A stunningly concentrated and hefty galaxy cluster, from a time in the universe's history when such massive structures aren't expected to have fully formed yet, is challenging cosmic evolution theories. Across a series of three recent papers, a team led by researchers from IPAC—a science and data center for astrophysics and planetary science at Caltech—have revealed that the cluster is the most distant example of strong gravitational lensing with a galaxy cluster. ...read more read less