Interactions in the Early Universe

The top image on the first page of the left panel represents the most interacting galaxies yet found in a single cluster (not all of the hundreds of galaxies in the image are members of the same cluster, but at least 81 appear to be and 13 of those are interacting). Since we are seeing the cluster as it looked 8 billion years ago, this suggests that interactions of galaxies may have been common in the early Universe.