According to our current understanding of physics, the concept of "heat death" or the "end of time" refers to a hypothetical state in the far future of the universe where the entropy (or disorder) reaches its maximum value and no further useful work can be extracted. In this state, the universe is at equilibrium, and the entropy remains constant rather than decreasing.
Entropy is a measure of the disorder or randomness in a system, and it tends to increase over time in isolated systems according to the second law of thermodynamics. However, in the context of the heat death scenario, the entropy has already reached its maximum value, and there is no further increase or decrease in entropy beyond that point.
In the heat death scenario, all the usable energy in the universe has been exhausted, and all systems have reached thermal equilibrium. At this stage, no further changes or processes can occur, and the universe essentially enters a state of stagnation.
It's important to note that our understanding of the far future of the universe and the specific details of the heat death scenario are still areas of active scientific research and subject to ongoing investigation and refinement. New discoveries or theories may lead to revisions in our understanding of the ultimate fate of the universe.