Can gravitational effects create a plane of the ecliptic? Lots of questions about the why of the plane of the ecliptic, and good answers, but I was wondering about gravitational effects.
If we picture for example, Saturn as being a few degrees above the plane, then Jupiter and Uranus being a few degrees below the plane, would the gravitational pull of each of these planets tend to pull them into the same plane after millions, perhaps billions of years?
 A: @Bill Alsept:  Yes gravity effects this. As the planets orbit the sun they wobble above and below the plane slightly, some more than others. The solar system does the same thing as it orbits our galaxy. I suppose like a pendulum these wobbles are diminishing.
The Rest of the Story:  A pendulum slows down because of friction and air resistance (neither of which exist in space, okay there are tidal forces but these are not responsible for defining the ecliptic).  So if the wobbles are indeed decreasing, where does the lost energy go?  The classical many body system exhibits both "clockwork-like" behavior (yielding planetary motion mostly confined to the ecliptic) as well as "chaotic behavior" (like small objects not confined to the ecliptic being occasionally tossed out of orbit or into the outer Oort cloud thereby absorbing the lost energy).  See: https://en.wikipedia.org/wiki/N-body_problem#History    Over millions/billions of years the many smaller non-ecliptic objects in the planetary regions may get ejected and the larger ecliptic-confined objects become even more "clockwork-like."  Occasionally these non-ecliptic objects return to the inner solar system as long period comets.
A: Purely gravitational effects: no, because they are conservative and symmetric.  The Kozai-Mechanism can cause the planes of the different individual orbits to vary their inclination --- but in a periodic way, oscillating above and below the ecliptic.
Gravity can contribute to forming an ecliptic if you add dissipative effects, like  gas-drag from a gaseous/debris disk, or tidal-dissipation.
A: Yes gravity effects this. As the planets orbit the sun they wobble above and below the plan slightly, some more than others. The solar system does the same thing as it orbits our galaxy. I suppose like a pendulum these wobbles are diminishing. 
