One time, when I was little I went to sleep and after awhile somebody started pushing my room doors weakly. Somebody pushes them and doors go back, and all over again... White as a vampire I slowly crouched to my bed end to see what is going on and I noticed my turtle, he was trying to go through the doors, so he was pushing them quite a time...
I don't see reason why not to believe in ghosts. Some scientists explain that human can leave like a spiritual photo off his emotions in the place where he usually bin all over the years, after he dies, part his emotions leave and can be randomly show from time to time. Earth is like big voice recorder.