Danish Research Center To Explore Mysteries of Earth's Interior
An anonymous reader writes "The DanSeis Centre at the University of Copenhagen has just received a grant of more than €3 million from the Danish Ministry of Science, Innovation and Higher Education to investigate and tackle one of geoscience's great mysteries: do mantle plumes, hypothetically buoyant regions of heated mantle material rising towards the earth's surface, actually exist?"
"Why is the force of gravity at the core zero?"
Because the integral of the forces acting on some mass at the center of the Earth is zero. Or to put it differently: You are being pulled by (approximately) equal forces in all directions.