“A bird flies back and forth across the universe. Once every thousand years, it comes to sharpen its beak on a mountain which is one hundred miles long and one hundred miles high. When that mountain has been ground to sand, one second of eternity will have gone by.”
I’ve always been rather annoyed by this storicle—it plays out as if eternity is just a slowed-down version of…what really? Eternity is that which has no end, so if we were to say that the grinding-down of the mountain took a googol seconds of eternity it would be as true—there would still be exactly as much of eternity left.
And so, in what way is eternity different from the time we normally experience? Arguably we could imagine that in the far future of our expanding universe, it will become so dilute that there is no way even to count time and say that at this (fuzzy) point time has ended, and that our universe has had a finite existence. In this case we would need to posit some other universe which actually exists eternally. Had we this eternal universe we could subtract the lifetime of our universe from it, and there would still be as much left of eternity.
This may be because people really cannot comprehend something infinite, and assume there should still be an end stop even to eternity, just very far away. However, I am reminded of what Stanley Schmidt wrote on the subject once (“Finite cornucopias”, Analog Science Fiction/Science Fact, Feb 1986):
“The concept of infinity is deeply ingrained in the average layman’s mind at a very real, painfully practical level. Infinity is the amount of electricity in the wall socket, the amount of oil in Texas…”
So, by that count as well, the bird mountain story is pointless. Let us now forget it.