  Results from the RHIC and LHC experiments show, that in relativistic heavy
ion collisions, a new state of matter, a strongly interacting perfect fluid is
created. Accelerating, exact and explicit solutions of relativistic
hydrodynamics allow for a simple and natural description of this medium. A
finite rapidity distribution arises from these solutions, leading to an
advanced estimate of the initial energy density of high energy collisions.
These solutions can be utilized to describe various aspects of proton-proton
collisions, as originally suggested by Landau. We show that an advanced
estimate based on hydrodynamics yields an initial energy density in
$\sqrt{s}=7$ and 8 TeV p+p collisions at LHC on the same order as the critical
energy density from lattice QCD, and a corresponding initial temperature around
the critical temperature from QCD and the Hagedorn temperature. The
multiplicity dependence of the estimated initial energy density suggests that
in high multiplicity pp collisions at the LHC, there is large enough initial
energy density to create a non-hadronic perfect fluid.
