Subject: Dark Matter

Dark Matter
      Scientists predict the existence of "Dark Matter" in part 
because that matter would have to exist to satisfy the known laws of
gravity (both Newton's and Einstein's).  In other words, they see that
the "visible" matter present does not comply with the laws, so they
conclude that "dark matter" must be present.  How can this conclusion
be justified when the laws of gravity were formulated to agree with
empirical observation?

Re:Dark Matter