Traversing a hypothetical tunnel through the center of the Earth

Science News : In a recent thought experiment, Thomas Concannon and Gerardo Giordano of King’s College in Pennsylvania explore what it would be like to fall down a hole through Earth’s center to the other side. Because of the complexity of the problem, researchers in the past have simplified the calculations by making some broad assumptions, including that Earth has a uniform density and doesn’t rotate and that there is no drag from air resistance or friction along the tunnel’s sides. To create a more realistic model, Concannon and Giordano have now included drag forces in their calculations. They found that it would take at least 1.8 years just to reach Earth’s center through an air-filled tunnel. By evacuating the air, the total trip time to Earth’s center could be shaved down to just 19 minutes. But because of friction, it would never be possible to overcome gravity’s pull and make it to the other side.