the package in the course of his earlier experiment. Some strange radiation, capable of penetrating light-tight cardboard, was emerging from his fluorescent compound. Becquerel had discovered “radioactivity” whose source was eventually traced to the single uranium atom in every molecule of the compound.
Becquerel’s accidental, and apparently trivial discovery, was to turn physics, chemistry and geology entirely on their heads. Atoms must contain energy, as it happens vast amounts of energy, which they can occasionally emit. But if they can emit energy they must be changing inside, which implies they are not entirely indestructible, as chemists had supposed. And if the rocks of the Earth contain some radioactive atoms, then the Earth’s interior may actually be heating up instead of cooling down as everyone had supposed. But if it was heating up then the age of the Earth, calculated from its supposed rate of cooling to be in tens of millions of years only, must be entirely wrong. The vast aeons of time required by biologists to accommodate evolution, and by geologists to explain the gradual erosion of mountains and canyons, was now a possibility. Becquerel’s fortuitous discovery catapulted us into the previously unimaginable abyss of Deep Time.
Serendipitous, fortuitous discoveries are the sign of a science in birth – or about to be reborn: X-rays, cosmic radio-emissions, penicillin, Big-Bang radiation, blood-sugar, galvanism, small-pox immunity, bacterial disease agents, anaphylaxis, helium………….the list of chance scientific discoveries goes on and on and on…………