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> Gravity on the scales where dark matter is relevant has not been tested to this extent, so we're just assuming our theory is correct in this new regime Could
by AnIdiotOnTheNet 4y ago
> Gravity on the scales where dark matter is relevant has not been tested to this extent, so we're just assuming our theory is correct in this new regime
Couldn't we just as easily say the same about EM or any of the other forces?
The reason we think it is some kind of matter is because we know that matter interacts with gravity in ways that would explain our observations, as long as we assume that matter isn't visible for some reason. And it isn't like there aren't candidates even within the current standard model that might have the right properties.
> By contrast, modified gravity theories can match many of the predictions of DM theories using only direct observations of visible matter.
...and curve fitting. They keep having to add parameters to MOND to make it fit what we see and currently attribute to dark matter, like the bullet cluster. That's the physics equivalent of code-smell.
- naasking 4y ago> Couldn't we just as easily say the same about EM or any of the other forces? We've tested other forces in more regimes than gravity because gravity is so weak, but in principle, if predictions of those theories mismatched observations to the same extent as gravity, then we absolutely should be questioning those theories too. > They keep having to add parameters to MOND to make it fit what we see and currently attribute to dark matter, like the bullet cluster. I don't know why people keep saying this like cold dark matter model doesn't do this. LCDM has been refuted many times if this is your criterion. The review paper I cited shows numerous examples of parameterization and curve fitting for LCDM.