It starts with Earth having FTL travel, maybe already colonies in other planets but scientists were worried about Earth not being advanced enough on other fields to withstand war with other species. They sent some kind of space capsules to several places in the univers, so if they would be found by aliens they could be observed or spied by means that I'm not quite sure... telepathic link with one alien that touches the capsule? One of them is found by a war-like alien race, and then we see this civilization through the eyes of one member of that race, and see the events that lead to a conflict with mankind. There is a subplot of the "spy" connected with the alien having somekind of conflict? Doubts? I don't remember much more than that... It was a complete book, but not a very long one. Thanks for any help that you could provide.