Lawrence Krauss - The Greatest Story Ever Told--So Far Read online

  is no going back.

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  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.

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  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

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  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

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  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

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  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

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  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.

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  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

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  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.

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  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