From the introduction: The galaxy, SL2 is about 6000 mega-parsecs away from Earth. It is far different than Earth's Milky Way galaxy. SL2 is different from the Milky Way in that 99 percent of the mass of the galaxy exists in the form of dark matter, comparing to only 50 to 65 percent in the Milky Way. Dark matter has escaped detection at all wavelengths, from radio to gamma rays, not just light.