Okay, I'm not a physicist/cosmologist, but I was wondering about the expansion of the universe. Current theories suggest that heat death is the ultimate fate of the universe. The energy of the universe becomes diffuse to the point of irrelevancy as time approaches infinity. This is due to the observed acceleration of the expansion of the universe. But as any kid who's been through intro physics can assert, there's more to kinematics than just velocity and acceleration. Is the rate of acceleration of the universe a constant, or is it too a variable? Could the acceleration itself be decreasing over time, leading to the scenario where the universe's acceleration becomes static (briefly leading to a dynamic equilibrium where the expansion of the universe is at a constant velocity) and subsequently begins to accelerate negatively, I.E. contract? I hope someone can clear this up for me.