I personally believe it's selfish to think we are alone in the Universe
There is an estimated 15 billion stars for every person on Earth, and who knows how many planets. Our Solar System is tiny, I don't belive aliens will ever arrive here. [I mean beings from another planet arriving in some form of ship.]
I mean, look at the size of Earth compared to Sirius, or Sirius compared to VV Cephei. This universe is so much bigger than us, there is no way were are alone here.
I believe in aliens, I just don't think Aliens will ever come here. The chances must be very, very slim.