Earth's core has slowed so much it's moving backward

Moving backward in the rotating reference frame of the Earth. In other words, it's rotating slightly more slowly than the Earth as a whole.

Paper: <i>Inner core backtracking by seismic waveform change reversals</i> (11 points, 21 days ago) <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=40679957">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=40679957</a>

I wonder if that has any effect on the periodic flipping of the north and south magnetic poles. <i>Something</i> has to cause that to happen.