Today I was following a discussion on dark matter, on slashdot, and the usual type of discussion happened. A handful of people brought up the Electrical Universe theories and the conspiracies surrounding the supposed suppression of those theories. Now, imo the EU theory is a load of bunk, because it assumes principles that violate everything we know about electricity, and it does not have a model describing mathemetically how the known universe came to be and how things like stars work. EU is like the toothfairy of science. It only makes sense if you discard all existing knowledge and don't ask critical questions.

The EU proponents countered the usual arguments by stating that dark matter is just mathematical handwaving to fill in discrepancies in existing theories. And to some degree it is, but not in the sense that they think. Dark matter theory basically says that in order to explain the discrepancies between the known universe and our current understanding of physics, there has to be a gravitational influence not caused by the matter which we can observe (stars, interstellar clouds, etc). Hence, dark matter.

If we include dark matter, all discrepancies disappear. The EU vs DM argument kept going round in circles, but 2 people had a very interesting argument which is worth preserving.

The first one was this argument by cje

Back in the late 1700s, after the discovery of the planet Uranus, astronomers made careful calculations of its orbital elements and published a table the position of the planet in the sky over the years (and decades). As the years (and decades) wore on, they discovered a curious thing: the actual position of the planet was beginning to diverge from what had been predicted. At this point, there were a few different explanations:

1) Perhaps the initial orbital elements were incorrect.
2) Perhaps our fundamental laws of gravity and motion were incorrect.
3) Perhaps there was a massive, as-yet-undetected eighth planet whose gravity was influencing the orbit of Uranus.

Most astronomers fell into the third camp; after all, the observations of Uranus's orbit had been made with considerable precision (for the time) and there was little reason to believe that the fundamental laws of physics would start to break down as you move further away from the sun. And so they made their calculations and narrowed down the location of this hypothetical planet to a fairly small window in the sky. After that, it was just a matter of pointing a telescope there and looking.

This is the story of the discovery of the planet Neptune. Astronomers did not find this planet by accident. It was not discovered by a kid in the backyard with a streak of cosmic good luck. (In fact, many observers from antiquity had seen it, but had not realized what they were looking at.) They found it because they knew it had to be there.

Now, you might think that this comparison is a bit of a stretch. But it's just one example; there are countless more. Back in 1930, Wolfgang Pauli was studying beta decay in atomic nuclei. He realized that the process, as he was seeing it, could not possibly be happening unless there were (again, hypothetical) particles being emitted as a consequence. If there were not, then all sorts of fundamental principles of physics were being violated (e.g., conservation of matter / angular momentum / etc.)

This particle, eventually named the "neutrino", remained hypothetical and undetected for more than a quarter of a century until it was finally detected -- in 1956.

I could go on, but the point is that postulating the existence of something hypothetical in order to explain deviations between theory and observed results is part of the best traditions of natural science. It's not hand-waving or charlatanism. And it works more often than most people might think.

And the other one was the reply to the above argument, by bjorniac