Freeman Dyson explored the heat death of the universe in "infinite in all Directions": https://www.amazon.com/Infinite-All-Directions-Lectures-April-November/dp/0060728892 In chapter 6, he used an operational definition of life, which is organized systems using entropy to do work, and evaluated whether life could continue to exist in the universe at various stages in the heat death process.
His conclusion: life could exist at every stage of the universe he ran calculations on. However, not HUMAN life. He postulated that life could transform its fundamental substrate and matrix to other forms to continue to survive the universe's drop toward absolute zero. IE states like solid state supercooled zero loss systems on cold dark free planets using superconductivity to do their activities, or organized dust clouds in space changing their electric potential vs themselves thru rearrangement. These organized structural forms could survive billions and trillions of years after cellular organic life would not be viable.
