This is a two fold question
1)The plaque of darkness has considerable commentary, however I have yet to find a rabbi who speaks about what created the darkness. Therefore, What created the darkness keeping in mind that it did not effect the Jews?
2)A continuation of that question. When looking at science most of the plaques (except 10) can be explained. How is darkness explained in this science? (This does not take away from the miraculous nature of the plagues, this can be another question if someone desires).