Comparing varying speed of light theories with cosmological data.
Varying constants theories have become well established alternative theories of gravity nowadays. In this talk we will focus on the “Varying speed of light” (VSL) theories, which have been long analyzed and debated in the last years, with multiple theoretical approaches but very few applications to observational data. We will follow two approaches. First, we will discuss a method we have developed aimed to measure the value of the speed of light at cosmological scales and at different epochs (redshifts), using multiple and independent data from galaxy surveys. Given the way it is built up, this method can unequivocally test the constancy of the speed of light on cosmological scales (up to some error depending on the architectural properties and the sensitivity of a given observational survey) and, thus, eventually confirm or reject VSL theories.” Second, we will discuss which kind of constraints are set up by present cosmological observations on VSL theories.