A round earth makes life convenient. No one has to worry about falling off the edge into the void, the ocean does not dump its contents into space, and there are not any awkward corners or edges to navigate around. Earth exerts a gravitational force on its own mass, pulling itself into the most efficient shape possible: a sphere. Fish can swim with peace of mind that they will not end up washed into space, and people can walk around without imbalanced gravity crumbling them to their knees or whisking them into space. The gravity on a sphere makes traveling as straightforward as possible, and theoretically, it could be all it takes to transport people anywhere they want in under an hour.
Essentially, a network of slides running through the center of the Earth could transport people anywhere in exactly forty-two minutes. Robert Hooke proposed the idea to Sir Isaac Newton in the 17th century, and this “gravity train” has tantalized imaginations ever since (Boyd). A girl wants to go to her cousin’s house in Pittsburgh? That will take forty-two minutes. Versailles? Forty-two minutes. The North Pole? Forty-two minutes. Of course, the slides would need to be frictionless and without air resistance, and voyagers would require protection from the 9,800°F core. Moreover, engineers would have to install these slides delicately to prevent the Earth from collapsing on the oversized playground. Nevertheless, theoretically, people could get anywhere in less time than it takes to catch a few globe-trotting fish for dinner.
Since Earth has a radius of approximately 3,958.8 miles, an object in free fall would travel with an angular velocity of .00124 radians per second down a chute directly through the center of the Earth. The object would increasingly gain speed as it approaches the midpoint of its path, and it would slow down again as it reaches the other side. There, the negative acceleration due to gravity would cause it to stop instantaneously and then fall back up the chute. Undisturbed, it would continue falling up and down the chute until the end of time, with each voyage up or down taking exactly forty-two minutes. So, if a businessman in Baltimore hopped into such a slide, he would find himself, forty-two minutes later, somewhere off the coast of Australia (Antipodes Map). And if he did not hop out, in another forty-two minutes, he would find himself right back home.
However, what if he did not want to get stranded in the Indian Ocean? What if he wanted to make a quick pit stop at Versailles? With the slide adjusted to the desired angle, his velocity would have to be split across two components with only one part contributing to his speed down the slide. He would travel less quickly, but the overall distance he would travel would decrease proportionally. Consequently, the trip would still take forty-two minutes.
The whole concept is farfetched, but in theory, it could happen. Millions of people could be zipping all around the world by means of slides: business people with their suits and briefcases, tourists with their trunks full of souvenirs, delegates busily practicing their eloquent speeches, or maybe even the Queen of England could find herself rushing down her own private slide. But would they be able to slide around the globe and still keep straight faces?
AntipodesMap. Antipodes Map, OpenStreetMap, 2020, www.antipodesmap.com.
Boyd, Andrew. Gravity Train. 29 Mar. 2011, www.uh.edu/engines/epi2703.htm.