The following is not a question: Can something come from nothing?

[Alex K]

See my reply to Cato: the opposite of water falling down is water being thrown upwards.

Your reply to Cato appears to be a false analogy. Yes, an object can go up if a sufficient outside force is applied to it. In the ball example, there is such an outside force. In the waterfall example, there isn't.

My point: why isn't there such a force? Because it is unlikely that the molecules in the water (which possess enough energy to do so) would conspire to exert such a force. This would correspond to a significant downward fluctuation of entropy, and is therefore unlikely. That's precisely how the arrow of time arises.

Compare this to an idealized bouncing ball bouncing and bouncing up and down on a surface without friction. Look at it backwards and it will be precisely the same process, because Entropy is constant.