"Dark matter" is a term that means there is a discrepancy between the observed mass in the universe and how much theory says there should be. One possible expla

"Dark matter" is a term that means there is a discrepancy between the observed mass in the universe and how much theory says there should be. One possible explanation, and the leading hypothesis, is that there is some form of matter that only interacts gravitionally. Another possibility is that there is something wrong with our current theories. The last one is discussed in the article which is that undetected black holes contain the missing mass.