http://www.foxnews.com/scitech/2010/07/17/paper-worlds-smoothest-roller-coaster-ride/

Using the same equations that describe how the planets orbit the sun, Hanno Essén of Sweden's Royal Institute of Technology in Stockholm drew a series of potential roller coaster loops that have one thing in common -- the force that riders would feel pushing their stomachs down into their seats stays exactly the same all the way around the loop.

I agree with Mr. Stengel's comment at the end of the article. Sounds pretty lame to me.