Question: If a person were to fall through a hole that went from one end of the Earth to another, would gravity turn them upside down, thus causing them to fall through the hole again and again, making them stuck in an infinite loop (disregard the fact that they would pretty much disintegrate in the 5,000 degrees temperature in the middle of the Earth)?

Edward Bovill answered on 13 Mar 2013:

If you drilled a hole through the centre of the Earth, ignored the searing heat and plucked up the courage to jump in then you would fall for a very, very long time before you got the centre of the Earth.

If you pretend that inside this hole there is no air (and why not, just put on a space suit!) then by the time you got to the centre of the Earth you would be travelling at over 18,000 miles an hour, but it would only have taken 21 minutes to get there! If you had manage to stay upright all the way down, you would have felt gravity pulling you down feet first. When you got the the centre, gravity’s pull would just reverse, meaning you now felt like you were upside down. It wouldn’t flip you around.

Once you got to the other side of the Earth, you would appear out of the hole on the other side for only a split second, reaching the height you initially jumped in from, and then you would fall back down again. This would repeat infinitely!

However, if there was air inside the hole, then that would slow you down every trip you made and eventually you would be stuck in the centre of the Earth.