You're wrong about dark matter
Dark matter is a stop-gap to account for the incomplete theory of gravity. When the correct theory of gravity is widely known, the need for dark matter will go away.
No. Dark matter is matter that isn't putting out a lot of light and so is hard to spot and account for. There is no question that dark matter is out there, heck we are standing on some right now, and no amount of knowledge about gravity will ever change that. Some of it we can account for. For instance we can measure how many neutrinos we spot hitting us, and subtract out the ones that might be from the Sun, and get an idea of the density of neutrinos out there. Also we can estimate the amounts of normal matter in our galaxy because we have a pretty good idea of the structure of the local galaxy and we can see from speeds and radius of curvature what the acceleration should be, and then estimate how much weight has to be there that we can't see.
But a lot of forms of dark matter we don't know about. How empty is it, really, between the galaxies? Are there exotic types of dark matter that we haven't accounted for?
Now you're right that better theories would limit how much speculation about dark matter goes on because people want to reach certain magical numbers that fit specific cosmological theories. It is also obvious that our current theories will some day seem as ludicrous as we view the comet theories put forth by Newton's successor. (Note that I don't include the flat earth theory that Norm keeps blathering about because I know enough history to know that nobody believed that in Columbus' day - in fact the premise on which Columbus sailed was just plain wrong.)
But we know that dark matter really is out there, even though we can't see it.
Cheers,
Ben
