First, the simple fact that Seth Shostak and the rest of the "little green men" listening crew never let the public know is that they have long since given up any hope of "over-hearing" SETI signals randomly leaking into space. At this point of the "search" it is quite clear that the only possible signal that could be received from star systems that are over 40 light years away (everything closer has been checked) would be a "directed, high-intensity searchlight-like beam" headed straight for us. From 45 light years it would take several nuclear power plants directing all of their energy through a massive array of Arecibo-sized dishes to be detected.
Why they continually con the public into the "we might overhear" a civilization when even they must know the simple physics of the inverse square law. There is no way that our civilization's leakage into space would be detectable by our level of technology even 20 light years away. Its meaningless to talk about the Earth's expanding sphere of radio communication (50-60 light years, tops) without also noting that with that same expansion comes a dispersal of the signal strength to negligible levels. To a civilization 20 light years away the entire Earth's radio signal would be less than a cell phones.
SETI is not science, its not even science fiction, its fantasy. I find it on the same level as the Loch Ness or Bigfoot.
I would tend to agree. It was an interesting experiment, but it is looking less likely that any civilisation parallel to our own development would be overheard in this way. Transmissions to the general population are now either via low power cell systems or by directional satellite rather than a few high powered transmitters. Cable/Internet systems are also taking over a lot of the capacity. In addition to this, digital systems require less powerful transmitters, and are undetectable by older technology. If we make the (big) assumption than any alien civilisation is like our own, and this trend will continue, then the already over optomistic likelihood of detecting overspill of their domestic transmissions has diminished to a point where it is no longer good science. From an anthropological point of view it is not dissimilar to a kind of cargo cult. The listening has become little more than a sympathetic ritual. The equipment used is merely simulating a science fiction scenario in the hope that the same results will occur. (viz. contact with aliens). Of course the radio receivers are real receivers, not ones made out of coconuts, so there is always the chance that something will be discovered, even if it isn't aliens, but would it be recognised by people so narrowly fixed on the result they are looking for?
Celestron Nexstar8i (8" SCT).
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Aratus : I agree with this statement " Of course the radio receivers are real receivers, not ones made out of coconuts, so there is always the chance that something will be discovered, even if it isn't aliens, but would it be recognised by people so narrowly fixed on the result they are looking for?" , Our technology( encreption etc.) and medium ( Quantum entanglement of high energy neutrinos or something similar ) of advanced communications will be necessary to make contact over such large distances. However it appears every time I suggest something like their coconut transimitters and our elaborate coconut receivers will not work, that's all it takes to prove me wrong. I hope.
Shostack along with his employers and colleagues have a vested interest in maintaining sufficient public interest to keep the funds flowing in to SETI to support their salaries. So they continue to tease us about positive results likely to be obtained soon. As the OP suggests, they surely must know better. Of course they are hardly the lone manipulators of the public and its money. The list is endless. At least to SETI’s credit, their negative results over the last half century do have value.
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