Parallel Worlds (46 page)

Even if
intelligent creatures abandon their robotic bodies and transform themselves
into pure consciousness, there is still the problem of information processing.
As the temperature continues to fall, the only way to survive will be to
"think" slower. Dyson concludes that an ingenious life form would
still be able to think for an indefinite amount of time by spreading out the
time required for information processing and also by hibernating to conserve
energy. Although the physical time necessary to think and process information
may be spread out over billions of years, the "subjective time," as
seen by the intelligent creatures themselves, will remain the same. They will
never notice the difference. They will still be able to think deep thoughts but
only on a much, much slower time scale. Dyson concludes, on a strange but
optimistic note, that in this manner, intelligent life will be able to process
information and "think" indefinitely. Processing a single thought may
take trillions of years, but with respect to "subjective time," thinking
will proceed normally.

But if
intelligent creatures think slower, perhaps they might witness cosmic quantum
transitions taking place in the universe. Normally, such cosmic transitions,
such as the creation of baby universes or the transition to another quantum
universe, take place over trillions of years and hence are purely theoretical.
In stage 5, however, trillions of years in "subjective time" will be
compressed and may appear to be only a few seconds to these creatures; they
will think so slowly that they might see bizarre quantum events happen all the
time. They might regularly see bubble universes appearing out of nowhere or
quantum leaps into alternate universes.

But in light of
the recent discovery that the universe is accelerating, physicists have
reexamined the work of Dyson and have ignited a new debate, reaching the
opposite conclusions—intelligent life will necessarily perish in an
accelerating universe. Physicists Lawrence Krauss and Glenn Starkman have
concluded, "Billions of years ago the universe was too hot for life to
exist. Countless eons hence, it will become so cold and empty that life, no
matter how ingenious, will perish."

In Dyson's
original work, he assumed that the 2.7-degree microwave radiation in the
universe would continue to drop indefinitely, so intelligent beings might
extract usable work from these tiny temperature differences. As long as the
temperature continued to drop, usable work could always be extracted. However,
Krauss and Stackman point out that if the universe has a cosmological constant,
then temperatures will not drop forever, as Dyson had assumed, but will
eventually hit a lower limit, the Gibbons-Hawking temperature (about i0
^-29
degrees). Once this temperature is reached, the temperature throughout the
universe will be the same, and hence intelligent beings will not be able to
extract usable energy by exploiting temperature differences. Once the entire
universe reaches a uniform temperature, all information processing will cease.

(In the 1980s,
it was found that certain quantum systems, such as the Browning motion in a
fluid, can serve as the basis of a computer, regardless of how cold the
temperature is outside. So even as temperatures plunge, these computers can
still compute by using less and less energy. This was good news to Dyson. But
there was a catch. The system must satisfy two conditions: it must remain in
equilibrium with its environment, and it must never discard information. But
if the universe expands, equilibrium is impossible, because radiation gets
diluted and stretched in its wavelength. An accelerating universe changes too
rapidly for the system to reach equilibrium. And second, the requirement that
it never discard information means that an intelligent being must never forget.
Eventually, an intelligent being, unable to discard old memories, might find
itself reliving old memories over and over again. "Eternity would be a
prison, rather than an endlessly receding horizon of creativity and
exploration. It might be nirvana, but would it be living?" Krauss and
Starkman ask.)

In summary, we
see that if the cosmological constant is close to zero, intelligent life can
"think" indefinitely as the universe cools by hibernating and
thinking slower. But in an accelerating universe such as ours, this is
impossible. All intelligent life is doomed to perish, according the laws of
physics.

From the vantage
point of this cosmic perspective, we see therefore that the conditions for
life as we know it are but a fleeting episode in a much larger tapestry. There
is only a tiny window where the temperatures are "just right" to
support life, neither too hot nor too cold.

LEAVING THE UNIVERSE

Death can be
defined as the final cessation of all information processing. Any intelligent
species in the universe, as it begins to understand the fundamental laws of
physics, will be forced to confront the ultimate death of the universe and any
intelligent life it may contain.

Fortunately, there is ample time to assemble the energy for
such a journey, and there are alternatives, as we will see in the next chapter.
The question we will explore is: do the laws of physics allow for our escape
into a parallel universe?

Any sufficiently advanced technology is indistinguishable
from magic.

—Arthur C. Clarke

In the novel
Eon,
the science fiction author Greg Bear writes a harrowing tale
about fleeing a devastated world into a parallel universe. A colossal, menacing
asteroid from space has approached the planet Earth, causing mass panic and
hysteria. However, instead of striking Earth, it strangely settles into an
orbit around the planet. Teams of scientists are sent into space to
investigate. However, instead of finding a desolate, lifeless surface, they
find that the asteroid is actually hollow; it's a huge spaceship abandoned by
a superior technological race. Inside the deserted spaceship, the book's heroine,
a theoretical physicist named Patricia Vasquez, finds seven vast chambers,
entrances to different worlds, with lakes, forests, trees, even entire cities.
Next, she stumbles upon huge libraries containing the complete history of these
strange people.

Picking up an
old book, she finds that it is
Tom Sawyer,
by Mark Twain, but republished in 2110. She realizes that
the asteroid is not from an alien civilization at all, but from Earth itself,
1,300 years in the future. She realizes the sickening truth: these old records
tell of an ancient nuclear war that erupted in the distant past, killing billions
of people, unleashing a nuclear winter that killed billions more. When she
determines the date of this nuclear war, she is shocked to find that it is only
two weeks into the future! She is helpless to stop the inevitable war that
will soon consume the entire planet, killing her loved ones.

Eerily, she
locates her own personal history in these old records, and finds that her
future research in space-time will help to lay the groundwork for a vast tunnel
in the asteroid, called the Way, which will allow the people to leave the
asteroid and enter other universes. Her theories have proved that there are an
infinite number of quantum universes, representing all possible realities.
Moreover, her theories make possible the building of gateways located along
the Way for entering these universes, each with a different alternate history.
Eventually, she enters the tunnel, travels down the Way, and meets the people
who fled in the asteroid, her descendants.

It is a strange
world. Centuries before, people had abandoned strictly human form and can now
assume various shapes and bodies. Even people long dead have their memories and
personalities stored in computer banks and can be brought back to life. They
can be resurrected and downloaded several times into new bodies. Implants
placed in their bodies give them access to nearly infinite information.
Although these people can have almost anything they wish, nonetheless our
heroine is miserable and lonely in this technological paradise. She misses her
family, her boyfriend,
her
Earth, all of
which were destroyed in the nuclear war. She is eventually granted permission
to scan the multiple universes that lie along the Way to find a parallel Earth
in which nuclear war was averted and her loved ones are still alive. She
eventually finds one and leaps into it. (Unfortunately, she makes a tiny
mathematical error; she winds up in a universe in which the Egyptian empire
never fell. She spends the rest of her days trying to leave this parallel Earth
to find her true home.)

Although the
dimensional gateway discussed in
Eon
is purely fictional, it raises an interesting question that relates to us:
could one find haven in a parallel universe if conditions in our own universe
became intolerable?

The eventual
disintegration of our universe into a lifeless mist of electrons, neutrinos,
and photons seems to foretell the ultimate doom of all intelligent life. On a
cosmic scale, we see how fragile and transitory life is. The era when life is
able to flourish is concentrated in a very narrow band, a fleeting period in
the life of the stars that light up the night sky. It seems impossible for life
to continue as the universe ages and cools. The laws of physics and
thermodynamics are quite clear: if the expansion of the universe continues to
accelerate in a runaway mode, intelligence as we know it cannot ultimately
survive. But as the temperature of the universe continues to drop over the
eons, can an advanced civilization try to save itself? By marshaling all its
technology, and the technology of any other civilizations that may exist in
the universe, can it escape the inevitability of the big freeze?

Because the rate
at which the stages of the universe evolve is measured in billions to trillions
of years, there is plenty of time for an industrious, clever civilization to
attempt to meet these challenges. Although it is sheer speculation to imagine
what kinds of technologies an advanced civilization may devise to prolong its
existence, one can use the known laws of physics to discuss the broad options
that may be available to them billions of years from now. Physics cannot tell
us what specific plans an advanced civilization may adopt, but it might tell us
what the range of parameters are for such an escape.

To an engineer,
the main problem in leaving the universe is whether we have sufficient
resources to build a machine that can perform such a difficult feat. But to a
physicist, the main problem is different: whether the laws of physics allow for
the existence of these machines in the first place. Physicists want a
"proof of princi- ple"—we want to show that, if you had sufficiently
advanced technology, an escape into another universe would be possible according
to the laws of physics. Whether we have sufficient resources is a lesser,
practical detail that has to be left for civilizations billions of years in the
future that are facing the big freeze.

According to
Astronomer Royal Sir Martin Rees, "Wormholes, extra dimensions, and
quantum computers open up speculative scenarios that could transform our
entire universe eventually into a 'living cosmos.' "

TYPE I, II, AND III CIVILIZATIONS

To understand
the technology of civilizations thousands to millions of years ahead of ours,
physicists sometimes classify civilizations depending on their consumption of
energy and the laws of thermodynamics. When scanning the heavens for signs of
intelligent life, physicists do not look for little green men but for civilizations
with the energy output of type I, II, and III civilizations. The ranking was
introduced by Russian physicist Nikolai Kardashev in the 1960s for classifying
the radio signals from possible civilizations in outer space. Each civilization
type emits a characteristic form of radiation that can be measured and
cataloged. (Even an advanced civilization that tries to conceal its presence
can be detected by our instruments. By the second law of thermodynamics, any
advanced civilization will create entropy in the form of waste heat that will
inevitably drift into outer space. Even if they try to mask their presence, it
is impossible to hide the faint glow created by their entropy.)

A type I
civilization is one that has harnessed planetary forms of energy. Their energy
consumption can be precisely measured: by definition, they are able to utilize
the entire amount of solar energy striking their planet, or 10
¹⁶
watts. With this planetary energy, they might control or modify the weather,
change the course of hurricanes, or build cities on the ocean. Such
civilizations are truly masters of their planet and have created a planetary
civilization.

A type II
civilization has exhausted the power of a single planet and has harnessed the
power of an entire star, or approximately 10
²⁶
watts. They are able
to consume the entire energy output of their star and might conceivably control
solar flares and ignite other stars.

A type III
civilization has exhausted the power of a single solar system and has colonized
large portions of its home galaxy. Such a civilization is able to utilize the
energy from 10 billion stars, or approximately 10
³⁶
watts.