The present mainstream realizes that non-Fourier phenomena in heat transfer are arisen
from the time-delay in heat diffusion; however, in this paper we mathematically prove this
realization an untruth. The analysis is based on the construction of 2D transfer function for
the parabolic equation with time-delayed Laplacian that governs the assumed non-Fourier
heat transfer. There, functional representation of this spatio-temporal dynamics is performed
by the composite of Laplace transform and Galerkin projection. With 2D transfer
function, the heat-transfer dynamics is further represented by feedback interconnection
of thermal capacitance and time-delayed diffusion, which makes it possible for Nyquist
to perform stability and bifurcation analyses on this spatio-temporal dynamics. It comes
out that the heat-transfer dynamics under investigation is unstable no matter how small
the time-delay in heat diffusion is. That is, time-delayed heat diffusion contradicts the first
law of thermodynamics and thus cannot be observed. This paper continues to show that
the realization of thermal inertia by thermal inductance is supported by the principle of
electro-thermal analogy and compatible with experimental observations.