Known as the oscillating universe hypotheses....
Terms like “eternal” and “beginning” are metaphysical terms..No human, as far as we know, was there to recount the beginning” and “eternity” can never occur cause there’s always just one more measurement of time...if no extra time, then there is no eternal. It’s then called “the end”
Is the best our science can come up with is this: “Nothing made Everything”?
IMHO
Freegards.
Reality and the universe is eternal.