Editing Horizon problem (section)

==Variable-speed-of-light theories==
{{further|variable speed of light}}
Cosmological models employing a [[variable speed of light]] have been proposed to resolve the horizon problem of and provide an alternative to [[cosmic inflation]]. In the VSL models, the fundamental constant ''c'', denoting the [[speed of light]] in vacuum, is greater in the [[early universe]] than its present value, effectively increasing the particle horizon at the time of decoupling sufficiently to account for the observed isotropy of the CMB.