I think Apas has something to do with "charge". Apas is the sap of life, characterised by diffusion and a first medium of permanent attractions and repulsions. This seems logical because Apas corresponds to taste (Rasa) which can be seen as the result of charge. The symmetry groups which give conservation laws of physics also need to be included somewhere. It is unclear if this might come under cohesion, which is Prithvi. Tattwa:Senses:Particle physics Akasha :Sound: Fields Vayu : Touch: Boson Agni : Sight : Radioactive decay, etc Apas : Taste: Charge Prithvi : Fermion (Pauli exclusion) This is as far as my Yogic intuition can go. Its going to take a real physicist to work the rest out ! Then we can claim that Sri Aurobindo in the LD gave the correct interpretation of Sankhya which matches particle physics as well.