Dear Janet;
Science deals with matters, hence it has limitations. Science can not prove beauty of Rose, but it is there and we experience it. Science can prove love, but we know it is there. Science can not prove existence of our soul, but we experience it. So do not worry about science.
Regarding existence of Ghosts let me tell you that the way it is described in films or literature or in stories and even in claimed true films/photos of ghosts are all humbug. Several souls, specifically very good quality or very bad quality need to wait for suitable opportunity to take birth and they all move around us. They are called ghosts. They can enter in human body when the mental state of a person is not healthy (over feared or over sexy or over religious). You will find several cases all over the world. And 70% of such cases are true. Remember soul alone can not do anything, it requires body to do any action. So never fear of ghosts. I hope you will agree with me.
His Blessings;
Sharad Shah