By Linda Luo

Remember that one kid who was always hogging up the sandbox trying to “dig to China”? Each year, countless naïve children spend hours of their precious childhood trying to achieve a feat no known man has ever been able to accomplish. 

Is it even a good idea in the first place?

Pushing aside the fact that humans have yet to obtain the technology to dig more than 12 kilometres into the Earth’s crust, a tunnel through the Earth is actually not the worse idea humans have ever thought of.

The idea of connecting two points through the interior of a sphere for transportation purposes is a hypothetical called gravity train. Not only will the trip solve all your plane hating, ship loathing, and car detesting problems, but it’s also time-efficient. According to the British scientist and inventor Robert Hooke in a letter to Issac Newton 400 years ago, a trip from any two points of the earth would only take 42 minutes!

Why would the trip be so short?

Using the antipodes Spain and New Zealand as an example, a flight between the two countries will take around 25 hours and 7 minutes. The reason why these flights take so long is that they travel around half the globe. The Earth’s circumference is estimated to be around 40,075 kilometres, so the distance between antipodes is approximately 20,037 kilometres. With commercial aircrafts going only up to 925 kilometres per hour, it shouldn’t be a surprise that it takes more than an entire day to travel from one end of the Earth to the other.

A gravity train, on the other hand, doesn’t require nearly as much time or energy. Depending on where the tunnel is, it shouldn’t be longer than 13,000 kilometres (unless you want to show up on the top of Mount Everest). With the help of the Earth’s gravitational pull, a train could accelerate up to the speed of 28,000 kilometres per hour within the first 21 minutes. Ignoring the possibility of any sort of friction, the train will be able to have the exact amount of acceleration to get past the centre of the Earth, and will come to a complete stop at exactly 21 minutes away from the Earth’s core.

Is it actually possible?

Despite the fact that humans have not and cannot fulfill this brilliant hypothetical right now, the future is unbeknownst to us. There could be an ingenious machine created by future engineers just for such a tunnel in a century. But nevertheless, it does feel like an idea that is too good to be true and for now, we can just imagine the wonders we could be experiencing if we were born in a different era.

Admittedly, gravity trains sound quite a lot simpler than reality. Not only will engineers have to drill past the Earth’s crust and reach insanely horrid temperatures, but they will also have to dig through parts of the Earth that are yet to be discovered. For instance, the Earth’s mantle – which is about 2,900 kilometres thick – is the remains of molten materials created when the Earth formed and it can be as hot as 3700°C. Skin burns at 44°C. However, never underestimate your fellow humans and have faith in humanity.

Last but not least, to all acrophobics out there who want a different type of stress while travelling, you might want to start now. After all, it did take the Soviets 20 years to dig 12 kilometres.