While I have no doubts there is life out there in the vastness of space, I feel I have to point out the following:
This was a famous photograph taken in 1990 by the Voyager 1 Space Probe, at the time it was only 3.7 billion miles from Earth (approx). Earth is the lPale Blue Dot, low down on the righthand side.
This was taken 12 years after Voyagers Launch, it was at the edge of our solar system, last year 35 years after it was launched it finally entered interstellar space.
So a Alien traveling to Earth would have to really really want to and know we are here.
Ah but what about Radio Waves, well we have been broadcasting them for a while now:
Unless of course the Vogons are comming.......