Final answer:
The statement is true; Earth's magnetic field has gone through several reversals, and these are global events. Magnetic poles always occur in pairs and this applies to all scales, and Earth's magnetic field reversal is part of a natural process.
Step-by-step explanation:
True or false: reversals of Earth's magnetic field have occurred many times and are simultaneous worldwide events. This statement is true. Earth's magnetic field has experienced many reversals, and these are indeed worldwide events. Earth undergoes a magnetic reversal about once every 200,000 years, where the magnetic north pole and the magnetic south pole switch positions. These reversals are due to the dynamic processes in the Earth's outer core and are part of a natural phenomenon known as the geodynamo.
When talking about magnets, whether it's the Earth or a bar magnet, it is a fundamental property that magnetic poles always occur in pairs of north and south. This concept applies to all scales, from the magnetic atoms that make up the Earth's geodynamo to sunspots on the sun. If a magnet shatters into many small pieces, each piece will retain a north and a south pole. The geomagnetic polarity of the Earth is currently normal, with magnetic north near the geographic north pole. However, during reversed polarity, the magnetic north pole would be near the geographic south pole.
Research into the geodynamo and magnetic field reversals is ongoing, with scientists like Glatzmaier and Olson conducting experiments and modeling to better understand the source and mechanics behind these magnetic events. Despite much being known, certain aspects such as the precise triggers for field reversals and the variability of solar cycles are still subject of scientific investigation.