What a Wonderful World (11 page)

Isaac Newton epitomised the merger of the craft and philosophy traditions. He looked at the world, theorised about why it behaved the way it did, then got his hands dirty by carrying out experiments to test his theories against reality. The idea that by observing the world systematically it was possible to gain new knowledge was extraordinarily productive. It has led us to aeroplanes and antibiotics, cars and computers, neutron stars and nuclear reactors.

Science, the industrial revolution, ocean-going ships, and so many other things, were born in Europe. Together, such technologies ensured that it was Europeans who colonised the Americas and Australia and ultimately spawned our modern global society. This prompts a question. It was asked by the American geographer Jared Diamond in his book
Guns, Germs and Steel
: ‘Why did human development proceed at such different rates on different continents for the last 13,000 years?’
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Diamond believes it was not because of any intrinsic differences in human beings – people in the Americas and Australia were not more stupid or more lazy than their European counterparts – but because of differences in their circumstances. Together, Europe and Asia – the source of so many of Europe’s innovations – had a far bigger and more diverse population than
either the Americas or Australia. Not only were there more societies to interact with each other but there were more individuals within each society interacting with each other. The overall effect was to boost the exchange of ideas and accelerate the rate at which people invented new things.

This, of course, prompts yet another question: why did Europe and Asia have a bigger population than the Americas and Australia? The answer, according to Diamond, was because they had a big head start in food production. This, in turn, was because the Fertile Crescent had a wider range of habitats, from deserts to rich soils to snowy mountaintops, which created a super-abundance of different plant species. At least a dozen of these were candidates for domestication compared with only a couple in, for instance, the Americas. These domesticated species were carried by farmers as they migrated from south-west Asia to Europe. Ultimately, the dominance of European culture comes down not to any intrinsic superiority of Europeans but to a mere accident of birth.

Even with the domestication of animals, Europe and Asia had significant advantages over the Americas and Australia. The ultimate reason for this actually pre-dates even the birth of modern agriculture in the Fertile Crescent. It has to do with the date at which humans arrived on different continents. People flooded into Europe and Asia very early in human history. Consequently, they carried unsophisticated stone tools and were not particularly effective hunters. Animals were able to live alongside them for a long while and learn to be fearful of them. This ensured the survival of the big mammals that one day would be candidates for domestication.

The Americas and Australia, on the other hand, were reached relatively recently by humans – Australia in about 50,000
BC
and
the Americas only in about 14,000
BC
. Consequently, the first colonists were fully modern. Far from being unsophisticated hunters, they were lethal killers. And, sure enough, the arrival of humans in both Australia and the Americas appears to have coincided with the extinction of pretty much all of their giant mammals with the exceptions of the bison in North America and the llamas and alpacas in the Andes. The result of this was that, thousands of years later, when animals were first being domesticated in the Fertile Crescent, there were few suitable candidates for domestication in Australia and the Americas.

The huge disadvantages people in the Americas and Australia faced in domesticating crops and domesticating animals is why their populations did not grow big enough to permit the feverish level of interaction necessary to create novel inventions. And this explains why it was the Spanish who sailed across the ocean to South America and not the Aztecs and Incas who sailed in the opposite direction to Europe. Furthermore, the empires of South America did not have horses, steel armour or guns, which meant that bands of a few dozen mounted Spaniards were able to rout native armies numbered in thousands.

In North America, the Native Americans who met the first Europeans were at an even bigger disadvantage than their cousins in the south of the continent. They possessed only weapons of stone and wood and no animals that could be ridden.

In the human catastrophe that unfolded, something like 95 per cent of the native people of the Americas were wiped out. Although many succumbed to guns, it was not actually superior technology that killed most of the people in the Americas, not to mention Australia. It was diseases such as smallpox and measles brought by the Europeans. This poses yet another puzzle. ‘It’s
striking’, says Diamond, ‘that Native Americans evolved no devastating epidemic diseases to give to Europeans, in return for the many devastating epidemic diseases that Indians received from the Old World.’

Yet again, the explanation has to do with the head start Europe and Asia enjoyed in food production. Many human diseases originate in common domestic animals such as pigs and chickens. Over thousands of years, the farming of many more animals, and many more types of animals, had created many more animal diseases. Occasionally, these spread to people and became human diseases. Measles and tuberculosis, for instance, evolved from diseases of cattle, flu from a disease of pigs, and smallpox possibly from a disease of camels. The Americas, by contrast, had very few native domesticated animal species from which humans could catch diseases.

The animal diseases that adapted themselves to humans in Europe and Asia ravaged the large population. Countless millions died but the survivors were left with immunity – immunity that, crucially, the conquered peoples of the Americas and Australia simply did not have. ‘Civilisation is what makes you sick,’ observed artist Paul Gauguin.

The differences between human societies on different continents, according to Diamond, are not down to any biological differences between people but down to differences in continental environments. Mark Twain recognised this even in the nineteenth century. ‘There are many humorous things in the world,’ he wrote, ‘among them the white man’s notion that he is less savage than the other savages.’
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Looking back over the past 13,000 years since the end of the last ice age, it is clear what the driving force of most human innovation has been: Interaction. Interaction. Interaction. The settlement of people, first in villages, then cities, boosted the opportunities for people to exchange ideas and ramped up the rate of technological advance. Today, we have a global civilisation with more than 7 billion people and the confluence of computers and telecommunications has spawned the internet, which has exponentially boosted the number of interactions between people. In 2012, the number of text messages sent a year was estimated to be a staggering 8.7
trillion
.
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But things are not looking good for the human race. Not only do we have the ability to destroy our global civilisation in a single day with nuclear weapons but our sheer numbers are putting the global environment under creaking strain. The climate is changing, the seas are losing their productivity and the species we share the planet with are suffering a major extinction event. Not since the advent of cyanobacteria, which poisoned the planet with oxygen, has a single species had such a devastating effect on the Earth. All we can hope is that the unprecedented level of interactions between human beings will throw up the solutions we need to head off a catastrophe.

Our extinction now would be a terrible shame because we have come so far and have achieved so much. Perhaps the most extraordinary development occurred on 20 July 1969 when a human being for the first time set foot on another world. In the annals of life on Earth, Neil Armstrong’s ‘one small step for [a] man, one giant leap for mankind’ was the most significant development
since the first amphibian crawled out of the ocean onto dry land 350 million years ago. Who would have guessed, when
australopithecines
left footprints in the Laetoli dust that, 3.6 million years later, their descendants would leave footprints in the dust of the Sea of Crises?

But let us not get carried away. Let us remember why we are here: because our farming ancestors learned the subtle art of genetic engineering. As an anonymous writer observed, ‘Man – despite his artistic pretensions, his sophistication, and his many accomplishments – owes his existence to a six-inch layer of topsoil and the fact that it rains.’

A thin metal wire comes into your home and something
invisible
travels down it. The
something
not only has the
oomph
to spin the tumbler of a washing machine but to light every room in your home – and in winter even heat your home as well. Not only your home but millions of other homes.
Billions
even. Everyone knows that electricity powers the planet. But how in the world does it do it?

Here’s an explanation. It requires a little background. Imagine there is a force that behaves like gravity but differs from gravity in two key respects.
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First, instead of separate chunks of matter always attracting each other in the way that the Sun and Earth do, there are
two
types of matter that experience the force differently. Call them Type 1 and Type 2, or A and B, or positive and negative. It does not matter. The key thing is that
unlikes
attract with the force while
likes
repel with the same force.

A bunch of positives therefore repel and flee from each other in all directions and a bunch of negatives does exactly the same. However, with an evenly mixed bunch of positives and negatives, something quite different happens. The opposite pieces pull each other together and the like pieces drive each other apart. But, because the opposing forces are equal and opposite, there is a perfect balance.

It follows that if there are two bodies, each of which is an equal mixture of negatives and positives, they will neither attract nor repel each other.

A force that behaves like this does indeed exist. It is called the
electric force
. And ordinary matter – the stuff of which you and me and the world around us is made – turns out to be an even mixture of positively
charged
protons and negatively
charged
electrons. (Protons are confined to the core, or nucleus, of each atom, whereas electrons orbit the nucleus.) The balance of attraction and repulsion is so perfect that, when you stand near someone else, neither of you feels the slightest force. In fact, in everyday life, there is very little hint that the electric force exists at all.

A force that can be both attractive and repulsive but which, in normal circumstances, is cancelled out perfectly probably seems dull and unremarkable. But, remember, the electric force differs from gravity in not one but
two
respects. While the first difference ensures that the force is pretty much always nullified, the second difference is at the very root of the force ’s extraordinary ability to power the modern world. The electric force is
stronger
than gravity. But not by a factor of 10. Or of 100. Or even a million. No, the electric force is stronger than the force of gravity by a factor of
10,000 billion billion billion billion
.
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To get some idea of what this enormous number means, imagine a mosquito buzzing in a jar. Say, by some wizardry, it is possible to remove all the negative electrons from the atoms of the mosquito so that all that are left behind are the positive atomic nuclei.
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These will, of course, repel each other. The mosquito will explode. The question is: with how much energy will the mosquito explode?

Perhaps you think the answer is (b) a stick of dynamite, or maybe (c) a 1 megatonne H-bomb? If you think (c), you are at least on the right track. A hydrogen bomb is a useful comparison. But not a
single
hydrogen bomb.
A million billion 1-megatonne H-bombs
. The mosquito will explode with an energy equivalent to the city-sized asteroid that slammed into the Earth 65 million years ago and wiped out the dinosaurs. The answer is (d). The mosquito will explode with the energy of a
global mass extinction
. Were it not for the fact that the mind-bogglingly huge electric force – 10,000 billion billion billion billion times stronger than gravity – is invariably cancelled out, each and every mosquito on Earth would be a potential world-destroyer. Thank goodness that in physics, as in life, opposites attract.

Now perhaps it is possible to appreciate the potential of the electric force for energising the world.

Removing all the electrons from a mosquito – if it were possible – would create a dramatic charge imbalance and unleash a truly extraordinary amount of electric energy.
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It follows that creating even a modest charge imbalance might unleash a significant amount of electric energy. This is what happens in a thunder storm. Here, a charge imbalance builds up between a cloud and the ground (or, more commonly, between one cloud and another). Specifically, the underside of a cloud builds up a negative charge at the expense of the ground, which becomes positively charged. Eventually, the electric force between the cloud and the ground becomes so immensely strong that it is able to rip the outer electrons from the atoms in the air between.
This breakdown of the air sends an avalanche of electrons – typically, 100 billion billion of them – surging down to the ground to cancel out the charge imbalance. In short, it creates a lightning bolt.

A flow of electrons is called an electric current.
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Typically, in the case of a lightning bolt, the current is about 10,000 amps, though it can be as high as a few hundred thousand amps (by comparison, many household electrical appliances use less than 10 amps). For just a tenth of a second or so, the current surges down a channel the width of a pencil.
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The electrons that compose it slam into air atoms, like a myriad tiny ball bearings, transferring energy to their still-bound electrons. The air atoms gain so much energy that the temperature can soar to about 50,000 °C – almost 10 times hotter than the surface of the Sun. It is the supersonic expansion of this blisteringly hot air on either side of the lightning channel that creates the clap of thunder. And it is the atomic electrons, shedding their excess energy as photons, that
light up
the lightning bolt.

Lightning demonstrates some key properties of electricity. One is that, if a charge imbalance is created, the electric force is presented with an opportunity to unleash a large amount of energy.
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Another is that electrical energy can be transferred
across a distance
by an electric current. In a lightning bolt, the distance is typically a couple of kilometres. However, the longest recorded streak of lightning, observed near Dallas, Texas, was almost 200 kilometres long. The ability to transfer energy across a distance by an electric current has been of huge significance in creating the modern technological world.

Lastly, of course, lightning demonstrates that, by means of an electric current, it is possible to change electrical energy into
other forms of energy – specifically, heat and light. The ‘killer app’, responsible for kick-starting the electrical revolution of the late nineteenth century, was in fact the light bulb. The electrical pioneers were not thinking about putting electricity into the home or even electrical appliances in the home. They were thinking about putting
light in the home
. ‘The light bulb is what wired the world,’ says Jeff Bezos, founder of Amazon.com.

Just as a current in lightning transfers energy to the air – heating and lighting it up – a current in a light bulb transfers energy to a filament – heating and lighting it up. The clever bit – perfected, though not invented, by Thomas Edison – is putting a filament in an oxygen-free glass bulb so that it glows
without burning away
.
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But although lightning demonstrates some key properties of electricity, building up a huge charge imbalance and waiting for the air to break down catastrophically is hardly a practical way to generate an electric current. Fortunately, there is a more convenient and controlled way. To understand it, however, it is first necessary to appreciate how exactly the electric force of an electric charge reaches out across space and influences other charges.

If you rub a balloon against a nylon sweater, loose electrons get transferred from one to the other. It does not matter which way they go – and, in fact, it is not entirely clear. The point is that both the balloon and sweater become electrically charged.
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If you now bring the charged-up balloon close to a small scrap of paper, the scrap will leap through the air, yanked by the electric force, and glue itself to the balloon.
10
Somehow, the electric force of
the balloon has reached out through the air and grabbed the scrap of paper.

Physicists say that extending out through space from an electric charge is an invisible electric
force field
, rather like a
Star Trek
tractor beam. When the paper finds itself in the field, it experiences a force towards the charge.
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The field of force around a charged balloon is feeble but between a storm cloud and another cloud or between a cloud and the ground it can be enormous. And it is this field that eventually becomes so irresistibly strong that it tears electrons from the very atoms of the air, creating the electron avalanche of a lightning bolt. In fact, the field in a thunderstorm can be strong enough to be
felt
, prickling the skin and even making hair stand on end. Mind you, if you experience either of these sensations, throw yourself flat to the ground. A lightning strike is imminent and your name is written on it.

But there is more to the electric field than an invisible force field that extends outwards from an electric charge (pulling in unlike charges and pushing away like charges). This merely describes the force surrounding a
static
charge. If the charge is
moving
relative to a second charge, a new force puts in an appearance. The second charge, in addition to the electric force, experiences a
magnetic force
.

The magnetic force field is easier to imagine than an electric force field. After all, if you have a bar magnet and a nail and bring them together, you can actually
feel
the invisible tractor beam of the magnetic field of the magnet clamping onto the nail. In fact,
it was seeing the needle of a magnetic compass respond to the Earth’s magnetic field that blew the mind of Albert Einstein, aged four or five, switching him on to science and teaching him a lesson about nature that he never forgot: there is ‘something behind things, something deeply hidden’.
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The fact that a magnetic field is caused by a
moving electric charge
helps explain the origin of the magnetic field of permanent magnets. Every material, including the flesh and blood of which you are made, consists of countless charged electrons, not only moving in orbit around the nuclei of atoms but actually behaving like tiny spinning tops themselves. This means every atom and every electron is like a tiny magnet. In most materials, all the countless mini-magnets are orientated randomly and so, overall, their magnetic fields cancel out. However, in some materials, this cancellation is not perfect. Such materials are permanent magnets.

The fact that a moving electric charge creates a magnetic field was first noticed in 1820 by Danish physicist Hans Christian Ørsted. He saw that the needle of a magnetic compass was deflected when he brought it close to a conducting wire carrying an electric current. A current, by definition, is electric charge in motion, and electric charge in motion obviously has a changing electric field. What Ørsted realised was that
a changing electric field creates a magnetic field
.

Bring two magnets together and feel the powerful force between them.
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As Ørsted discovered, a current-carrying coil of wire, with its changing electric field,
is
a magnet. Bring it together with a permanent magnet and there will be a force between the two, just as there would be between two permanent magnets. Arrange the coil and the magnet in the right way – and
this takes some ingenuity – and the force will cause the coil of wire to
spin. Voilà
. You have created an electric motor.

The reason a magnetic field can spin something is that it has what physicists call curl. Whereas an electric field extends radially outwards from a charge, a magnetic field – for instance, one created by a current-carrying wire – swirls around like a miniature tornado of force.

With the aid of an electric motor, it is possible to do a lot more with an electric current than merely create heat and light. It is possible to
move
things. In the motor of an electrical appliance, the changing electric field of an electric current generates a magnetic field of the force that propels a spindle. It is possible to drive everything from washing machines to automatic doors to electric cars and trains. And this is all down to the simple fact that a
changing electric field creates a magnetic field
.

Of course, it goes without saying that the prerequisite for running an electric motor is an electric current. Nature can create one – fleetingly and chaotically – in a lightning bolt. But how is it possible to create an electric current in a practical and controlled way? The answer is by exploiting another property of electric and magnetic fields. It was first noticed in 1831 by English physicist Michael Faraday. Faraday was the father of our electrical power system. ‘Even if I could be Shakespeare I think that I should still choose to be Faraday,’
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wrote Aldous Huxley, author of
Brave New World
. And, famously, when asked by William Gladstone, Chancellor of the British Exchequer, ‘What is the practical use of electricity?’, Faraday replied, ‘Why, sir, there is every probability that you will soon be able to tax it.’