Made up of the minutest structures drawn from past impressions, samskaras and emotions, is the coded record of one's past deeds. It operates under the feedback of the law of action and reaction, cause and effect. The law of karma is immutable.
The karmic body is a most subtle body consisting of subatomic small particles [mass = 0 (zero), like photons etc.] in motion, which surround the soul more or less completely, limiting its influence on our awareness.
These most subtle particles are the result of materialisation processes caused by thoughts, spoken words, deeds and feelings in our actual and previous lifes. The existence of those karma particles are causing mentality, causing thoughts, causing words, causing deeds, causing feelings into the material world of our 5 sense organs.
On each step from cause to effect there are feedback loops leading back to the karmic particles and by "feeding" them, their potentiality (mass stays zero / energy level rises) gets amplifyed and their impact on our life increases.
This subtlest body always stays with the soul wandering from existence (life) to existence. It enables soul to materialise a new body according to the "virtual quality" of it's massless most subtle particles.
The karmic body is vibrating with our thoughts, emotions, resolutions and actions. [feedback circuit]
Connections (top to bottom]:
jiva, soul
- immaterial point, zero
karmic body
- massless particles
tejas body
- bio-electrical field
physical body
- bio-chemical molecules