But the point of it all is hidden in the white snout, the part of the mechanism that’s just behind the blades. If I push my nose up against the glass and look up, I can see the whole hub rotating. Right above my head, the edge of the hub closest to the tower spins smoothly around a stationary inner ring. This edge is lined with strong permanent magnets, so the magnets are rotating past the inside of the hub. And the inner ring is lined with copper coils, each connected to the circuitry behind. As each magnet whizzes past each coil, it generates a current through the wire. Electrons are shoved through the coil, and then pulled back again by every magnet that goes past. Without the magnets and the wires touching, energy is transferred from the rotation to become electrical energy in the wires. The blades are driving the magnets past the coils, and the rules of electromagnetic induction are creating a current in each coil. This is how electricity is born.
The same principle operates in all our power stations, whether they’re producing coal, gas, nuclear, or wave energy. Magnets are pushed past wires, and so movement energy is transferred into electrical current. The beauty of a wind turbine is that this is as raw as it gets; the wind turns magnets which generate current. In a coal-fired plant, water is heated to turn a steam turbine, which turns magnets. The outcome is the same, but it takes a few extra stages to get there. Every time you plug anything in, you’re using energy that flowed into the grid as a magnet pushed on the electrons in a coiled copper wire. Electricity and magnets are inseparable. Our civilization relies on energy that is harvested and distributed using the dance between these two twins. We have done spectacularly well at hiding the dance away, trapping it in shielded wires and behind walls and in buried cables. We’ve done so well at masking it that a child born today may never directly see or experience electricity or magnetism at all. Future generations could be deprived of any contact with the elegance and importance of electromagnetism, as the invisible cloak of progress settles over it all. But it matters, because these days the fabric of our civilization is sewn together with electromagnetic threads.
* The newer pennies are ever so slightly thicker because they’ve been made to weigh exactly the same as the older ones (the same mass of steel takes up slightly more space than copper). That’s why vending machines have to be changed when the Mint alters the material of the coins—different metals take up a different amount of space for a given mass. Vending machines also test that the magnetic properties are correct for the coin type.
? I’m not even joking. They’re very proud of it. Little Miss Vegetarian here was excused, but I gather it’s mostly made up of giant marine mollusks and garlic.
? Molecules are formed when electrons shift around so they’re being shared between different nuclei: This sharing forces the nuclei to stay close together, forming a single molecule made up of different atoms. The only thing that holds atoms and molecules together is that positive charges attract negative charges. Sometimes, electrons shuffle around between molecules, changing which nuclei are pinned together, and the pattern made by those nuclei. We call that a chemical reaction. Chemistry is the study of this electronic dance, and the fantastic complexity it produces.
§ There’s one more twist in the tale of the bee. Researchers from Bristol University discovered in 2013 that each flower has a slight negative charge that’s neutralized as the bee arrives. They demonstrated that bees can tell a neutral flower from a negatively charged one without landing on it. They suggested that bees might avoid neutralized flowers, because it suggests that another bee got there first and took the lion’s share of the nectar. For more on this, see the papers by Clarke et al. and Corbet et al. listed in the References section at the end of the book.
? This is all that happens in an electric heater in your home. Electrons are forced through a huge resistance, and their electrical energy is converted to heat. Every other energy conversion process is inefficient, because some energy is always lost to heat, but if heat is what you want, you can have 100% efficiency . . . perfect!
# For the pedants out there, yes, there are superconductors. But cooling things down to close to absolute zero uses huge amounts of energy and produces huge amounts of heat. So it doesn’t really help if you’re after energy efficiency.
** So it gets back to where it started 50 times each second—this is what it means to say that the UK power supply runs at 50 Hz.
?? For those who like the details: There are two steps to what the adapter does. It changes the voltage from 220V to 20V or whatever the laptop needs. And then it has to cut off half of every cycle so that it only gets the current when it’s going in one direction and not when it’s going back again. After that it smooths it out a bit to make the same sort of steady current that you get from a battery.
?? This discovery caused enormous excitement. Physicists had detected a pattern in the particles that make up our universe, a pattern they call “the Standard Model” of particle physics. But the pattern could only be correct if one very specific particle existed: the Higgs boson. It took decades to find it, and it was a tremendous boost to confidence in our understanding of our world when it was proven to exist.
§§ Or possibly two numbers that are different by 18 (09-27, for example). That’s because you can take off and land either way along the runway, but obviously your heading would be different by 180 degrees.
?? The Canadian Lawrence Morley had also proposed the same idea at the same time, but his paper had been rejected by journals for being laughably silly.
## It’s often said that it’s growing at about the same rate as your fingernails.
CHAPTER 9
A Sense of Perspective
EACH OF US relies on three life-support systems: the human body, planet Earth, and our civilization. The parallels between the three systems are powerful, because they all exist in the same physical framework. Having a better understanding of all three may be the best thing that we can do to keep ourselves alive and keep our society thriving. Nothing could be both more pragmatic and more fascinating. So this final section of the book will provide some perspective, taking each of our life-support systems in turn.
Human