Let’s figure it out!
The most successful attempt
The largest well that has been drilled on our planet is the famous Kola well, the depth of which is just over 12 km. However, this most complex structure by technological standards cannot be even closely correlated with what needs to be done to “pass” through the planet.
What obstacles await us?
First you need to overcome almost 75 km of continental crust. Then, to get to the Earth’s mantle, you will need to cover a distance of already 3000 km. And also the same amount to the core of the planet, which the planet almost entirely consists of liquid iron with a temperature of 5500°C.
Now multiply this by 2 – and in the end we need to cover almost 13 thousand kilometers if we want to drill a direct tunnel inside the planet, and almost the entire path will run through hot metal and magma!
Don’t forget about air pressure, which increases with increasing depth. After just 100 km, there will be very strong pressure in the tunnel, which can only be compared with the pressure exerted by water at the bottom of the Mariana Trench (more than 11 kilometers deep).
Because of this, when flying through such a tunnel a person will experience enormous overloads, like when a rocket takes off. By the way, it is precisely because of air friction that we still cannot create super-fast trains.
Where to dig a tunnel?
As you know, most of the surface of the Earth consists of water. It is quite possible to connect two points on land that can be connected using a through tunnel, but there will be not so many of them.
For example, if you start digging a tunnel in Argentina, then theoretically its exit will be in China. The tunnel, which will begin to be drilled in Portugal, will lead to New Zealand.
But in Russia, the starting point for a tunnel is not so easy to find; only a small area, which is located near Lake Baikal, is suitable for starting to drill a through tunnel. The final point will be in the Falkland Islands.
What if you don’t dig a through tunnel?
Let’s say we pumped out all the air from the tunnel and made the train resistant to high temperatures. What then?
In this case, there is no point in drilling a tunnel through the entire planet; it would be enough to simply connect two large cities. Then we will be able to travel to any two points of the world, connected by a tunnel inside the planet.
This concept is called “Gravity Train”, and it would allow us to travel using the force of Earth’s gravity and spending a minimum amount of energy!
What if you drill right through the Earth?
If a tunnel was drilled exactly along the axis of the planet, then the traveler would begin his movement at enormous speed: starting from 9.8 m/s, he would slow down, gradually approaching the center of the planet , and could even become practically weightless (in the center of an ideal ball, gravity acts from all sides and therefore all forces are balanced).
Having crossed the center of the Earth, the traveler will begin to accelerate and “fly out” at great speed at the other end of the tunnel. But if no one catches him, he will begin to fall back and end up doing this route again. And this can be like this ad infinitum…
Unfortunately, we do not have the capabilities to create such technologies. It’s a pity: we could greatly reduce travel time and connect the planet with a network of tunnels!