A Scientific Explanation for Ghosts?

To start with at beginning, the fourth dimension is time, and this refers to all the time in our existence. From things long passed to things yet to happen. We live in this dimension and therefore can only see a cross section of it, this being the present.
To see time as a whole you must, like with all dimensions, be one dimension higher than the one your observing.
Just like we can see the whole of a two dimensional object, from its insides to the surrounding area. While the two dimensional being would only be able to see one dimensional lines and thus not the insides of enclosed objects.
With use of this same principle we can assume that a five dimensional being would be able to see time as a whole, like we see a drawing on paper.
This being would to see us as long snakes, starting at our birth and ending at our death. But not only us, they would see this with everything that exists in our dimension, from the smallest particle to the very universe itself.

full article here. Via professor hex