# Fastest path for a gravity train [duplicate]

On wikipedia > gravity train, the time to go from any point A to any point B at the surface of the earth (assuming earth is a perfect sphere and absence of friction) by a straight line takes a constant ~42 minutes.

Intuitively, I would expect that a fastest path would be curved and pass closer to the center of the earth.

What is the fastest path between two points A and B with a gravity train?

• Possible duplicates: physics.stackexchange.com/q/7421/2451 and links therein. – Qmechanic Feb 9 '17 at 22:17
• My question is indeed a duplicate! Thanks. Should I delete my post and let people close it? – Remi.b Feb 10 '17 at 11:15
• Leave it as is. Your post is clearly written, and it may help others as a stub/bookmark. – Qmechanic Feb 10 '17 at 11:55