[CraigS]

Hi Ray;
Its interesting …
As Steven said, huge volumes of gas, (with high entropy), pull together under gravitational attraction and form denser clumps. Further collapse then gives off large amounts of heat into the surrounds which, overall, offsets the resulting entropy of the well-ordered structures formed at the larger scales.

I think the classic example of this is a Black Hole, where as (almost) nothing can escape its event horizon, they are the icons of maximal entropy in our present universe (compared with anything else of the same size). They give out (virtually) no information about their state of disorder, thus they have the highest entropy. Gravity could thus be viewed as the most efficient generator of entropy in the known universe.

Extrapolating this further, the ultimate source of an ordered, low entropy state must therefore be the big bang itself. It must have been filled with a hot, low density, uniform gaseous mixture (of hydrogen and helium). Ever since everything we observe has been increasing in entropy (at the larger scales), but with gravity acting to form lower entropy structures at the smaller (local) scales. This then must have been what gave time its direction and has been continuing the same way ever since. (Increasing time => increasing disorder, increasing entropy).

I think the key to all this is the overwhelming proportion of observational evidence in favour of disorder at the larger scales. Disorder also is seen at the smaller scales too: ice cubes melt (they don't freeze), milk mixes with coffee (but doesn't unmix), we remember the past, but not the future and gold nuggets form. There's also an asymmetry in all of this which also adds weight to time's arrow.

Pretty logical stuff. Noteworthy for me, is that both disorder and order occur side-by-side, simultaneously, but at the largest scale, the overall effect is towards disorder (higher entropy).

Cheers