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

by Why Are We Here (pdf)

  beneath. And how fascinating it is to discover that order, and to

  piece together a coherent picture of the universe on scales far

  beyond those that we may ever directly experience—a picture woven

  together by our ability to predict what will happen next, and the

  consequent ability to control the environment around us. How lucky

  to have our brief moment in the Sun. Every day that we discover

  something new and surprising, the story gets even better.

  ͢͝

  P a r t O n e

  G E N E S I S

  ͣ͝

  C h a p t e r 1

  F R O M

  T H E

  A R M O I R E

  T O

  T H E C AV E

  The simple inherit folly, but the prudent are crowned with

  knowledge.

  —PROVERBS 14:18

  In my beginning there was light.

  Surely there was light at the beginning of time, but before we can

  get to the beginning of time, we will need to explore our own

  beginnings, which also means exploring the beginning of science.

  And that means returning to the ultimate motive for both science

  and religion: the longing for something else. Something beyond the

  universe of our experience.

  For many people, that longing translates into something that

  gives meaning and purpose to the universe and extends to a longing

  for some hidden place that is better than the world in which we live,

  where sins are forgiven, pain is absent, and death does not exist.

  Others, however, long for a hidden place of a very different sort, the

  physical world beyond our senses, the world that helps us

  understand how things behave the way they do, rather than why.

  This hidden world underlies what we experience, and the

  understanding of it gives us the power to change our lives, our

  environment, and our future.

  The contrast between these two worlds is reflected in two very

  different works of literature.

  ͤ͝

  The first, The Lion, the Witch and the Wardrobe, by C. S. Lewis, is

  a twentieth-century children’s fantasy with decidedly religious

  overtones. It captures a childhood experience most of us have had—

  looking under the bed or in the closet or in the attic for hidden

  treasure or evidence that there is more out there than what we

  normally experience. In the book, several schoolchildren discover a

  strange new world, Narnia, by climbing into a large wardrobe in the

  country house outside London where they have been sequestered for

  their protection during the Second World War. The children help

  save Narnia with the aid of a lion, who lets himself be humiliated

  and sacrificed, Christlike, at an altar in order to conquer evil in his

  world.

  While the religious allusion in Lewis’s story is clear, we can also

  interpret it in another way—as an allegory, not for the existence of

  God or the devil, but rather for the remarkable and potentially

  terrifying possibilities of the unknown, possibilities that lie just

  beyond the edge of our senses, just waiting for us to be brave enough

  to seek them out. Possibilities that, once revealed, may enrich our

  understanding of ourselves or, for some who feel a need, provide a

  sense of value and purpose.

  The portal to a hidden world inside the wardrobe is at once safe,

  with the familiar smell of oft-worn clothes, and mysterious. It

  implies the need to move beyond classical notions of space and time.

  For if nothing is revealed to an observer who is in front of or behind

  the wardrobe, and something is revealed only to someone inside,

  then the space experienced inside the wardrobe must be far larger

  than that seen from its outside.

  Such a concept is characteristic of a universe in which space and

  time can be dynamical, as in the General Theory of Relativity, where,

  for example, from outside the “event horizon” of a black hole—that

  radius inside of which there is no escape—a black hole might appear

  ͥ͝

  to comprise a small volume, but for an observer inside (who has not

  yet been crushed to smithereens by the gravitational forces present),

  the volume can look quite different. Indeed, it is possible, though

  beyond the domain where we can perform reliable calculations, that

  the space inside a black hole might provide a portal to another

  universe disconnected from our own.

  But the central point I want to return to is that the possibility of

  universes beyond our perception seems to be tied, in the literary and

  philosophical imagination, at least, to the possibility that space itself

  is not what it seems.

  The harbinger of this notion, the “ur” story if you will, was written

  twenty-three centuries before Lewis penned his fantasy. I refer to

  Plato’s Republic, and in particular to my favorite section, the Allegory

  of the Cave. But in spite of its early provenance, it illuminates more

  directly and more clearly both the potential necessity and the

  potential perils of searching for understanding beyond the reach of

  our immediate senses.

  In the allegory, Plato likens our experience of reality to that of a

  group of individuals who live their entire lives imprisoned inside a

  cave, forced to face a blank wall. Their only view of the real world is

  that wall, which is illuminated by a fire behind them, and on which

  they see shadows moving. The shadows come from objects located

  behind them that the light of the fire projects on the wall.

  ͜͞

  I show the drawing below, which came from the high school text

  in which I first read this allegory, in a 1961 translation of Plato’s

  dialogues.

  The drawing is amusing because it clearly reflects as much about

  the time it was drawn as it does the configuration of the cave

  described in the dialogue. Why, for example, are the prisoners here

  all women, and scantily clad ones at that? In Plato’s day, any sexual

  allusion might easily have displayed young boys.

  Plato argues that the prisoners will view the shadows as reality

  and even give them names. This is not unreasonable, and it is, in one

  sense, as we shall soon see, a very modern view of what reality is,

  namely that which we can directly measure. My favorite definition of

  reality still is that given by the science fiction writer Philip K. Dick,

  who said, “Reality is that which, when you stop believing in it,

  doesn’t go away.” For the prisoners, the shadows are what they see.

  They are also likely to hear only the echoes of noises made behind

  them as the sounds bounce off the wall.

  Plato likened a philosopher to a prisoner who is freed from

  bondage and forced, almost against his will, to not only look at the

  fire, but to move past it, and out to the daylight beyond. First, the

  poor soul will be in distress, with the glare of the fire and the

  sunshine beyond the cave hurting his eyes. Objects will appear

  completely unfamiliar; they will not resemble their shadows. Plato

  argues that the new freeman may still imagine the shadows that he is

  used to as truer represent
ations than the objects themselves that are

  casting the shadows.

  If the individual is reluctantly dragged out into the sunshine,

  ultimately all of these sensations of confusion and pain will be

  multiplied. But eventually, he will become accustomed to the real

  world, will see the stars and Moon and sky, and his soul and mind

  will be liberated of the illusions that had earlier governed his life.

  ͞͝

  If the person returns to the cave, Plato argues, two things would

  happen. First, because his eyes would no longer be accustomed to

  the darkness, he would be less able to distinguish the shadows and

  recognize them, and his compatriots would view him as

  handicapped at best, and dim at worst. Second, he would no longer

  view the petty and myopic priorities of his former society, or the

  honors given to those who might best recognize the shadows and

  predict their future, as worthy of his respect. As Plato poetically put

  it, quoting from Homer:

  “Better to be the poor servant of a poor master, and to endure

  anything, rather than think as they do and live after their manner.”

  So much for those whose lives are lived entirely in illusion, which

  Plato suggests includes most of humanity.

  Then, the allegory states that the journey upward—into the light

  —is the ascent of the soul into the intellectual world.

  Clearly in Plato’s mind only a retreat to the purely “intellectual

  world,” a journey reserved for the few—aka philosophers—could

  replace illusion with reality. Happily, that journey is far more

  accessible today using the techniques of science, which combine

  reason and reflection with empirical inquiry. Nevertheless, the same

  challenge remains for scientists today: to see what is behind the

  shadows, to see that which, when you drop your preconceptions,

  doesn’t disappear.

  While Plato doesn’t explicitly mention it, not only would his

  fellow prisoners view the poor soul who had ventured out and

  returned as handicapped, but they would likely think he was crazy if

  he talked about the wonders that he had glimpsed: the Sun, the

  Moon, lakes, trees, and other people and their civilizations.

  This idea is strikingly modern. As the frontiers of science have

  moved further and further away from the world of the familiar and

  the world of common sense as inferred from our direct experience,

  ͞͞

  our picture of the reality underlying our experience is getting

  increasingly difficult for us to comprehend or accept. Some find it

  more comforting to retreat to myth and superstition for guidance.

  But, we have every reason to expect that “common sense,” which

  first evolved to help us cope with predators in the savannas of Africa,

  might lead us astray when we attempt to think about nature on

  vastly different scales. We didn’t evolve to intuitively understand the

  world of the very small, the very big, or the very fast. We shouldn’t

  expect the rules we have come to rely on for our daily lives to be

  universal. While that myopia was useful from an evolutionary

  perspective, as thinking beings we can move beyond it.

  In this regard, I cannot resist quoting one last admonition in

  Plato’s allegory:

  “In the world of knowledge the idea of good appears last of all and

  is seen only with an effort; and, when seen, is also inferred to be the

  author of all things good and right, parent of light, and . . . the

  immediate source of reason and truth.”

  Plato further argues that this is what those who would act

  rationally should strive for, in both public and private life—seeking

  the “good” by focusing on reason and truth. He suggests that we can

  only do so by exploring the realities that underlie the world of our

  direct experience, rather than by exploring the illusions of a reality

  that we might want to exist. Only through rational examination of

  what is real, and not by faith alone, is rational action—or good—

  possible.

  Today, Plato’s vision of “pure thought” has been replaced by the

  scientific method, which, based on both reason and experiment,

  allows us to discover the underlying realities of the world. Rational

  action in public and private life now requires a basis in both reason

  and empirical investigation, and it often requires a departure from

  the solipsistic world of our direct experience. This principle is the

  ͟͞

  source of most of my own public activism in opposition to

  government policies based on ideology rather than evidence, and it

  is also probably why I respond so negatively to the concept of the

  “sacred”—implying as it does some idea or admonition that is off-

  limits to public questioning, exploration, discussion, and sometimes

  ridicule.

  It is hard to state this view more strongly than I did in a New

  Yorker piece: “Whenever scientific claims are presented as

  unquestionable, they undermine science. Similarly, when religious

  actions or claims about sanctity can be made with impunity in our

  society, we undermine the basis of modern secular democracy. We

  owe it to ourselves and to our children not to give a free pass to

  governments—totalitarian, theocratic, or democratic—that endorse,

  encourage, enforce, or otherwise legitimize the suppression of open

  questioning in order to protect ideas that are considered ‘sacred.’

  Five hundred years of science have liberated humanity from the

  shackles of enforced ignorance.”

  Philosophical reflections aside, the prime reason I am introducing

  Plato’s cave here is that it can provide a concrete example of the

  nature of the scientific discoveries at the heart of the story I want to

  tell.

  Imagine a shadow that our prisoners might see on the wall,

  displayed by an evil puppeteer located on a ledge in front of the fire:

  This shadow displays both length and directionality, two concepts

  that we, who are not confined to the cave, take for granted.

  However, as the prisoners watch, this shadow changes:

  ͞͠

  Later it looks like this:

  And again later like this:

  And later still, like this:

  What would the prisoners infer from all of this? Presumably, that

  concepts such as length or direction have no absolute meaning. The

  objects in their world can change both length and directionality

  arbitrarily. In the reality of their direct experience, neither length nor

  directionality appears to have significance.

  What will the natural philosopher, who has escaped to the surface

  to explore the richer world beyond the shadows, discover? He will

  see that the shadow is first of all just a shadow: a two-dimensional

  image on the wall cast from a real, three-dimensional object located

  behind the prisoners. He will see that the object has a fixed length

  that never changes, and that it’s accompanied by an arrow that is

  always on the same side of the object. From a vantage point slightly

  above the object, he sees that the series of images results from the

  project
ion of a rotating weather vane onto the wall:

  When he returns to join his former colleagues, the philosopher-

  scientist can explain that an absolute quantity called length doesn’t

  ͞͡

  change over time, and that directionality can be assigned

  unambiguously to certain objects as well. He will tell his friends that

  the real world is three-dimensional, not two-dimensional, and that

  once they understand, all of their confusion about the seemingly

  arbitrary changes will disappear.

  Would they believe him? It would be a tough sell because they

  won’t have an intuitive idea of what a rotation is (after all, with an

  intuition based purely on two-dimensional experience, it would

  likely be difficult to “picture” mentally any rotations in a third

  dimension). Blank stares? Probably. The loony bin? Maybe.

  However, he might win over the community by stressing attractive

  characteristics associated with his claim: behavior that on the surface

  appears to be complex and arbitrary can be shown to result from a

  much simpler underlying picture of nature, and seemingly disparate

  phenomena are actually connected and can be part of a unified whole.

  Better still, he could make predictions that his friends could test.

  First, he could argue that, if the apparent change in length of the

  shadows measured by the group is really due to a rotation in a third

  dimension, whenever the length of the object briefly vanishes, it will

  immediately reemerge with the arrow pointing in the opposite

  direction. Second, he could argue that as the length oscillates, the

  maximum length of the shadow when the arrow is pointing in one

  direction will always be exactly the same as the maximum length of

  the shadow when it is pointing in the other direction.

  Plato’s cave thus becomes an allegory for far more than he may

  have intended. Plato’s freed man discovers the hallmarks of the

  remarkable true story of our own struggle to understand nature on

  its most fundamental scales of space, time, and matter. We too have

  had to escape the shackles of our prior experience to uncover

  profound and beautiful simplifications and predictions that can be as

  terrifying as they are wonderful.

  ͢͞

  But just as the light beyond Plato’s cave is painful to the eyes at

  first, with time it becomes mesmerizing. And once witnessed, there