I got this from a pretty nice site with an
Introduction to Cosmology.
I quote for those of you who also did not know this:
The snag is that, according to the standard and highly successful calculations of what went on at the birth of the Universe, the amount of deuterium around is very closely tied to the total amount of atomic matter made in the Big Bang. The more deuterium there is, the less atomic matter there can be overall.
Using the deuterium abundances measured for stars in our Galaxy, the Big Bang could have produced ten times more atomic matter than we see in bright stars. But using the new figures from the Keck observations, there is barely enough scope to make the stars themselves, and no room for MACHOs.
The implication is clear -- any dark matter around must be in the form of WIMPs, after all. Only, something is making the stars in the LMC flicker as we watch them, and nobody knows how WIMPs could be made to clump together to make the kind of massive, compact objects needed to do the gravitational lensing trick.
So, my question, is simple:
Why exactly are MACHOs not an option? And how exactly do they go from there can be more to there can be less, so therefor there must be more; thus we can conclude there is none of it. :/
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