Cosmic crash unmasks dark matter

news.bbc.co.uk

5 points·rrf··5 comments

It's things like galaxies with quadrillions of times the mass of our sun colliding that make me remember just how small a piece of the universe we are. It's awesome that they got to see that... And identify some dark matter in the process!

Heck, our caveman brains taught us that size is a significant quality. If Ugg kills a rabbit, and Garr kills an elephant, Garr is definitely the better hunter. But what really matters is organization... Galaxies are a chaotic mess compared with a rabbit.

> what really matters is...

"I used to think that the brain was the most wonderful organ in my body. Then I realized who was telling me this."

This article seems to suffer from even more than the usual level of "The author has no clue about the science" Syndrome, especially the bits about gravitational lensing.

Now, I thought that galaxies were so sparse that most of the interactions two "colliding" galaxies would have would be gravitational (rather than an actual collision). In this case, the finding would seem to imply that dark matter isn't affected by gravity the same way, which would be darned weird.

It's true that the stars in colliding galaxies don't actually collide, but they are looking at the collision between two clusters of galaxies. Clusters contain hot, X-ray emitting gas. And gas does collide, whereas the dark matter passes through.

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