Does anybody have any thoughts about this idea? According to thermodynamics the law of conservation of momentum only applies to closed systems in which the amount of particles and their momentum is always constant because matter cannot be exchanged through its 'boundary' into the surroundings and only external forces can change the velocity of the objects in such a system. Can we safely assume then that the solar system is closed because the momentum of the planets and all that revolves around them together around the sun stays the same and neither do they travel further away enough from the center of mass to go outside the systems parameters or 'boundaries' or is some kind of inverted system where it is open and matter can enter it from outside but the matter inside cannot go out of its periphery? But if we think outside of closed systems and open ones like the planet earth, where external forces can act upon things in space (which will either accelerate or decelerate them) such as the whole universe which is isolated because a system with no outside environment certainly cannot interact beyond its boundary physically, then could there be any with so much potential energy that when converted into kinetic something could have so much velocity that even colliding with space matter would not ever slow down its momentum? They say the expanding universe is actually stretching like a rubber band, could this slingshot our world into motion forever despite otherwise influences?