Skepticism, Science & Pseudoscience

IIRC, the mantle has currents and convection, which would create different speeds in different places. If that's true, then there wouldn't be much reason for the liquid outer core to rotate at a uniform rate across its surface. No idea about the inner core though. It has to rotate, but I have no idea how fast. I also read somewhere that the inner and outer cores rotate at different speeds.

ETA: I looked it up and found this--http://www.livescience.com/9313-earth-core-rotates-faster-surface-study-confirms.html I slapped my forehead when I read it too (figuratively), because of course a liquid iron outer core would generate a magnetic field that interacts with the inner core, potentially affecting its rotation.

EATA: I meant to say a liquid iron core rotating at a different speed than a solid nickle-iron core.