Exploring Gravity Trains, in MatLab

Many of us American children have probably wondered at some point in our lives if it would be possible to dig a hole to China: would we be able to actually travel through it to the other side of the planet?  While China is not on the exact opposite side of the Earth from us, this need not be only the musing of young children.  A way to travel through the Earth, instead of over it in the fashions we do now, would take advantage of the shortest direct route.

A gravity train is such a (theoretical) form of transportation, that takes advantage of the Earth's natural gravitational pull downward to accelerate into the planet, and that also takes advantage of that same pull to slow down on approach to the destination.  Ideally, the train would move through a frictionless environment, so that it doesn't have to provide its own thrust.  While such a means of transportation is very likely not feasible because of the amount of energy needed to maintain a several thousand kilometer-long vacuum tube (and electromagnetic rail for levitating, so on), we can still model how it would behave if it existed.

I'll walk through the equations governing the train's motion and how I attempted to model said motion using the math-based coding language MatLab, and also explore some possible density distributions for a given planet and how that affects the travel time for the train.

Student Loans - Democrats v. Republicans

Recently you may have heard in the news that the Senate has failed to pass a resolution that would stop subsidized Stafford student loan interest rates from doubling from 3.4% to 6.8%.  The sunset of the College Cost Reduction and Access Act, originally scheduled for this year but then moved forward a year (to 2012), and then extended back again to this year, came with the passing of July 1st while all of Congress was out of session for the holiday week.

And cue the mud-slinging: