Putting certain pesky physics and geological principles aside, if you drilled a hole through the middle of the Earth from one side to the other and jumped in, how long would it take for you to fall all the way through?
It would take you 42 minutes and 12 seconds to get to the other side. Now, this is to say you could survive to get to the other side and that you wouldn’t be instantly crushed by the Earth’s pressure (in the core, it’s about 3.6 million atmosphere) as well as the temperature at the hottest part of Earth’s core, which is estimated to be 10,800 degrees Fahrenheit (6,000 degrees Celsius). This is about the same temperature on the surface of the sun.
You also have to take away the friction you would generate with the air from the speed of your body hurtling through the hole, at least until the hole collapsed due to the intense pressure and temperature. You now have an exercise in futility. But what if you could somehow suspend all those things and make the trip perfectly safe? For one thing, you’re going to be in for quite a ride.
You would initially accelerate as you dropped in the hole, but as you approached the center of the Earth, your acceleration would decrease. You would then be weightless as you moved through the center of the Earth while traveling at about 17,700 miles per hour (28,485 kilometers per hour).
You would slow as you made your way to the other side after a lovely 42-minute journey. But that’s not all. If you didn’t use something to stop yourself, you would take a return journey through the middle of the Earth just like a mass on the end of a spring since gravity will now be trying to pull you back to the center. This is according to Hooke’s Law. A round trip would take 84.5 minutes.
But there is one more consideration about this thought experiment that wouldn’t allow you to exit the hole very safely and make a return journey. Your forward momentum relative to the center of mass of the Earth would make you bounce off the sides of the hole as you went down, creating rapid oscillations. You would also have to be elastic as you traveled through the hole so as not to get crushed hitting the sides.
Things would only get worse going the rest of the way as the oscillations would increase in frequency. When you exited the hole, you would be speeding at 930 meters per second or Mach 2.7. That would make for one heck of a trip.
Source: Hyperphysics, Physics Central
How far have humans gone to make that imaginary hole?