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Comment by ricardo81 | Hacker News Reader

Given that a huge amount of mass in the universe is unaccounted for with current models, the idea of masses unaccounted for like this surely are still reasonable possibilities.

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This is called the MaCHO (massive compact halo object) hypothesis, and it’s pretty close to dead based on the evidence we’ve been able to collect.

Yes, and there are different levels of "close to dead" with this one being in a very much dead one...

But still, every hypothesis for explaining dark matter is close to dead right now. Theoreticians reopening closed cases is a good thing.

It wouldn't have to be the main explanation for dark matter though to still be a phenomena. I agree that the evidence is pretty clear that it's not the main driving factor.

Only "dead" in the sense it can't explain all the missing matter.

I like Occam's razor as much as anyone, but it really is starting to seem like there might be more than one cause of the phenomenon called dark matter. My understanding is that WIMPs (weakly-interacting massive particles) are in trouble too, as the LHC has failed to produce them in the expected energy regimes.

Or perhaps it is more evidence that a variant of MOND theory is responsible for our observations and there is no dark matter.

No current MOND theories account for the state of our observations of the Cosmic Microwave Background, or the ratios of "things" left from nucleogenesis. The biggest gotcha for MOND is there's no way to reverse the direction of gravity, which would be needed to explain large scale structures without dark matter. (With dark matter, you see things moving toward where the matter is. Absent dark matter, you see things moving away from where matter is, because there is only ordinary matter.)

MOND theories are dark matter theories. They posit explanations for the observed behaivor, that behavior is dark matter.

AFAIK there are plenty of observations that can't be accounted for by any MOND theory either.

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