Figure 3. Mechanisms by which entropy can be increased by the stacking of two thylakoid membranes.

(a), areas of opposite charge approach each other in a Velcro effect, expelling pairs of counterions which then diffuse freely as individual ions. (b), loosely-bound water molecules are released from the inter-membrane gap when areas of opposite charge approach each other, thereby diffusing freely. (c), in an unstacking ionic medium, the electric field strength adjacent to the membrane surface is sufficient to align water dipoles, but is diminished on adding Mg²⁺ (details in Methods and Discussion); loss of alignment increases the orientational freedom of water dipoles.