  The emergence of a highly improbable coincidence in cosmological observations
speaks to a remarkably simple cosmic expansion. Compelling evidence now
suggests that the Universe's gravitational horizon, coincident with the better
known Hubble sphere, has a radius improbably equal to the distance light could
have travelled since the Big Bang. The confirmation of this unexpected result
would undoubtedly herald the influence of new physics, yet appears to be
unavoidable after a recent demonstration that the
Friedmann-Lemaitre-Robertson-Walker metric is valid only for the so-called zero
active mass equation of state. As it turns out, a cosmic fluid with this
property automatically produces the aforementioned equality, leaving little
room for a cosmological constant. The alternative---a dynamical dark
energy---would suggest an extension to the standard model of particle physics,
and a serious re-evaluation of the Universe's early history.
