<<Mentor note: Thread split from Is Dark matter homogeneous in Universe?>> Not to be rude..... but how do you know it even exists? Dark matter is a place holder used to make a hypothesis work mathematically with actual observations. Dark energy.... Ditto. And the original hypothesis itself is based on the assumption that gravity is the dominant force in observed cosmological phenomenon. It sounds like a contrivance based on an assumption. If we have to create some exotic "thing" like dark matter, and dark energy, to make the math support our hypothesis - we should seriously consider that our hypothesis might be wrong. If I can make an analogy. Theists have their "god of the gaps" and cosmologists have their "cosmology of the gaps" Sorry, Dark matter / dark energy; it sounds like voodoo.