An interesting theory trying to explain The Fermi paradox (“the apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their probability“). SETI is essentially a search for waste products from other civilizations (heat, light, electromagnetic signals), what if we can’t see or hear them because they don’t generate waste? Maybe the reason for the Great Silence is that “any sufficiently advanced technology is indistinguishable from Nature.”
In the Great Silence, we see the future of technology, and it lies in achieving greater and greater efficiencies, until our machines approach the thermodynamic equilibria of their environment, and our economics is replaced by an ecology where nothing is wasted. […]
[P]roducts of traditionally ‘advanced’ technological civilizations, such as Dyson spheres, should be visible to us from Earth. No comprehensive search has been done, to my knowledge, but no candidate objects have been stumbled upon in the course of normal astronomy. The Matrioshka brains, the vast computronium complexes that harvest all the resources of a stellar system… we’re just not seeing them. The evidence for that model of the future is lacking.