Here I remind the reader of the quantum-mechanical linear response theory (LRT),
as applied to a chaotic system.
LRT in electron transport is considered to originate with Kubo [122]
and Greenwood [84], and is often called the `Kubo formalism'
[99].
It has more recently been applied to dissipation in closed chaotic systems
[118,200,47,46].
As a primer,
I will start with a conventional presentation of
perturbation theory in a fixed basis.
Then, once stochastic energy-spreading is established, I link up with the
classical picture of Section 2.1.
In particular, my aim is to show the connection between heating rate
and a certain correlation spectrum
.
Finally, because the energy-spreading
picture differs markedly
from the language of LRT in the condensed matter literature,
I will make contact with the latter.
I hope this will provide a useful bridge to the unified picture
of Cohen[46].