The left image is a combination of optical and near-infrared images showing four bright images of the quasar around a central red galaxy which is acting as a lens. The right image shows faint extended light suggestive of a ring which is expected when the source and lensing galaxy are closely aligned. Einstein's Theory of General Relativity predicted the gravitational pull from massive objects would be able to deflect rays of light. Astronomers say they can use the relative brightness and position of the individual images in a gravitationally-lensed system to determine how rapidly the Universe is expanding and whether it will continue to expand forever, or if it eventually will slow down and collapse. Single isolated galaxies actually are rare in the Universe.
Galaxies tend to clump together.
A system of two galaxies is a binary galaxy. A system containing more than two, but less than several dozen, is called a group. An even bigger system is called a cluster. And then there are groups of clusters known as superclusters. Often, in groups of galaxies, the members are in so small a space that they are appear to be touching each other.