Now, what allows these fossilipids to actually move along that direction? Well, basically, as the fossilipid moves along the lateral direction those bonds between the water molecules and the polar heads remain. And likewise, the bonds between the jason hydrocarbon non polar tails also remain. And so there's really not too much energy that must be overcome as these phospholipids actually move along any given leaflet. But let's suppose, instead of moving along the lateral direction one of these phospholipids, let's say this one here wants to actually rotate and move from one side of the membrane from one leaflet to the other side of the membrane, that opposing leaflet. Will this actually take place.