  We consider the AdS/dS CFT correspondence and study the nature of the thermal
bath of the de Sitter field theory using holography. Unlike the temperature of
a thermal field theory in flat spacetime, the temperature of a superconformal
field theory on de Sitter space is an integral part of the theory and leaves
intact the conformal symmetry and supersymmetry. In the dual AdS side, there is
no black hole. Instead we have cosmological expansion of the de Sitter factor.
We consider a number of different observables, such as the entanglement
entropy, two point correlation function, Wilson loops corresponding to static
and spinning mesons in the field theory, and study their thermal properties
using holography. The former two quantities have trivial temperature dependence
due to conformal symmetry. We compute the energy of the quark anti-quark bound
state for a static meson, as well as the energy and the angular momentum for a
spinning meson. We find that there is a maximum distance, as well as a maximum
spin for the latter case, beyond which the bound state become unstable. The
temperature behavior of the physical quantities in these meson systems are
similar to that of the usual thermal field theory with holographic black hole
dual. With these examples, we show clearly how the field theory observables get
their thermal properties from the bulk despite the absence of a black hole,
with the role of the black hole horizon played by the cosmological expansion of
the de Sitter factor of the AdS metric.
