Now, this article goes on to be able to tell if we contact an alien world, how could we tell over radio signals if they were anit-matter or not..... Well, this brought a question to me..... If that world were completely opposite and we did contact them by radio signals, isn`t there a good chance that their signals would be opposite as well. Which lead me to contemplate two things happening.... 1. Once the signals touched each other, couldn`t there be some sort of destruction that could occur at the point of contact? (Personally, I do not think so) or 2. Wouldn`t they just cancel each other out and then there would be no sound at all. So, in essence, we could never actually contact them. I think 2 is more likely, as we are able to now dampen sound electronically by using the opposite frequency or something like that. So, essentially wouldn`t their signals do the same thing?