- 2081
- Are We Alone in the Universe? 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. To date, over 3,700 planets have been discovered
orbiting other stars. Life appeared on
Earth rapidly, as soon as conditions would allow.
-
-
-
----------------------------------- 2081
- 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. 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).
-
- 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. This array is under construction in the
Cascade Mountains 250 miles northeast of San Francisco. 350 antennas that are being built. The whole array will spread over 2/3rds of a
mile in diameter.
-
- 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. 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.
-
- In our Milky
Way Galaxy, how many intelligent beings are likely to have their transmitters
switched on?
-
---------------------------------- Carl Sagan says 1,000,000
-
---------------------------------- Isaac Asimov says 500,000
-
---------------------------------- Frank Drake says 10,000
-
- 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. To date, over 3,700 planets
have been discovered orbiting other stars.
-
- 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.
-
- But, will we
know alien life when we find it?
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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?
-
- 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.
-
- 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.
-
- 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.
-
---------------------------------------------------------------
-
- The tree of life has its roots as
thermopiles. Its main branches are
archaea, bacteria, eukarya, animals and plants.
-
----------------------------------------------------------------------------------------
----- Comments appreciated and Pass it on to
whomever is interested. ----
---
Some reviews are at:
--------------
http://jdetrick.blogspot.com -----
--
email feedback, corrections, request for copies or Index of all reviews
------------------------- Sunday, April 22, 2018
--------------------------------
-----------------------------------------------------------------------------------------
No comments:
Post a Comment