Slowes and his team have discovered a group of quasars that challenges Einstein's Large Scale Homogeneity Principle. This principle is simply the expression that, at large scales, the universe looks homogeneous.
However, going through the Sloan Digital Sky Survey, he and his team found a group of quasars that is above the limit generally admitted to be "large scale", meaning that in order to maintain the principle as valid, its lower limit has to be increased dramatically. Which also means that Astrophysics just got a bit harder ;-)
Here is the link to the article in the New Scientist and the published paper on Arxiv.