A Quick Look at the Universe's Expansion May Not Be The Same In All Directions

One of the fundamental ideas of cosmology is that everything looks the same in all directions over large enough distances. A new study using data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton is challenging that basic notion. Astronomers studied hundreds of galaxy clusters, the largest structures in the universe held together by gravity, in X-rays across the sky. They may have found differences in how fast the universe is expanding depending on which way they looked. This latest test uses a