Professor Lars Stixrude
How did Earth begin? Throughout history, we have wondered, constructing origin myths of order arising out of chaos. To James Hutton, the founder of geology, who saw "no vestige of a beginning, no prospect of an end" in the rock record, the question could not be answered by science. The modern study of Earth's origins had to await the discovery of radioactivity, and in the 1950's, the first reliable determination of the age of the Earth.
Today we understand that Earth is the product of an evolutionary process that began with a largely molten initial condition. Melting is the engine of Earth's chemical evolution, which makes possible the formation of core, mantle, crust, and atmosphere, and internal mantle differentiation. The magma ocean is central to our understanding of Earth's differentiation since much of it happened early: as Earth solidified, chemical evolution slowed to the trickle of partial melt that continues to form crust today. Melting is also our window into the Earth's interior, bringing magma to the surface, and the only samples of the deep interior we are every likely to see in the form of xenoliths. Melting processes provide us with a book of Earth's history, but one that we cannot read, particularly the early chapters that set the stage. The reason for this is simple: we still know very little of the melting process over almost the entire pressure regime of Earth, a major gap in our knowledge that MoltenEarth aims to fill.