Fig. 1.

Illustration of chemical composition (CC) space, where each point corresponds to the difference in concentration of all chemical species between a pixel in physical space, [X_i]_p, and its environment, [X_i]_e, weighted by the internal energy of that chemical species U_i. CC space has as many axes as there are chemical species, but just two axes are shown for illustrative purposes. The streaks depict the expected change in chemical compositions of a pixel in physical space as a consequence of chemical reactions occurring in the pixel, in the absence of noise or interactions with other pixels. The shaded areas correspond to the zones of attraction around three different metastable attractors, here interpreted as life states.