is no going back.
ͣ͞
C h a p t e r 2
S E E I N G I N T H E D A R K
Let there be light: and there was light.
—GENESIS 1:3
In the beginning there was light.
It is no coincidence that the ancients imagined in Genesis that
light was created on the first day. Without light, there would be little
awareness of the vast universe surrounding us. When we nod and
say, “I see,” to a friend who is trying to explain something, we convey
far more than just an observation, but rather a fundamental
understanding.
Plato’s allegory was appropriately centered on light—light from a
fire to cast the shadows on the cave wall and light from the outside
to temporarily blind the freed prisoner and then illuminate the real
world for him. Like the prisoners in the cave, we too are prisoners of
light—almost everything we learn about the world we learn from
what we see.
While the most significant words in the Western religious canon
may be Let there be light, in the modern world this phrase now has a
completely different significance from what it once did. Human
beings may be prisoners of light, but so is the universe. What once
appeared as a whim of a Judeo-Christian God, or other gods before
that one, we now understand to be required by the very laws that
allow both heaven, and more important, Earth, to exist. You cannot
have one without the other. Earth, or matter, follows light.
ͤ͞
This change in perception underlies almost every development in
the edifice we call modern science. I am writing these words as I
stare out from a ship at one of the Galápagos Islands, which Charles
Darwin made famous, and which made him famous in return, as he
changed our perception of life and its diversity with a single brilliant
realization: that all living species developed through the natural
selection of small inherited variations that are passed along to future
generations by survivors. As surely as the understanding of evolution
changed everything about our understanding of biology, our
changing understanding of light changed everything about our
physical understanding of our place in the universe. As a useful
fringe benefit, this change resulted in virtually all of the technology
on which the modern world is based.
The extent to which our observations of the world imprison our
minds, and frame our description of the fabric of the universe,
remained unappreciated for more than twenty centuries following
Plato. Once serious minds began to investigate in detail the hidden
nature of the universe, it took over four centuries for them to fully
resolve the question What is light?
Perhaps the most serious modern mind, although certainly not
the first, to ask this question was also one of the most famous—and
oddest—scientists in history: Isaac Newton. It is not inappropriate to
classify Newton as a modern mind—after all, his seventeenth-
century Principia: Mathematical Principles of Natural Philosophy
uncovered the classical laws of motion and laid the basis for his
theory of gravity, both of which form the foundation of much of
modern physics. Nevertheless, as John Maynard Keynes pointed out:
Newton was not the first of the age of reason, he was the last of the
magicians, the last of the Babylonians and Sumerians, the last
great mind that looked out on the visible and intellectual world
ͥ͞
with the same eyes as those who began to build our intellectual
inheritance rather less than 10,000 years ago.
The truth of this statement reflects the revolutionary importance
of Newton’s work. After the Principia, no rational person could view
the world the same way the ancients had viewed it. But it also
reflects the character of Newton himself. He devoted far more time,
and far more ink, to writing about the occult, alchemy, and
searching for hidden meanings and codes in the Bible—focusing in
particular on the Book of Revelation and mysteries associated with
the ancient Temple of Solomon—than he did to writing about
physics.
Newton was also one in a long line of people, which extends
before and after him, who felt that he had been specifically chosen
by God to help reveal the true meaning of the Scriptures. To what
extent his studies of the universe derived from his fascination with
the Bible is not clear, but it does seem reasonable to conclude that
his primary interest was in theology, and that natural philosophy
came in well below that, and probably below alchemy as well.
Many individuals point to Newton’s fascination with God as
evidence of the compatibility between science and religion, and to
assert that modern science owes its existence to Christianity. This
confuses history with causality. It is undeniable that many of the
early giants of modern Western natural philosophy, from Newton
onward, were deeply religious, although Darwin lost much, if not all,
of his religious belief later in life. But remember that during much of
this period there were primarily two sources of education and
wealth: the Church and the Crown. The Church was the National
Science Foundation of the fifteenth, sixteenth, and seventeenth
centuries. All institutions of higher learning were tied to various
denominations, and it was unthinkable for any educated person to
not be affiliated with the Church. And as Giordano Bruno and later
͟͜
Galileo discovered, it was unpleasant at best to counter its doctrine.
It would have been remarkable for any of these leading early
scientific thinkers to have been anything but religious.
The religiosity of the early scientific pioneers is also cited today by
sophists who claim that science and religious doctrine are
compatible, but who confuse science and scientists. In spite of
frequent appearances to the contrary, scientists are people. And like
all people they are capable of holding many potentially mutually
contradictory notions in their head at the same time. No correlation
between divergent views held by any individual is representative of
anything but human foibles.
To claim that some scientists are or were religious is like saying
some scientists are Republicans or some are flat-earthers or some are
creationists. It doesn’t imply causality or consistency. My friend
Richard Dawkins has told me of a professor of astrophysics who,
during the day, writes papers that are published in astronomical
journals assuming that the universe is more than 13 billion years old,
but then goes home and privately espouses the literal biblical claim
that the universe is six thousand years old.
What determines intellectual consistency or lack thereof in the
sciences is a combination of rational arguments with subsequent
evidence and continued testing. It is perfectly reasonable to claim
that religion, in the Western world, may be the mother of science.
But as any parent knows, children rarely grow up to be
models of
their parents.
Newton may, following tradition, have been motivated to look at
light because it was a gift from God. But we remember his work not
because of his motivation, but because of what he discovered.
Newton was convinced that light was made of particles, which he
referred to as corpuscles, while Descartes, and later Newton’s
nemesis Robert Hooke, and still later the Dutch scientist Christiaan
͟͝
Huygens, all claimed that light was a wave. One of the key
observations that appeared to support the wave theory was that
white light, such as light from the Sun, could split into all the colors
of the rainbow when passed through a prism.
As was often the case during his life, Newton believed that he was
correct and several of his most famous contemporaries (and
competitors) were wrong. To demonstrate this, he devised a clever
experiment using prisms that he first performed while at home in
Woolsthorpe, to escape the bubonic plague ravaging Cambridge. As
he reported at the Royal Society in 1672, on the forty-fourth try, he
observed precisely what he hoped he would see.
Advocates of the wave theory had argued that light waves were
made of white light and that the light split into colors when it passed
through a prism because of “corruption” of the rays as they traversed
the glass. In this case, the more glass, the more splitting.
Newton reasoned that this was not the case, but that light is made
of colored particles that combine together to appear white. (With a
nod to his occult fascination, Newton classified the colored particles
of the spectrum—a term he coined—into seven different types: red,
orange, yellow, green, blue, indigo, and violet. From the time of the
Greeks, the number seven had been considered to possess mystical
qualities.) To demonstrate that the wave/corruption picture was
incorrect, Newton passed a beam of white light through two prisms
held in opposite orientations. The first prism split the light into its
spectrum, and the second recomposed it back into a single white
light beam. This result would have been impossible if the glass had
corrupted the light. A second prism would have simply made the
situation worse and would not have caused the light to revert back to
its original state.
This result does not in fact disprove the wave theory of light (it
actually supports it, because light slows down as it bends upon
͟͞
entering the prism, just as waves would do). But since the advocates
of that theory had argued (incorrectly) that the spectral splitting was
due to corruption, Newton’s demonstration that this was not the
case struck a significant blow in favor of his particle model.
Newton went on to discover many other facets of light that we
use today in our understanding of the wave nature of light. He
showed that every color of light has a unique bend angle when
passing through a glass prism. He also showed that all objects appear
to be the same color as the color of the light beam illuminating
them. And he showed that colored light will not change its color no
matter how many times it is reflected by or passes through a prism.
All of these results, including his original result, can be explained
simply if white light is indeed composed of a collection of different
colors—that much he got right. But they can’t be explained if light is
made of different-colored particles. Rather, white light is composed
of waves of many different wavelengths.
Newton’s opponents did not give up easily, even in the face of
Newton’s rising popularity and the death of his chief opponent,
Hooke. They did not give up even after Newton’s election as
president of the Royal Society in 1703, the year before he actually
published his research on light in his epic Opticks. Indeed, the debate
on the nature of light continued to rage on for over a century.
Part of the problem with a wave picture of light was the question
“What is it that light is a wave of, exactly?” And if it is a wave, then
since all known waves require some medium, what medium does it
travel in? These questions were sufficiently perplexing that
practitioners of the wave theory had to resurrect a new invisible
substance permeating all space, the ether.
The resolution of this conundrum came, as such resolutions often
do, from a totally unexpected corner of the physical world, one full
of sparks, and spinning wheels.
͟͟
When I was a young professor at Yale—in the ancient but huge
office I was lucky enough to commandeer when an equally ancient
colleague retired—there was left hanging for me a copy of a
photograph of Michael Faraday taken in 1861. I have treasured it
ever since.
I don’t believe in hero worship, but if I did, Faraday would be up
there with the best. Perhaps more than any other scientist of the
nineteenth century, he is responsible for the technology that powers
our current civilization. Yet he had little formal education and at age
fourteen became a bookbinder’s apprentice. Later in his career, after
achieving world recognition for his scientific contributions, he
insisted on keeping to his humble roots, turning down a knighthood
and twice turning down the presidency of the Royal Society. Later on
he refused to advise the British government on the production of
chemical weapons for use in the Crimean War, citing ethical
reasons. And for more than thirty-three years he gave a series of
Christmas lectures at the Royal Institution to excite young people
about science. What’s not to like?
Much as one might admire the man, it is the scientist who
matters here for our story. Faraday’s first scientific lesson is one I tell
my students: always suck up to your professors. At the age of twenty,
after completing seven years of apprenticeship as a bookbinder,
Faraday attended the lectures of the famous chemist Humphry Davy,
then the head of the Royal Institution. Afterward Faraday presented
Davy with a three-hundred-page, beautifully bound book containing
the notes Faraday had taken during the lectures. Within a year,
Faraday was appointed Davy’s secretary and shortly thereafter got an
appointment as chemical assistant in the Royal Institution. Later on,
Faraday learned the same lesson but with the opposite result.
Following his excitement over some early, quite significant
experiments that he performed, Faraday accidentally forgot to
͟͠
acknowledge work with Davy in his published results. This
accidental snub probably resulted in his being reassigned to other
activities by Davy and delaying his world-changing research by
several years.
When reassigned, Faraday had been working on the “hot” area of
scientific research, the newly discovered connections between
electricity and magnetism, driven by results of the Danish physicist
Hans Christian Oersted. These two forces seem quite different, yet
have odd simi
larities. Electric charges can attract or repel. So can
magnets. Yet magnets always seem to have two poles, north and
south, which cannot be isolated, while electric charges can
individually be positive or negative.
For some time, scientists and natural philosophers had wondered
if the two forces might have some hidden connection, and the first
empirical clue came to Oersted by accident. In 1820, while
delivering a lecture, Oersted saw that a compass needle was
deflected when an electric current from a battery was switched on. A
few months later he followed up on this observation and discovered
that a current of moving electric charges, which we now commonly
call an electric current, produced a magnetic attraction that caused
compass needles to point in a circle around the wire.
He had blazed a new trail. Word spread quickly among scientists,
through the Continent and across the English Channel. Moving
electric charges produced a magnetic force. Could there be other
connections? Could magnets in turn influence electric charges?
Scientists searched for such a possibility, without success. Davy
and another colleague tried to build an electric motor based on the
connection discovered by Oersted, but failed. Faraday ultimately got
a wire with a current in it to move around a magnet, which did form
a crude sort of motor. It was this exciting development that he
reported without citing Davy’s name.
͟͡
Partly this was mere gamesmanship. No new fundamental
phenomenon was being uncovered. Perhaps this was the rationale
for one of my favorite (likely apocryphal) stories about Faraday. It is
said that William Gladstone, later to be British prime minister, heard
of Faraday’s laboratory, full of weird devices, and asked in 1850 what
the practical value of all this study into electricity was. Faraday was
purported to have replied, “Why, sir, there is every probability that
you will soon be able to tax it.”
Apocryphal or not, both great irony and truth are in that witty
comeback. Curiosity-driven research may seem self-indulgent and
far from the immediate public good. However, essentially all of our
current quality of life, for people living in the first world, has arisen
from the fruits of such research, including all the electric power that