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On 22 September 1791 Michael Faraday was born in a London slum, the
third son of a poor blacksmith. Although denied a formal education, Faraday
rose from poverty and obscurity to secure a central place in science. He
was a truly great British hero, but the popular image of him as a kind of
‘Isambard Kingdom Brunel’ of science does not do his memory justice.

Faraday’s bicentenary is being celebrated in Britain in several ways.
An exhibition of his life and work will continue at the Science Museum until
the end of December (reviewed in New Scientist, 29 June). Several new books
about Faraday and the Royal Institution have been published. His name and
picture feature on a new stamp and a new £20 note. A memorial service
was held in Westminster Abbey on 20 September. All these will have gone
some way towards raising awareness of Faraday among the British public.

Imagine asking the average person to name half a dozen famous scientists.
Whose names might they be? Albert Einstein? Isaac Newton? Charles Darwin?
Richard Feynman? James Watson? Stephen Hawking? What distinguishes these
scientists from others, including Faraday? Rightly or wrongly, they are
known for their contributions to theoretical science. It appears that we
prize great thinkers above all others.

Faraday – so the story goes – was not a great thinker. We have a persistent
image of him as a very practical scientist, experimenting in a dingy laboratory
with coils of wire, bar magnets and iron filings. Nobody would dispute the
claim that his experimental discoveries about electricity dramatically and
irreversibly changed the shape of society. But for many people who have
only studied physics at school, even these achievements suffer from overfamiliarity.
Compared with exotic phenomena such as warped space-time or rotating black
holes, which are definitely not part of the school physics curriculum, Faraday’s
achievements might seem mundane.

Our image of Faraday is the result of myth-making that started a year
after his death. In 1868 John Tyndall, Faraday’s successor at the Royal
Institution, published a short biography that was to become a benchmark
for many future assessments of Faraday’s life and work.

In his biography, Tyndall was almost dismissive of Faraday’s theoretical
speculations, claiming that they ‘. . . lack that precision which the mathematical
habit of thought confers’. Better to stick to the experimental facts, Tyndall
suggested, which ‘. . . are sure to form the body of grand theories yet
to come’. So there it is: we should admire Faraday for his technical ability
with experimental apparatus, but pay less attention to his theorising. The
message seems to be that as a man with no mathematical training Faraday
was not really qualified to have opinions on matters of theoretical science.

Tyndall was not alone in dismissing Faraday’s theories. To understand
why, we need to remember that, in the first half of the 19th century, the
foundations of physics laid down nearly 200 years before by Isaac Newton
were still in pretty good shape. Admittedly, Newton’s theory that light
is made up of tiny corpuscles was under threat from Thomas Young’s experiments
on light interference that demonstrated light’s wave-like properties (experiments
carried out in the Royal Institution in 1802). But Young himself was savagely
attacked for his views by members of the scientific establishment.

Newton had developed theories based on concepts of force still familiar
today. Central to these is the idea of action at a distance – two bodies
may exert forces on each other without direct contact. For example, in Newton’s
theory of gravitation, the force of attraction between two bodies is inversely
proportional to the square of the distance between them. Similar inverse-square
laws were established for other forces. But then the question was: if the
forces are intrinsic to matter (gravitating bodies or charged particles)
how do their influences pass through the empty space in between?

On 29 August 1831, Faraday experimented with a soft iron ring around
which two wires were wound on opposite sides (see opposite). He found that
by connecting and disconnecting a battery to one of the wires, he could
induce an electrical current to flow in the other. The two wires were insulated
from each other and so, Faraday reasoned, the current in the second wire
must result from an influence of the force generated in the first.

Faraday tested this idea in many subsequent experiments over two months.
In one, he succeeded in generating an electric current in a helical coil
of wire by moving a bar magnet up and down its centre (see opposite, lower
figure). He had discovered the principle of electromagnetic induction, thereby
laying the foundations of the electrical industry.

Faraday’s induction experiments convinced him that action at a distance
could not explain the effects he was seeing. If you try to push the north
poles of two bar magnets together you can feel the resistance between the
magnetic forces literally in mid-air. The forces seem to act outside the
material. Faraday speculated that the space in between matter was somehow
responsible for the forces, and went on to develop the idea of a force field.
Induction worked because of theinfluence of the changing electric or magnetic
force field on the wire in which the induced current was generated.

In one of Faraday’s favourite demonstrations, he revealed the ‘lines
of force’ of the magnetic force field by sprinkling iron filings on a sheet
of paper held over a bar magnet. This experiment has since been repeated
by generations of schoolchildren. The iron filings become aligned in the
magnetic field, along the lines of force. They strikingly show what the
eye cannot normally see: beautiful patterns of forces spreading out in the
space between matter.

Images such as these led Faraday to believe that the current induced
in the coil of wire depends on the number of lines of magnetic force it
cuts. Although it lies outside matter, the force is real; it can produce
real effects. But Faraday went much further. He speculated that all forces
are, in principle, interconvertible. This was a radical departure from
the Newtonian concept of force.

Faraday emerges, therefore, not as an inveterate tinkerer in the laboratory
but as a man of genius with a clear vision wrought from purely speculative
reasoning. Convinced of the unity of forces, he used his superb talents
as an experimentalist to pursue his belief. Finding connections between
apparently disparate forces was to be a central theme of his scientific
work for the rest of his life.

However, Faraday’s belief in an underlying unity is not so surprising.
He was a devout member of the Sandemanian Church, a fundamentalist Christian
order that demanded total faith and total commitment. Sandemanians organised
their daily lives through their literal interpretation of the Bible. Both
Faraday’s father and grandfather had been Sandemanians and, when he married
Sarah Bernard in 1821, he married into a leading Sandemanian family.

Faraday found no conflict between his religious beliefs and his activities
as a scientist and philosopher. He viewed his discoveries of nature’s laws
as part of the continual process of ‘reading the book of nature’, no different
in principle from the process of reading the Bible to discover God’s laws.
A strong sense of the unity of God and nature pervaded Faraday’s life and
work.

On 30 August 1845, this sense of unity led Faraday to investigate the
connection between electricity, magnetism and light. He began with some
experiments on the effects of electricity on light, but failed to find any.
(It was John Kerr who, eight years after Faraday’s death, discovered the
effect of electricity on light which now bears his name.) Having failed
with electricity, Faraday then turned to magnetism.

Faraday was again initially unsuccessful. He placed a variety of transparent
materials in the magnetic lines of force generated by an electromagnet and
looked for an effect on the state of polarisation of light when passed through
each material. Eventually, on 13 September 1845, his persistence paid off.
He passed plane-polarised light through an old sample of lead borate glass
he had made himself over 20 years earlier. The light emerged with its plane
of polarisation rotated. This is the magneto-optical, or Faraday, effect.
Its discovery was to have a profound impact on the later development of
the wave theory of electromagnetic radiation by James Clerk Maxwell. In
typical style, Faraday’s diary entry reads: ‘have got enough for today’.
Using a stronger electromagnet, Faraday quickly demonstrated that the effect
he had seen was common to a variety of materials. He moved each material
around in the magnetic field and looked at the effect on the polarisation
of the light. He found that he could use the effect to map out the magnetic
lines of force in much the same way that they can be revealed using iron
filings.

By the end of September 1845, he had enough experimental evidence to
show that the effect was not due to the direct interaction of the magnetic
field with the light, but was due instead to the interaction of the magnetic
field with the material through which the light was passing. This was a
crucial observation. Magnetism had changed from being a force associated
only with certain magnetic materials or generated in an electromagnet to
a force universal to all matter.

Faraday’s work with light gave him the opportunity to express his views
on another problem facing science in the mid-19th century. Thomas Young’s
experiments on light interference appeared to show that light should be
thought of as a wave. Physicists generally agreed that, just as water waves
require a medium, so do light waves. This all-pervadingmedium for light
waves was called the ether.

Now if it existed, the ether had to have certain properties that made
it unlike any matter then known. This was the one weak spot of wave theory
exploited by diehards who wanted to stick with Newton’s ideas of light corpuscles.
Arguments about the ether became quite mathematical, and must have convinced
Faraday that the protagonists in the debate had lost sight of the important
issues.

On Friday 3 April 1846, Faraday stepped in to deliver an impromptu Evening
Discourse at the Royal Institution. Legend has it that the invited speaker,
Charles Wheatstone, took fright minutes before he was about to deliver his
lecture and fled the building. (It is now a tradition at the Royal Institution
that speakers are locked in a room half an hour before their discourse is
due to start.) Faraday spoke about Wheatstone’s work but, realising that
he would finish 20 minutes early,decided to add some of his own thoughts
on the ether theory.

Against the tide of opinion, Faraday said he did not believe the ether
existed. He speculated instead that light is a wave disturbance in a force
field. He pictured vibrations travelling along the lines of force between
matter, much like the vibrations that can be made to pass the length of
a taut string. What Faraday was proposing was astonishingly radical: vibrations
without a vibrating medium.

It is always dangerous to use the hindsight of 20th-century physics
when assessing the contributions of a 19th-century scientist. However, Faraday’s
speculations have proved incredibly far-sighted. In 1887, 20 years after
Faraday’s death, Albert Michelson and Edward Morley proved in a famous experiment
that the ether could not exist. It is impossible to reconcile this fact
with light interference and other wave effects. The answer, such that it
is, lies in quantum field theory, in which particles of light (photons)
are treated as wave disturbances in the quantum electromagnetic field.

Are we justified in crediting Faraday with such far-sightedness? Judge
for yourself. In 1849, he attempted toshow that the forces of electricity
and gravity could be interconverted. Remember that he was convinced of the
underlying unity of forces and it was logical for him to pursue his conviction
through experiment. Although he failed, he was not unduly perturbed. He
wrote: ‘The results are negative; they do not shake my strong feeling of
an existence of a relation between gravity and electricity, though they
give no proof that such a relation exists.’

Faraday was searching for a connection that still eludes physicists.
Einstein devoted the whole of his intellectual energy in the latter half
of his life in a failed attempt to unify the fundamental forces. There have
been some notable successes, such as the unification of the electromagnetic
and weak nuclear forces by Sheldon Glashow, Abdus Salam and Steven Weinberg
in the late 1960s, but gravity has so far stayed out in the cold.

It would be wrong to imply that Faraday in any way anticipated modern
field theories. However, his ideas about force fields mark him out as a
bold and radical thinker. Because he did not express his theoretical ideas
in mathematics – the language of the theoretical physicist – they were not
taken very seriously by his peers. Some, including Lord Kelvin and James
Clerk Maxwell, did acknowledge his contribution to theoretical science,
but in the myth that came to be built around Faraday, his experimental work
overshadowed all else. But Faraday laid down the conceptual framework of
modern physics, later to be expressed in elegant mathematical form by Maxwell
and others. So let us respect his work and remember him, not only as an
experimental physicist and chemist, but also as a philosopher and the grandfather
of field theory.

Jim Baggott is a freelance science writer.

Further reading: Faraday as a Natural Philosopher, by Joseph Agassi,
University of Chicago Press, Chicago, 1971; Faraday Rediscovered, edited
by David Gooding and Frank A. L. James, Stockton Press, New York, 1985;
Michael Faraday and the Royal Institution, by John Meurig Thomas, Adam Hilger,
Bristol, 1991.

* * *

Davy, Faraday and the Royal Institution

The Royal Institution of Great Britain was founded in 1799 by Count
Rumford, a colourful character variously described as a traitor, spy, opportunist,
womaniser, inventor, plagiarist and expert on heat. He left after only three
years following a row with the Institution’s managers, and went to live
in Paris, where he later married Anne Lavoisier, the widow of Antoine Lavoisier
– the famous chemist guillotined in the French Revolution.

In 1801 Rumford appointed Thomas Young as his professor of natural philosophy
and Humphry Davy as assistant lecturer. Both were brilliant scientists,
and Davy quickly established a reputation for his eloquent and visually
spectacular public lectures. Davy became professor of chemistry in 1802
and director of the institution in 1804.

In 1812, Davy (by now Sir Humphry) presented a course of four lectures
on chemical philosophy that greatly inspired a young apprentice bookbinder
sitting in the audience. Born into a poor family but dedicated to the ethic
of self-improvement, the young man took copious notes which he later rewrote
and to which he added illustrations and an index. These notes he lovingly
bound into a book.

He then decided on the bold step of writing to Davy asking if it might
be possible for him to enter into the services of science through an appointment
at the Royal Institution, enclosing the book he had made. His name was Michael
Faraday.

Davy summoned Faraday for an interview but, paraphrasing Newton, warned
him that science ‘is a harsh mistress’ and recommended that he stick to
his trade. Then, in February 1813, one of Davy’s assistants was dismissed
for brawling, and Faraday was duly offered the vacant position, which he
eagerly accepted.

Faraday’s rise was swift. He quickly showed that he could be trusted
around the laboratory and was given more responsibility. By October he had
established for himself a pre-eminent position with Davy, and was invited
to join him and his wife on a grand scientific tour of Europe as his secretary
and personal assistant. Faraday returned to the institution in May 1815,
taking up an official position with the grand title: ‘Assistant in the Laboratory
and Mineral Collection and Superintendent of the Apparatus’.

Faraday went from strength to strength. He assisted Davy in his work
on the miner’s safety lamp and followed this with a succession of original
discoveries in chemistry. But it was his work on electromagnetic rotations
that was to mark him out as one of the world’s greatest experimental scientists.

In 1820, the Danish physicist Hans Christian Oersted discovered that
a compass needle is deflected when brought close to a wire carrying an electric
current. This discovery was shortly followed by another. The French physicist
Andre-Marie Ampere showed that two wires carrying electric currents are
attracted or repelled depending on the directions in which the currents
are flowing.

In September 1821 Faraday had just completed a definitive survey of
all that was then known about the forces of electricity and magnetism. He
used this knowledge to devise an experiment to show that a wire carrying
an electric current could be made to rotate around a stationary magnet,
and that a magnet could rotate around a stationary wire. Faraday’s discovery
allowed him to design the first primitive electric motor, and his fame as
a great scientist was assured.

Faraday’s breakthrough was marred by the accusation that he had stolen
the idea from William Wollaston, a close personal friend of Davy. Faraday
had been present during a discussion between Davy and Wollaston on how electromagnetic
rotations might be achieved. But he had provided his own solution, a fact
that was quickly recognised. Faraday diplomatically acknowledged Wollaston’s
contribution, fences were mended and the matter largely forgotten.

With success came honours. In 1824, Faraday was elected as a Fellow
of the Royal Society (despite the fact that Davy opposed his nomination).

In 1826, he launched two initiatives for the popularisation of science,
the Christmas Lectures and the Friday Evening Discourses. The success of
these, and Faraday’s own abilities as a lecturer, brought him right into
the heart of contemporary society.

Saddened that his marriage bore no children, he poured considerable
energy into the presentation of science for the young. His most famous Christmas
Lectures, on the ‘Chemical history of a candle’, first given in 1860, remain
today a classic of the science populariser’s art.

Faraday refused to be overwhelmed by his tremendous success. He turned
down both a knighthood and the presidency of the Royal Society, claiming
that he ‘must remain plain Michael Faraday to the last . . .’. He died in
1867 at Hampton Court, but his generous spirit lives on in the Christmas
Lectures and the Evening Discourses and in the very fabric of the building
that played such an important part in his life.