In a large gas cloud where stars are born, the magnetic field lines are roughly aligned in one direction, like the fibers in a piece of felt. But look inside, into the dense clumps that will eventually become stars, and the picture changes: there the lines are twisted every which way, like a ball of yarn after a kitten has played with it.
Astronomers measured the field directions in 79 such clumps across 14 different clouds. They used data on dust polarization: dust grains align along magnetic lines and slightly polarize the passing light, and from that glow the field direction can be reconstructed. It turned out that in the clumps the spread of field directions is noticeably larger than in the cloud as a whole. Moreover, the clump's field does not match either its own orientation or how it rotates. Everything looks as if on small scales the magnetic field ceases to be the boss and gives way to other forces — for example, turbulent gas flows.
This result is important for understanding how stars are born. If the magnetic field does not control the clumps at later stages, then their fate is decided by other processes — collisions, compression, internal flows. Previously it was thought that the field was a strict director of the whole process, but now it is clear: chaos appears on the stage, and a star can be born where the field does not expect it.
Dust grains in interstellar space can be smaller than a micron, but their collective 'alignment' reveals the direction of the magnetic field over distances of hundreds of light-years.
In the novel 'The Three-Body Problem,' a civilization controls stars, but even there magnetic fields do not follow simple rules — chaos is always nearby.