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.

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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?

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