Scientists may have an extra challenge when it comes to detecting alien civilizations: a time limit.

A new study suggests that intelligent aliens, if their technological progression is similar to that of humanity's, are likely to have moved away from noisy radio transmissions to harder-to-hear digital signals within a 100-year time frame. That offers Earth just a narrow window in which to pick up any signals from extraterrestrial civilizations

What if they go non-local, telepathic? There's plenty of anecdotal evidence that they do communicate in this fashion, so all of our primitive electromagnetic forms of communication may be moot.  To read the rest of the article, click here.