  We report the existence of an Unruh like effect, for physical observers
(cosmological and comoving observers) in the radiation dominated early
universe, which is possible due to the discovery of a new vacuum state
(referred here as the $T-$vacuum). Both the comoving and the cosmological
observers, who are crucial in our understanding of cosmology, observe this
$T-$vacuum as a particle excited state and are able to detect radiation due to
particle creation. We draw a robust analogy with the Unruh effect, whereby --
(i) the physical observers here are closely analogous to the accelerated
(Rindler) observers in the flat spacetime, and (ii) the $T-$vacuum plays the
role of the Minkowski vacuum state which contains particles when viewed from
the physical observers frame. Our analogy is further supported by a proof of
well-defined (hadamard) behavior of the $T-$vacuum in the entire spacetime. All
our analysis of the particle creation process is done here within a two
dimensional set up.
