And to anyone who claims that dark matter is not good science – there is a reason that dark matter is the leading theory in where the missing mass is. If it was bad science or there was a "simpler" explanation to it (like mismeasurement) the scientists would have gone for it.
Actually, a surprising number of them DID, and continue to do so.
The real appeal of the Dark Matter hypothesis is that its unfalsifiable. If you assume a priori
the existence of an undefined quantity called "dark matter" -- a substance which BY DEFINITION has no physical properties you can test -- then it is not possible to devise an experiment that could even theoretically
demonstrate its absence. Virtually any experimental setup would return either inconclusive or positive results; there is no way to test for its presence and conclude in any coherent way that it isn't
Dark matter fits with the observations
As does any fictional construct for which there is no corroborating evidence. Underpants Gnomes fit the observation that I am slowly running out of underwear, but there's no evidence that the gnomes themselves exist.
The logical proof for dark matter depends on a number of rather dubious assumptions, in particular, the assumption that the existing model of gravitational interactions cannot be wrong, and that the existing model of mass distribution and the composition of galaxies, also, cannot be wrong (in the latter case, the assumption that our estimates of the mass of galaxies based on observations are sufficiently accurate as to require an additional "unseen" factor).
I've seen the data astronomers have been using to support dark matter hypothesis. Been through it several times, each time scratching my head with a "what am I missing?" feeling. The most "conclusive" arguments in favor of it all have the same problem: if you don't start from a series of very specific and far-reaching assumptions, the entire theory stands on very shaky ground.
What's more weird is that there is nothing special about dark matter, and all the talk against it is some irrational dislike that has no grounds. Its existence would be no more weird than the existence of normal matter, which is already there.
Except that we have no primary evidence for the existence of dark matter; it is ASSUMED to be present based on distant observations of galaxies whose rotational velocity is higher than models predict it should be.
That is a bit like theorizing the existence of God based existence of the Bible, based purely on the assumption that only God could have written it (because the Bible says so).