The galaxies in the wall cannot be seen, but Dr. Pomarède and his colleagues were able to observe their gravitational effects by assembling data from telescopes around the world. And galaxies beyond the wall are moving outward more slowly than they otherwise should be, reined in by the gravitational drag of the wall. “One might wonder how such a large and not-so-distant structure remained unnoticed,” Dr. Pomarède mused in a statement issued by his university. But in the expanding universe, there is always something more to see. On the largest scales, cosmologists attest, the universe should be expanding smoothly, and the galaxies should be evenly distributed.

Source: International New York Times July 10, 2020 15:22 UTC