How hot is the Earth's core? What exactly is the core made of? These are age-old questions which scientists are still unable to answer with any confidence. Most people believe that it's something like 5,000 - 6,000 degrees Celsius down there, and everone agrees that there's a lot of iron in the core, but that's about as far as it goes. And it's really important to get better answers to these questions. Basically, the core drives the dynamics of the whole Earth. The tremendous heat flowing out of the core causes earthquakes, volcanoes and the drift of continents, and the turbulent swirling motion of the liquid part of the core creates the Earth's magnetic field.
In the last four years, in a collaboration between the UCL Physics & Astronomy and Geological Sciences Departments, we have launched a completely new assault on these key questions. The new approach is based on the idea of using quantum mechanics to predict the properties of materials at the extreme pressures and temperatures of the core. For example, we have demonstrated that density functional theory can be used to calculate the melting temperature of materials at high pressures. This is a big step forward, and has allowed us to make a new estimate of the temperature in the core (we estimate about 5,500 degrees at the boundary between the liquid outer core and the solid inner core). We've also discovered that this kind of calculation can help us to decide what the core is made of. This is important because it has implications for how the Earth was originally formed.
To find out more about this work, take a look at the home-pages of Dario Alfè, Lidunka Vocadlo, and Ché Gannarelli. Our work on the temperature in the core was reported in a letter in the journal Nature, which was commented on in their News and Views section. This paper attracted a lot of media interest, and there were interviews on the Channel 4 television programme and the Today radio show. There was even a half-page item ("Core, what a scorcher!") in the Daily Mirror national newspaper. Some of our work on the chemical composition of the core was reported in a separate letter in Nature, and a full write-up was submitted to J. Chem. Phys. in October 2001.
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Last updated 26 October 2001