Concerning the vibration levels: You cannot exactly compare this to stuff like vibrations of an EM-wave. It's sort of the way that lets you shift between the dimensions - that's why they're totally invisible to us when being in those higher "vibrations"...
Concerning the fear of people: Maybe read some reports or studies on this topic - single people may act intelligently but crowds of them tend to behave stupid. If suddenly aliens would show up or make broadcasts on TV without any warning or some people knowing about it there'll be a huge panic in lots of areas. That'll be for different reasons - the most striking certainly being the fear of the unknown together with all the stuff hammered into us from the movies. Then there would be religious people who'll find their entire world view shattered in a matter of seconds and that'll be lots of people. Then there's the part maybe forming up just slowly like us never being space pioneers. We'll never be the first to explore space as at times we'd get into space pretty much everything already would have been explored by someone else. Humanity will never "feel the same" again as we'd be rendered small, tiny and unimportant...
