We all have alot to learn and it is our obligation to help eachother evolve. Ghosts are souls that have become soo attached the thier preivious life that they refuse to leave this plane. Possibly they don't realize they are dead. Some souls feel that they can't leave until they have accomplished some goal that they failed to do in life. In any event the are choosing to be here for one reason or another.
Some ghosts are negative some are positive.
I think pure love is the greatest gift that we have been bestoyed by God. We all are a part of God and, have his love within us. Weather we choose to accept this or not is up to us. Now have aliens been here visiting earth. That should be more than enough on that.