[AndrewC]

Speed of light may have changed recently

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

I never considered 2 billion years as recent.

[Colorado Doug]

I never considered 2 billion years as recent.

Agreed. A billion years here and a billion years there and pretty soon you are talking about a lota time.