Carrigan notes that Earth's early radio ramblings have already traveled some fifty light years away (A light year
is the distance that light travels in a vacuum in one year, equal to 5.88 trillion miles). An order of 400 stars are within 50 light years of Earth..so..any civilization out at that distance may have immediately repsponded and sent a signal back to Earth. That signal could be useful or harmful. Carrigan introduced a recent scientific paper presented at the 54th International Astronautical Congress, held September 29th - October 3 in Bremen, Germany.
Carrigan warns that simply put, "the receiver needs virus protection." An electric condom maybe!
Seth Shostak, Senior Astronomer at the SETI Institute in Mountain View, California has quoted as saying:
"No need to worry about alien viruses infecting our machinery," Schostak added, "because this signal averaging is like a microbe filter, screening them out!" For optical SETI experiments -- looking for flashes of laser-carried chatter from ET -- thsi is less true, as these searches could, in principle rather easily record a large series of "ones and zeroes" that might be sent our way on a beam of light, Shostak told SPACE.com
My question is: How do we know what to look for? It's a pretty big assumption to assume an alien computer virus would be transmitted the same way we understand transmission technology...