In the galaxy, too, the magnetic field has a tendency to change direction, so if you were to move through space, a compass wouldn't do a very good job of telling how to navigate. That means sorting out where the tangled threads came from is a knotty problem. One of the predominant ideas about magnetic fields, called dynamo theory, says that a very weak field gets amplified by the motion of all the gas in a galaxy or the sun, or in the case of the Earth, the motion of the magma. It's like winding a thread onto a spool, says Dr. Olinto. But when you put it all together in that spool that makes a very strong field.
Interstellar gas flowing throughout a galaxy provides the twisting motion to amplify the field.
But the real question is where did the field come from to begin with, says Dr. Olinto. After you have one, you can make it stronger by playing with it. Dynamo theory, she says, is pretty good at explaining magnetic fields on Earth, but it doesn't work so well for the sun or galaxy or galaxy cluster. But at the physics meeting, Stirling Colgate, a Los Alamos National Laboratory physicist, presented a dynamo theory that might account for the magnetic fields in galaxy clusters. These jets are amazing things.