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2122 - Are We Alone in the Universe? -
Astronomers only started looking for alien life in the Universe 50 years
ago. So far, we have not found any sign
of alien life. Life is one thing but
intelligent life is something else again.
Intelligent life is even more unlikely on this tree of life and the
evolution processes. If the Universe is
infinite, the impossible will happen somewhere.
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---------------------------------- 2122
- Are We Alone in the Universe?
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- Astronomers only started looking for alien
life in the Universe 50 years ago. So
far, we have not found any sign of alien life.
The first signals we tried to detect were at 1,420 megahertz, or 21
centimeters wavelength. 21 centimeters
was picked because it matched the radiation of neutral hydrogen, interstellar
gas. (See Review #714, "The New
Astronomy").
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- Today, radio interferometers are just
beginning to be used to increase this detection with greater resolution. Instead of a single radio dish antenna being
used to detect a signal, hundreds of dishes each 20 feet in diameter will be
connected together into a giant array.
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- This
array is under construction in the Cascade Mountains 250 miles northeast of San
Francisco. 350 antennas are being
built. The whole array will spread over
2/3rds of a mile in diameter.
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- The radio interferometer will detect
frequencies from 500 to 11,200 megahertz all at the same instance. Its field of view will be 2.5 degrees. The massive, single reflector dish in Puerto
Rico has a field of view of only 0.6 degrees.
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- You too can participate in this search for
alien life. By putting SETI@home
screensaver on your home computer you can help hunt through all the
extraterrestrial signals pouring in from the cosmos in bits and bytes. The screen saver is free off the internet.
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- In our Milky Way Galaxy, how many intelligent
beings are likely to have their transmitters switched on?
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---------------------------------- Carl Sagan says 1,000,000
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---------------------------------- Isaac Asimov says 500,000
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---------------------------------- Frank Drake says 10,000
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- Astronomers are narrowing the number of
possible targets in their search by selecting metal rich stars, which are
thought to be more likely to have rocky planets. Even better target selection will occur when
future telescopes can identify planets containing oxygen and methane, a sure
sign of biology.
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- If we take Frank Drake’s most conservative
estimate for detecting aliens in our own Milky Way and with the current
improvements in technology we should be able to discover an alien transmitter
by 2025.
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- But, will we know alien life when we find it?
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- Life is a complex chemical system that is
able to replicate itself and undergo evolution.
Those organisms that survive in large numbers and reproduce the most
drive the diversity needed for them to adapt to their environments.
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- All
known life is carbon-based. This is
because of all the over 100 elements carbon is the most flexible in reacting
with the other elements. All life seems
to require liquid water, H2O, hydrogen and oxygen, two of the most abundant
elements in the Universe. Water provides
the liquid solvent for biochemistry to work.
80% of the human body is water.
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- The
proportions of the elements in the body exactly match the proportions of these
elements in the Universe. Hydrogen is
the most abundant, then helium, which is inert and does not react with other
elements, then oxygen, carbon, nitrogen, etc.
We are of this Universe, so we should expect aliens to be similarly, “of
this Universe”. They would just likely
look a lot different as a result of their own evolution.
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- Earth is 4,460,000,000 years old. The first sign of biochemistry for life on
this planet was found to be 3,850,000,000 years old. That is only 610 million years later. Life appeared on Earth rapidly, as soon as
conditions would allow.
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- Microorganisms are found today in conditions
once thought too hostile for life. Life
is tenacious, it occupies every available environment and survives under the
most astonishing conditions.
Hyperthermophiles thrive in deep sea vents at high pressures, 242
degrees F, without sunlight, or oxygen.
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- Astonishingly as this may seem, the RNA,
ribonucleic acid, found in every cell in all life on Earth, has a chemical
sequence revealing the roots of the tree of life starting and being with these
hyperthermophiles. That is how it
started and look where we are today.
Could similar evolution have occurred on another planet?
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- There are 10^21 stars in the Observable
Universe, more stars than grains of sand on all the beaches on Earth. Think of the diversity of life that exists on
Earth, not only animals, but plants, bacteria and microorganisms. Add to that all the life forms that once
lived here and are now extinct. If
aliens do exist it is safe to expect them to be much different than us.
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- Life is one thing but intelligent life is
something else again. Intelligent life
is even more unlikely on this tree of life and the evolution processes. Even our human intelligence has only been smart
enough to bring us the technology capable of responding to alien signals in the
last 75 years. That is 75 years out of
billions of years of life on Earth.
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- If the Universe is infinite, the impossible
will happen somewhere. But our
Observable Universe is finite. And, the
Observable Universe that we can reach with our best technology is even more
finite. What a difference it would make
in our world if we do detect some intelligence out there.
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(1) The tree of life has its roots as
thermopiles. Its main branches are
archaea, bacteria, eukarya, animals and plants.
----------------------------------------------------------------
- October 11, 2018. This Review was 716
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“Jim Detrick” -----------
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--------------------- Thursday, October 11, 2018 -------------------------
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