This is the train through the core of the Earth that the movie Total Recall (2012), features. How is this supposed to work, the pressure at the core of the Earth is many, many times that at the surface and the temperature is 5430 °C, the temperature of the photo-sphere of the Sun. The outer core of the Earth is solid due to the immense pressure, it is a giant spinning core the size of Mars and made of iron, that is how we get our magnetic field that protects us from stellar radiation. How could they put a tunnel through the core if it is spinning? The inner core is about 1220 Kilometers in diameter and would be another obstacle to constructing our train tunnel since it is massively compressed and it is as hot as the Sun. What is the tunnel supposed to be made of? Unobtanium I suppose, but that old trope has no basis in reality, the tunnel would be facing seismic activity, the unimaginable pressures and the heat from underground. Everyone has seen National Geographic channel and the volcanoes spewing lava, that is a glimpse of what is underground.
How are they supposed to have built this in the first place, we can not even go 4 Kilometers underground without being uncomfortably hot, I can not imagine being 600 Kilometers down working on the tunnel. This concept is called a Gravity Train and has been investigated before, but no materials exist that could withstand the immense pressure. it is about 3,600,000 times the atmospheric pressure of the Earth at the core, possibly strong enough even in the mantle alone to crush Carbon into diamonds, therefore there is nothing in materials science we could build the tunnel out of that would withstand the conditions. What happened to the aircraft? Or the cruise ships?
Another good reference: http://www.math.purdue.edu/~eremenko/train.html
Another here: http://www.scientificamerican.com/article.cfm?id=would-you-fall-all-the-wa
If gravity is pulling from Australia to the center of the earth, wouldn’t it also be pulling from UK to the center? Once you get to the core wouldn’t you be stuck? I don’t understand how the gravity would push you up to the surface from the core. Anyway this is my problem with the concept. The added heat and pressure you are talking about is an another problem. Don’t think Id like to be stuck in the core.
There is no gravity at the core of the Earth; so nothing would grab you there; you would fly past.
Assuming you don’t lose any speed going through the hole due to air friction, you would gradually pick up speed until you’ve reached terminal velocity. Once you hit the middle, that’s when things get a little weird. Gravity hasn’t reversed but the direction has. Instead of falling down, your now being sling shot upward. Gravity is now pulling from the opposite direction you were traveling and slows you down until you’ve reached zero. Now unless you have something to catch you once you lose all your speed, you’ll just start the trip all over again. There’s a lot more you have to worry about as well but hopefully that clears it all up