== The problem with this "paradox"... == 

 The following section was originally under they are here unobserved section, but does not fit this description as it is claiming observations and intentional communication are occurring, albeit via non-ordinary modes of biological consciousness, instead of electromagnetic radiation.  Hence, I created a new category as follows:  Also, restored the deleted material on Terence McKenna, since it is quite germane as the point of this section of the article is to discuss modes of thought alien to our own, that we may well not recognize or be unjustifiably dismissing as 'ridiculous', which McKenna was the exemplar of. 

 :... and they are communicating, but not via radio waves  

 :A related series of views consider that alien entities have been communicating with humans throughout history, but utilizing methods and technologies that are non-electromagnetic in nature, perceivable via what are conventionally known as altered states, which are outside most people's experience or imagination. "Signals" are arriving, but only a few individuals perceive them, and then rarely and possibly in a distorted manner. Accounts of communication have perhaps been reported in ancient religious texts (accounting for the wide variety of anecdotal reports of angels, demons, and so on) but have been dismissed or overlooked. 

 :As an example: if the human brain utilizes quantum mechanical processes in its operation (as theorized by Roger Penrose, Stuart Hameroff, and others) then it may be open to receiving some form  of nonlocal "psychic" communication, perhaps using quantum entanglement. It has been proposed that some accounts of mystics, shamans, schizophrenics, and channelers may be such "garbled" communications, transmitted by non-human intelligences in this manner. According to quantum mechanics the transfer of information in the context of information theory is not possible using quantum nonlocal correlations. However, supporters of the idea of this form of communication idea believe that this may explain the "garbled", associative, and inspirational nature of the "messages" recorded in the world's religious and anthropological history. This idea also explains the evident absence of space travel, which is unnecessary to the community of alien intelligence communicating via this medium.  

 :However, the theories of Penrose, Hameroff, and others are not universally accepted, and have met with skepticism, nor has it yet been shown that quantum mechanical effects are required for consciousness to occur. 

 :Another useful example of a theoretical means of communication that would appear so very alien to most people's way of thinking, that it would most likely be misinterpreted or dismissed outright, is the controversial proposals of Terence McKenna that the psychoactive drugs psilocybin and/or Dimethyltryptamine (DMT) is an alien technology, "seeded" here on Earth by non-human intelligence, as part of a "biological communication strategy", in order to alter the perceptive processes of the human mind so that it may receive messages being transmitted to us.