Best sign of extraterrestial inteligence is that no extraterrestials conntacted us.
I think that cockroaches are extraterrestrial. Thats for sure. If you cut their head off, they died by inanition in a few days. That is horrible! And also they are intelligent, they leaves you in peace when they want, not when you want no matter you use poisson or not.
The best proof of extra terrestrial intelligence is that they never contacted us...
I think this image displays the best yet sign of extraterrestrail intelligence, the sign that SETI missed.
Any advanced alien civilization which had enough excess energy to build a 'Dyson Sphere' would certainly not need to build one to get more energy.
You may mistake a Dyson shell for a Dyson "swarm" of satellites. The later could start in the near future. One could argue that the first satellite using solar power were the first part of a Dyson "swarm".
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