[Boiler Plate]

Can they replicate? Do they encode inforamtion and pass it on to future generations? Or do they in the absence of light return to their original state?

[ahayes]

I thought your question was regarding the Second Law and that your complaint was that light would inevitably degrade molecules. Why don't we stick with that for now?

Light is used by chemists to catalyze a wide variety of reactions that are thermally forbidden, and yes, most of these are irreversible. Previously these reactions used to be done just by setting the reaction flask in the windowsill or on the benchtop. Now we have apparatuses that produce the optimal frequences, but the principle is the same. Here is an example:

This is a nice example because it is an intermolecular reaction resulting in a product that is very highly functionalized.

"Photochemistry of Benzotriazole: An Unprecedented Tautomer-Selective Intermolecular [2+2] Photocycloaddition." Booker-Milburn, K.; Wood, P.; Dainty, R.; Urquhart, M.; White, A.; Lyon, H.; Charmant, J. Organic Letters, 2002, 4, 1487-1489.

Obviously then light can initiate such reactions and objections on Second Law grounds are not in keeping with reality.