The constancy of speed of light is crucial in metabology. It explains why we can distinguish between ontology, phenomenoloy and metabology (see hypertextual.net)
But now scientists deliver a surprising breaking news: the speed of light, one of the most sacrosanct of the universal physical constants, may have been lower as recently as two billion years ago - and not in some far corner of the universe, but right here on Earth !
A varying speed of light contradicts Einstein's theory of relativity, and would undermine much of traditional physics. But some physicists believe it would elegantly explain puzzling cosmological phenomena such as the nearly uniform temperature of the universe. It might also support string theories that predict extra spatial dimensions.