If the future's electric, why isn't the past? Think a little bit
about that simple-sounding question and you'll understand what
science is all about and why it matters so much to humankind.
Consider this: the ancient Greeks knew some basic things about
electricity over 2500 years ago, yet
they didn't have electric cookers or fridges,
vacuum cleaners. How come?
Electricity is just the same as it was back then:
it works in exactly the same way.
What's changed is that we understand how it works now and we've figured out effective ways to
use it for our own ends. In other words, science (how we
understand the world) has gradually helped us to produce effective technology
(how we harness scientific ideas for human benefit). The steadily
advancing science of electricity has led to all kinds of electrical
technologies that we can no longer live without. It's been an incredible
achievement, but where and how did it begin? Let's take a closer look!
Photo: A statue of Thales of Miletus gripping the discovery for which he's best known: electricity.
Photo of a statue by Louis St. Gaudens at Union Station, Washington, DC. Credit: Photographs in the Carol M.
Highsmith Archive, courtesy of Library of Congress, Prints and Photographs Division.
Science historians have charted human knowledge of magnetism as far back as 2637BCE, which seems to be the date when compasses were used for the first time. 
Archeologists have found indications that primitive, perhaps "accidental" electroplating (coating one metal with another) dated back almost as long, but the scientific history of electricity is much more recent. 
Way back in 600BCE, a Greek mathematician and philosopher named
Thales (c.624–546BCE), who lived in the city of Miletus (now in Turkey), kicked off our story when he discovered the
basic principle of static electricity (electricity that builds up in
one place). As he rubbed a rod made of amber (a fossilized tree
resin), he found he could use it to pick up other light objects, such
as bits of feathers. (You've probably done a similar experiment
rubbing a ruler or a balloon and using it to pick up pieces of
Before Thales came along, people might well have explained
something like this as magic: ancient people didn't reason
things out scientifically the way we do today. Their explanations
were often a muddled mixture of magic, superstition, folklore (stories), and
Thales is often called the world's first scientist,
because he was one of the very first people who tried to find
sensible, rational explanations for things. His explanations weren't
always correct (he thought everything in the Universe was ultimately made of
water and believed Earth was a flat disc), but they were the best
logical deductions he could make from his observations of the
world—and, in that sense, they were scientific. 
Photo: "Aristotle" pictured at the National Academy of Sciences, Washington, D.C. Credit: Photographs in the Carol M. Highsmith Archive, courtesy of Library of Congress, Prints and Photographs Division.
The logical, scientific ways of doing things we rely on today were
developed by later Greeks such as Aristotle (348–322BCE)
and Archimedes (287–212BCE), who built on Thales' work, and
Islamic scholars such as Alhazen (965–1040CE), who
gave us the scientific method: coming up with a tentative explanation for
something (a hypothesis), which is then tested through experiments
to make a more robust explanation (a theory).
Important though these people were, electricity (as we know it today) didn't figure in
their thinking. They had little conception of how useful it could be—or
what it would eventually lead to. They were more concerned with astronomy,
mathematics, matter, and optics (how light works). Science might have
been in its advent, but electricity was still just a "magical"
curiosity—of very little practical use.
Incredibly, the scientific study of electricity didn't really advance any
further for a full 2000 years after Thales' original discovery. But
around 1600CE, Englishman William Gilbert (1544–1603), a physician to the
English Queen Elizabeth I, started to probe it further. Gilbert
was the person who coined the Latin term "electricus" (a word meaning "like amber,"
reflecting Thales' original discovery) and he believed electricity was caused by a fluid called
"effluvium" that could move from place to place.
This was an important insight because it was the first real suggestion
that electricity could form what we now call a current, as well as
remain static (in one place). Although Gilbert is much better known
for his work on magnetism (he made the important deduction that Earth
behaves like a giant magnet), and compared it with electricity,
he didn't unite the two things in a single theory. If he'd done so, he
probably would have gone down in history as one of the greatest
physicists of all time. (As we'll see later, the person who finally
achieved that, James Clerk Maxwell, is celebrated in exactly that way.)
Artwork: "Experiments and Observations Tending to Illustrate the Nature and Properties of Electricity": The cover of William Watson's book of electrical research.
It was now becoming clear that there was much more to electricity
than the ancients had realized. In 1733/4, almost 150 years after
Gilbert's death, a French physicist named
Charles du Fay
(1698–1739) made the next important breakthrough when his
experiments revealed that static electricity could come in two
different (opposite) flavors, which he named "vitreous" and "resinous."
If you rubbed some objects, they gained one kind of electricity; if you rubbed others, they gained the opposite
kind. Just as two "like" magnets (two north poles or two south
poles) will repel, so two objects with "like charges" of
electricity will also repel, while objects with unlike charges (like
magnets of opposite poles) will attract.
Although we now know this
idea is correct, back in the 18th century, such a convoluted
explanation sounded wrong to some people. Why should there be two
kinds of electricity? Didn't it flout a basic scientific principle
called Occam's razor—the idea that explanations should be as simple
Englishman Sir William Watson (1715–1787)
thought there was just one kind of electricity,
with an ingenious explanation much more like our modern view:
if we have too much electric charge, it seems like one kind of electricity; if too little, the other kind.
Watson gave us the concept of electric circuits (closed paths around which charge flows)
and made an important distinction between conductors and insulators.
He was also one of the first to show that electricity could zip down very long wires,
and his other experiments included passing electricity through lines of several people to give them surprising
Photo: A museum exhibit at Independence National Historical Park in Philadelphia, Pennsylvania,
illustrating Benjamin Franklin's highly dangerous attempt to catch electricity in a thunderstorm. Credit: Carol M. Highsmith's America Project in the Carol M. Highsmith Archive, courtesy of Library of Congress, Prints and Photographs Division.
Two decades later, the question of how many kinds of electricity
there were was effectively settled by Watson's contemporary, the American
polymath Benjamin Franklin (1706–1790). Printer, journalist,
inventor, statesman, scientist and more, he made all sorts of
contributions to 18th-century American life. One of his most
important achievements was confirming that there was a single "electric fluid,"
giving rise to the two "kinds" of electricity, which he named
(as we still do today) "positive" and "negative."
Like Watson, Franklin helped to tease out the mystery between static
and current electricity. In his most famous (and indeed most
dangerous) experiment, he flew a kite in a thunderstorm with a metal
key attached to it by a long string. The basic idea was to catch
electrical energy in the clouds (static electricity) from a lightning
strike (current electricity), which he hoped would travel down the
string to the key (more current electricity). Fortunately, lightning
didn't strike the kite, which might well have killed Franklin,
but he was able to detect charges and sparks, so confirming his ideas.
DON'T try anything like this at home!
“And when the rain has wet the kite and twine, so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle.”
Franklin's electrical research marked a new milestone and
hinted of much more to come, because it suggested electricity could be captured and
stored as a form of energy. But electricity turned out to be
even more useful when people discovered how it could exert a force.
That was demonstrated by Frenchman
Charles Augustin de Coulomb
(1736–1806), who charged up two small spheres with positive
electricity and then measured the (repulsive) force as they pushed
away from one another (repelling the same way as two magnets with like
charges). Coulomb found that the force between charges depended not
just on their size but also on the distance between them—something
now known as Coulomb's law. (The basic unit of electric charge is also named the Coulomb in his
Electrical experiments were still hampered by the sheer difficulty
of making and storing electricity, which, at this time, essentially relied on
rubbing things to build up a good static charge.
The study of electricity really advanced when a group of European
scientists devised ways of storing electrical charges in glass jars
with separate pieces of metal attached to the inside and outside
surfaces—devices known as Leyden jars, which were the first
effective capacitors (charge-storing devices). Developed
independently in the 1740s by German Ewald Georg von Kleist and Pieter van Musschenbroek (of the city of Leyden, hence the
name), they offered a much more convenient way of studying electricity.
Ever since Thales' original discovery, scientists knew that
static electricity could be made by rubbing things, but no-one knew
exactly why this was so or where the electricity ultimately came
from. In the late 18th century, Italian biologist
(1737–1798) found he could make electricity in a completely
different—and totally unexpected—way: using the legs of a dead
frog. In his most famous experiment of all, when he pushed brass
hooks into a frog's legs and hung them from an iron post, he saw
the legs twitch from time to time as electricity flowed through them.
That led him to think that living things like frogs contained
something he called "animal electricity," which the metals were
Artwork: Luigi Galvani believed he'd discovered "animal electricity" when he
hung a frog's legs from a metal hook (left) and watched them twitching. Illustration courtesy of US Library of Congress.
In fact, as another Italian, physicist
(1745–1827) soon discovered, Galvani had leaped to the wrong
conclusion. The twitching frog was merely the current detector, not
the source of the current. The important thing, as Volta discovered
when he experimented with all sorts of different materials, was "the
difference in the metals." What was really happening was that the
two different metals, connected through the moist, fleshy, froggy tissue, were
producing electricity chemically.
Volta managed to recreate this
effect with discs of two different metals, silver and zinc, separated
by pieces of cardboard soaked in saltwater, and that was how he came
to invent the world's first proper battery—an invention that
revolutionized the history of electricity. It was a perfect example
of how a scientific discovery can be rapidly turned into a
practical technology—and one that allowed science to advance
even further by making experiments easier.
Even in Volta's time, the discovery was considered
so impressive that the inventor was asked to demonstrate it
before the great French emperor Napoleon I, who set up the Galvanism Prize
in his honor. (His nephew, Napoleon III, set up a Volta Prize to reward
great scientific discoveries some years later.)
Volta's invention also led to the development of a new branch of science called
electrochemistry. One of its founding fathers,
Sir Humphry Davy
(1778–1829), used a kind of electrochemistry known as electrolysis (effectively,
making a battery work in reverse) to discover a number of chemical elements, including sodium
and potassium, and later barium, calcium, magnesium, and strontium. Fittingly, he
was awarded a Galvanism Prize for his work in 1807.
There's electricity—and there's magnetism. That's how people
like William Gilbert saw the world and it's still how we study it in schools to this day.
The idea is not wrong, but it's a little bit misleading, because electricity and magnetism are
essentially two different ways of looking at the same, bigger
phenomenon. They're like two sides of the same coin or the front
and back of a house. There had been various clues about the links
between electricity and magnetism over the years. (In 1735, for
example, the scientific journal Philosophical
Transactions of the Royal Society of London had carried
"An account of an extraordinary effect of lightning in communicating magnetism": according to a doctor in Yorkshire,
a lightning bolt had struck the corner of a house where a large box of
metal knives and forks were stored, scattering them around and, curiously, magnetizing them in the
process.) But the definitive connection between electricity and
magnetism was really first established by a series of revolutionary
experiments that European scientists carried out in the 19th century.
The person who gets the credit for discovering what we now know as
electromagnetism was Danishman Hans Christian Oersted
(1777–1851), a physics professor in Copenhagen who had
been inspired by Volta's invention of the battery. 
Around 1820, during a student lecture, he just happened to place a compass near an
electric wire and switched on the current. Incredibly, he noticed that the sudden
current made the compass needle move, while reversing the current
made the needle move the opposite way, suggesting the electricity
flowing through the wire was making magnetism (because that's what
a compass detects). 
Though this was a major discovery, it wasn't
the first proof of electromagnetism. About 20 years earlier,
an Italian philosopher named Gian Domenico Romagnosi (1761–1835) had done a
similar experiment, but few remember him today. 
Animation: Oersted's experiment: When he placed a compass near a wire and switched on the current, the compass needle moved one way; when he reversed the current in the wire, the needle moved the opposite way.
“...the magnetical effects are produced by the same powers as the electrical...
all phenomena are produced by the same original power”
After learning of Oersted's work, Frenchman Andre-Marie
Ampère (1775–1836) carried out another groundbreaking
experiment with two wires placed side by side. When he switched on
the current, he found the wires could push apart or pull together.
One of his important conclusions was that a current-carrying wire
makes a magnetic field at right angles, in concentric
circles around the wire—rather like the ripples on a pond when you drop a stone
This was all very interesting, but what use could it possibly be?
Step forward English chemist and physicist Michael Faraday (1791–1867),
originally an assistant to Sir Humphry Davy, who took "Ampère's
beautiful theory" (as he called it) a stage further. 
Ingeniously, he found he could make a wire rotate by passing electricity through it,
because the flowing current created a magnetic field around it that would push against the field of a nearby magnet—and
so invented a very primitive and not very practical electric motor. A few years later, he realized
this invention would also work in reverse: if he moved a wire through
a magnetic field, he could make electricity surge through it. That
marked the invention of the electricity generator—a simple but
revolutionary device that now provides virtually all the electricity
we use to this day. Faraday, though he stood on the shoulders of Oersted, Ampère, and those
who came before, arguably made the greatest contribution to our modern age of electric power.
Photo: Joseph Henry, America's answer to Michael Faraday,
is honored by this statue at the US Library of Congress Thomas Jefferson Building.
Photo by Carol M. Highsmith. Credit: Library of Congress Series in the Carol M. Highsmith Archive, courtesy of Library of Congress, Prints and Photographs Division.
Faraday wasn't the only pioneer of electromagnetism, however.
Elsewhere in the UK, William Sturgeon (1783–1850), a
brilliant but undeservedly forgotten inventor, was carrying out very similar
experiments. In 1825, between Faraday's inventions of the
electric motor and generator, Sturgeon built the first powerful
electromagnet by coiling wire around an iron bar and sending a
current through it. Over in the United States, in 1831, physicist
Joseph Henry (1797–1879) made far bigger and better electromagnets (reputedly boosting the strength of the magnetic
field by using wire insulated with cloth torn from his wife's
undergarments) until he'd built a huge electromagnet that could lift
a ton in weight.  Powerful electromagnets like this
are still used in junkyards to this day to heave metal car bodies
from one place to another. The following year, Sturgeon built the
first practical, modern electric motor,
using an ingenious device called a commutator
that keeps the motor's axle rotating in the same direction.
A powerful force
Motors and generators—two parts of Faraday's very impressive
legacy—are the twin bedrocks of our modern electric world.
Generators make electric power, motors take that power and do useful
things, from pushing
down the road to sucking up dirt in your vacuum. But electrical energy doesn't come from thin air;
as Volta showed, it doesn't even come magically from dead
animals. If we want a certain amount of electrical energy, we have to
produce it from at least as much of another kind of energy. That's
a basic law of physics known as the law of conservation of energy,
largely figured out by Scottish physicist James Prescott Joule
(1818–1889) in the 1830s. Joule showed how different kinds of
energy—including ordinary movement (mechanical energy), heat, and
electricity—could be converted into one another.  What Joule's
work means, essentially, is that if you want to run a huge city like
New York or Sao Paulo off electricity, you'll need to harness huge
amounts of some other kind of energy to do it. So, for example,
you'll need a giant power station burning huge amounts of coal,
hundreds of wind turbines, or a vast area of
Photo: Power pioneer: Thomas Edison built the first practical power plants, which made
electricity from coal using dynamos like this evolved by Michael Faraday's generator.
Photo by H.C. White Co., courtesy of US Library of Congress.
Making enough energy to supply towns and cities with electricity
became possible when a Belgian engineer named
(1826–1901) built the first large-scale, practical direct-current (DC) generators in
the 1870s. In 1881, the world's first power plant opened in the small town of Godalming, England. The following year,
Thomas Edison (1846–1931) built the first full-scale power plant at
257 Pearl Street in Manhattan, New York City.
While Edison opted for plants that produced DC
electricity, his former employee turned bitter rival Nikola Tesla
(1856–1943) thought alternating current would work much better,
since, among other things, it could be used to transmit power
efficiently over very long distances. Tesla teamed up with engineer George
Westinghouse (1846–1914), and the two launched a bitter battle with
Edison—now known as the
of the Currents—until they'd firmly
established AC as the victor. Today, though AC remains the heart of
the electricity "grid" systems that provide much of the world's
power, DC has again grown in importance thanks, in particular, to things
like solar cells, which generate direct (rather than alternating)
By the end of the 19th century, electricity and magnetism were
happily married in motors and generators, but what was the
real connection between them? Why did one produce the other?
The mystery was largely solved in the second half of the 19th century by a
brilliant Scottish physicist named
James Clerk Maxwell (1831–1879).
In 1873, building on Michael Faraday's work, Maxwell
published a complete theory of electromagnetism, neatly summarizing everything that was then known
about electricity and magnetism in
four apparently simple mathematical equations.
Maxwell's theory explained how static or moving electric charges create electric
fields around them, while magnetic poles (the ends of magnets) make
magnetic fields. It also showed how electric fields can create
magnetism and magnetic fields can make electricity, and tied
electromagnetism together with light. This was
one of the most fundamental and far-reaching theories of physics advanced so far—as
radically important as Newton's work on gravity.
Of course, electricity and magnetism were just the same as they had always been.
What was different, following the work of James Clerk Maxwell, was a
bold new understanding of how they worked together: a revolutionary new
piece of science. And as the 19th century rolled on, technology advanced
too: with the work of Edison, Tesla, and others, there was a growing understanding of how
electromagnetism could put to good use as a practical way of storing and transmitting energy.
All that was remarkable enough, but thanks to Maxwell's insights,
linking electricity and magnetism to light waves,
electromagnetism would soon change the world in another very
important way: as a form of communication.
The first inkling of an exciting new form of electromagnetism came
the decade after Maxwell had died. Maxwell had realized that
electromagnetism could travel in waves. In 1888, a German physicist named
Heinrich Hertz (1857–1894)
found he could make some of these waves, in which electrical and magnetic energy tangoed through the
air at the speed of light. 
Apart from confirming Maxwell's ideas,
this scientific advance opened up another new bit of technology:
a practical way for sending information wirelessly from one
place to another. English physicist Sir Oliver Lodge
(1851–1940), who had been carrying out similar research to Hertz,
Guglielmo Marconi (1874–1937), a brilliant showman with a gift for popularizing science, were among those who
developed this technology. Originally called "ether waves," and
now much better known to us as radio, it evolved into
and a whole variety of other things.
The source of electricity
Electricity has always been magical. Imagine how enthralled Thales
must have been when he first saw static over 2500 years ago.
Or what Heinrich Hertz felt like as he made
the first radio waves in his laboratory in Karlsruhe in 1888. At the dawn of
the 20th century, electricity seemed magical in all sorts of ways.
Thomas Edison was building bold power plants and switching the world to
the wonders of incandescent electric light. Marconi, meanwhile, was
bouncing radio waves around the world. And there was a new kind
of electrical magic as well: the dawning realization that electricity
and magnetism originated from tiny particles inside atoms.
The idea that there must be a kind of "particle of electricity"
had originally been put forward in 1874 by Irishman
George Johnstone Stoney
(1826–1911), who had previously studied the kinetic theory (how gas particles carried heat). 
Similar ideas were advanced in 1881 by German physicist Hermann von Helmholtz (1821–1894) and Dutchman
named Hendrik Antoon Lorentz (1853–1928);
together, these three developed the modern "particle" theory of electricity, in which static
charges are seen as a build up of electric particles, while electric
currents involve a flow of these particles from place to place.
But what were the particles? The growing understanding of atoms and the
world inside them, by
Ernest Rutherford (1871–1937) and his colleagues, offered up a
possible candidate in the shape of the electron,
a particle Stoney named in 1891.
Electrons were finally discovered in 1897 by British physicist
J.J. Thomson (1856–1940), while he was playing around with a gadget called a
cathode-ray tube, rather like an old-fashioned TV set. 
Animation: Solid-state physics explains that electric current is carried
by electrons (blue) moving through materials.
During the 20th century, scientists came to understand not just
how electrons power electricity and magnetism, but how they're
involved in all kinds of other physical phenomena, including heat and
light. Known as solid-state physics, these scientific ideas have led to some
revolutionary electronic technologies, including the transistor,
for computers, solar cells,
and superconductors (materials with little or no electrical resistance).
Today, as the world grapples with pressing problems like
air pollution and
climate change, the need to switch from dirty fuels to
cleaner forms of power has made electricity more important to
us than ever. Back in Thales' time, electricity was just a
take-it-or-leave-it, magical curiosity; today, it's central to our
world and everything we do. The story of electricity runs, like a current,
right through our past. Thanks to the brilliant work of these scientists
and inventors, it also points to a bright and hopeful future.
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