PBS Space Time

Earth’s Core Should Be Impossible. A New State of Matter Explains It.

The video explores the ongoing mystery surrounding Earth's inner core, which current seismic data suggests possesses properties that defy our traditional understanding of a solid, crystalline structure. While we've long known about Earth's liquid outer core and a solid inner core, recent seismic wave analysis has revealed anomalies, particularly concerning shear waves (S-waves). The journey to understanding Earth's interior has been a gradual process, relying heavily on seismology – the study of seismic waves generated by earthquakes. Early discoveries in the 20th century, like Andrija Mohorovičić's identification of the crust-mantle boundary in 1909 and Benno Gutenberg's discovery of the liquid outer core in 1914, were groundbreaking. Inge Lehmann's crucial discovery in 1936 of the solid inner core, based on P-waves reflecting off it, further refined our model. This led to the established view of Earth's layered structure: a crust, a mantle, a liquid outer core, and a solid inner core, all primarily composed of iron. This model effectively explained phenomena like volcanism, plate tectonics, and Earth's magnetic field.