Scientists based in Germany and Norway today published new results about a geophysical theory known as true polar wander. That is a drifting of Earth's solid exterior -- an actual change in latitude for some land masses -- relative to our planet's rotation axis. These scientists used hotspots in Earth's mantle as part of a computer model, which they say is accurate for the past 120 million years, to identify four possible instances of true polar wander in the past. And, they say, true polar wander is happening now... The scientists -- including Pavel V. Doubrovine and Trond H. Torsvik...