Write your abstract here.November 07, 2007
PART I - Michio Kaku''s
Civilizations of the Cosmos
"What does
it mean for a
civilization to be a
million years old? We have had radio telescopes and spaceships for a
few decades; our technical civilization is a few hundred years old ...
an advanced civilization millions of years old is as much beyond us as
we are beyond a bushbaby or a macaque."
Carl Sagan
Michio Kaku, professor of theoretical physics at City University of
New York, in the current issue of Cosmos writes that Sagan''s question is no longer just a matter of idle speculation. Soon,
humanity may face an existential shock as we discover Earth-sized twins
of our planet orbiting nearby solar systems. This may usher in a new
era in our relationship with the universe, so that we will never see
the night sky in the same way. Realizing that scientists may eventually
compile an encyclopedia identifying the precise coordinates of perhaps
hundreds of Earth-like planets, gazing at the night sky, we will
forever after wonder if someone is gazing back at us.Kaku
takes up where some/one of the world''s pioneer astronomers left off
with a definition of
civilizations in the universe that mimics the work
of Russian astrophysicist Kardashev. Inspired at the age of five by a
Moscow Planetariumshow about Giordano Bruno, Kardashev definined three
levels of advanced civilizations based on how they harness energy to
fuel their societies. All three categories of civilizations, even the
most advanced Type 111, would still be bound by the laws of physics
thatallow us to predict the behavior of the universe from the subatomic world to
the large-scale structure of the universe, through a staggering 43
orders of magnitude (a factor of 10 million billion billion billion
billion).
Type 1 civilizations would have a technological level similar to
ours at present, as measured by total energy consumption. Carl Sagan
estimated that Earth qualifies as a Type 0.7 civilisation.Type
11 civilizations would be capable of harnessing the energy of their own
star -constructing, for example, a Dyson Sphere. And Type 111
civilizations would be able to utilize energy on the scale of their own
galaxies. Kardeschev and Kaku believe there is an extremely low
probability of detecting Type 1 civilizations and suggests that type 11
or 111 civilizations would make better targets.Kardeschev calculated
that the energy consumption of these three types of
civilizations would be separated by a factor of about 10 billion.
In 1963 Kardeschev searched for traces of the more advanced type 11
and 111 at the 920 MHz wavelength creating an uproar of excitement
thinking he had discover signals from a Type 11 civilization that later
proved to be an ordinary quasar with a large redshift. A similar uproar
occurred in 1967 when regular signals were detected by radio telescopes
at Cambridge, England, which turned out to be the first discovery of
neutron stars.
Over the next few years, according to Kaku, "New spaceborne
telescopes will finally become powerful enough to identify twins of
Earth. The Kepler telescope, to be launched in 2008, will probably be
able to identify terrestrial planets – rocky worlds rather than gas
giants like Jupiter and Saturn. Until 2012 it will scan as many as
100,000 Sun-like stars up to 2,000 light years away, and perhaps
identify hundreds of Earth-like worlds by detecting the slight loss of
light they cause as they pass in front of their mother star. Kepler
will hopefully identify 185 such planets with less than 1.3 times the
radius of Earth, and as many as 640 terrestrial planets less than 2.2
times."
The Terrestrial Planet Finder, expected to be launched in about 2014,
will scan the brightest 1,000 stars within 50 light years of Earth, and
focus on the 50 to 100 brightest planetary systems, analyzing the faint
light reflected fese planets to determine if they can support the
organic chemistry that make life possible.
All this, Kaku predicts "will stimulate an active effort to discover
if any of them harbor life, perhaps some with civilizations more
advanced than ours. According to the laws of planetary evolution, any
advanced civilization must grow in energy consumption faster than the
frequency of life-threatening catastrophes, such as meteor impacts, ice
ages, or supernova explosions. If their growth rate stays any slower,
they are doomed to extinction. Thus, this places mathematical lower
limits on the growth rates of these civilizations.
Kaku believes along Princeton physicist Freeman Dyson, that although
human civilization has only recently begun to master planetary energies
-fossil fuels, passive solar, wind, geothermal and nuclear fission, and
may one day soon crack nuclear fusion-hat, within a century or two, we should attain Type I status. In fact,
growing at a modest rate of 1 per cent per year, Kardashev estimated
that it would take only 3,200 years to reach Type II status, and 5,800
years to reach Type III status. Because of limited space, please read continuation in PART II - Michio Kaku''s Civilizations of the Cosmos.