Researchers have for the first time experimentally mimicked the pressure conditions of Earths' deep mantle to measure thermal conductivity using a new measurement technique on the mantle material magnesium oxide. They found that heat transfer is lower than other predictions, with total heat flow across the Earth of about 10.4 terawatts, about 60 percent of the power used today by civilization. They also found that conductivity has less dependence on pressure conditions than predicted.