Dark Matter

March 2, 2008
It’s a bright and sunny summer day so you decide to fly the kite that you’ve recently built. You run outside and soon it begins to catch some strong wind. Before you know it, the kite is a speck of red in the sky and harder and harder to keep hold of. You start to think that the wind may send the kite hurling into some other part of town but, luckily, the thin and nearly invisible length of string attached to it is just strong enough for the job and keeps the kite from flying off into the sky.

This visual is a likely comparison of what happens with substantial amounts rotating matter in the outer regions of our universe. Dark matter corresponds to its name because of its unusual property of not reflecting light. Scientists believe that the particles of dark matter actually absorb electromagnetic radiation (light) therefore making it invisible.
Scientists became aware of the possibility of “unseen matter” when an astronomer named Fritz Zwicky attempted to estimate the mass of a galaxy cluster using two different methods; the second method used resulted in a number 400 times that of the first. Wondering where all the missing matter was, the assumption of dark matter came
into place. This assumption was not entirely new to the face of astronomy. Albert Einstein mentioned something fairly similar in his general theory of relativity. Soon scientists realized that matter wasn’t missing, light was, henceforth the name, dark matter.

But, if we can’t see it, how do we know that its there? The realization of the total percentage of how much dark matter there is in the universe gave astronomers a chance to think. They used methods such as Fritz Zwicky did to estimate the total amount of mass and matter in an object so that we don’t judge based on what we see but rather on what’s truly there. Other methods include using cryogenic and xenon detectors.

As astronomers began to question the subject, they realized that dark matter acted as gravitational glue to “normal” matter (matter that reflects light). Without it, our own Milky Way galaxy would have flown apart as the kite would have without the string, as well as any other spiral, rotating structures. And as scientists expanded with research on the subject, they found that dark matter dominates 90% of the matter in our universe. We can only see 10% because it’s “normal” matter. Now we understand that we can’t find 90% of the universe because we can’t see it.

Astronomers also classified dark matter into two different groups; MACHOs (Massive Astrophysical Compact Halo Objects) and WIMPs (Weakly Interacting Massive Particles). MACHOs are the larger, stronger varieties of dark matter such as black holes, star clusters, galaxies, etc. They are made of ordinary or baryonic matter which we can see and are only held together by non baryonic matter. WIMPs are particles of non-baryonic matter that float through space, baryonic matter, and even you.

Dark matter is a stunning revelation to the face of science. The reason why is because this mysterious substance has properties as such that we don’t find normal. This unexplained material has opened the minds of people everywhere and is quite frustrating to figure out. But it also makes us curious. Now we have found dark matter, so who knows what we may discover next?

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