  The evolution equation for inhomogeneous and anisotropic temperature
fluctuation inside a medium is derived within the ambit of Boltzmann Transport
Equation (BTE) for a hot gas of massless particles. Also, specializing to a
situation created after heavy-ion collision (HIC), we analyze the Fourier space
variation of temperature fluctuation of the medium using its temperature
profile. The effect of viscosity on the variation of fluctuations in the latter
case is investigated and possible implications for early universe cosmology,
and its connection with HICs are also explored.
