https://www.engadget.com/2017/04/12/dark-matter-web-composite-image/
The Waterloo researchers used a technique called weak gravitational lensing to create the composite. It's an effect that causes images of distant galaxies to warp slightly when an unseen mass such as a black hole, or dark matter, is present. The composite is made up of more than 23,000 galaxy pairs located 4.5 billion light-years away. «By using this technique, we're not only able to see that these dark matter filaments in the universe exist, we're able to see the extent to which these filaments connect galaxies together,»
