![]() Here, the poking is equivalent to the force and the movement is equivalent to the acceleration. If you poke it harder, it’ll move faster. In a nutshell, this means that if you poke an object, which has some mass, that object will move. The same laws that govern the trajectory of a cannonball are used to predict atomic motion. Mathematically, we can incorporate Newton’s laws of motion to simulate an atom’s trajectory by treating it as if it is a classical object, or an object that we can see with the naked eye. This property is important because it allows scientists to treat atoms as a mathematical problem. So, you can think of atoms as the building blocks of minerals. For example, rock salt is a mineral called “halite,” and its chemical composition is comprised of two atom types called sodium and chlorine, or together can be abbreviated by NaCl. Here, I’ll be emphasising the chemical composition aspect of a mineral, or in other words the arrangement of atoms that make up the mineral. But before we talk about how minerals can be simulated, we first must understand what a mineral is.įigure 1: Atomic structure of halite, NaCl, generated from CrystalMaker.Ī mineral is defined as naturally occurring, inorganic, solid, having a well-defined crystalline structure, and having a well-defined chemical composition ( Nickel, 1995 Nickel and Grice, 1998). The theoretical side, which I will be focusing on from here on out, involves using computer models of minerals and materials at these extreme conditions. The experimental side involves laboratory work, where minerals are squeezed and heated to high pressures and temperatures– mimicking the conditions of a planetary interior – so that we can understand how materials behave at such extreme conditions. Like many other STEM disciplines, mineral physics has both an experimental and theoretical side. Different mineral assemblages and phases within Earth’s interior produce different seismic wave velocity profiles that can be imaged. You can compare imaging the interior of the Earth using seismic waves to imaging the insides of human bodies using X-ray CT scans. ![]() This technique is called “seismic tomography,” which is very similar to receiving a medical X-ray computed tomography scan, or better known as a CT scan. Every time an earthquake occurs, seismic waves propagate through the Earth and we gain insight as to what the inside of the Earth looks like. Additionally, we have another constraint provided by seismic observations. The composition of the Earth cannot be very different from that of the Sun or meteorites, thus providing a chemical constraint on the building blocks of Earth ( McDonough and Sun, 1995). Mineral physics is a discipline that involves understanding materials in planetary interiors while trying to fit the observed chemical and seismological constraints. So how is it that scientists can boldly claim to know what’s inside of the Earth without ever having seen the interior? The answer is complex, but it can boil down to the combination of astronomical, chemical constraints, seismology, and mineral physics. This week UCLA PhD student Leslie Insixiengmay takes us on a microscopic journey to the Earth’s interior and tells us all about the atomic forces that shape the deep Earth behaviour!Ī question I get asked a lot is: “How do we know what’s inside of the Earth?” It’s a good and valid question considering that the deepest hole humans have dug only reaches about 12.2 km, which is about 0.2% of the Earth itself ( Kozlovsky, 1984). ![]()
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