If you want to travel from one side to another side of the Earth A jet plane will take around 22 hours to reach there. But will it not be a long cut for us? What if we can dig a tunnel that will help us travel directly from one side of the Earth to another? We can reach till there faster! So let’s think if we could make a tunnel that passes through the center of the Earth, then what would happen? So we’ll have to think about two situations here First situation would be where we dig a tunnel through the center of the earth. Now just think about it.. What if we jump into this tunnel, what will happen? So, the answer is, you may actually never be able to reach the other side. And the reason behind this is the “Coriolis Effect.” If you have ever played in a merry go round during childhood, you must’ve noticed how the ball curled in a weird way when you threw the ball from one end to another This phenomenon is called the “coriolis Effect.” So now let’s think about the Earth Earth is constantly rotating on its axis from West to East at 1,670 km/hr And as we go deeper, then even there Earth’s particles are constantly rotating once per day, albeit, at a slower pace because they don’t have much area to cover So if we jumped a tunnel, then only in a few seconds we will start moving towards East, faster than Earth’s rocks in the East Hence, only after reaching a few kilometers deep, We will crash with Earth’s rocks in the East And this effect has been tested before Near the world’s largest fresh water lake, Lake Superior, few miners tested it by dropping cannon balls in a 1.5 km deep tunnel But the balls never reached the bottom! But now let’s think about the second situation What if we dug a tunnel from one pole to the another, where the Coriolis effect will not take place? So because the center of the earth, called as the core, is more concentrated in mass So its gravity will definitely pull you down, For early few kilometers And the force with which it will pull you down, will be the same constant force of Earth’s gravity, 9.8 metres/sec.2 So this means our speed of the fall would be 8 km/sec. And it’ll only take us 13 mins to reach the core! This area is called the outer core, where the gravity is the strongest But it’ll just be 10% more than the force we experience on the earth’s surface So as we’ll start moving towards the exact center of the Earth, We’ll have so much mass above us that, it will literally start cancelling out gravity from the mass below us And subsequently, the speed of our fall (acceleration due to gravity) will start reducing This speed will keep on reducing Till we reach the center of the earth And once we reach the center, we will stop feeling any type of gravitational pull. because Earth will be pulling on us from every direction We’ll feel as if we are just floating on it’s center! But still because we will be charged with a forward momentum, so we’ll be falling with a speed of 10 km/hr. And once we pass the center, then the entire process will get reversed! And we’ll start getting slower and slower Less slow in the beginning, then slower and slower as we keep moving downwards until we reach the other side of the Earth And if there is no type of external force, or we simply don’t wanna come out So we can forever keep moving up and down! So this will basically happen if you jump a tunnel from one side of the Earth to another! But this is not possible in reality, and we all know this The deepest we have been able to dig till now is in Russia, named Kola super deep borehole. But this is only 12 km in depth The digging had to stop at this depth Because the temperatures started reaching around 180 degree Celsius And this is the reason why we cannot go much deep into the Earth because temperatures start getting extremely high there Temps can reach anywhere from 200 degree to 6,000 degree Celsius which is the temperature of the surface of the sun! But what would’ve happened if the earth was hollow from inside? So first of all Earth’s magnetic field wouldn’t have been there because that is generated from earth’s molten iron core So this means we wouldn’t be able to protect ourselves from sun’s harmful UV rays And if we decide to dig a hole into the hollow Earth, then Gravitational pull would be the same from each side. Because of this we will float in the air as if there is no Earth around us. But we’ll also not be able to stay alive because our atmosphere doesn’t have enough air to fill in our hollow Earth so that we can breathe! So that is why it is better the Earth is not Or else we wouldn’t exist!