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Posted on 05/30/2005 2:25:11 AM PDT by RWR8189
HAT CREEK, Calif. -- Astronomer Michael M. Davis checked his computer. One of the antennas on the state-of-the-art radio telescope being built in the valley outside his office was picking up an unusual pulse from beyond the Earth. A signal from another intelligent civilization? Not today. It was the Rosetta Satellite, en route to study a comet.
Hopeful moments followed by disappointments like this are par for the course for researchers at the SETI Institute, the privately funded successor to the now defunct government project dedicated to searching for alien life. They have been searching the heavens for decades, but they have not been able to gather enough data to conclude, or even guess, whether we are alone in the universe.
This time, however, the scientists hope things might be different. This month, the first telescope designed specifically for such a search began scanning the skies. It is still in its early stage of development, but when it is completed the telescope will be so powerful that it will be able to look at more stars in a year or two than we have in the past 45 years.
"The absence of a signal so far is not particularly compelling," said Davis, an adjunct professor emeritus at Cornell University who recently joined SETI to oversee the telescope project. "We could have a billion intelligent cultures with radio waves buzzing around them . . ., but we haven't had the capability to detect them."
(Excerpt) Read more at washingtonpost.com ...
I think it's only a matter of time - not whether there is life out there. There has to be.
Radio is starting to become an archaic form of communication here. SETI should be looking for other manifestations of advanced civilizations.
Such as?
Laser emissions, artificial structures near planets, radiation plumes. Granted this may be beyond our current detection technology but radio emmissions have only been persistent on earth for less than a 100 years and may be a relic in another 100. More promising may be searches throughout the electromagnetic spectrum that are tell tale signatures as by-products of an advanced civilization. Or maybe the "universal beacon" used is yet to be discovered by us, maybe from advanced quantum mechanics.
Your point to look for other forms of radiation makes some intial sense, however the assumnption is being made that the technology we use would be available elsewhere and that radio would be the most simple form of technology.
Since humans have now sent radio waves for about 125 years, we can assum we can be detected by an exremely advanced civilization that is 125 light years away or less.
For us to detect any other civilization it would have had to exist (or have existed) for a period of time long enough for its radio waves to travel to us.
Unless there are ways to send information or travel faster than the speed of light, we will always be seeing very old re-runs of civilization that quite possible no longer exist.
If humans ever really do leave our solar system and intelligent life that has created advanced technological civilizations is detected, we may initally find ourselves surrounded only by ghosts. But, it would still be interesting.
They have to look no further than my refrigerator. Not necessarily "advanced" but rather "advancing" daily....
And then we have to hope that the period of time we have been able to detect them overlaps the period of time in which their signals have reached Earth. If a civilization a hundred light years away stopped using radio a thousand years ago, we're not going to find them.
Good point.
So, we have to hope that either intelligent, advanced civilizations are relatively frequent, long-lasting and nearby. Eliminate any of those factors without allowing for faster-than-light travel and the hope of detecting that life is fairly remote.
Didn't Asimov do a calculation to this effect?
" More promising may be searches throughout the electromagnetic spectrum"
I always thought that radio waves were 'electromagnetic' in nature..
That's why the use of 'spread spectrum' detection would probably be the best hope of finding any intelligent signal.
I particularly love this... "There has to be."
All of which only can be seen using the Electromagnetic Spectrum (EM). There are already searches being conducted using the visible wavelengths, however, I still personally think microwave (which also is an EM emanation) is still the best method to date.
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Since humans have now sent radio waves for about 125 years
I would change that to only about 60 years of detectible EM shouting to the universe that there is a tool building species here.
OTOH, our very planet has been sending a "signature (spectrum from our atmosphere)" of a possible life-bearing planet for a very long time.
In the absence of data, it is only possible, not necessary.
SETI (at least the current trend) is searching for extremely narrowband carrier signals that are Doppler shifted due to planetary rotation. The Doppler shift is extremely important since if it is not there, we know the signal is either terrestrial or an artifact of the equipment itself. The other thing that is very important is the two-antenna approach. If two antennas, separated by a thousand miles, were pointed at the same patch of sky, this would not allow a satellite to "spoof" the system. First, the likelihood of it being within the footprint of both antennas are exceedingly small, and the Doppler characteristics between the two antennas would rule it out if such a thing happened.
All that said, I agree with the advances in communications technology can cause a search to be futile for many types of broadcasts. Frequency hopping spread spectrum and the like will make it far harder to detect a tool building species that uses radio (EM).
To be fair to the other side there is another factor in this conjecture. A race is progressing along and figures out that the electromagnetic spectrum is the only real practical method of long-range communications. So high-powered transmitters are built as this technology is in its infancy. As the engineering and science of radio advances, they figure out that tight beam, spread spectrum, synthetic aperture, frequency hopping, etc. are a way of not only saving power, but also bandwidth. So for the first 50 years they have been "bleeding" EM into space across a huge range of frequencies into and ever-increasing sphere of radio noise. However, do to technological advances, this RF that is being bled into space quiets down dramatically.
Now, lets jump a few years. This race has expanded off its initial planet and is exploring the solar system it resides in. (IMHO, star travel still remains firmly in the realm of SiFi) Somehow they have to communicate. So again high power transmitters are employed to accomplish this. Light is not out of the question, however, microwave is easy, cheap, less pointing accuracy requirements, and wont be drowned out by the star. So suddenly this race again is radiating RF into the universe. So according to this scenario, a race can emit RF then grow silent for a time, and then restart emitting RF.
Actually SETI is not looking for "information". Just the detection of an extremely narrowband RF signal (the carrier of most radio transmissions) is enough to suspect it was a non-natural emanation.
While that is technically true, with 100 billion plus galaxies and each containing a similar number of stars the odds are very high there is life elsewhere.
Next, you'll be claiming that ships do not make big loud booms when they explode out in space.
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My theory is that what these guys do is gather up hydrogen into these big balls that then ignite and give off radiation all across the spectrum. They use these as navigation beacons.