-6 -3  0  3  6  0  0.5  1  1.5  2 (t) t IS fluid non-viscous fluid particular -2  0  2  4  6  0  0.1  0.2  0.3  0.4  0.5 q(t) t IS fluid non-viscous fluid particular Fig. 3: Left panel: bulk pressure Π depicted in dependence on t . At small t , Π jumps from negative to positive values. At larger t , Π vanishes as the case in the non-viscous fluid (dashed line). The bottom line gives Π according to first particular solution, Eq. (33). Right panel: deceleration parameter q is depicted with t . Straight and dotted lines represent non-viscous fluid and first particular solution, Eq. (34), respectively. Top curve represents second particular solution, Eq. (44). viscous fluid results in different a ( t )-behaviors with increasing t . At t = 0, a ( t ) remains finite. Correspondingly, H ( t ) remains also finite. In general, the dependence on t is much more complicated than in Eq. (46). Here we have an A/ P root of an exponential function. If exp( − Bt/ P ) >> A , a remains constant. Fig. 2 illustrates the dependence of the two thermodynamical quantities, ρ and T , on the comoving time. The non-viscous Universe shows a singular behavior in ρ at vanishing t , as shown in the left panel of Fig. 2. This is not obvious in the case where we have taken into consideration a finite viscosity coefficient, i.e., ρ is finite at t = 0. In both cases, ρ is decreasing with increasing t , reflecting that the Early Universe was likely expanding. Also the life time of the thermal viscous Universe seems to be shorter than for the non-viscous Universe. Almost the same behavior is observed in the right panel of Fig. 2. The temperature T seems to be finite at vanishing t in the viscous Universe. The T -singularity is only present, if we assume that the background matter is non-viscous ideal gas. In left panel of Fig. 3, we show the dependence of the bulk viscous pressure Π on t . Π takes negative values at very small t . Then it switches to positive values at some values of t . After reaching the maximum value, Π decays exponentially with increasing t . At larger t , Π entirely vanishes. The deceleration parameter q , given by Eq. (28), is depicted in the right panel of Fig. 3, and it is compared with q for a non-viscous fluid, q = − 3. 12