Just how long would it take to fall through the center of the Earth, traveling from one side of our planet to the other?
Physicists have long calculated the answer to that question as being 42 minutes, but now, new calculations show that the theoretical trip would actually take around 38 minutes -- and we can blame gravity for the discrepancy.
The traditional calculation to measure a fall through Earth assumes that our planet has a constant density throughout its many layers. Since the gravitational attraction between two objects is proportional to their masses (or density) and inversely proportional to the square of the distance between them, if Earth's density were constant, the only change in gravity we'd experience would be due to how far we were from Earth's center.
But as Alexander Klotz, a graduate student at McGill University in Canada, came up with the new calculations, he took into consideration how Earth's density changes layer by layer. And as a result, the gravitational speed at which we would fall through each layer changed too.
Klotz measured the different densities found in Earth's interior using seismic data. Indeed, our planet has a less dense crust and mantle and a more dense core, Science magazine reported.
A paper describing the new thought experiment results was published in the March 2015 issue of the American Journal of Physics.
"This is the kind of paper we love," Dr. David Jackson, editor of the journal and a physicist at Dickinson College in Carlisle, Pennsylvania, told Science magazine. "This is a nice addition to the classic problem."
Want to learn more about our planet's internal layers? Take a journey to the center of the Earth in the "Talk Nerdy To Me" video below.