Three Concepts of Eternity

The most obvious meaning of eternity (if not the current pandemic) is one-damn-thing-after-another. I'll call this Eternity-1, one tick of an imperishable clock and then another ad infinitum. This makes sense in closeup, looking at moment such as death. But if we back off and keep on backing--and backing and backing up more and more--we begin to see why Aristotle doubted that actual infinities exist. Some concepts, of course, don't impose limits. The future, as far as we know, has no definite end-point, but time may not be endless. Infinite doesn't follow from indefinite . Suppose we define A as the age of the universe in years--over 13 billion--and run a chain of calculations. Let the square of A equal B, the square of B equal C, and so forth. Keep calculating, using A' after you reach Z, A'' after you reach Z', and so forth. Fill a million libraries the size of the solar system with books of calculations (nearly all containing nothing...