A model-independent test of speed of light variability with cosmological
  observations
  A powerful test of fundamental physics consists on probing the variability of
fundamental constants in Nature. Although they have been measured on Earth
laboratories and in our Solar neighbourhood with extremely high precision, it
is crucial to carry out these tests at the distant Universe, as any significant
variation of these quantities would immediately hint at new physics. We perform
a cosmological measurement of the speed of light using the latest Type Ia
Supernova and cosmic chronometer observations at the redshift range $0<z<2$.
Our method relies on the numerical reconstruction of the data in order to
circumvent {\it a priori} assumptions of the underlying cosmology. We confirm
the constancy of the speed of light at such redshift range, reporting a $\sim
5$\% precision measurement of $c = (3.22 \pm 0.16) \; \mathrm{km \; s}^{-1}$ in
$z \simeq 1.60$ at a $1\sigma$ confidence level
