What Is Dark Matter, And How Do We Find It?

For thousands of years, we thought that everything that we could see was all there was to the universe. Only recently did we discover that this was far from the truth. What we consider "Matter" accounts for about 15% of all of the matter in the universe. Ok so if there is so much of this stuff why can't we see it? The answer to that is simple. It does not react with matter, or light, in any form that we can detect. There is only one way, so far, that we can observe dark matter. That is through gravity. By observing the rotations of galaxies, astronomers can deduce that there is an additional force holding them together. Stars in galaxies are moving with such speeds that gravity alone can not hold them in their orbits. Unless there is a form of matter spread throughout the entire system.

Nobody knows for certain what dark matter is. Until we observe it directly we may never find out. Some hypotheses include Weakly Interacting Massive Particles, or WIMPs. Which is exactly what they sound like. Massive particles that only interact with the weak force, and gravity. Another is the Axion, which are very light particles that only interact with themselves, and gravity. This makes them suitable dark matter candidates. Massive Compact Halo Objects, or MACHOs, are another. They are objects like black holes, white dwarfs, or neutron stars. Objects that do not, or weakly, emit light.

There is indirect evidence for dark matter. Like gravitational lensing. We find a point in the sky where nothing is visible, yet when something passes by its light gets bent by seemingly nothing. There are many accounts of this phenomenon. We know that it is there, but we do not know what it is. Yet the big discovery has yet to happen, direct observation. There are detectors all over the world, deep underground, trying to find a small sign. Something has happened that can't be explained by regular matter. A flash of light in the darkness. It's too deep to be cosmic rays, or solar radiation.

We Are just waiting for that flash, waiting to find out if dark matter is a particle, or could it be the effects of gravity from matter in a higher dimension. Leaking though some unknowable barrier. Undetectable except through our observations of gravity. Forever out of our reach due to our dimensional challenges. Who knows?

What do you think?