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ZL2VAL > SETI 02.09.04 14:15l 120 Lines 5199 Bytes #999 (0) @ WW
BID : 380112ZL2VAL
Read: OE1DMB GUEST
Subj: ET should write, not phone
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<ZL2BAU<ZL2BAU<ZL2AB
Sent: 040902/1106Z @:ZL2AB.#46.NZL.OC #:46690 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : SETI@WW
*Researchers: ET Should Write, Not Call *
By Robert Roy Britt
Senior Science Writer
posted: 01 September 2004
02:42 pm ET
A fresh perspective on searching for aliens suggests ET is more likely
to send us something akin to a message in a bottle rather than relying
on energy-intensive, inefficient radio messages.
The professional hunt for ET (http://www.space.com/searchforlife/)
depend largely on huge telescopes that scan for electronic intelligence
in the ether, on the assumption that an brainy, technologically advanced
civilization might try to reach out to others, or that their
communications would leak into space.
But sending a signal across the cosmos is expensive an inefficient,
argues Christopher Rose, a professor of electrical and computer
engineering at Rutgers University. The idea is detailed in the Aug. 25th
issue of the journal `Nature'.
Tortoise and hare
Rose and physicist Gregory Wright initially set out to learn how to send
the most information over a wireless channel. They then considered the
amount of energy needed to send a signal over greater distances. As
logic suggests, more energy is needed to send a message farther, and the
signal weakens.
Radio waves, laser beams or X-ray pulses and other electromagnetic
signals all travel at the speed of light. But the farther they go, the
more they disperse. That makes them harder to detect.
"Think of a flashlight beam," Rose said. "Its intensity decreases as it
gets farther from its source."
Seth Shostak knows about this problem. Shostak worked on the SETI
Institute's Project Phoenix, a just-finished search for extraterrestrial
radio signals (they didn't hear any) that was the most comprehensive so
far. Not involved in Rose's research, Shostak wrote recently that
sending a barely detectable radio-based signal across 100 light-years
and in all directions would require 100 billion watts of power.
Translation: You'd have to focus the output of all American power
planets to do the job.
(http://www.space.com/searchforlife/seti_targeted_040401.html)
Interstellar radio programs face another problem in garnering listeners.
Once an electronic signal passes its intended recipient, it is gone for
good. If the creatures on a target planet have their electronic ears
tuned to some other frequency when a signal arrives, or if they have yet
to develop the right listening technology, the effort to make contact is
wasted.
A written message in a space capsule, however, could have landed on
Earth millennia ago and await discovery. And a spacecraft, once up to
speed, can cruise for long periods with little additional power input.
Time to spare?
The downside to the message-in-a-bottle approach: Human technology, at
least, can't propel a spacecraft to even a significant fraction of
light-speed. So getting a note from one star system to the next would
take more generations than the average human mind can contemplate.
The most distant probe sent by earthlings is Voyager 1, just crossing
the outer boundary of the solar system. After a 27-year journey it is
90 times the distance from Earth to the Sun, or nearly 8.4 billion miles
(13.5 billion kilometers). A radio signal can go that far and back in
about a day -- well more than 26 years more quickly!
The next nearest stars, in the Alpha Centauri system, are
4.3 light-years distant. That's more than 3,000 times what Voyager has
so far covered.
However, so long as time is not of the essence, Rose and Wright figure
hard copy would be the preferred method to talk across the stars.
"If haste is unimportant, sending messages inscribed on some material
can be strikingly more efficient than communicating by electromagnetic
waves," Rose said.
Outbound examples
Further, he points out, long messages are handled more efficiently by
inscription.
NASA's two Voyager probes exhibit such an effort.
(http://www.space.com/missionlaunches/top10_voyager_020820-1.html). Each
carries a 12-inch, gold-plated copper disk with sounds and images that
portray terrestrial life and culture. The cost to send the records was
practically inconsequential to the overall price tag of the mission,
whose main purpose was to study the planets.
Radio pulses announcing anything more than "we exist" would consume more
energy (which requires money) for every word.
Rose is not against listening. He just thinks looking might prove more
fruitful. He also notes that messages might not arrive as language, per
se. Perhaps organic material embedded in an asteroid, the Moon or a
satellite of Jupiter would reveal the presence of life elsewhere. That
of course is not a new idea. Other scientists have considered that
unintelligent (microbial) life could even travel between planets
embedded in a rock kicked up by an asteroid impact. No calling card
required.
* SETI: The Search for Life: http://www.space.com/searchforlife/
* Voyager: What's Onboard,
http://www.space.com/missionlaunches/top10_voyager_020820-1.html
73 - Alan, ZL2VAL @ ZL2AB.#46.NZL.OC
zl2val@qsl.net
Message timed: 23:05 on 2004-Sep-02
Old Age
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The older we get, the fewer things seem worth waiting in line for.
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