I just wrote an article on my tech blog about why aliens probably don't use EM waves:
I often watch TV shows that talk about the SETI project and how it failed to meet expectations. However, people seem to forget that humankind invented radio waves little more than a hundred years ago, and will probably abandon that technology within the next thirty or forty years, a hundred maximum. So, how on Earth should alien civilizations that are many light years away just coincidentally happen to use exactly the same technology while we’re aiming our measly telescopes at them? This is ridiculous and completely unlikely.
To illustrate that, I’ll explain to you why we might be abandoning electromagnetic communication in the near future. Since the discovery of quantum physics it has apparently been observed that two particles can exist in so-called quantum entanglements, in which one particle seems to transmit information to the other instantaneously, regardless of distance. Now imagine that such an entangled particle could be captured within a computer chip, and its peer within another chip. Put one chip in a home computer, and another at an ISP’s data center, and bam, you have a network connection which requires neither a cable, nor a radio transmission. Within only a few years after such an invention, electromagnetic communication would vanish altogether, and aliens on other planets would pick up zip with their radio telescopes.