THE SCIENTIFIC EXPLANATION OF TOUCHING FEET(CHARAN-SPARSH)

Usually, the person of whose feet you are touching is either old or pious.
When they accept your respect which came from your reduced ego (and is called your shraddha) their hearts emit positive thoughts and energy

(which is called their karuna) which reaches you through their hands and toes.
In essence, the completed circuit enables flow of energy and increases cosmic energy, switching on a quick connect between two minds and hearts.
To an extent, the same is achieved through handshakes

and hugs.
The nerves that start from our brain spread across all your body. These nerves or wires end in the fingertips of your hand and feet.
When you join the fingertips of your hand to those of their opposite feet, a circuit is immediately formed and the energies of two bodies

are connected.
Your fingers and palms become the 'receptor' of energy and the feet of other person become the 'giver' of energy.

Hare Krishna