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# Why Take a Plane? Why Not Just Go Through the Earth?

Using physics to prove why someone in our office was wrong (or right)

On second glance, the title of this blog post is actually not as stupid as it looks. Creating a network of underground transportation is already something that is thought of (subway system, anyone?), transcontinental underground transportation across long distances sounds impossible, or is it? This post will try to use Physics (don’t worry, there won’t be hard numbers) to prove (or disprove) that transcontinental underground transportation is impossible.

Digging a Hole to China

We have all heard stories that if you dug a hole large enough from South America, you’ll end up in China. If you’re in the UK or Europe, you might end up in Antarctica… but that’s no fun. If you’re in Canada, you might end up in Australia… if you’re lucky. Or you’ll just drown or get eaten by a fish. So, a trip from South America to China is your best bet. Let’s use a picture as a reference to see how this will work.

So… suppose your construction crew managed to dig all the way through the earth’s hard bedrock, somehow managed to create an insulated pipe going through the mantle and outer core, finally hitting the inner core, where they overcame temperatures as hot as the sun, and pressure that is the equivalent of being crushed by the entire Pyramid of Giza. But, let’s pretend they are all supermen wearing ultra-insulated titanium alloy suits that would not melt or burn under these temperatures, and managed to create ultra-insulated pipe transport system that protects its travelers from the “elements.”

Down the Rabbit Hole

So now we jump in and go to China? Well not quite. There’s one little problem of air resistance. In Physics I we are always told to “neglect” air resistance. Unfortunately, real life doesn’t neglect air resistance. With air resistance you’d be lucky if you even escaped Earth’s core before eventually getting stuck somewhere around the center of the earth. Well, that sucks. But there is a better way!

Around the World

Rather than going through the Earth linearly, we could use gravity to our advantage without pesky air resistance by changing our route.

This way, gravity isn’t so intense that we run into air resistance, because air resistance increases proportionally to velocity squared! So we could just create a golf-ball shaped capsule the size of a small person, and tumble down a sloped tunnel that is dug underground. Then, when we are directly underneath China, we can just take a giant elevator to the surface. Oh, and we also don’t have to go through the core. Just make sure to bring a paper bag in case you blow chunks from all that tumbling.