Collective, or coordinated behavior is routine in liquids, where waves can occur as atoms act together. In a milliliter (mL) of liquid water, 1022 molecules bob around, colliding. When a breeze passes by, waves can form across the surface. These waves are not present in the same volume of air, where only 1019 gas molecules randomly move about.

Astrophysicists looking through the Hubble Space Telescope have identified a black hole that appears to be helping new stars to form amongst its encircling gas clouds. Black holes had been thought to hinder the birth of stars, since their gravitational forces propel a strong flow of material that sweeps away the gas clouds from which stars are made. Now the scientists have found evidence that these same flows can also compress regions of...