  Inspired by non-Hermitian physics, Li et al. (Science 364, 170-173)
theoretically predicted and experimentally demonstrated a stationary
temperature profile in a diffusive heat transfer system - seemingly indicating
that heat "stops" diffusing. By analogy to the wave physics framework, the
motionless and moving temperature profiles are manifestations of the
anti-parity-time APT symmetry and symmetry breaking states, respectively. Their
experimental setup consists of two thermally coupled rings rotating in the
opposite direction. At a particular rotation speed, known as the exceptional
point, the APT symmetry of the system changes, resulting in the temperature
profile switching between stationary and moving states. In fact, this seemingly
unusual and exotic behavior can be elegantly captured and predicted using a
conventional heat transfer framework with similarity and scaling analysis. In
this work, we show the system behavior can be characterized into three zones by
two widely-used dimensionless parameters on a regime map. The exceptional
point, discovered using wave physics, is located precisely on the zone boundary
on the regime map, indicating a balance between the contribution of thermal
coupling and mechanical motion. Furthermore, the observed cessation of thermal
diffusion is merely a result of the long diffusion time constant of the
experimental setup. The unfamiliarity of concepts in another scientific field
as well as the remarkable equivalence of the two points of view prompts this
in-depth discussion of the analogy between wave physics and heat transfer. We
believe that this work can help bridge the gap and promote new developments in
the two distinctly different disciplines.
