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Bracewell Probes: Part One
Posted by Mac Tonnies, Friday, March 07, 2008 at 10:00 AM by Mac Tonnies
Lately much speculation has trended away from the "classic" SETI paradigm and into the domain of hypothetical ET devices such as self-replicating spacecraft and automated communications platforms (an idea proposed by astronomer Ronald Bracewell in his book "The Galactic Club").
Both concepts come as invigorating alternatives to the original SETI paradigm championed by Frank Drake and Carl Sagan. On the other hand, they leave us faced with the unnerving prospect of a galaxy bereft of intelligent life. If deep-space is impregnated by the robotic emissaries of far-flung galactic intelligences intent on achieving long-range contact, we have yet to receive an irrefutable signal. No sign of the telltale prime numbers celebrated in Sagan's "Contact." No invitations to subscribe to the "Encyclopedia Galactica," however hard we might wish to mingle with our elders in the local stellar neighborhood.
Or so it might seem.
SETI pundits tend to assume that contact with an alien device would unfold basically along the lines as direct contact with an actual civilization. Even Bracewell, an adventurous thinker in many respects, assumed that his eponymous probes would be little more than advanced versions of our own far-flung exploratory spacecraft; he envisioned Earth-based radio astronomers striking up a rudimentary dialogue with a probe dispatched to monitor the potential emergence of intelligence in our sector of the galaxy. After learning of our technological capacity (specifically, our ability to communicate via radio transmissions), the probe would then alert its makers, who might then choose to communicate in "person."
If this scenario sounds cumbersome, that's because it's inherently limited by the speed of light. Any ET civilization capable of wafting its cybernetic spore into the galaxy might very well have achieved effective immortality, but prospects for our own world are less certain; we could self-destruct or succumb to environmental catastrophe many thousands of years before achieving a meaningful long-distance relationship. Knowing we're not alone may come with a certain existential comfort, but, by itself, would be of no specific practical value.
And although SETI advocates almost invariably expect that ET societies will want to communicate with us, we shouldn't dismiss the unflattering possibility that we're subject to some form of quarantine. Perhaps we're being watched by "intellects vast, cool and unsympathetic," if not as war-like as H.G. Wells' imperious Martians.
Does the apparent absence of Bracewell probes prove that we have yet to be visited? Hardly. Maybe we're just not looking hard enough. Maybe we need to think like an alien.
Mac Tonnies
5 Comments:
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Posted by Dennis McClain PhD
March 11, 2008 at 01:23 PM
\"Like an alien\"? Like what kind of alien? Unless there is only one other species/civilization in potential contact with us, we should consider the \"like an alien\" concept to be a variable.
An advanced civilization might have the time and inclination to search out and understand life forms very different from their own. On the other hand, they may conserve in terms of understanding in order to devote more time and energy to exploration, to find those who are more like them and easier to set up communication with. Arguments can be made for both of these being based on intelligent choices, and so similarly likely tactics for other species/civilizations. Where we fall within the range of these is a variable we can\\'t predict. If we don\\'t fit the criteria (given the range of possibilities, more likely than not) what may look like quarantine might actually be disinterest.
It is frequently stated that contact would be a massively societal altering event. And so it might. But so was Marconi\\'s radio, relativity, global communication (including but not limited to the net) and walking on the moon. They were true revolutions at the time. Within a short amount of time, they were prosaic concepts. The next generation accepted these as historical facts rather than social upheavals. It is unlikely contact would significantly alter the course of our civilization. However, this resiliency makes us a better candidate for contact. Consider how many civilization have been contacted by more advanced civilizations here on Earth, that were fairly destroyed by the contact. As a global civilization, with more cultural and intellectual diversity, we could better survive such contact.
As for signal contact, we should consider whether an advanced civilization would employ an advanced communication method. We focus on single frequency signals such as come through the \"hydrogen window\". Between this serial (ie. slow) method and the embedded method that Sagan wrote into \"Contact\" lies a commonly used technique, multiple frequency parallel signals (modems use this). If a biologically water based civilization wanted to contact another that recognized the centrality of water to their existence, and so was more likely similar, using the several frequencies involved in the vibrational modes of water (http://www.lsbu.ac.uk/water/vibrat.html) would provide for up to 16 simultaneous channels (think 16 bit data bus). It takes little investigation to realize that sending and receiving these could not be done from the ground, as water in the atmosphere absorbs at these frequencies. But if the \\'others\\' wanted to search out an advancing civilization, they would likely want to search other those who\\'ve begun to develop the ability to communicate from positions outside their atmosphere. If the receiver couldn\\'t get into space to pick up these signals, they might be too primitive for contact and susceptible to destructive influence of contact with a civilization too advanced for them to survive, and a species with ethics that precludes such damage to others may steer clear.
In keeping with the first statements, we should also consider signal methods based on something other than water. Other biochemistries have been hypothesized. And, in order to be more open to different designs of life, something more basic and non-biocentric might be used, such as a series of frequencies spaced according to the atomic weights of the elements. Using these frequencies would be a signal in itself, as we would recognize the intelligent origin. The number of possible channels being around 100, the contact of these channels could provide for far more content transfer than the single hydrogen frequency. Again, these would require an alien to have an open mind with regards to possible life forms, and more restrictive techniques would be used by those with narrower definitions of life, or at least the life of interest to them. This is consideration of the \\'what kind of alien\\' variable.
But to address the direction of the article, we might well look for a technique that would incorporate physical media. To make the communication effective, we should look to one that \"violates\" the speed of light. We are presently very early in experimentation with quantum effects of entanglement leading to information transportation, and we\\'re aware of the Bell Theorem violation. If I wanted to contact someone else, I\\'d send a probe that might take a long time to get there, but used a quantum entanglement communications system, cutting the signal return time significantly. A technique that allowed us to search for purposely entangled devices built on such as Bose-Einstein condensates, might turn up something like Bracewell probes with a reasonable communication time.
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Posted by Pndxtr
March 10, 2008 at 08:58 AM
We've limited ourselves to communication methods as WE know it. Think outside the box and what we know as physics! Try searching for light wave communication signals. Transmission through light spectrums may be more efficient than we know and maybe even more far reaching. Just the thoughts of a simple guy! Sometimes, the answers to the most difficult questions are the most simple answers!
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Posted by Mac Tonnies
March 08, 2008 at 09:04 PM
Joseph--
Thanks for citing "Inflation Theory Implications." SETI pundits seem content to endlessly parrot the Fermi "paradox," yet ignore informed attempts to counter it.
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Posted by Joseph Capp
March 08, 2008 at 11:55 AM
The lack of humility among scientist who believe they've figured out the bulk of what is out there is disheartening. The hundreds of thousands of ongoing UFO reports now back by multiple witnesses as they are being filmed seems to suggest rather strongly Fermi's Paradox was right and wrong at the same time
. Yes they should be here and no - they are here.
INFLATION-THEORY IMPLICATIONS FOR EXTRATERRESTRIAL VISITATION
Published in mainstream science journal.
http://www.ufoskeptic.org/ scroll down to bottom of the page; PDF file
Looking for species who may not use tom tom may only mean in this part of the galaxy they use quantum entanglement.
As far as mainstream science, it has always been the keeper of the faith but as science history always proves the faith has many levels.
Joseph Capp
UFO Media Matters
Non-Commercial Blog
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Posted by WMBear
March 07, 2008 at 09:50 PM
"Does the apparent absence of Bracewell probes prove that we have yet to be visited? Hardly."
Right you are, Mac. "Absence of evidence is not evidence of absence."
But...
I totally disagree with your statement: "Knowing we're not alone may come with a certain existential comfort, but, by itself, would be of no specific practical value."
The simple discovery of an ETI signal even if we could not decipher its meaning would have preofound effects on human culture and the course of future history. I believe that I could make an excellent case for this notion but I'm not going to do that here.
--WMB
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