We've heard about extra terrestrials but are we ready to them to present themselves and all the advanced technology they work with.
After all, how can they even get here from such distant worlds?
How again will we even relate to each other and the "modern" world we've been living in? It's hard enough for our scientists to accept most new discoveries that are man-made.
Alan Steinfeld, the author of "Making Contact" has a very comprehensive book about all natures of this and other considerrations of what contact will mean to our world.