Deep Space Inhabitants - Dark Matter

Credit: NASA/ESA/M.J. Jee and H. Ford (Johns Hopkins University)

Much like black holes, dark matter suffers from a lack of visibility. It may make up almost all of the mass in the universe, but it doesn't emit or reflect light or other forms of radiation.

So what is the evidence of its existence? Astronomers infer its presence from gravitational effects on visible matter. In the Hubble Space Telescope composite image above, you can see an ethereal ring of dark matter in a galaxy cluster. How is that possible? Light from more distant galaxies is bent by the galaxy cluster. By observing those distortions, astronomers can map them and determine how the dark matter is distributed.

Credit: NASA/ESA/C. Heymans (Univ. of British Columbia, Vancouver)/M. Gray (Univ. of Nottingham, U.K.)/M. Barden (Innsbruck), the STAGES collaboration, C. Wolf (Oxford Univ., U.K.)/K. Meisenheimer (Max-Planck Inst. for Astronomy, Heidelberg)/COMBO-17 collaboration

Another composite image shows clumps of dark matter around a galaxy supercluster.

There's got to be some frustration for astronomers in not being able to see most of the universe, of only being able to infer it. Then again, the vast majority of knowledge we receive is indirect. Any new item I read or view is inferred, in that I'm not there to witness the event. Even knowledge of other people is second-hand. We have to trust they're being honest when we ask what they're thinking or feeling.

The hardest thing to accept, though, is that even with ourselves, direct knowledge of the psyche is hard to come by. We have our habits and compulsions, our little ways, but self-knowledge is largely intimated, and true insight is rare.

But the night has not left us without resources. So I'll be turning my attention from the night sky and toward the inner landscape as revealed by our dreams. Stay tuned.