What do we Jews believe as far as whether or not people who have died can see the past, present and future happenings in this world?
It is not clear exactly the extent of what or how much they know, and it seems controversial. See Berachos 18a-19a where this is discussed. They definitely know about future happenings, as the gemorah says regarding the story of the two neshomos that went to find when it was going to rain that year. It is also brought down that the parents and grandparents come to the weddings of their children and grandchildren. However the extent of what they know and what they don’t know, is not clear to me.