SETI - Just Getting Started


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I have discussed the null results of SETI several places before and I often run into people who have the mistaken impression that so much as been searched and nothing found that that something is amiss. On a re-run episode of Deep Space Marvels - episode named "life" [2011] on the Science Channel they did one of the better graphics I have seen illustrating how little has been searched in our galaxy so far. In the first graphic they have a sphere representing how much has been searched within a cube volume - the sphere is about 1/1000 of the cube. They then zoom out again to the scale of our galaxy and the cube doesn't make more

than a pixel on the screen. It would be generous to say the cube was 1 part in a billion of the volume occupied by our galaxy. So the search has been underway for 35 year over about 1 part in a trillion of our galaxy volume. Another illustration I saw last year compared it to the volume you would get using your index finger for a radius compared to the volume between there and some mountains in the distance [about 20 miles by the looks of it].

There are many assumptions behind a SETI search but unless a technological civilization spreads everywhere and then uses high power radio waves - like deep space radar or something similar - making no attempt to remain hidden - the search has not looked enough yet to find even one of a million randomly scattered civilizations in our galaxy.

I think the search so far can only eliminate one possibility - if there are intelligent aliens in our galaxy they have not occupied the volume available as noisy neighbors at radio frequencies - unless encoded enough to look like white noise - which is what an advanced user of radio signals might do and the military has looked into. That leaves a great many other possibilities.

Dennis

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Dennis wrote:

I think the search so far can only eliminate one possibility - if there are intelligent aliens in our galaxy they have not occupied the volume available as noisy neighbors at radio frequencies - unless encoded enough to look like white noise - which is what an advanced user of radio signals might do and the military has looked into. That leaves a great many other possibilities.

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Are there any recent “Carl Sagan like predictions” about the likelihood of a SETI contact, such as the approximate number of stars likely having inhabitable planets in our Galaxy, the time a planet has been inhabitable, the average time before an extinction level event, the possible level of communications sophistication and factor in the loss of power over distance, etc.? We can only use ourselves as a guide. How long have we been “readable” by other planets? How long will our “readable” civilization be broadcasting? How long do civilizations last? Imagine the civilizations that could rise and fall in one billion years, that do or do not reach a level that is readable over galactic distances.

Our “band widths of available methods of communication” are expanding and growing more sophisticated so we should continue to look for the low tech as we ourselves routinely use the higher tech. Science Fiction writers visualized time neutral communications through another dimension. We have just been awakened to quantum communications so we are very quickly realizing there are even more ways of communicating than, radio, TV, light signals or pulses.

A few Star Trek episodes imagined communication devices that continued to broadcast for millions of years after a civilization’s extinction as a memorial to who they were. Some contained their version of a Galactic Encyclopedia as a benevolent reward and prize to those listening. We should do the same. For now, just keep listening. Shhh! I thought I heard something.

Peter Taylor

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