Electricity is vital to our modern world. Without it, I couldn’t write this post, and you couldn’t read it. That alone should show you just how important it is, but if not, then how about anything from this list: air conditioning, TVs, computers, phones, music players. And that’s just what I can see in the room around me! So electricity seems like a good start for this series. It’s something we can’t live without, but its discovery was relatively recent, as eras go.
Intro
The knowledge of electricity, in some form, goes back thousands of years. The phenomenon itself, of course, began in the first second of the universe, but humans didn’t really get to looking into it until they started looking into just about everything else.
First came static electricity. That’s the kind we’re most familiar with, at least when it comes to directly feeling it. It gives you a shock in the wintertime, it makes your clothes stick together when you pull them out of the drier, and it’s what causes lightning. At its source, static electricity is nothing more than an imbalance of electrons righting itself. Sometimes, that’s visible, whether as a spark or a bolt, and it certainly doesn’t take modern convenience to produce such a thing.
The root electro-, source of electricity and probably a thousand derivatives, originally comes from Greek. There, it referred to amber, that familiar resin that occasionally has bugs embedded in it. Besides that curious property, amber also has a knack for picking up a static charge, much like wool and rubber. It doesn’t take Ben Franklin to figure that much out.
Static electricity, however, is one-and-done. Once the charge imbalance is fixed, it’s over. That can’t really power a modern machine, much less an era, so the other half of the equation is electric current. That’s the kind that runs the world today, and it’s where we have volts and ohms and all those other terms. It’s what runs through the wires in your house, your computer, your everything.
Theory
The study of current, unlike static electricity, came about comparatively late (or maybe it didn’t; see below). It wasn’t until the 18th century that it really got going, and most of the biggest discoveries had to wait until the 19th. The voltaic pile—which later evolved into the battery—electric generators, and so many more pieces that make up the whole of this electronic age, all of them were invented within the last 250 years. But did they have to be? We’ll see in a moment, but let’s take a look at the real world first.
Although static electricity is indeed interesting, and not just for demonstrations, current makes electricity useful, and there are two ways to get it: make it yourself, or extract it from existing materials. The latter is far easier, as you might expect. Most metals are good conductors of electricity, and there are a number of chemical reactions which can cause a bit of voltage. That’s the essence of the battery: two different metals, immersed in an acidic solution, will react in different ways, creating a potential. Volta figured this much out, so we measure the potential in volts. (Ohm worked out how voltage and current are related by resistance, so resistance is measured in ohms. And so on, through essentially every scientist of that age.)
Using wires, we can even take this cell and connect it to another, increasing the amount of voltage and power available at any one time. Making the cells themselves larger (greater cross-section, more solution) creates a greater reserve of electricity. Put the two together, and you’ve got a way to store as much as you want, then extract it however you need.
But batteries eventually run dry. What the modern age needed was a generator. To make that, you need to understand that electricity is but one part of a greater force: electromagnetism. The other half, as you might expect, is magnetism, and that’s the key to generating power. Moving magnetic fields generate electrical potential, i.e., current. And one of the easiest ways to do it is by rotating a magnet inside another. (As an experiment, I’ve seen this done with one of those hand-cranked pencil sharpeners, so it can’t be that hard to construct.)
One problem is that the electricity this sort of generator makes isn’t constant. Its potential, assuming you’ve got a circular setup, follows a sine-wave pattern from positive to negative. (Because you can have negative volts, remember.) That’s alternating current, or AC, while batteries give you direct current, DC. The difference between the two can be very important, and it was at the heart of one of science’s greatest feuds—Edison and Tesla—but it doesn’t mean too much for our purposes here. Both are electric.
Practice
What does it take to create electricity? Is there anything special about it that had to wait until 1800 or so?
As a matter of fact, not only was it possible to have something electrical before the Enlightenment, but it may have been done…depending on who you ask. The Baghdad battery is one of those curious artifacts that has multiple plausible explanations. Either it’s a common container for wine, vinegar, or something of that sort, or it’s a 2000-year-old voltaic cell. The simple fact that this second hypothesis isn’t immediately discarded answers one question: no, nothing about electricity requires advanced technology.
Building a rudimentary battery is so easy that it almost has to have been done before. Two coins (of different metals) stuck into a lemon can give you enough voltage to feel, especially if you touch the wires to your tongue, like some people do with a 9-volt. Potatoes work almost as well, but any fruit or vegetable whose interior is acidic can provide the necessary solution for the electrochemical reactions to take place. From there, it’s not too big a step to a small jar of vinegar. Metals known in ancient times can get you a volt or two from a single cell, and connecting them in series nets you even larger potentials. It won’t be pretty, but there’s absolutely nothing insurmountable about making a battery using only technology known to the Romans, Greeks, or even Egyptians.
Generators a bit harder. First off, you need magnets. Lodestones work; they’re naturally magnetized, possibly by lightning, and their curious properties were first noticed as early as 2500 years ago. But they’re rare and hard to work with, as well as probably being full of impurities. Still, it doesn’t take a genius (or an advanced civilization) to figure out that these can be used to turn other pieces of metal (specifically iron) into magnets of their own.
Really, then, creation of magnets needs iron working, so generators are beyond the Bronze Age by definition. But they aren’t beyond the Iron Age, so Roman-era AC power isn’t impossible. They may not understand how it works, but they have the means to make it. The pieces are there.
The hardest part after that would be wire, because shuffling current around needs that. Copper is a nice balance of cost and conductivity, which is why we use it so much today; gold is far more ductile, while silver offers better conduction properties, but both are too expensive to use for much even today. The latter two, however, have been seen in wire form since ancient times, which means that ages past knew the methods. (Drawn wire didn’t come about until the Middle Ages, but it’s not the only way to do it.) So, assuming that our distant ancestors could figure out why they needed copper wire, they could probably come up with a way to produce it. It might not have rubber or plastic insulation, but they’d find something.
In conclusion, then, even if the Baghdad battery is nothing but a jar with some leftover vinegar inside, that doesn’t mean electricity couldn’t be used by ancient peoples. Technology-wise, nothing at all prevents batteries from being created in the Bronze Age. Power generation might have to wait until the Iron Age, but you can do a lot with just a few cells. And all the pieces were certainly in place in medieval times. The biggest problem after making the things would be finding a use for them, but humans are ingenious creatures. They’d work something out.