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The evidence that it exists boils down to: gravitational anomalies. It's not multimodal, which is a problem because you're saying "it must exist because of x t
by throwawaymaths 4y ago
The evidence that it exists boils down to: gravitational anomalies. It's not multimodal, which is a problem because you're saying "it must exist because of x therefore it must exist" versus "it must exist because of x, which has a side effect of y, which aha also we see". That's why it's weak.
> the simplest explanation is that there is invisible matter that reacts gravitationally.
That's the whole point of the poltergeist example. If someone said: "Oh, that urn on your mantle just fell over? Must have gotten knocked over by a rogue ball of dark matter. The simplest explanation is that dark matter must exist". You would think they are insane.
- ndsipa_pomu 4y agoYou can think of dark matter as gravitational anomalies that aren't distributed uniformly. If we assume that physical laws are constant throughout the universe, then it becomes difficult to account for those anomalies without saying that there is "something" there that is influencing gravity. Obviously, we've labelled that "something" as dark matter and figured out what properties it can and can't have. With your poltergeist example - if it was relatively common for urns on mantle to be knocked over, then it would make sense to come up with a hypothesis. If objects around the urn were affected gravitationally just before the urn falls over, then dark matter would appear to be a rational hypothesis.