The term “decoupling” is used by cosmologists for separating the epochs of the universe between radiation dominated era and matter dominant, approximately 300000 years after the big bang or 1/50000 of the age of the present universe. Cosmic decoupling is then defined as the time that cosmologists effectively “look back to” when they are observing the CMBR (cosmic microwave background radiation). However, for more down to earth usage electrical engineers define it as the removal of any unwanted alternating current component from a circuit or circuit element. These unwanted components are sometimes caused by coupling between circuits, particularly those with a common power supply. Decoupling is usually achieved by using series inductance or parallel capacitance. The third new usage is the separation of a quantum field from its field quantum. Its domain values lie between 0 and 1 inclusively: 0 ≤ �� ≤ or [0,1] such that if ��=0 then the coupling is 1 and if ��=1 then the coupling is 0. This numerical normalization is analogous to the coupling constants of the fundamental forces of nature and also analogous to the domain of probability theory where zero indicates impossibility, while unity indicates possibility or certainty.

Since decoupling is the exact opposite of coupling, understanding the latter will help clarify the concept of the former. Two terms in physics with almost the same physical meaning are resonance and interaction. Therefore, coupling, resonance, and interaction all imply the transfer of energy from one system to another. Complete energy transfer is indicated by a coupling value of unity and zero coupling means no energy exchange. As it stands today in physics, there is no mechanism that can alter the near unity of quantum vacuum decoupling to zero, which will help initialize the corresponding cold fusion process for the following nuclear reaction: �� + �� ⟶ ���� + energy. This is the fusion of two deuteron nuclei producing one helium nucleus plus excess energy.