Or at least that is the problem that has plagued astronomers. The idea is that a spiral galaxy such as our own Milky Way, should have a number of smaller, satellite galaxies around it. Ours does have a few, but not nearly as many as there should be in order to support the theory. Currently, it is thought that many of our own orbital galaxies are composed of dark matter, rendering them virtually unable to be seen. So how would we even know they are there?
A new method has been proposed to investigate this: Look for the trails of hydrogen gas that the galaxies leave behind, rather like a wake left by a boat. Should this result in detecting "dark" or "dwarf" galaxies, then the same method could be employed to uncover yet more distant galaxies that have gone cloaked for all this time. It could also go a fair ways in aiding our understanding of dark matter.
And that's where I run into a hang up. For whatever reason, I'm not completely sold on the idea of dark matter. It's supposed to make up about 85% of our universe, but what is it? We have no idea. Arguments supporting dark matter begin to sound more and more like the old Greek concept of "the ether" to me. I'm not saying that dark matter doesn't exist, I'm merely a bit hinky to jump on the dark matter bandwagon just yet. The math is probably right (for all I know, a mathematician I am not), but still...
If it is a physical reality and it truly does compose 85% of existence, then what the hell is it? That very question could become one of the greatest riddles of our time and answering it would not only help us to understand the universe better, but our own place in it as well.
"The universe isn't stranger than we imagine. It is stranger than we can imagine."--Albert Einstein
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