Murray and Holman ran numerical simulations of the planets positions over a 200 million year period using their new technique. They discovered that although the outer planets appear in stable orbits, over longer time scales their classical ‘predicted’ orbit diverges from the simulations due to chaotic effects. One resonance is caused by interactions between Jupiter, Saturn, and Uranus. The second, weaker effect originates from the gravity wells of Saturn, Uranus, and Neptune. According to their calculations there is a 20 percent chance that the outer planets are now in a chaotic state.