I was just watching NextWorld on Discovery Channel. The subject was trains. There was this interesting concept of gravity trains. I tried to find the footage from TV, but I could only find it in Spanish. This video shows the same concept, so I used this one; >
Within 100 years or so :) In the beginning of this year i tried to explain this to my physics teacher, but he didn't understand...
No, he was unable to "understand" because this is not how physics works. And let's ignore for a second that a few 100 meters below surface, the temperature is already high enough to cook your passengers... Potential energy is determined by the distance of two physical bodies - start distance and end distance are equal, so the energy you gain by "rolling down" is fully consumed by the energy needed to "roll back to the surface" - which would be still neat free way to transport people: but only in a universe without friction... From the "gravity" PoV, you don't even have to spend energy when you travel by car from south africa to norway - because the distance to the gravity center (earth center) stays the same.... (well, roughly) In a universe w/o friction we could simply go by train, once accelerated to the maximum speed, the train would not consume energy anymore - so still no need to dig holes thru good ol' mother earth. (if you could stop revolving with earth, you could travel fro free, too... ;) ) ;)
