If space is literally expanding, then why is the distance from earth to sun not increasing?

As for entropy, I'd like to know something. If I have some food colouring, and put a droplet into a tub of water, we can expect to see the colouring spread out. Eventually it will be evenly distributed, it will be of equal concentration. When that point is reach, would it be possible (in theory, not practise) to use retroanalysis of the motion of the particles to determine exactly how much food colouring was added, when, from what height etc, or is all this information lost?

It seems to me that either a) eqilibrium is appraoched but never reached, or b) information is lost.

Where is the flaw in my thinking?