Magnum 4.4 Million Lightyear Linkdump

The arXive blog is a brilliant site posting about some of the more interesting scientific papers that appear on the famous pre-print server.

Thanks to fiat_knox for the link

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While on there I ran across a recent observation that suggests that Dark Matter exists, and it can't be explained by modifying gravity, or rotational mechanics.

There's a Cluster of Galaxies that have ripped through another like a bullet. Using different techniques it's possible to look at the stars, the dust, and the Dark Matter concentrations separately. It's clear that the Dark Matter has raced ahead, since it hasn't been slowed by collisions with matter.

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In tangentially related matters, I've been thinking about the foreshadowing in Dr Who.

Are the hints of things to come like Chekhov's guns, and will come to pass. Or are they like Hitchcock's bombs, and will build tension before a big switch?

{edit: size of bullet based very loosly off this}