Parallel Worlds (4 page)

This tiny
string, in turn, vibrates at different frequencies and resonances. If we were
to pluck this vibrating string, it would change mode and become another
subatomic particle, such as a quark. Pluck it again, and it turns into a
neutrino. In this way, we can explain the blizzard of subatomic particles as
nothing but different musical notes of the string. We can now replace the
hundreds of subatomic particles seen in the laboratory with a single object,
the string.

In this new
vocabulary, the laws of physics, carefully constructed after thousands of years
of experimentation, are nothing but the laws of harmony one can write down for
strings and membranes. The laws of chemistry are the melodies that one can play
on these strings. The universe is a symphony of strings. And the "Mind of
God," which Einstein wrote eloquently about, is cosmic music resonating
throughout hyperspace. (Which raises another question: If the universe is a
symphony of strings, then is there a composer? I address this question in
chapter i2.)

THE END OF THE UNIVERSE

The WMAP not only gives the most accurate glimpse of the
early universe, it also gives the most detailed picture of how our universe
will die. Just as the mysterious antigravity force pushed the galaxies apart at
the beginning of time, this same antigravity force is now pushing the universe
to its final fate. Previously, astronomers thought that the expansion of the
universe was gradually winding down. Now, we realize that the universe is
actually accelerating, with the galaxies hurtling away from us at increasing
speed. The same dark energy that makes up 73 percent of the matter and energy
in the universe is accelerating the expansion of the universe, pushing the
galaxies apart at ever increasing speeds. "The universe is behaving like
a driver who slows down approaching a red stoplight and then hits the
accelerator when the light turns green," says Adam Riess of the Space
Telescope Institute.

Unless something
happens to reverse this expansion, within 150 billion years our Milky Way
galaxy will become quite lonely, with 99.99999 percent of all the nearby
galaxies speeding past the edge of the visible universe. The familiar galaxies
in the night sky will be rushing so fast away from us that their light will
never reach us. The galaxies themselves will not disappear, but they will be
too far for our telescopes to observe them anymore. Although the visible universe
contains approximately 100 billion galaxies, in 150 billion years only a few
thousand galaxies in the local supercluster of galaxies will be visible. Even
further in time, only our local group, consisting of about thirty-six
galaxies, will comprise the entire visible universe, with billions of galaxies
drifting past the edge of the horizon. (This is because the gravity within the
local group is sufficient to overcome this expansion. Ironically, as the
distant galaxies slip away from view, any astronomer living in this dark era
may fail to detect an expansion in the universe at all, since the local group
of galaxies itself does not expand internally. In the far future, astronomers
analyzing the night sky for the first time might not realize that there is any
expansion and conclude that the universe is static and consists of only
thirty-six galaxies.)

If this
antigravity force continues, the universe will ultimately die in a big freeze.
All intelligent life in the universe will eventually freeze in an agonizing
death, as the temperature of deep space plunges toward absolute zero, where the
molecules themselves can hardly move. At some point trillions upon trillions of
years from now, the stars will cease to shine, their nuclear fires extinguished
as they exhaust their fuels, forever darkening the night sky. The cosmic
expansion will leave only a cold, dead universe of black dwarf stars, neutron
stars, and black holes. And even further into the future, the black holes
themselves will evaporate their energy away, leaving a lifeless, cold mist of
drifting elementary particles. In such a bleak, cold universe, intelligent life
by any conceivable definition is physically impossible. The iron laws of
thermodynamics forbid the transfer of any information in such a freezing
environment, and all life will necessarily cease.

The first
realization that the universe may eventually die in ice was made in the
eighteenth century. Commenting on the depressing concept that the laws of
physics seemingly doom all intelligent life, Charles Darwin wrote,
"Believing as I do that man in the distant future will be a far more
perfect creature than he now is, it is an intolerable thought that he and all
other sentient beings are doomed to complete annihilation after such
long-continued slow progress." Unfortunately, the latest data from the
WMAP satellite seem to confirm Darwin's worst fears.

ESCAPE INTO HYPERSPACE

It is a law of
physics that intelligent life within the universe will necessarily face this
ultimate death. But it is also a law of evolution that when the environment
changes, life must either leave, adapt, or die. Because it is impossible to
adapt to a universe that is freezing to death, the only options are to die—or
to leave the universe itself. When facing the ultimate death of the universe,
is it possible that civilizations trillions of years ahead of us will assemble
the necessary technology to leave our universe in a dimensional
"lifeboat" and drift toward another, much younger and hotter
universe? Or will they use their superior technology to build a "time
warp" and travel back into their own past, when temperatures were much
warmer?

Some physicists
have proposed a number of plausible, although extremely speculative schemes,
using the most advanced physics available, to provide the most realistic look
at dimensional portals or gateways to another universe. The blackboards of
physics laboratories around the world are full of abstract equations, as
physicists compute whether or not one might use "exotic energy" and
black holes to find a passageway to another universe. Can an advanced civilization,
perhaps millions to billions of years ahead of ours in technology, exploit the
known laws of physics to enter other universes?

Cosmologist
Stephen Hawking of Cambridge University once quipped, "Wormholes, if they
exist, would be ideal for rapid space travel. You might go through a wormhole
to the other side of the galaxy and be back in time for dinner."

And if wormholes
and dimensional portals are simply too small to permit the final exodus from
the universe, then there is another final option: to reduce the total
information content of an advanced, intelligent civilization to the molecular
level and inject this through the gateway, where it will then self-assemble on
the other side. In this way, an entire civilization may inject its seed through
a dimensional gateway and reestablish itself, in its full glory. Hyperspace,
instead of being a plaything for theoretical physicists, could potentially
become the ultimate salvation for intelligent life in a dying universe.

But to fully
understand the implications of this event, we must first understand how
cosmologists and physicists have painstakingly arrived at these astounding
conclusions. In the course of
Parallel Worlds,
we review the history of cosmology, stressing the paradoxes
that have infested the field for centuries, culminating in the theory of
inflation, which, while consistent with all the experimental data, forces us to
entertain the concept of multiple universes.

Had I been present at the creation, I would have given some
useful hints for the better ordering of the universe.

—Alphonse
the Wise

Damn the solar
system. Bad light; planets too distant; pestered with comets; feeble
contrivance; could make a better [universe] myself.

—Lord
Jeffrey

In the
play
A
s
You
Like It,
Shakespeare wrote the immortal words

All the world's a stage,

And all the men and women merely players.

They
have their exits and their entrances.

During the
Middle Ages, the world was indeed a stage, but it was a small, static one,
consisting of a tiny, flat Earth around which the heavenly bodies moved
mysteriously in their perfect celestial orbs. Comets were seen as omens
foretelling the death of kings. When the great comet of 1066 sailed over
England, it terrified the Saxon soldiers of King Harold, who quickly lost to
the advancing, victorious troops of William the Conqueror, setting the stage
for the formation of modern England.

That same comet
sailed over England once again in 1682, again instilling awe and fear
throughout Europe. Everyone, it seemed, from peasants to kings, was mesmerized
by this unexpected celestial visitor which swept across the heavens. Where did
the comet come from? Where was it going, and what did it mean?

One wealthy
gentleman, Edmund Halley, an amateur astronomer, was so intrigued by the comet
that he sought out the opinions of one of the greatest scientists of the day,
Isaac Newton. When he asked Newton what force might possibly control the motion
of the comet, Newton calmly replied that the comet was moving in an ellipse as
a consequence of an inverse square force law (that is, the force on the comet
diminished with the square of its distance from the sun). In fact, said Newton,
he had been tracking the comet with a telescope that he had invented (the
reflecting telescope used today by astronomers around the world) and its path
was following his law of gravitation that he had developed twenty years
earlier.

Halley was
shocked beyond belief. "How do you know?" demanded Halley.
"Why, I have calculated it," replied Newton. Never in his wildest
dreams did Halley expect to hear that the secret of the celestial bodies, which
had mystified humanity since the first humans gazed at the heavens, could be
explained by a new law of gravity.

Staggered by the
significance of this monumental breakthrough, Halley generously offered to pay
for the publication of this new theory. In 1687, with Halley's encouragement
and funding, Newton published his epic work
Philosophiae Naturalis Principia Mathematica (Mathematical Principles of
Natural Philosophy).
It has been hailed as one of the most important works ever
published. In a single stroke, scientists who were ignorant of the larger laws
of the solar system were suddenly able to predict, with pinpoint precision, the
motion of heavenly bodies.

So great was the
impact of
Principia
in the salons
and courts of Europe that the poet Alexander Pope wrote:

Nature and
nature's laws lay hid in the night,

God said,
Let Newton Be!
and all was
light.

(Halley realized
that if the comet's orbit was an ellipse, one might be able to calculate when
it might sail over London again. Searching old records, he found that the
comets of 1531, 1607, and 1682 were indeed the same comet. The comet that was
so pivotal to the creation of modern England in 1066 was seen by people throughout
recorded history, including Julius Caesar. Halley predicted that the comet
would return in 1758, long after Newton and Halley had passed away. When the
comet did indeed return on Christmas Day that year, on schedule, it was
christened Halley's comet.)

Newton had
discovered the universal law of gravity twenty years earlier, when the black
plague shut down Cambridge University and he was forced to retreat to his country
estate at Woolsthorpe. He fondly recalled that while walking around his estate,
he saw an apple fall. Then he asked himself a question that would eventually
change the course of human history: if an apple falls, does the moon also fall?
In a brilliant stroke of genius, Newton realized that apples, the moon, and the
planets all obeyed the same law of gravitation, that they were all falling
under an inverse square law. When Newton found that the mathematics of the
seventeenth century were too primitive to solve this force law, he invented a
new branch of mathematics, the calculus, to determine the motion of falling apples
and moons.

In
Principia,
Newton had also written down the laws of mechanics, the
laws of motion that determine the trajectories of all terrestrial and
celestial bodies. These laws laid the basis for designing machines, harnessing
steam power, and creating locomotives, which in turn helped pave the way for
the Industrial Revolution and modern civilization. Today, every skyscraper,
every bridge, and every rocket is constructed using Newton's laws of motion.