MemeMachineGo!

Perhaps you thought that one thing in this world you could count on was the constancy of the speed of light. Well, maybe not.

In science, no truth is forever, not even perhaps Einstein's theory of relativity, the pillar of modernity that gave us E=mc2.

As propounded by Einstein as an audaciously confident young patent clerk in 1905, relativity declares that the laws of physics, and in particular the speed of light — 186,000 miles per second — are the same no matter where you are or how fast you are moving.

[...] Guided by ambiguous signals from the heavens, and by the beauty of their equations, a few brave — or perhaps foolhardy — physicists now say that relativity may have limits and will someday have to be revised.

There was once an sf story about humanity dying out, and actually going quietly into that long night, and engaging in a massive project to make monoliths with collected human wisdom on them and distribute them throughout the solar system for the benefit of intelligent successors that would evolve. They're designed to be impervious to harm, unscratchable, to last millions of years.

And the story concludes with our hero seeing a beaver (I think it was) looking at one of the monoliths and proceeding to add graffiti with what looks like a sharp stick. As I recall, in response to E=mc^2, the beaver wrote "Sometimes."