Right after a star explodes, a liquid layer appears on its superdense remnant — a neutron star (a city-sized ball of neutrons). This material, which fell back, is superheated to two billion degrees. Whirlpools rage within it, stirring the plasma (hot gas of charged particles) like a chef kneading dough.
Why does this boost the magnetic field? In plasma, invisible magnetic field lines are frozen into the material: as plasma moves, it drags them along, twisting and stretching them. Thus, from whirlpool to whirlpool, the field accumulates and grows. Scientists call this process magnetic dynamo (self-amplification of the field by the motion of a conducting fluid).
Computer simulations confirmed these ideas. Scientists recreated the layer's conditions and saw the field saturate with energy within one millisecond. Such a hidden powerful field explains why some magnetars (neutron stars with anomalously strong flares) behave so violently.
In the time it takes you to blink (about 100 milliseconds), the magnetic field in a newborn neutron star's liquid layer would have amplified a hundredfold and reached saturation. Yet neutrino cooling, the dominant cooling mechanism, would have sapped less than a millionth of the thermal energy in that same instant: the cooling takes weeks.
In Robert Forward's novel 'Dragon's Egg', a neutron star is the cradle of hyperdense life whose civilization evolves on the surface at a furious pace. If such creatures existed, turbulent eddies on millisecond timescales would be geological epochs to them, and magnetic field surges would be natural cataclysms that give birth to 'magnetic mountains' and aurorae of unimaginable scale.