Sunday, October 14, 2018

Are We Alone in the Universe?



-  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.
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-  October 11, 2018.       This Review was 716
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 ---------------------   Thursday, October 11, 2018   -------------------------
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