42

If you dug a tunnel from LA to Paris thru the Earth and created a freefalling transportation vehicle, it would take 42min to get there. 42min travel works for any 'thru the Earth, point-point tunnel' using gravity, unassisted, as an accelerator and decelerator.

 

I'd like to see the math behind this, but I'd believe it. You get pulled the entire way down and then slowed the whole way back out.

 

http://badcontrol.com/?p=1315

 

/42

isnt that just the answer from hitchhikers... i will click link now.

Yes, 42 is the answer to the ultimate question of life, the universe and everything. It's also my baseball jersey number. Which of those factoids is more relevant, I leave for the reader to decide.

 

LA to Paris wouldn't take you through the centre of the earth, so you wouldn't be falling straight down the tube - You'd be rolling down one side of it. You would gather some momentum on your way to the midpoint, but your battered corpse would probably stop rolling before you even got halfway.

 

If you made the tunnel walls perfectly smooth, replaced the tumbling corpse with a vehicle with frictionless wheels, and evacuated all air from the tunnel to eliminate wind resistance, you might stop just as you reached the far end. Murphy's Law would dictate that the exit of the tunnel would probably turn out to be at a few feet higher altitude than the entry end, causing you to stop just before the end and roll all the way back to the start.

 

In any case there is no such thing as "frictionless", so a real vehicle would end up stuck at the midpoint, awaiting certain death as the next test car was sent hurtling towards you to see how you were doing.