Posted on 12/02/2005 8:35:59 AM PST by ckilmer
SETI and Intelligent Design By Seth Shostak SETI Institute posted: 01 December 2005 06:37 am ET |
If youre an inveterate tube-o-phile, you may remember the episode of "Cheers" in which Cliff, the postman whos stayed by neither snow, nor rain, nor gloom of night from his appointed rounds of beer, exclaims to Norm that hes found a potato that looks like Richard Nixons head.
This could be an astonishing attempt by taters to express their political views, but Norm is unimpressed. Finding evidence of complexity (the Nixon physiognomy) in a natural setting (the spud), and inferring some deliberate, magical mechanism behind it all, would be a leap from the doubtful to the divine, and in this case, Norm feels, unwarranted.
Cliff, however, would have some sympathizers among the proponents of Intelligent Design (ID), whose efforts to influence school science curricula continue to swill large quantities of newspaper ink. As just about everyone is aware, these folks use similar logic to infer a "designer" behind such biological constructions as DNA or the human eye. The apparent complexity of the product is offered as proof of deliberate blueprinting by an unknown creatorconscious action, presumably from outside the universe itself.
What many readers will not know is that SETI research has been offered up in support of Intelligent Design.
The way this happens is as follows. When ID advocates posit that DNAwhich is a complicated, molecular blueprintis solid evidence for a designer, most scientists are unconvinced. They counter that the structure of this biological building block is the result of self-organization via evolution, and not a proof of deliberate engineering. DNA, the researchers will protest, is no more a consciously constructed system than Jupiters Great Red Spot. Organized complexity, in other words, is not enough to infer design.
But the adherents of Intelligent Design protest the protest. They point to SETI and say, "upon receiving a complex radio signal from space, SETI researchers will claim it as proof that intelligent life resides in the neighborhood of a distant star. Thus, isnt their search completely analogous to our own line of reasoninga clear case of complexity implying intelligence and deliberate design?" And SETI, they would note, enjoys widespread scientific acceptance.
If we as SETI researchers admit this is so, it sounds as if were guilty of promoting a logical double standard. If the ID folks arent allowed to claim intelligent design when pointing to DNA, how can we hope to claim intelligent design on the basis of a complex radio signal? Its true that SETI is well regarded by the scientific community, but is that simply because we dont suggest that the voice behind the microphone could be God?
Simple Signals
In fact, the signals actually sought by todays SETI searches are not complex, as the ID advocates assume. Were not looking for intricately coded messages, mathematical series, or even the aliens version of "I Love Lucy." Our instruments are largely insensitive to the modulationor messagethat might be conveyed by an extraterrestrial broadcast. A SETI radio signal of the type we could actually find would be a persistent, narrow-band whistle. Such a simple phenomenon appears to lack just about any degree of structure, although if it originates on a planet, we should see periodic Doppler effects as the world bearing the transmitter rotates and orbits.
And yet we still advertise that, were we to find such a signal, we could reasonably conclude that there was intelligence behind it. It sounds as if this strengthens the argument made by the ID proponents. Our sought-after signal is hardly complex, and yet were still going to say that weve found extraterrestrials. If we can get away with that, why cant they?
Well, its because the credibility of the evidence is not predicated on its complexity. If SETI were to announce that were not alone because it had detected a signal, it would be on the basis of artificiality. An endless, sinusoidal signal a dead simple tone is not complex; its artificial. Such a tone just doesnt seem to be generated by natural astrophysical processes. In addition, and unlike other radio emissions produced by the cosmos, such a signal is devoid of the appendages and inefficiencies nature always seems to add for example, DNAs junk and redundancy.
Consider pulsars stellar objects that flash light and radio waves into space with impressive regularity. Pulsars were briefly tagged with the moniker LGM (Little Green Men) upon their discovery in 1967. Of course, these little men didnt have much to say. Regular pulses dont convey any informationno more than the ticking of a clock. But the real kicker is something else: inefficiency. Pulsars flash over the entire spectrum. No matter where you tune your radio telescope, the pulsar can be heard. Thats bad design, because if the pulses were intended to convey some sort of message, it would be enormously more efficient (in terms of energy costs) to confine the signal to a very narrow band. Even the most efficient natural radio emitters, interstellar clouds of gas known as masers, are profligate. Their steady signals splash over hundreds of times more radio band than the type of transmissions sought by SETI.
Imagine bright reflections of the Sun flashing off Lake Victoria, and seen from great distance. These would be similar to pulsar signals: highly regular (once ever 24 hours), and visible in preferred directions, but occupying a wide chunk of the optical spectrum. Its not a very good hailing-signal or communications device. Lightning bolts are another example. They produce pulses of both light and radio, but the broadcast extends over just about the whole electromagnetic spectrum. That sort of bad engineering is easily recognized and laid at natures door. Nature, for its part, seems unoffended.
Junk, redundancy, and inefficiency characterize astrophysical signals. It seems they characterize cells and sea lions, too. These biological constructions have lots of superfluous and redundant parts, and are a long way from being optimally built or operated. They also resemble lots of other things that may be either contemporaries or historical precedents.
So thats one point: the signals SETI seeks are really not like other examples drawn from the bestiary of complex astrophysical phenomena. That speaks to their artificiality.
The Importance of Setting
Theres another hallmark of artificiality we consider in SETI, and its context. Where is the signal found? Our searches often concentrate on nearby Sun-like star systems the very type of astronomical locale we believe most likely to harbor Earth-size planets awash in liquid water. Thats where we hope to find a signal. The physics of solar systems is that of hot plasmas (stars), cool hydrocarbon gasses (big planets), and cold rock (small planets). These do not produce, so far as we can either theorize or observe, monochromatic radio signals belched into space with powers of ten billion watts or morethe type of signal we look for in SETI experiments. Its hard to imagine how they would do this, and observations confirm that it just doesnt seem to be their thing.
Context is important, crucially important. Imagine that we should espy a giant, green square in one of these neighboring solar systems. That would surely meet our criteria for artificiality. But a square is not overly complex. Only in the context of finding it in someones solar system does its minimum complexity become indicative of intelligence.
In archaeology, context is the basis of many discoveries that are imputed to the deliberate workings of intelligence. If I find a rock chipped in such a way as to give it a sharp edge, and the discovery is made in a cave, I am seduced into ascribing this to tool use by distant, fetid and furry ancestors. It is the context of the cave that makes this assumption far more likely then an alternative scenario in which I assume that the random grinding and splitting of rock has resulted in this useful geometry.
In short, the champions of Intelligent Design make two mistakes when they claim that the SETI enterprise is logically similar to their own: First, they assume that we are looking for messages, and judging our discovery on the basis of message content, whether understood or not. In fact, were on the lookout for very simple signals. Thats mostly a technical misunderstanding. But their second assumption, derived from the first, that complexity would imply intelligence, is also wrong. We seek artificiality, which is an organized and optimized signal coming from an astronomical environment from which neither it nor anything like it is either expected or observed: Very modest complexity, found out of context. This is clearly nothing like looking at DNAs chemical makeup and deducing the work of a supernatural biochemist.
JPL has a nice site on extra-solar plants, and a cool Shockwave atlas.
RA isn't here, so I'll attempt an answer. We've discovered about 150 extra-solar planets, some as far as 500 light years away. I don't know the number of stars in a sphere with that radius, but within a radius of only 250 light years there are 260,000 stars, according to this source: The Universe within 250 Light Years.
Or if there were a duplicate of Earth around a particular star, could it be detected with our equipment?
Actually imaging Earth-like planets may someday be done with massive interferometers in orbit. I'd consider O2 in the atmosphere a sign of life.
We can't forget that Earth is 4.5 billion years old, over half that time there were no eukaryotes, big animals date from the half a billion ya, and we've only been broadcasting radio for 100-odd years.
Yes, we ought to see at least generally how to put it into a shape that can make a prediction (preferably lots of them) we can test practically.
It's not clear if you mean using SETI technology, or using ANY technolgy. If the latter, PH has already provided you with an answer. If the former, which is in effect the same as asking how far away can we or a similar civilization of similar technology detect the sorts of radio signals that are generated on earth by humans, the answer is somewhere beyond 1000 LY, and substantially more if you use something the size of the Arecibo dish for your antenna. And even more than that again if Alfred the Alien is using an Arecibo size antenna to transmit his signals!
I'm quoting RA for the 1000 LY number, so if it turns out wrong, blame him!
That small device inserted into your sinus cavity.
Here's a link to one of RA's more technical explanations of how the distance over which one can detact a signal is calculated. You'd have to fill in values for the various factors and do the calculation to see what the answer would be. Heavy GEEK ALERT:
http://www.freerepublic.com/focus/f-news/1289285/posts?page=28#28
Veger?
It was a joke, and humor is the only possible way to deal with quote-miners and board spammers such as yourself.
Thanks, 1000 LY radius is a LOT of stars!
There is a conjecture that all possible sequences of digits appear in pi. IIRC, this is true for almost all real numbers, but no-one knows how to prove (or disprove) it for pi.
Canard. Those aren't "designed emissions", they're emissions from designed things. Those emissions are incidental to the functions of carpet cleaning and mechanical destruction. "Designed emission" means that the EM signal itself is intelligently designed.
(But in any case, I waive the point as irrelevant. There's no way to cut the Fermilab data such that every top quark is identified, and no background events remain in the sample. In fact, out of millions of top quarks produced, only a handful get reconstructed, but that's more than enough not only to prove they exist, but to measure their properties.)
What ID advocates are essentially looking for is the equivalent -- something biological that's could have been created but can't also be explained by a known natural process.
You said it, right there. The ID proponents are looking for such an effect. But the entire claim of the ID sales force is that such an effect manifestly exists, and they are proposing ID as a candidate explanation! They couch it in terms of "here we have a mystery...oh, look! an explanation!", when in reality it's an age-old supposition in search of some type of evidence that might someday lend it credence. ID has no phenomena, no way to distinguish such phenomena, and gives no reason to expect that such phenomena exist.
Don't keep on insisting that SETI is the same thing, though. It's different on two key counts. First, SETI has unambiguous examples of both designed and natural signals. Both definitely exist in the universe. By contrast, ID--proposed as an explanation of the origin of life--only has one sort of life to ponder, and it's either all designed, or all natural (except for a growing handful of uninstructive exceptions, easily identified by their patents).
Second, SETI has a quantitative, testable method of separating the natural from the designed. ID has only subjectivity: "this looks designed to me" and "I don't see how this could have happened naturally" and finally "OK, it could have happened in one of those several ways, but you can't prove that it actually did, and besides, here's this other thing I don't understand..."
Look at the resistance to such ideas as continental drift and so on.
One of the great success stories of science. When the only evidence was "the continents look like they fit together", it was ignored. When the hard evidence came in, it was embraced. It would have been irresponsible to embrace it any sooner than it was. I say the same thing about ID that I say about free energy schemes: get back to me after you make it work.
That's is only true if the designer's hand is heavy or they seek to be detected.
The entire impetus behind ID is that the designer's hand is so obvious, one must willfully avert his gaze not to see it. But no matter: if the designer truly is a deity (as essentially all ID marketeers believe) AND he wishes his seams not to be visible, we don't have a prayer of ever finding them.
And if the aliens are really tech-savvy and intent on hiding, we won't ever find them, either.
Right. But say at the quadrillionth decimal place you find a sequence of a million zeros, then a million ones, then a sequence of ones and zeros that forms a recognizable picture when plotted as a bitmap. Even though you'd expect that sequence to appear *somewhere* in pi, the odds against it occuring so early by "chance" would be astronomical.
Wow.
Hmmmmm... a frog eye. Quite nice, and delicious.
There will never be such a signal.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.