The Klan Is Not Going To Be Happy About This

[polymath257]

I dont get it.

The Raw Story Article does provide a sourced link early on under blue "here", and that takes you to a college research article. But what am I missing? The Raw Story article talks about proof of dark matter, but the college article talks about the behavior of hydrogen atoms and going back to the 180,000,000 years after the big bang. What do the behaviors of hydrogen atoms have to do with "dark matter"?

That's a very good question. What happens is that dark matter affects the rate of universal expansion, and thereby of the cooling that leads to the formation of hydrogen atoms (as opposed to ions, which were there before). So, the amount of dark matter determines *when* those hydrogen atoms form. And *that* leaves a signature on the background radiation, which is what was detected here. There also seems to be a higher level than expected of interaction between the dark matter and ordinary matter at that point--which is very interesting. This also affected the cooling rate.

So the point is that the rate of expansion (and hence, the cooling) is affected by dark matter and *that* is what we are detecting.

Unfortunately, such indirect measurements are required for dark matter because dark matter doesn't interact strongly with light or ordinary matter (hence, why it is termed 'dark'). So we can only really detect it through its gravitational effects (or, if a certain type of particle, by its decay--not done yet, but possible). In this case, it is the gravitational effects changing the rate of expansion at the stage where hydrogen atoms are formed.