What would happen if you dug a tunnel through the earth?
Imagine you have a super-duper excavator that lets you dig as deep as you want. You use it to dig a tunnel from here to another point on the other side of the world, like New Zealand. What would happen if you jumped into that tunnel? Would you end up in New Zealand?
Faster than a fighter jet
Let’s pretend the earth is a perfect sphere and has a uniform weight. While we’re at it, let’s ignore the heat and pressure in the earth’s core. And let’s imagine you can handle falling much faster than the speed of sound.
If you jumped into your tunnel through the earth, you’d drop straight down. You’d fall faster and faster for 21 minutes, at the end of which you’d arrive at the centre of the earth. This is when you’d reach your top speed: around 28,000 kilometres per hour. That’s about four times faster than the fastest fighter jet ever made!
Upside down
Once you move past the centre, you’d begin to slow down. After another 21 minutes, you’d stop falling and become stationary. That’s the exact moment you’d arrive in New Zealand.
But mind your step: you’d be hanging upside down! You’d need to grab onto something fast, otherwise you’d fall back to the Netherlands.
You’d have completed a journey of 12,742 kilometres in 42 minutes, falling straight through the earth and onto the other side. If only trains could go as fast!
Slide
In theory, you could also build a tunnel to other parts of the world: a Greek island, Brazil or somewhere else altogether. In that case, you’d fall diagonally rather than straight down. Imagine sitting on a slide, sloping down for the first half of your journey and back up for the second.
Travelling diagonally means you’d be moving more slowly. But because you wouldn’t be going all the way to the other side of the world, you’d be travelling a shorter distance. That means your trip would last just as long as your journey to New Zealand. Wherever your tunnel leads, you’d always arrive – upside down – after 42 minutes.
Answered by Yannick Fritschy
